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RENATO SEEBER

PROFESSORE FUORI RUOLO Esterno
Dipartimento di Scienze Chimiche e Geologiche sede ex-Chimica

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Pubblicazioni

2019 - A flexible platform of electrochemically functionalized carbon nanotubes for NADH sensors [Articolo su rivista]
Heras, A.; Vulcano, F.; Garoz-Ruiz, J.; Porcelli, N.; Terzi, F.; Colina, A.; Seeber, R.; Zanardi, C.
abstract

A flexible electrode system entirely constituted by single-walled carbon nanotubes (SWCNTs) has been proposed as the sensor platform for β-nicotinamide adenine dinucleotide (NADH) detection. The performance of the device, in terms of potential at which the electrochemical process takes place, significantly improves by electrochemical functionalization of the carbon-based material with a molecule possessing an o-hydroquinone residue, namely caffeic acid. Both the processes of SWCNT functionalization and NADH detection have been studied by combining electrochemical and spectroelectrochemical experiments, in order to achieve direct evidence of the electrode modification by the organic residues and to study the electrocatalytic activity of the resulting material in respect to functional groups present at the electrode/solution interface. Electrochemical measurements performed at the fixed potential of +0.30 V let us envision the possible use of the device as an amperometric sensor for NADH detection. Spectroelectrochemistry also demonstrates the effectiveness of the device in acting as a voltabsorptometric sensor for the detection of this same analyte by exploiting this different transduction mechanism, potentially less prone to the possible presence of interfering species.

2018 - Prediction of parameters related to grape ripening by multivariate calibration of voltammetric signals acquired by an electronic tongue [Articolo su rivista]
Pigani, Laura; VASILE SIMONE, Giuseppe; Foca, Giorgia; Ulrici, Alessandro; Masino, Francesca; Cubillana Aguilera, L.; Calvini, Rosalba; Seeber, Renato
abstract

An electronic tongue (ET) consisting of two voltammetric sensors, namely a poly-ethylendioxythiophene modified Pt electrode and a sonogel carbon electrode, has been developed aiming at monitoring grape ripening. To test the effectiveness of device and measurement procedures developed, samples of three varieties of grapes have been collected from veraison to harvest of the mature grape bunches. The derived musts have been then submitted to electrochemical investigation using Differential Pulse Voltammetry technique. At the same time, quantitative determination of specific analytical parameters for the evaluation of technological and phenolic maturity of each sample has been performed by means of conventional analytical techniques. After a preliminary inspection by principal component analysis, calibration models were calculated both by partial least squares (PLS) on the whole signals and by the interval partial least squares (iPLS) variable selection algorithm, in order to estimate physico-chemical parameters. Calibration models have been obtained both considering separately the signals of each sensor of the ET, and by proper fusion of the voltammetric data selected from the two sensors by iPLS. The latter procedure allowed us to check the possible complementarity of the information brought by the different electrodes. Good predictive models have been obtained for estimation of pH, total acidity, sugar content, and anthocyanins content. The application of the ET for fast evaluation of grape ripening and of most suitable harvesting time is proposed.

2018 - Synthesis, spectroscopic and electrochemical characterization of Co(II)-terpyridine based metallopolymer [Articolo su rivista]
Zanardi, C.; Zanfrognini, B.; Morandi, S.; Terzi, F.; Pigani, L.; Pasquali, L.; Seeber, R.
abstract

A new oligothienyl-based metallopolymer including Co(terpyridine)2complex units is synthesised by electrochemical oxidation of the relevant monomer. The chemical structure of the polymer chains and the electronic interaction between the organic portions and the metal centres are investigated by spectroscopic (X-rays photoelectron spectroscopy included), electrochemical, and spectroelectrochemical techniques. Thanks to the low potential of the Co(III)/Co(II) redox couple in the Co(terpyridine)2complex and to the presence of oligothienyl spacer, strong electron interaction between the organic backbone and the metal centres have been demonstrated.

2018 - Voltammetric behaviour of Cu alloys toward hydrogen peroxide and organic species [Articolo su rivista]
Ruggeri, Stefano; Miles, Emily; Poletti, Fabrizio; Pigani, Laura; Zanardi, Chiara; Zanfrognini, Barbara; Corsi, Elia; Dossi, Nicolò; Seeber, Renato; Terzi, Fabio
abstract

The communication reports on the electrocatalytic properties exhibited by five Cu alloys (Cu-Zn, Cu-Sn, Cu-Ni, Cu-Zn-Ni, Cu-Al) and of pure Cu, Ni and Al in the reduction or oxidation of a number of representative species. A prototypical strong oxidising agent, namely hydrogen peroxide, and some of the most important oxidisable species, namely methanol, ethanol, and formaldehyde, are tested. Both cathodic and anodic processes are facilitated by using specific alloys in the case of strong oxidants and different organic molecules, respectively.

2017 - Analog and digital worlds: Part 2. Fourier analysis in signals and data treatment [Articolo su rivista]
Seeber, Renato; Ulrici, Alessandro
abstract

The most direct scope of Fourier Transform (FT) is to give an alternative representation of a signal: from the original domain to the corresponding frequency domain. The original domain can be time, space or any other independent variable that can be used as the domain of the function. This subject has been treated in Part 1 [1]. In particular, the FT of a signal, also referred to as the frequency spectrum of a signal, has been used to calculate the lowest sampling frequency that provides a correct representation of the signal itself. At the beginning of this contribution, it is illustrated how to implement the so-called windowing process to periodic sequences. Then, the meaning of the operations denominated convolution and deconvolution is discussed. It is shown how FT provides a very effective path to the execution of these operations in the alternative domain by employing the convolution theorem. Finally, the application of convolution and deconvolution operations to experimental signals associated with the 'spontaneous' convolution of two concurrent events is analysed by different examples.

2017 - Electroanalytical determination of soluble Mn(II) species at high concentration levels [Articolo su rivista]
Ruggeri, Stefano; Terzi, Fabio; Zanfrognini, Barbara; Corsi, E.; Dossi, N.; Zanardi, Chiara; Pigani, Laura; Seeber, Renato
abstract

Glassy carbon electrodes have been successfully employed for the determination, by differential pulse voltammetry, of Mn(II) ions dissolved in aqueous solutions. In particular, a simple and fast procedure also suitable for on-line or at-line process control has been developed. Statistical analysis of the results obtained reveals that the procedure can be adopted in the range 0.59–57.30 mM Mn(II). The electrochemical responses are repeatable and reproducible. Repeatability is testified by the lack of variation of peak current values calculated from 20 subsequent scans carried out at the maximum explored concentration (relative standard deviation <1%). Reproducibility of the responses is supported by the data from the responses on three different electrodes. The proposed procedure does not require any pre-concentration of Mn species at the electrode surface or de-aeration of the solution. By adopting the developed procedure for the analysis, the GC electrode demonstrates to be suitable also for application in real matrices, namely solutions from spent battery recycling; in particular the results from the present electrochemical method are not significantly different from those obtained through inductively plasma coupled mass spectrometry. Interference from other metal species, such as Zn(II) and Fe(III), is negligible. This result is particularly meaningful, since the experimental conditions chosen, implying particularly high concentrations of heavy metals, are representative of those adopted in recovery and recycle processes of Mn species from batteries.

2017 - Synthesis and investigation on processing-depending polarized fluorescence emission in thin-films of 2,2′-([2,2′-bithiophene]-5,5′-diyl)bis(5-octyl-4-phenyl-4: H -thieno[2,3- c] pyrrol-6(5 H)-one) [Articolo su rivista]
Favaretto, L.; Zambianchi, M.; Lopez, S. G.; Mazzanti, A.; Zanardi, C.; Seeber, R.; Gentili, D.; Valle, F.; Benvenuti, E.; Muccini, M.; Ruani, G.; Mercuri, F.; Milita, S.; Liscio, F.; Cavallini, M.; Toffanin, S.; Melucci, M.
abstract

Thienopyrrole-dione (TI) end capped materials have recently emerged as polymorphic molecular semiconductors suitable as active layers of ambipolar light emitting transistors, photovoltaic cells and time temperature integrator devices. Here, we report the synthesis of a new derivative, namely 2,2′-([2,2′-bithiophene]-5,5′-diyl)bis(5-octyl-4-phenyl-4H-thieno[2,3-c]pyrrol-6(5H)-one) (R-NT4N), having monoreduced TI moiety (R-TI) end groups. Ring opening of the TI moiety by Grignard reagent addition followed by one-pot reduction/ring closure by triethylsilane afforded the R-TI precursor that was then exploited for the preparation of the target R-NT4N compound. Investigation of the fluorescence properties of thin films, as a function of the processing conditions, showed that different from all the other TI derivatives so far reported, R-NT4N exhibits linearly polarized fluorescent microstructures. Combined micro-Raman and confocal laser-scanning fluorescence microscopies on lithographically controlled wetting (LCW) patterned R-NT4N films allowed us to correlate the emission polarization directions with the microcrystal structures.

2017 - Systematic study of the correlation between surface chemistry, conductivity and electrocatalytic properties of graphene oxide nanosheets [Articolo su rivista]
Maccaferri, Giulio; Zanardi, Chiara; Xia, Zhen Yuan; Kovtun, Alessandro; Liscio, Andrea; Terzi, Fabio; Palermo, Vincenzo; Seeber, Renato
abstract

A main advantage of graphene oxide (GO) over other materials is the high tunability of its surface functional groups and of its electric conductivity. However, the complex chemical composition of GO renders difficult to unravel the correlation between structural and electric properties. Here, we use a combination of electron spectroscopy and electrochemistry to correlate the surface chemistry of GO to its electrical conductivity and electrocatalytic properties with respect to two molecules of high biological interest: β-nicotinamide adenine dinucleotide (NADH) and vitamin C. We demonstrate that the electrocatalytic properties of the material are due to hydroxyl, carbonyl and carboxyl groups residues that, even if already present on pristine GO, become electroactive only upon GO reduction. The results of this study demonstrate the advantages in the use of GO in amperometric biosensing and in enzymatic biofuel cells: it allows the oxidation of the target molecules at low potential values, with a sensitivity &gt;15 times higher with respect to standard, carbon-based electrode materials. Finally, we demonstrate that the right amount of chemical groups to achieve such high performance can be obtained also by direct electrochemical exfoliation of bulk graphite, without passing through GO production, thus rendering this approach suitable for cheap, large-scale applications.

2016 - A novel unsymmetrically substituted chiral amphiphilic perylene diimide: Synthesis, photophysical and electrochemical properties both in solution and solid state [Articolo su rivista]
Asir, Suleyman; Zanardi, Chiara; Seeber, Renato; Icil, Huriye
abstract

A novel unsymmetrically substituted chiral amphiphilic perylene diimide with two different quaternary stereocenters was synthesized. For comparison, symmetrically substituted chiral perylene diimide containing the same quaternary stereocenters was prepared. The dehydroabietylamine was specifically selected in order to minimize stacking properties and maximize solubility. Intermolecular interactions kept under control via l-lysine moiety. The specific optical rotation ([α]D20,alpha) of symmetrically and unsymmetrically substituted perylene dyes measured at 20 °C in chloroform as -105 and +200, respectively. Both of the compounds have excellent solubility in a wide range of organic solvents and symmetrically substituted chiral perylene diimide gives strong fluorescence emission (632 nm) in solid state. Concentration dependent self-aggregation of both compounds results in tunability of fluorescence emission. Compounds are thermally, photophysically and electrochemically stable.

2016 - Analog and digital worlds: Part 1. Signal sampling and Fourier Transform [Articolo su rivista]
Seeber, Renato; Ulrici, Alessandro
abstract

Proper data sampling of a continuously varying quantity that describes the proceeding of a natural process leads to a simpler equivalent representation. This representation consists of a sequence of discrete data, which is more suitable to be mathematically handled and allows one not to lose essential information provided by the original signal. The discrete values of the sequence obtained by sampling differ from one another by finite quantities. In the ideal case, the original representation should be perfectly reconstructed by a backward procedure. The rules that should be respected in order to satisfy this basic condition are very simple, but require the decomposition of the signal into a suitable set of elementary components. This may be performed by applying to the sequence the algorithm called Discrete Fourier Transform (DFT). The direct result of the transformation consists of the spectrum of the signal, which can be analysed in many ways. The mathematics to make the FT algorithm work, eventually in an as fast as possible way (FFT – Fast Fourier Transform) is perhaps of less interest to the chemists and will not be treated here. Rather, the aim is to address the reader about what FT allows to obtain.

2016 - Anthracene-based molecular emitters for non-doped deep-blue organic light emitting transistors [Articolo su rivista]
Zambianchi, M; Benvenuti, E.; Bettini, C.; Zanardi, Chiara; Seeber, Renato; Gentili, D.; Cavallini, M.; Muccini, M.; Biondo, V.; Soldano, C.; Generali, G.; Toffanin, S.; Melucci, M.
abstract

A new anthracene-based twisted oligomer combining a rigid anthracene-xylene core with diphenylamine ends 4,4′-(anthracene-9,10-diyl)bis(2,5-dimethyl-N,N-diphenylaniline), DiPAXA, is herein presented as an efficient and deep blue emitter material. By exploiting DiPAXA as an emissive layer and 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) as a p-type semiconducting layer, we realize a blue emitting unipolar light emitting transistor (OLET) with a maximum external quantum efficiency (EQE) of 0.13%, a charge mobility up to 0.32 cm2 V-1 s-1 and CIE color coordinates of (0.18, 0.21), i.e. closer to currently available standards (PAL, NTSC). Moreover, comparison with other anthracene-based blue emitters highlights the suitability of this family of twisted anthracene-xylene compounds for unipolar blue OLET applications as a result of the enhanced performances in terms of CIE coordinates and light emission output of newly synthesized DiPAXA.

2016 - Determination of polyphenol content and colour index in wines through PEDOT-modified electrodes [Articolo su rivista]
Pigani, Laura; Rioli, Cristina; Foca, Giorgia; Ulrici, Alessandro; Seeber, Renato; Terzi, Fabio; Zanardi, Chiara
abstract

Poly(3,4-ethylenedioxythiophene)-modified electrodes have been used for the estimation of the polyphenolic content and of the colour index of different samples of wines. Synthetic wine solutions, prepared with different amount of oenocyanins, have been analysed spectrophotometrically and electrochemically in order to find a correlation between the total polyphenolic content or colour index and the current peak. The regression curves obtained have been used as external calibration lines for the analysis of several commercial wines, ranging from white to dark red wines. In this way, a rapid estimation of the total polyphenolic content and of the colour index may be accomplished from a single voltammetric measurement. Furthermore, principal component analysis has also been used to evaluate the effect of total polyphenolic content and colour index on the whole voltammetric signals within a selected potential range, both for the synthetic solutions and for the commercial products.

2016 - Development of a redox polymer based on poly(2-hydroxyethyl methacrylate)for disposable amperometric sensors [Articolo su rivista]
Zanardi, Chiara; Pigani, Laura; Maccaferri, Giulio; DEGLI ESPOSTI, Micaela; Fabbri, Paola; Zannini, Paolo; Seeber, Renato
abstract

Membranes based on poly(2-hydroxyethyl methacrylate), chemically modified with ferrocene functionalities, are proposed as novel coatings for the development of disposable amperometric sensors. They are mass-produced on an inert support through an UV photo-induced polymerization, forming self-standing films that can be transferred on an electrode surface. Thanks to the characteristic of the functionalized methacrylate matrix to rapidly and reversibly swell by incorporation of large amounts of water, the ferrocene moieties are in intimate contact with the electrolytic solution. They can activate effective electrocatalytic processes that can be exploited in the field of amperometric sensing. The performance of the methacrylate coating with respect to the determination of hydroquinone benchmark analyte has been tested both in a static solution and in a flux cell.

2016 - Electrocatalytic and antifouling properties of CeO2-glassy carbon electrodes [Articolo su rivista]
Palacios Santander, J. M.; Terzi, Fabio; Zanardi, Chiara; Pigani, Laura; Cubillana Aguilera, L. M.; Naranjo Rodriguez, I.; Seeber, Renato
abstract

Binary metal oxides with different degrees of covalent/ionic character of the oxygen-metal bond are tested as a partial coating of glassy carbon electrode surfaces. The electrocatalytic and antifouling properties of the resulting bicomponent electrode systems are analysed in view of possible applications in different fields of electrochemistry, such as electroremediation and electroanalysis. Based on the performance with respect to oxidation of ascorbic acid, as to sensitivity, repeatability of the responses, and activation of electrocatalytic oxidation, CeO2 has been preferred. This same electrode system has been further studied in respect to a trickier electrochemical process, namely the anodic oxidation of a chlorophenol derivative, which induces massive passivation of bare electrode surfaces. The effectiveness of the bicomponent electrode system in anodic oxidation of 2,4,6-trichlorophenol has been ascertained, over a wide range of concentrations, by comparison with pure glassy carbon surfaces.

2016 - Electronic tongue and electronic eye for monitoring maturation level of grapes [Abstract in Atti di Convegno]
Pigani, L.; Vasile Simone, G.; Foca, G.; Ulrici, A.; Masino, F.; Seeber, R.
abstract

2016 - The inherent coupling of charge transfer and mass transport processes: the curious electrochemical reversibility [Articolo su rivista]
Seeber, Renato; Zanardi, Chiara; Inzelt, György
abstract

As a complement to a previous contribution from us, the mass transport mechanisms of the electroactive species to and from the electrode in an uncomplicated electrode mechanism are considered. The electrode process as a whole is discussed, with emphasis to its reversibility degree, as results from the relevant responses in controlled potential techniques, such as chronoamperometry and current sampling voltammetry, linear sweep and cyclic voltammetry, and in rotating disk voltammetry. The electrode process as a whole, composed by charge transfer and mass transport steps that concur to condition the current flowing, is analysed on the basis of the relative rates of the two steps, as well of the time window within which the process is observed. The so-called 'boundary value problem' for uncomplicated charge transfers with different reversibility degrees is outlined. Supplementary Material is available, in which the simulated concentration profiles for reduced and oxidised species reacting at an electrode, at which a triangular potential waveform is applied, are linked to the corresponding current densities.

2015 - Amperometric sensing. A melting pot for material, electrochemical, and analytical sciences [Articolo su rivista]
Seeber, Renato; Pigani, Laura; Terzi, Fabio; Zanardi, Chiara
abstract

The critical review discusses the key points of the main blocks leading to the development and use of an amperometric sensing system. On the one side, most attention is paid to the electrode materials that may potentially induce impressive progresses in the performance of the device. On the other side, comparable room is given to the remaining parts constituting the sensing system as a whole, from tests in different solutions to problems arising from data processing. All these steps require care and knowledge of the manifold branches of science and technology that concur to realise and use the device at best. However, some of these aspects are too often underestimated, also due to the different scientific origin of researchers or analysts who are directly involved. The discussion is centred on both the virtues of amperometric sensing systems and on the limits they present. The last are especially evidenced, in order to induce full consciousness of the complexity and interdisciplinary features of this kind of analytical tools. Exemplificative literature dealing with the issues dealt with is cited and critically inserted in the frame of the overall picture.

2015 - Carbon Black/Gold Nanoparticles Composite for Efficient Amperometric Sensors [Relazione in Atti di Convegno]
Zanardi, Chiara; Pigani, Laura; Seeber, Renato; Terzi, Fabio; Arduini, Fabiana; Cinti, Stefano; Moscone, Danila; Palleschi, Giuseppe
abstract

A screen-printed electrode (SPE) modified with a carbon black and Au nanoparticles bilayer was developed and proposed as an amperometric sensor for ascorbic acid quantification in pharmaceutical products and for dopamine estimation in the presence of large excess of ascorbic acid. Electrochemical investigations highlight the performances of the resulting modified electrode with respect to SPEs modified with a single component of the nano-composite.

2015 - Development of an Electrochemical Sensor for NADH Determination Based on a Caffeic Acid Redox Mediator Supported on Carbon Black [Articolo su rivista]
Zanardi, Chiara; Ferrari, Erika; Pigani, Laura; Arduini, Fabiana; Seeber, Renato
abstract

Screen-printed electrode (SPE) modified with carbon black nanoparticles (CB) has been tested as a new platform for the stable deposition of caffeic acid (CFA) on the electrode surface. The electrochemical performance from varying the amount of CFA/CB composite has been tested with respect to NADH determination. The electrocatalytic activity of CFA/CB has also been compared with that of SPEs modified by a single component of the coating, i.e., either CFA or CB. Finally, glycerol dehydrogenase, a typical NADH-dependent enzyme, was deposited on the CFA/CB coating in order to test the applicability of the sensor in glycerol determination.

2015 - Effective electrochemical sensor based on screen-printed electrodes modified with a carbon black - Au nanoparticles composite [Articolo su rivista]
Arduini, Fabiana; Zanardi, Chiara; Cinti, Stefano; Terzi, Fabio; Moscone, Danila; Palleschi, Giuseppe; Seeber, Renato
abstract

A screen-printed electrode (SPE) modified with a carbon black (CB)-Au nanoparticles (AuNPs) compositeis assembled and tested. Electrochemical and morphological investigations highlight the physico-chemical properties of the resulting AuNP-CB-SPE amperometric device with respect to SPEs modifiedwith a single component of the nanocomposite. The effective performance of such a modified elec-trode in activating electrocatalytic processes, consisting both in oxidation and reduction reactions, isdemonstrated. In particular, electrochemical tests on analytes such as glucose, hydrogen peroxide, hydro-quinone, and ascorbic acid, evidence that the composite possesses electrocatalytic performance wellsuperior with respect to the relevant mono-component modified SPE. As a consequence, a meaningfullowering of the peak potentials and improvement of the sensor sensitivities is observed when usingAuNP-CB-SPEs with respect to both CB-SPEs and AuNP-SPEs. In the case of H2O2reduction, the occur-rence of the electrochemical process at less negative potentials is coupled to an improvement of sensorsensitivity of about one order of magnitude. Concurrently, lower limit of detections, ranging from 20 to99% less, have been obtained for the major part of the analytes studied, i.e. glucose, hydrogen peroxideand hydroquinone. Preliminary results reported here indicate that AuNP-CB-SPE can be proposed as anefficient amperometric sensor to be used in many analytical applications.

2015 - Links between electrochemical thermodynamics and kinetics [Articolo su rivista]
Seeber, Renato; Zanardi, Chiara; Inzelt, György
abstract

Redox systems are considered when proceeding (a) in an electrochemical cell (heterogeneous reactions), and (b) in a single compartment (homogeneous reactions), also including the case of a solution in contact with solid phases. Special emphasis is given to the electrochemical systems. Starting from equilibrium states in the individual half-cells, the cell as a whole is (1) made to work spontaneously (batteries, fuel cells) and (2) forced to induce non-spontaneous transformations (electrolysis). Kinetics needs to be considered in both cases: phenomenological aspects and rigorous mathematic tools are intended to concur to draw the picture. Supplementary material is given in order to help visualise what the equations given express.

2015 - Ti metal electrode as an unconventional amperometric sensor for determination of Au(III) species [Articolo su rivista]
Terzi, Fabio; Zanfrognini, Barbara; Ruggeri, Stefano; Maccaferri, Giulio; Pigani, Laura; Zanardi, Chiara; Seeber, Renato
abstract

The control of the noble metal concentration is crucial in order to increase the efficiency of hydrometallurgic processes in mining and in the recovery of precious materials from electronic waste. The present study is devoted to the development of an effective procedure for the quantification of Au(III) species dissolved in aqueous solutions, similar real complex matrices included. In particular, a novel electrode system based on Ti has been studied. This electrode material is still poorly investigated in the framework of electroanalysis, despite its lack of sensitivity to common interfering species, such as oxygen; hence, the determination of metal species can be carried out without performing deaeration of the solution. In addition, the interfering effect due to the presence of other heavy metal ions, such as Ag, Fe and Pb, has been minimised by a proper choice of the conditions adopted for the amperometric measurements. Ti electrodes exhibit reproducible electrochemical responses, even in the presence of high concentration of organic fouling species typical of biosorption processes.

2014 - A Feature Selection Strategy for the Development of a New Drug Sensing SystemSensors [Relazione in Atti di Convegno]
Ulrici, Alessandro; Calderisi, Marco; Seeber, Renato; J., Uotila; A., Secchi; A. M., Fiorello; M., Dispenza
abstract

In order to efficiently detect four drug precursor molecules in presence of interfering species and background air, using a EC-QCLPAS sensor operating in the mid-infrared region, a complex strategy of spectral response simulation has been developed. In this context, spectra of gases from literature databases have been collected, denoised by means of the Wavelet Transform and mixed together according to a concentration matrix, which was specifically designed to represent a comprehensive combination of possible realistic cases. To scale database spectra to the appropriate concentration levels, an ad-hoc algorithm based on a sigmoidal transfer function has been used. In this way the baseline shape and intensity is preserved. Afterwards, a preliminary wavelength selection has been carried out to exclude noisy regions. The optimal range has finally been defined by maximizing the classification efficiency for all the target gases by means of Partial Least Squares-Discriminant Analysis.

2014 - Adsorptive-Stripping Voltammetry at PEDOT-Modified Electrodes. Determination of Epicatechin [Articolo su rivista]
Pigani, Laura; Seeber, Renato; Alessandro, Bedini; Enrico, Dalcanale; Michele, Suman
abstract

The food industry has a direct interest to bitter-tasting substances, either for the identification of negative off-flavors or for the monitoring of organoleptic quality. Polyphenols (such as catechins and epicathechins) are among the main molecular components responsible for the bitter taste of coffee/cocoa/chocolate-based products. The electrochemical detection of epicatechin through adsorptive stripping voltammetry on poly(3,4-ethylenedioxythiophene)-modified Pt electrodes has been investigated. The accumulation conditions were defined in order to record repeatable and reproducible electrochemical signals. Calibration plots were built in the 0.2-2.5 ppm concentration range of epicatechin in phosphate buffer solutions, pH 7. Preliminary tests in aqueous extraction solutions of biscuits containing different percentages of cocoa were performed; they confirmed, in principle, the effectiveness of the device and of the procedure proposed for the epicatechin determination by simple extraction from complex food matrices

2014 - Algorithms and strategies for extracting optimal information from chemical sensing systems [Relazione in Atti di Convegno]
Ulrici, Alessandro; Foca, Giorgia; Seeber, Renato
abstract

The output signals of chemical sensing systems, i.e. of sensors used to detect chemical quantities, typically consist of a complex superimposition of three different contributions: useful information, non relevant (but systematic) variations, and noise. For an efficient extraction of the highest possible amount of useful information, the application of multivariate methods is definitely more effective than commonly used univariate approaches. However, multivariate methods themselves could not allow the extraction of the whole information content of interest. The goal may be achieved by an efficient use of additional strategies, suitable to consider other aspects such as signal shape, time-evolution of a given sensor response or interactions among signals measured with different sensors. The performance of the sensor(s) is improved and the final output may consist of an optimized set of parameter values.

2014 - Amperometric Determination of Strong Oxidising Species Through Titanium Electrode Systems [Relazione in Atti di Convegno]
Terzi, Fabio; Zanfrognini, Barbara; Pelliciari, J.; Pigani, Laura; Zanardi, Chiara; Seeber, Renato
abstract

The amperometric determination of strong oxidising species has been carried out through an unusual electrode material, namely, Ti. In particular the study involves H2O2 and HClO, even at high concentration levels. A complex real matrix, such as an industrial detergent, containing high H 2O2 concentrations, has been taken as a meaningful study case to check the effectiveness of the electrode system and procedure proposed.

2014 - Controlled potential techniques in amperometric sensing [Capitolo/Saggio]
Ligia Maria, Moretto; Seeber, Renato
abstract

Basic thermodynamics and kinetics of electrochemical cells are given. An excursus on the main electrochemical techniques is made.

2014 - Determination of Polyphenols in Bakery Food Matrices with New Detection Methods [Relazione in Atti di Convegno]
Pigani, Laura; Seeber, Renato; Bedini, A.; Dalcanale, E.; Suman, M.
abstract

The food industry is continuously looking for reliable methods useful to standardize different control parameters and has a direct interest into bitter‐tasting substances, either for the identification of negative off‐flavors or for the monitoring of a desired organoleptic quality. The exploitation of dedicated panel tests for sensory purposes is useful, but it suffers from limitations related to subjectivity, reproducibility, and number of analysis per day (Profile Attribute Analysis). On the contrary, sophisticated analytical solutions, such as HPLC, need trained personnel and are often too expensive or time consuming. The target of the present research work is the development of alternative techniques potentially able to detect taste molecular markers in bakery commodities, with particular attention to polyphenol detection. In particular, two different analytical approaches were developed and compared to a reference LC-MS protocol in order to detect the polyphenol concentration inside real food matrices like biscuits: FT-NIR and electroanalytical methods.

2014 - Development of Nanostructured Electrode Coatings for Amperometric Sensors [Relazione in Atti di Convegno]
Terzi, Fabio; Pigani, Laura; Zanardi, Chiara; Zanfrognini, Barbara; Seeber, Renato
abstract

The goal of the communication is to illustrate the main advantages of the use of nanostructured materials as electrode modifiers in the frame of electroanalysis. Particularly meaningful examples extracted from the activity of the research group are discussed. The aim is to evidence the main properties of the single material and the synergic activity deriving from the combination of different materials in hybrids or composites electrode modifiers.

2014 - Electroanalytical applications of a graphite-Au nanoparticles composite included in a sonogel matrix [Articolo su rivista]
Crespo Rosa, Joaquin Raphael; Zanardi, Chiara; Elkaoutit, Mohammed; Terzi, Fabio; Seeber, Renato; Naranjo Rodriguez, Ignacio
abstract

A novel sonogel composite stably including graphite grains studded with Au nanoparticles (AuNPs) has been synthesised with the aim of obtaining an electrode characterised by electrocatalytic activity, reduced surface passivation and simple and reproducible surface renewal. The impregnation of graphite grains with pre-synthesised AuNPs constitutes a valid approach to stably fix a high amount of AuNPs in such an inorganic matrix. As verified by TEM images, AuNPs fixed on carbon grains surface maintain their individual nature, constituting the basic feature for exerting their electrocatalytic and antifouling properties at best. The electrode was characterised through morphological and electrochemical investigations, demonstrating the uniform distribution of AuNPs on the surface and at different depth of the bulk. Finally, electrochemical tests carried out on the cathodic reduction of H2O2 and on the anodic oxidation of glucose demonstrate the electrocatalytic activity of the AuNPs, the high repeatability of the responses obtained and the reproducibility of the electrode systems, simply restored by routine mechanical cleaning procedure. At variance with many non-enzymatic electrode systems developed for glucose determination, the sensor proposed is suitable for the determination of such a species even at the physiologic neutral pH.

2014 - Electrochemistry of Electroactive Materials [Articolo su rivista]
A., Robert Hillman; Peter, Pickup; Seeber, Renato; Magdalena, Skompska; Mikhail A., Vorotyntsev
abstract

non c'è

2014 - Functional Materials in Amperometric Sensing. Polymeric, Inorganic, and Nanocomposite Materials for Modified Electrodes Series: Monographs in Electrochemistry [Monografia/Trattato scientifico]
Seeber, Renato; Terzi, Fabio; Zanardi, Chiara
abstract

Amperometric sensors, biosensors included, particularly rely on suitable electrode materials. Progress in material science has led to a wide variety of options that are available today. For the first time, these novel functional electrode coating materials are reviewed in this monograph, written by and for electroanalytical chemists. This includes intrinsically conducting, redox and ion-exchange polymers, metal and carbon nanostructures, silica based materials. Monolayers and relatively thick films are considered. The authors critically discuss preparation methods, in addition to chemical and physical characteristics of these new materials. They present various examples of emerging applications in electroanalysis. Due to its comprehensive coverage, the book will become an indispensable source for researchers working on the development and even proper use of new amperometric sensor systems.

2014 - Novel electrode systems for amperometric sensing: the case of titanium [Relazione in Atti di Convegno]
Terzi, Fabio; Pigani, Laura; Zanardi, Chiara; Zanfrognini, Barbara; Ruggeri, Stefano; Maccaferri, Giulio; Seeber, Renato
abstract

fter working for years on organic materials, e.g., polythiophenes and relevant composites with metal nanoparticles, we shifted our attention to unusual metals, chosen as candidates to effective amperometric sensing on the basis of the atomic structure and crystalline properties. The present contribution aims at proposing an electrode material rarely employed in electroanalysis, namely Ti. We have experimented that the peculiar nature of Ti leads to electrochemical behavior quite different with respect to the conventional electrode materials, including those based on TiO2 (nano) particles. Our work focuses on the determination of strong oxidizing species, namely H2O2 and HClO, and noble metal ions, namely Au(III). Strong oxidizing species are commodity chemicals employed in a number of different industrial processes, in which usually high concentration levels should be monitored. The procedures proposed have been successfully applied also in complex matrices, such as detergent samples. As to Au(III) determination, it also constitutes a crucial tool in order to increase the efficiency of hydrometallurgic processes and of the recovery of precious materials from electronic waste. Ti electrodes allow the determination of dissolved Au species in the presence of other metal ions. In any cases the electrodes exhibit reproducible and repeatable electrochemical responses, even in the presence of high concentration of organic fouling species typical of bio-sorption processes.

2014 - Simulation of an experimental database of infrared spectra of complex gaseous mixtures for detecting specific substances. The case of drug precursors [Articolo su rivista]
Calderisi, Marco; Ulrici, Alessandro; Sauli, Sinisalo; Juho, Uotila; Seeber, Renato
abstract

This work is motivated by the need to develop suitable databases in absence of real experimental data, for instance when spectra measured with a newly developed instrumentation on real samples are not available yet. This notwithstanding, in fact, the realization of the physical project should be addressed by a starting database, also invaluable in order to test its effectiveness. In this article we face the issue of simulating gas mixtures spectra for the development of a new sensor for External Cavity-Quantum Cascade Laser Photoacoustic Spectroscopy (EC-QCLPAS) starting from literature FT-IR spectra of pure components: a dataset is realized suitable to realistically represent the ensemble of spectra of the gas mixtures of interest. The informative data deriving from the literature spectra were combined with the stochastic component extracted from a sample spectrum recorded with a prototype instrument, allowing us to build a matrix containing thousands of simulated spectra of gaseous mixtures, accounting for the presence of different components at different concentrations. Signal processing and experimental design techniques were used along the whole path leading to the dataset of simulated spectra. In particular, the goal of the construction of the database lies in the development of a final system to detect drug precursors in the vapour phase. The comparison of some EC-QCLPAS spectra with the corresponding simulated signals confirms the validity of the proposed approach.

2014 - Toward a Compact Instrument for Detecting Drug Precursors in Different EnvironmentsSensors [Relazione in Atti di Convegno]
Terzi, Fabio; Ulrici, Alessandro; Seeber, Renato; A., Secchi; A. M., Fiorello; M., Dispenza; J. C., Antolín; T., Kuusela; A., Varriale; S., D’Auria; I., Tittonen; F., Colao; I., Menicucci; M., Nuvoli; P., Ciambelli; V., Venditto; J., Uotila; G., Maisons; M., Carras
abstract

Law enforcement agencies world-wide are keenly aware that chemical control is a crucial element to monitor the manufacture and distribution of illegal narcotics and synthetic substances. For this purpose components able to perform chemical identifications in contexts such as custom offices are needed, where inspection of trucks, cars, containers, as well as people and baggage, is required. Such components should be assembled as simple machines to be employed on-field by custom officers with no specific skill. In the following the last results of the research project CUSTOM will be presented. The work has been supported by the European Commission under the 7th Framework Programme through the Project SEC-242387: "Drugs and Precursors Sensing by Complementing Low Cost Multiple Techniques" (CUSTOM).

2013 - Amperometric sensing — Bioelectroanalysis [Articolo su rivista]
Seeber, Renato; Wolfgang, Schuhmann; Terzi, Fabio; Zanardi, Chiara; Nicolas, Plumere; Magdalena, Gebala
abstract

This editorial introduces to a Special Issue of Analytical and Bioanalytical Chemsitry dedicated to Amperometric Sensing. The progresses made in this scientific field are introduced and critically discussed.

2013 - Behaviour of Ti electrode in the amperometric determination of high concentrations of strong oxidising species. [Articolo su rivista]
Terzi, Fabio; Pelliciari, Jonathan; Zanfrognini, Barbara; Pigani, Laura; Zanardi, Chiara; Seeber, Renato
abstract

The study of the capabilities of an unusual electrode material, namely, Ti, is presented: the amperometric determination of species showing responses that, on different materials, cannot be often profitably exploited, is proposed. H2O2 and HClO are successfully analysed, even at high concentrations. In similar conditions, which are quite common in industrial environments, these strong oxidising species are determined by time-consuming, off- or at-line, and multistep procedures. A complex real matrix, such as an industrial detergent, containing high H2O2 concentrations, has been taken as a meaningful study case to check the effectiveness of the electrode system and procedure proposed.

2013 - Development of a Sensor System for the Determination of Sanitary Quality of Grapes. [Articolo su rivista]
Zanardi, Chiara; Ferrari, Luca; Zanfrognini, Barbara; Pigani, Laura; Terzi, Fabio; Cattini, Stefano; Rovati, Luigi; Seeber, Renato
abstract

An instrument for the automatic quantification of glycerol in grapes has been developed. We verify here that this analyte can be taken as a benchmark of a serious disease affecting the grapevines, namely Botrytis cinerea. The core of the instrument is an amperometric biosensor consisting of a disposable screen printed electrode, generating the analytical signal thanks to a bi-enzymatic process involving glycerol dehydrogenase and diaphorase. The full automation of the analysis is realised by three micropumps and a microprocessor under control of a personal computer. The pumps allow the correct and constant dilution of the grape juice with a buffer solution also containing [Fe(CN)6]4- redox mediator and the injection of NAD+ cofactor when the baseline signal reaches a steady state; the instrument leads to automated reading of the analytical signal and the consequent data treatment. Although the analytical method is based on an amperometric technique that, owing to heavy matrix effects, usually requires an internal calibration, the analyses indicate that a unique external calibration is suitable for giving accurate responses for any grapes, both white and black ones.

2013 - Electropolymerization of ortho-phenylenediamine. Structural characterisation of the resulting polymer film and its interfacial capacitive behaviour [Articolo su rivista]
Vanossi, Davide; Pigani, Laura; Seeber, Renato; Paolo, Ferrarini; Baraldi, Pietro; Fontanesi, Claudio
abstract

The physico-chemical characteristics of thin poly-(orth o-phenylenediamine) (PPD) films, obtained by electrochemical oxidation of the relevant monomer, are investigated using electrochemical, morpholog-ical and spectroscopic techniques. In particular, cyclic voltammetry and electroche mical impedance spec-troscopy (EIS) techniques are used to collect information concerning the redox, conductivity and double layer capacitance properties of the PPD film. AFM imaging and Raman spectroscopy results are exploited to characterize the film structure. In this respect, Raman spectra of two possible PPD oligomers are cal-culated at the B3LYP/6-311G level of the theory.

2013 - Graphene-modified electrode. Determination of hydrogen peroxide at high concentrations. [Articolo su rivista]
Terzi, Fabio; Pelliciari, Jonathan; Zanardi, Chiara; Pigani, Laura; Antti, Viinikanoja; Jukka, Lukkari; Seeber, Renato
abstract

A gold electrode partially coated by graphene multilayer is developed and tested with respect to high concentrations of hydrogen peroxide. The effective use of conventional electrode materials for the determination of such an analyte by anodic oxidation or cathodic reduction is prevented by the occurrence of adsorptions fouling the electrode surface. This prevents reliable and repeatable voltammetric curves for being recorded and serious problems arise in quantitative analysis via amperometry. The gold–graphene electrode is shown to be effective in quantitative evaluation, by cathodic reduction, of hydrogen peroxide at concentration levels that are of interest in an industrial. Acid, neutral, and basic pH values have been tested through correct adjustment of a Britton Robinson buffer. The experiment s have been performed both by cyclic voltammetry and with amperometry at constant potential in unstirred solution. The latter technique has been employed in drawing a calibration linear plot. In particular, the performances of the developed electrode system have been compared with those of both pure gold and pure graphene electrode materials. The bi-component electrode was more sensitive; co-catalytic action by the combination of the two components is hypothesised. The system is stable over many potential cycles, as checked by surface-enhanced Raman spectra recorded over time.

2013 - György Inzelt, Andrzej Lewenstam and Fritz Scholz (Eds.): Handbook of reference electrodes [Articolo su rivista]
Seeber, Renato
abstract

Comments about a new book are made

2013 - Homoleptic Ru(II) complex with terpyridine ligands appended with terthiophene moieties. Synthesis, characterization and electropolymerization [Articolo su rivista]
Roberta, Scanu; Paola, Manca; Antonio, Zucca; Gavino, Sanna; Nadia, Spano; Seeber, Renato; Zanardi, Chiara; Maria I., Pilo
abstract

A new Ru(II) complex, [Ru(TTT)2][PF6]2 (TTT = 4’-[(2,2’:5’,2”-terthien-3’-yl)methoxy]-2,2’:6’,2”-terpyridine) has been synthesized and characterized by 1H NMR and UV-Vis spectroscopy and by cyclic voltammetry. The electrosynthesis of the corresponding conductive polymer, P[Ru(TTT)2], is reported, as well as its voltammetric and spectroelectrochemical characterization. The comparison between [Ru(TTT)2][PF6]2 and TTT voltammetric data shows that the presence of the metal ion makes easier the oxidation and the polymerization of the organic framework. On the other hand, UV-Vis data confirm that the presence of the –O-CH2-spacer between coordinating and polymerizing unit (terpyridine and terthiophene, respectively) reduces the electronic delocalization among these moieties, analogously to that observed in the TTT ligand alone. As far as P[Ru(TTT)2] is concerned, the voltammetric characterization evidences the so-called ‘charge-trapping phenomena, already observed also in PTTT, too. Moreover, spectroelectrochemical characterization shows a likely overlapping of the p-p* polymer and MLCT complex absorption bands, causing a bathocromic shift with respect to PTTT.

2013 - Polythiophenes and polythiophene-based composites in amperometric sensing [Articolo su rivista]
Zanardi, Chiara; Terzi, Fabio; Seeber, Renato
abstract

An overview of the polythiophene-based materials introduces the critical exam of meaningful examples of applications of similar electrode materials in electroanalysis. The advantages arising from the use of polythiophene derivatives in such an applicative context is discussed, by considering the organic conductive material as such, and as one of the components of hybrid materials. The rationale at the basis of the combination of two or even more individual components into a hybrid material is discussed with reference to the active electrode processes and to the consequent possible improvements of the electroanalytical performance. With this respect, study cases are presented, considering different analytes, chosen among those that are most frequently reported within the classes of organics and inorganics. The use of a polythiophene matrix to stably fix biological elements at the electrode surface, for the development of catalytic biosensors and genosensors, is also discussed. Finally, a few possible lines along which the next researches in the field could be fruitfully addressed, are outlined. On the other hand, the work still to do in order to exploit the possibilities offered by novel products of organic synthesis, even along paths already traced in other fields of electrochemistry, is invoked.

2013 - Studies of the interface of conducting polymers with inorganic surfaces [Articolo su rivista]
Terzi, Fabio; Pasquali, Luca; Seeber, Renato
abstract

Many of the properties of multi-material systems and relevant devices depend on the interfaces between the different components. This review focuses on characteriza- tion of the interfaces between intrinsically conducting poly- mers and inorganic materials consisting of metals and metal oxides. These materials are chosen because of their impor- tance in several analytical applications. Although use of conducting polymers and metals or metal oxides in analyt- ical systems, specifically in sensing, is well established, the number of novel materials used for analytical purposes is continuously increasing. This further increases the possible number of effective combinations of different materials within multicomponent systems. As a consequence, innova- tive characterization techniques have become as important as more conventional techniques. On the other hand, sophis- ticated characterisation techniques are increasingly wide- spread and, consequently, also readily accessible. This critical review is not an exhaustive discussion of all possible analytical techniques suitable for characterization of interfaces. It is, instead, limited to an overview of the most effective, relatively widespread techniques, emphasising their most significant recent advances. Critical analysis of the individual techniques is complemented by a few selected examples.

2012 - A feature selection strategy for the analysis of spectra from a photoacoustic sensing system [Relazione in Atti di Convegno]
Ulrici, Alessandro; Seeber, Renato; Calderisi, Marco; Foca, Giorgia; Juho, Uotila; Mathieu, Carras; Anna Maria, Fiorello
abstract

In the frame of the EU project CUSTOM, a new sensor system for the detection of drug precursors in gaseous samples is being developed, which also includes an External Cavity-Quantum Cascade Laser Photo Acoustic Sensor (ECQCLPAS). In order to define the characteristics of the laser source, the optimal wavenumbers within the most effective 200 cm -1 range in the mid-infrared region must be identified, in order to lead to optimal detection of the drug precursor molecules in presence of interfering species and of variable composition of the surrounding atmosphere. To this aim, based on simulations made with FT-IR spectra taken from literature, a complex multivariate analysis strategy has been developed to select the optimal wavenumbers. Firstly, the synergistic use of Experimental Design and of Signal Processing techniques led to a dataset of 5000 simulated spectra of mixtures of 33 different gases (including the 4 target molecules). After a preselection, devoted to disregard noisy regions due to small interfering molecules, the simulated mixtures were then used to select the optimal wavenumber range, by maximizing the classification efficiency, as estimated by Partial Least Squares - Discriminant Analysis. A moving window 200 cm -1 wide was used for this purpose. Finally, the optimal wavenumber values were identified within the selected range, using a feature selection approach based on Genetic Algorithms and on resampling. The work made will be relatively easily turned to the spectra actually recorded with the newly developed EC-QCLPAS instrument. Furthermore, the proposed approach allows progressive adaptation of the spectral dataset to real situations, even accounting for specific, different environments.

2012 - Development of a gold-nanostructured surface for amperometric genosensors [Articolo su rivista]
Zanardi, Chiara; Bandoli, Clara; Lisandro, Emanuela; Terzi, Fabio; Seeber, Renato
abstract

A gold nanostructured surface has been obtained by stable deposition of chemically synthesized gold nanoparticles on a gold substrate, through a dithiol linker. The method proposed for the obtainment of the nanostructure results suitable for the further stable anchoring of peptide nucleic acids (PNA) through four amines from lysine terminal residues, leading to fairly reproducible systems. The geometric area of the nanostructured surface is compared with those of a smooth and of an electrochemical generated nanostructured surface, by depositing a probe bearing an electrochemically active ferrocene residue. Despite the area of the two nanostructures results quite similar, the response toward 2 nM target oligonucleotide sequence is particularly high when using the surface built up by nanoparticles deposition. This aspect indicates that morphologic details of the nanostructure play a key role in conditioning the performances of the genosensors.

2012 - Drugs and precursor sensing by complementing low cost multiple techniques: overview of the European FP7 project CUSTOM [Relazione in Atti di Convegno]
Alberto, Secchi; Anna Maria, Fiorello; Massimiliano, Dispenza; Sabato, D'Auria; Antonio, Varriale; Ulrici, Alessandro; Seeber, Renato; Juho, Uotila; Vincenzo, Venditto; Paolo, Ciambelli; Juan Carlos, Antolín; Francesco, Colao; Tom, Kuusela; Ilkka, Tittonen; Päivi, Sievilä; Grégory, Maisons
abstract

A large number of techniques for drug precursors chemical sensing has been developed in the latest decades. These techniques are able to screen and identify specific molecules even at very low concentration in lab environment, nevertheless the objective to build up a system which proves to be easy to use, compact, able to provide screening over a large number of compounds and discriminate them with low false alarm rate (FA) and high probability of detection (POD) is still an open issue. The project CUSTOM, funded by the European Commission within the FP7, deals with stand alone portable sensing apparatus based on multiple techniques, integrated in a complex system with a complimentary approach. The objective of the project is to achieve an optimum trade-off between opposite requirements: compactness, simplicity, low cost, sensitivity, low false alarm rate and selectivity. The final goal is the realization of an optical sensing platform able to detect traces of drug precursors compounds, such as ephedrine, safrole, acetic anhydride and the Benzyl Methyl Keton (BMK). This is reached by implementing two main sensing techniques: the fluorescence enhanced by the use of specially developed Organic macro-molecules, and a spectroscopic technique in Mid-IR optical range. The fluorescence is highly selectivewith respect to the target compounds, because it is based on properly engineered fluorescent proteins which are able to bind the target analytes, as it happens in an 'immune-type' reaction. The spectroscopic technique is based on the Photo-Acoustic effect, enhanced by the use of a widely Tunable Quantum Cascade Laser. Finally, the sensing platform is equipped with an air sampling system including a pre-concentrator module based on a sorption desorption cycles of a syndiotactic polystyrene polymer.

2012 - Electroreduction of chloramines through novel electrode materials [Articolo su rivista]
Terzi, Fabio; Zanfrognini, Barbara; Zanardi, Chiara; Pigani, Laura; Seeber, Renato
abstract

Novel electrode materials have been developed and applied to the determination of chloramines by amperometric methods. In particular, a thin layer of a conducting polymer, namely poly(3,4-ethylenedioxythiophene) (PEDOT) has been tested for the first time in the presence of chloramines. Significant improvements in the performance of the modified electrodes are obtained by using composite materials based on differently encapsulated Au nanoparti-cles and PEDOT. The resulting electrode system exhibits repeatability and reproducibility of the voltammetric re-sponses, as well as low limit of detection and high sensitivity in the determination of monochloramine, as testified by the cyclic voltammetric curves and the calibration plots obtained by a rotating disk electrode.

2012 - Experimental design-based strategy for the simulation of complex gaseous mixture spectra to detect drug precursorsOptical Materials and Biomaterials in Security and Defence Systems Technology IX [Relazione in Atti di Convegno]
Calderisi, Marco; Ulrici, Alessandro; Pigani, Laura; Alberto, Secchi; Seeber, Renato
abstract

In the frame of the EU project CUSTOM, a new sensor system for the detection of drug precursors in gaseous samples is being developed, which also includes an External Cavity-Quantum Cascade Laser Photo Acoustic Sensor (ECQCLPAS). In order to define the characteristics of the laser source, the optimal wavenumbers within the most effective 200 cm-1 range in the mid-infrared region must be identified, in order to lead to optimal detection of the drug precursor molecules in presence of interfering species and of variable composition of the surrounding atmosphere. To this aim, based on simulations made with FT-IR spectra taken from literature, a complex multivariate analysis strategy has been developed to select the optimal wavenumbers. Firstly, the synergistic use of Experimental Design and of Signal Processing techniques led to a dataset of 5000 simulated spectra of mixtures of 33 different gases (including the 4 target molecules). After a preselection, devoted to disregard noisy regions due to small interfering molecules, the simulated mixtures were then used to select the optimal wavenumber range, by maximizing the classification efficiency, as estimated by Partial Least Squares – Discriminant Analysis. A moving window 200 cm<sup>-1</sup> wide was used for this purpose. Finally, the optimal wavenumber values were identified within the selected range, using a feature selection approach based on Genetic Algorithms and on resampling. The work made will be relatively easily turned to the spectra actually recorded with the newly developed EC-QCLPAS instrument. Furthermore, the proposed approach allows progressive adaptation of the spectral dataset to real situations, even accounting for specific, different environments.

2012 - PEDOT modified microelectrodes. Preparation, characterisation and analytical performances [Articolo su rivista]
Pigani, Laura; Zanfrognini, Barbara; Seeber, Renato
abstract

Poly(3,4-ethylenedioxythiophene) (PEDOT) modified microelectrodes were prepared by electropolymerisation of therelevant monomer from CH3CN and H2O solutions. The electrochemical behaviour of the obtained coatings wasinvestigated by cyclic voltammetry in both organic and aqueous media. The anodic responses obtained for a typicalbenchmark analyte such as ascorbic acid have been chosen in order to test the different coatings; calibration curves havebeen built up in order to evaluate the repeatability of the response and reproducibility of the realised sensing system.Moreover, the ability of the modified microelectrodes to work in low conductivity media has been studied, and exploratorytests in dense food matrix have been performed

2012 - Peptide Nucleic Acids tagged with four lysine residues for amperometric genosensors [Articolo su rivista]
Zanardi, Chiara; Terzi, Fabio; Seeber, Renato; Bandoli, Clara; Lisandro, Emanuela; Majorana, Stefano
abstract

A homothymine PNA decamer bearing four lysine residues has been synthesized as a probe for the development of amperometric sensors. The four amino groups introduced, on one hand make this derivative nine times more soluble than the corresponding homothymine PNA decamer and, on the other hand, allow the stable anchoring of this molecule on Au nanostructured surface through the terminal –NH2 moieties. In particular, XPS and electrochemical investigations carried out with hexylamine, as a model molecule, indicate that the stable deposition of primary amine derivatives on such a nanostructured surface is possible and involves the free electron doublet on the nitrogen atom. This finding indicates that this PNA derivative is suitable to act as the probe molecule for the development of amperometric sensors.Thanks to the molecular probe chosen and to the use of a nanostructured surface as the substrate for the sensor assembly, the device proposed makes possible the selective recognition of the target oligonucleotide sequence with very high sensitivity.

2012 - Photoemission and X-Ray Absorption Study of the Interface between 3,4-Ethylenedioxythiophene Related Derivatives and Gold [Articolo su rivista]
Pasquali, Luca; Terzi, Fabio; B., Doyle; Seeber, Renato
abstract

The chemisorption of 3,4-ethylenedioxythiophene (EDOT) derivatives on Au(111) single crystal and polycrystalline surfacesis studied with valence band photoemission and near edge x-ray absorption (NEXAFS). Different EDOT derived molecules are considered, namely EDOT, its dimer (bi-EDOT), 3’,4’-ethylenedioxy-2,2’:5’,2’’-terthiophene (TET) and the relevant electro-generated polymer, PEDOT, at different stages of substrate coverage. The interpretation of the spectra is carried out comparing with the DFT calculations of the densities of states of different possible reaction products that can be formed at the interface. Simulation of the NEXAFS spectrum of EDOT and comparison with literature work on thiophene and ologothiophene films are used for the interpretation of the X-ray absorption spectra of bi-EDOT and PEDOT as a function of the electro-polymerization time. Valence band features that are associated to EDOT products are identified together with new structures that are ascribed to reactive dissociation products at the interface. In particular the presence of thiophene/oligothiophene molecules is observed, together with possible alkyl chains. NEXAFS indicates that the thiophene rings tend to adopt a planar configuration at the interface.

2011 - A UV-Visible /Raman spectroelectrochemical study of the stability of poly(3,4-ethylendioxythiophene) films [Articolo su rivista]
Zanfrognini, Barbara; A., Colina; A., Heras; Zanardi, Chiara; Seeber, Renato; J., López Palacios
abstract

Poly(3,4-ethylendioxythiophene) films were electropolymerized in aqueous medium without using any surfactant, on glassy carbon electrodes. UV/Vis and Raman spectroelectrochemical techniques were used to analyze the degradation of the polymer film occurring at different pH values. Spectroelectrochemistry has proven to be a very useful analytical tool for this purpose, thanks to its ability to provide information not only about the extent of degradation, but also about mechanistic aspects of t he process. From our results we extracted important information about the main factors that play a role in the degradation, inparticular about the influence of repetitive doping and de-doping cycles and of photo-induced processes, as a function of the characteristics of the solution, i.e. of pH

2011 - Au/Pt nanoparticle systems in methanol and carbon monoxide electroxidation [Articolo su rivista]
Terzi, Fabio; Zanardi, Chiara; Sergio, Daolio; Monica, Fabrizio; Seeber, Renato
abstract

Different Au/Pt bimetallic systems have been synthesised by following the approach suggested by Brust. The nanoparticles have been anchored to glassy carbon surface through a place-exchange reaction involving dithiol molecules. The resulting modified electrode consists of heterogeneous nanostructured Au and Pt patchwork. The different nanoparticles systems developed have been employed for the electroxidation of methanol and carbon monoxide in alkaline aqueous media. The results show that the electrocatalytic activity of the bimetallic systems is enhanced with respect to the single monometallic NP systems.

2011 - Composite PEDOT/Au Nanoparticles Modified Electrodes for Determination of Mercury at Trace Levels by Anodic Stripping Voltammetry [Articolo su rivista]
Marco, Giannetto; Francesca, Amico; Giovanni, Mori; Terzi, Fabio; Zanardi, Chiara; Seeber, Renato
abstract

Electrode modifications consisting of poly(3,4-ethylenedioxythiophene) (PEDOT), including gold nanoparticles according to simple though innovative procedure, are developed. The resulting nanocomposite shows interesting performances as electrode material for determination of mercury by anodic stripping technique, even down to concentration levels as low as 0.46 ng/ml. The analytical performance is evaluated by optimized experimental parameters such as the charge spent during the potentiostatic electrodeposition of PEDOT, the preconcentration time, and the waveform parameters for the Differential Pulse Voltammetry (DPV) redissolution scan. No evidence of significant oxidative degradation of the polymer over repeated analysis cycles is evidenced

2011 - Layer-by-layer deposition of a polythiophene/Au nanoparticles multilayer with effective electrochemical properties [Articolo su rivista]
Zanfrognini, Barbara; Zanardi, Chiara; Terzi, Fabio; T., Aaritalo; A., Viinikanoja; J., Lukkari; Seeber, Renato
abstract

Multilayers consisting of a water soluble polythiophene derivative and Au nanoparticles have been deposited onto different electrode substrates by means of layer-by-layer deposition technique. The assembly of the films has been performed by taking advantage of the electrostatic interactions between the positively charged imidazolic moiety of the polythiophene chain and the negative charges of citrate ions surrounding Au nanoparticles, as well of the affinity of S to Au. The nanoparticles result stably grafted to the organic matrix. The resulting modified electrodes have been characterised through electrochemical, spectroelectrochemical and microscopic techniques. The results evidenced that a high number of individual nanoparticles is present inside the multilayer. The presence of nanoparticles is of chief importance for most effective charge percolation through the multilayer, as suggested by the responses to electroactive probe species in solution. The electrocatalytic performances of the modified electrodes have been tested with respect to the oxidation of ascorbic acid.

2011 - New Insights on the Interaction between Thiophene Derivatives and Au Surfaces. The Case of 3,4-Ethylenedioxythiophene and the Relevant Polymer [Articolo su rivista]
Terzi, Fabio; Pasquali, Luca; Montecchi, Monica; Nannarone, Stefano; A., Viinikanoja; T., Aaritalo; M., Salomaki; J., Lukkari; B. P., Doyle; Seeber, Renato
abstract

The nature of the interface between electrogen-erated poly(3,4-ethylenedioxythiophene) and the Au substrateis studied in detail. In particular, the adsorption of the relevantmonomer, namely, 3,4-ethylenedioxythiophene, is investigatedand compared with that of other thiophene derivatives. Di!er-ent deposition procedures have been adopted: very thin "lms ofthe thiophene derivatives have been obtained through chemi-sorption processes from vapor and liquid phases, on Au poly-crystalline substrates, Au nanoparticles possessing di!erent size,and a Au(111) single crystal. Di!erent techniques, operatingboth in situ and ex situ, have been employed for the characterization of these deposits, that is, X-ray photoemission and surface- enhanced Raman spectroscopy. The results show that the poly(3,4-ethylenedioxythiophene)/metal interface is far from being simply constituted by unreacted molecules in contact with the substrate; rather, the formation of oligothiophene species and sulfur atoms at the interface has been ascertained.

2011 - PEDOT modified electrodes in amperometric sensing for analysis of red wine samples [Articolo su rivista]
Pigani, Laura; A., Culetu; Ulrici, Alessandro; Foca, Giorgia; M., Vignali; Seeber, Renato
abstract

A poly(3,4-ethylendioxythiophene) modified electrode has been considered as a potentially useful amperometric sensor to use either alone or in the frame of a set of sensors bearing complementary information, i.e. within an electronic tongue. The sensor is proposed in blind analysis of red wines, for classificationand calibration purposes. The data obtained from voltammetric measurements have been treated using partial least squares analysis. A calibration procedure has been performed to correlate results from analyses of wines, executed with traditional analytical methods, with the corresponding voltammetricresponses. Moreover, classification models of the wine samples, based on quantitative parameters and qualitative information about origin and variety, have been built. The developed electrochemical sensor also allows the fast identification of samples exceeding threshold limits of meaningful parameters forquality control in the wine industry, such as SO2, colour intensity and total polyphenols. The application of the system within a sensor array (electronic tongue) to fast pre-screening routine control procedure is proposed.

2011 - Poly(3,4-ethylenedioxythiophene)/Au-nanoparticles composite as electrode coating suitable for electrocatalytic oxidation [Articolo su rivista]
Terzi, Fabio; Zanfrognini, Barbara; Zanardi, Chiara; Pigani, Laura; Seeber, Renato
abstract

Composite materials consisting of poly(3,4-ethylenedioxythiophene) including Au nanoparticles, encapsulated by citrate anions, have been firmly deposited on an electrode surface through a simple method, taking advantage of the interaction between Au metal and thiophene polymeric backbone. A series of similar electrode coatings, also including different amounts of nanoparticles inside, has been characterised in terms of thickness and surface morphology, through different microscopic techniques. The electrocatalytic properties have been studied with respect to the oxidation of glucose in alkaline media,which is prevented from occurring on the pure organic material.

2011 - The evolution of amperometric sensing from the bare to the modified electrode systems [Articolo su rivista]
Seeber, Renato; Terzi, Fabio
abstract

The article aims at giving a critical overview ofthe passage from bare to modified electrode systems,proposed for amperometric sensing. An introduction ismade with reference to the development of modifiedelectrodes since the beginning, i.e. from the 1970s. Asubsequent time border is arbitrarily identified around themiddle of 1990s. Since those years, many novelties, comingin part from chemistry and in big part from physics andengineering, induced deep changes in the approach to theelectroanalytical research; they are tentatively outlined. Theterm “research” is intentionally used to underline that wideroom is still available to applications, waiting for efforts byelectrochemists. It is also emphasised that the nature of themodifying systems has been only occasionally tailor-made,i.e. designed and developed on purpose. A strict enoughconnection between the electrochemists and the chemistsexpert in synthesis has been and still is often scarce. Thisnotwithstanding, the number of novel potentially interestingmaterials suitable to develop electroanalytical systemshighly effective in applications is so high that the nextfuture of electroanalysis seems definitely promising. A briefcritical analysis of electrode systems based on similarmaterials is made.

2011 - UPS, XPS, and NEXAFS Study of Self-Assembly of Standing 1,4 Benzenedimethanethiol SAMs on Gold [Articolo su rivista]
PASQUALI, Luca; TERZI, Fabio; SEEBER, Renato; NANNARONE, Stefano; D., Datta; C., Dablemont; H., Hamoudi; M., Canepa; V. A., Esaulov
abstract

We report a study of the self-assembly of 1,4-benzenedimethanethiol monolayers on gold formed in n-hexane solution held at 60 °C for 30 min and in dark conditions. The valence band characteristics, the thickness of the layer, and the orientation of the molecules were analyzed at a synchrotron using high resolution photoelectron spectroscopy and near edge X-ray adsorption spectroscopy. These measurements unambiguously attest the formation of a single layer with molecules arranged in the upright position and presenting a free SH group at the outer interface. Near edge X-ray absorption fine structure (NEXAFS) measurements suggest that the molecular axis is oriented at 24° with respect to the surface normal. In addition, valence band features could be successfully associated to specific molecular orbital contributions thanks to the comparison with theoretically calculated density of states projected on the different molecular units.

2010 - Composite electrode coatings in amperometric sensors. Effects of differently encapsulated gold nanoparticles in poly(3,4-ethylendioxythiophene) system [Articolo su rivista]
Zanardi, Chiara; Terzi, Fabio; Seeber, Renato
abstract

Composite materials consisting of poly(3,4-ethylendioxythiophene) including Au nanoparticles have been synthesised in order to develop new amperometric sensors with improved performances with respect to bare and to pure organic modified electrodes. The composite materials were prepared by including Au nanoparticles during the electropolymerisation process, by taking advantages to the anionic nature of the species surrounding the metal core. The resulting modified electrodes are found to preserve the repeatability and reproducibility of pure organic modified electrodes and to improve the selectivity toward anionic and cationic species chosen as the benchmark analytes, namely ascorbic acid and dopamine, respectively.

2010 - Effective catalytic electrode system based on polyviologen and Au nanoparticles multilayer [Articolo su rivista]
Zanardi, Chiara; Terzi, Fabio; Zanfrognini, Barbara; Pigani, Laura; Seeber, Renato; J., Lukkari; T., Ääritalo
abstract

Au nanoparticles encapsulated by very labile chloride ions are synthesised and characterised. Through layer-by-layer deposition technique they are stably anchored to an electrode surface, using a polyviologen derivative as the polycationic organic component. The structure and morphology of the multilayer is exhaustively studied by UV–vis spectroscopy, X-ray diffraction, scanning and transmission electron microscopy. The nanocomposite material shows very interesting electrocatalytic properties with respect to the reduction of H2O2, which occurs at particularly less negative potentials. Furthermore, the presence of Au nanoparticles inside the electrode coating greatly improves the sensitivity of the electrochemical system. The system results to be a well suitable sensor for H2O2 quantification, with high sensitivity and low detection limit.

2009 - Adsorption of 3,4-ethylenedioxythiophene (EDOT) on noble metal surfaces: a photoemission and x-ray absorption study [Articolo su rivista]
Pasquali, Luca; Terzi, Fabio; Montecchi, Monica; B., Doyle; J., Lukkari; Zanfrognini, Barbara; Seeber, Renato; Nannarone, Stefano
abstract

The adsorption of 3,4-ethylenedioxythiophene (EDOT) on Au and Pt surfaces is studied by core level and valence band photoemission using synchrotron radiation and by near edgeX-ray absorption spectroscopy.To closer simulate real applications, the films are grown from aqueous solution at room temperature and are compared to an ‘ideal’ film prepared by dosing the molecules from the vapour phase on a clean Au(1 1 1) single crystal. The S 2p, C 1s and O 1s levels show multiple components which are associatedto molecular fragmentation. NEXAFS confirms that fragmentation takes place at the surface. Thiophene species as well as alkyl chains and Sn species are identified as the most probable fragmentation products.

2009 - Classification of Red Wines by Chemometric Analysis of Voltammetric Signals from Pedot-Modified Electrodes. [Articolo su rivista]
Pigani, Laura; Foca, Giorgia; Ulrici, Alessandro; K., Ionescu; V., Martina; Terzi, Fabio; M., Vignali; Zanardi, Chiara; Seeber, Renato
abstract

Nine different types of Italian red wines of four different varieties were analysed, without any samplepre-treatments, by voltammetric techniques using a poly(3,4-ethylenedioxythiophene)-modified electrode.The data matrices consisting of the currents measured at different potentials, by repeated CyclicVoltammetry or Differential Pulse Voltammetry, are submitted to chemometric analysis. After explorativetests based on Principal Component Analysis, Partial Least Squares-Discriminant Analysis classificationmodels are built both for the training and for the test sets. To this aim, different classification strategiesare adopted, considering the responses from the two techniques either separately or joined together toform a data matrix including the whole voltammetric information.

2009 - Electrode coatings consisting of polythiophene-based composites containing metal centres. [Capitolo/Saggio]
Zanardi, Chiara; Terzi, Fabio; Pigani, Laura; Seeber, Renato
abstract

Polythiophene derivatives constitute nowadays the most extensively studied class of conducting polymers, thanks to their mechanical and thermal stability, as well as to their physical and chemical properties, such as electronic conductivity, electrochromism, solvatochromism, thermochromism and luminescence. These materials have been proposed for use in a wide range of applications, including chemical sensors, light emitting diodes, thin film transistors, different electrocatalytic systems, batteries, smart windows, and even artificial muscles.Peculiar systems are realised by anchoring similar materials on substrates. In particular, conductive substrates suitably coated by polythiophene derivatives constitute particularly interesting electrode systems that can be exploited in numerous electrochemical-electroanalytical applications. However, a notable part of the research activity in these fields is today evolving toward the insertion of metals into the polythiophenes matrix, in order to further improve the performances of the pure organic material. The driving force to these studies lies in the possibility to combine the properties of the organic and inorganic entities, taking advantage of their synergic interaction. Basically, two different approaches, resulting in hybrids/composites of quite different nature, have been followed: i) link of metal complexes to the polymeric backbone; ii) inclusion of metal ions and complexes, of clusters, oxides or nanoparticles into the polymer. In similar systems, the presence of the metal is supposed to deeply affect the electronic and electrochemical properties of the resulting hybrid/composite material.The aim of the present contribution is to give a picture of the variety of polythiophene-based hybrid/composite materials developed, with reference to the systems in which the polymer is supported on a conductive substrate, to constitute an electrode system. The different physico-chemical characterisations are treated, mainly devoted to clarify the interactions between the polymer and the metal centres, as well as the nature of the interface between the ambient and the composite as a whole. Description is given of some applications in electrochemical environments.

2009 - Erratum to "Electrochemical, spectroscopic and microscopic characterisation of novel poly(3,4-ethylenedioxythiopene)/gold nanoparticles composite materials" [Journal of Electroanalytical Chemistry 619-620 (2008) 75-82] (DOI:10.1016/j.jelechem.2008.03.009) [Altro]
Terzi, F.; Zanardi, C.; Martina, V.; Pigani, L.; Seeber, R.
abstract

2009 - Preparation and Characterization of a RedoxMultilayer Film Containing Au Nanoparticles [Articolo su rivista]
Terzi, Fabio; Zanardi, Chiara; Zanfrognini, Barbara; Pigani, Laura; Seeber, Renato; J., Lukkari; T., Aaritalo; J., Kankare
abstract

Gold nanoparticles encapsulated by negatively charged molecules have been stably anchored at a Au substratethrough layer-by-layer deposition technique, employing a redox polyviologen derivative as the cationiccounterpart. UV-vis spectroscopy, quartz crystal microbalance, transmission electron microscopy, scanningelectron microscopy, atomic force microscopy, and voltammetric measurements have been performed in orderto characterize the systems and to give a rationale to the effect of the deposition conditions on the propertiesof the resulting multilayers. The behavior of two benchmark electroactive species ([Fe(CN)6]4- and[Ru(NH3)6]3+) has been studied on nanoparticle-terminated multilayers. The nanoparticles provide chargepercolation through the multilayer and charge transfer with redox species in solution. The results imply thatthe electrochemical behavior of nanoparticle-containing films is partly dependent on the charge compensationmode within polyelectrolyte multilayers.

2009 - Sensori Amperometrici. Nuoivi materiali elettrodici [Articolo su rivista]
Seeber, Renato; Pigani, Laura; Zanardi, Chiara; Terzi, Fabio; Zanfrognini, Barbara
abstract

The article concerns the development of new materials for electrode systems. A complete characterisation of the materials and of the electrochemical systems is obtained by combiningthe results from different spectroscopic and electrochemical techniques. The resulting modified electrodes are tested as amperometric sensors. A particularly attractive applicationof these devices, even using (ultra)microelectrodes, is in the field of “blind analysis”, as elements of electronic tongues for the classification of real matrices.

2008 - Adsorption geometry variation of 1,4-benzenedimethanethiol self-assembled monolayers on Au(111) grown from the vapor phase [Articolo su rivista]
Pasquali, Luca; Terzi, Fabio; Seeber, Renato; B. P., Doyle; Nannarone, Stefano
abstract

1,4-benzenedimethanethiol was chemisorbed from the vapor phase onto Au(111). The chemisorption geometry, molecular orientation, and bonding properties were studied at different degrees of surface coverage by photoelectron spectroscopy, metastable deexcitation spectroscopy, and near-edge x-ray absorption fine structure spectroscopy at the carbon K edge. Two main chemisorption regimes were identified: at low coverage the molecules adopt a flat configuration, then, as the molecular density of the first layer increases, the reduction of the available chemisorption sites induces the newly bonded molecules to assume a vertical alignment, with only one of the sulphur head groups interacting with the substrate. Experimental results were interpreted on the basis of theoretical calculations that we performed on the free molecule concerning the molecular orbitals' density of states and simulated x-ray absorption. (c) American Institute of Physics.

2008 - Amperometric sensors based on poly(3,4-ethylenedioxythiophene)-modified electrodes: Discrimination of white wines [Articolo su rivista]
Pigani, Laura; Foca, Giorgia; K., Ionescu; Martina, Virginia; Ulrici, Alessandro; Terzi, Fabio; M., Vignali; Zanardi, Chiara; Seeber, Renato
abstract

The voltammetric responses on selected white wines of different vintages and origins havebeen systematically collected by three different modified electrodes, in order to check theireffectiveness in performing blind analysis of similar matrices. The electrode modifiers consistof a conducting polymer, namely poly(3,4-ethylenedioxythiophene) (PEDOT) and of compositematerials of Au and Pt nanoparticles embedded in a PEDOT layer. Wine samples havebeen tested, without any prior treatments, with differential pulse voltammetry technique.The subsequent chemometric analysis has been carried out both separately on the signals ofeach sensor, and on the signals of two or even three sensors as a unique set of data, in order tocheck the possible complementarity of the information brought by the different electrodes.After a preliminary inspection by principal component analysis, classification models havebeen built and validated by partial least squares-discriminant analysis. The discriminantcapability has been evaluated in terms of sensitivity and specificity of classification; in allcases quite good results have been obtained.

2008 - Deposition of Gold Nanoparticles on Thin Polyaniline Films [Articolo su rivista]
M., Sheffer; Martina, Virginia; Seeber, Renato; D., Mandler
abstract

Local and bulk deposition of gold particles was accomplished by the spontaneous reaction between chemically reduced polyaniline (PAN) thin films and AuCl4–. PAN layers were deposited on glass, indium tin oxide (ITO), and glassy carbon (GC) by the Langmuir–Blodgett method and spin-coating. Characterization of the PAN films was carried out by microscopy, UV–vis spectroscopy, and electrochemistry.We found that the nature of the gold deposit was greatly affected by the thickness of the PAN. Scanning electrochemical microscopy was used as a means of locally depositing gold nanoparticles on an unbiased PAN film by anodically dissolving a gold microelectrode. This represents a generic approach whereby a variety of metal micro- and nanoparticles can be locally deposited on insulating supports.

2008 - Development and characterisation of a novel composite electrode material consisting of poly(3,4-ethylenedioxythiophene) including Au nanoparticles [Articolo su rivista]
Zanardi, Chiara; Terzi, Fabio; Pigani, Laura; A., Heras; A., Colina; J., LOPEZ PALACIOS; Seeber, Renato
abstract

Composite materials consisting of poly(3,4-ethylenedioxithiophene) including Au nanoparticles encapsulatedby bulky anionic species have been electrogenerated and characterised through spectroscopic andmicroscopic techniques. The properties of electrodes modified by similar materials have been studiedwith respect to the oxidation of different benchmark electroactive species, such as negatively chargedascorbic and uric acids, and positively charged dopamine. The responses obtained evidence the dependenceof sensitivity and selectivity of the electrochemical responses on the presence and density of thenanoparticles and on the nature of the relevant encapsulating agent. In particular, the insertion of negativelycharged NPs activates a sort of electrostatic shield toward negatively charged molecules; however,also positively charged species result to be conditioned in accessing the redox active centres, locatedeither on the nanoparticle’s surface or on the conducting polymer’s molecules.

2008 - Electrochemical, Spectroscopic and Microscopic Characterisation of Novel Poly(3,4-ethylenedioxythiophene)/Gold Nanoparticles Composite Materials. [Articolo su rivista]
Terzi, Fabio; Zanardi, Chiara; V., Martina; Pigani, Laura; Seeber, Renato
abstract

Composite materials consisting of poly(3,4-ethylenedioxithiophene) including Au nanoparticles encapsulatedby bulky anionic species have been electrogenerated and characterised through spectroscopic andmicroscopic techniques. The properties of electrodes modified by similar materials have been studiedwith respect to the oxidation of different benchmark electroactive species, such as negatively chargedascorbic and uric acids, and positively charged dopamine. The responses obtained evidence the dependenceof sensitivity and selectivity of the electrochemical responses on the presence and density of thenanoparticles and on the nature of the relevant encapsulating agent. In particular, the insertion of negativelycharged NPs activates a sort of electrostatic shield toward negatively charged molecules; however,also positively charged species result to be conditioned in accessing the redox active centres, locatedeither on the nanoparticle’s surface or on the conducting polymer’s molecules.

2008 - Multicomponent analysis in the wavelet domain of highly overlapped electrochemical signals: resolution of quaternary mixtures of chlorophenols using a peg-modified sonogel-carbon electrode [Articolo su rivista]
J. M., PALACIOS SANTANDER; L. M., CUBILLANA AGUILERA; Cocchi, Marina; Ulrici, Alessandro; I., NARANJO RODRÍGUEZ; Seeber, Renato; J. L., HIDALGO HIDALGO DE CISNEROS
abstract

Chemometricmethods have been applied to resolve mixture of phenols; phenolic compounds are amongst themost interesting chemical species from an environmental viewpoint.However, the number of papers that applymultivariate calibration methods to resolve electroanalytical signals of mixture of phenols is low.In this paper, we propose a new chemometric methodology to resolve, in the wavelet domain, quaternary mixtures of chlorophenols: 4-chloro-3-methylphenol, 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol, in a concentration range from 0.05 to 0.25 mg·L−1, using differential pulse adsorptive stripping voltammetry (DPAdSV) as the electrochemical technique, and a new polyethylenglycol-modified Sonogel–Carbon electrode.The results obtained after applying a FastWavelet Transform (FWT)-based feature selection algorithm, coupled with different multivariate calibration methods (multilinear regression-MLR and partial least squares regression-PLS) are compared with those obtained from a direct PLS. Besides, an Orthogonal Signal Correction (OSC)-based Calibration Transfer procedure (OSC-CT) is also applied, as a pre-processing tool, in order to improve the results obtained with the previous techniques.

2007 - Bonding and orientation of 1,4-benzenedimethanethiol on Au(111) prepared from solution and from gas phase [Articolo su rivista]
Pasquali, Luca; Terzi, Fabio; Zanardi, Chiara; Seeber, Renato; N., Mahne; Nannarone, Stefano
abstract

The orientation and bonding of 1,4-benzenedimethanethiol molecules on Au(111) is studied by means of x-ray and ultraviolet (UV) photoemission, xray absorption and metastable deexcitation spectroscopy. The organic films are prepared both from solution and by exposing the clean substrate to the vapours of the substance in an evacuated environment. This leads to two different growth modes: when self-assembled monolayers (SAMs) are prepared from solution, the molecules tend to form a bilayer film with the molecules standing upright and with the molecular axis forming an angle of about 30 degrees with respect to the substrate normal; when growth is carried out from the gas phase, the molecules tend to assume at the earliest stages of exposure a flat-lying configuration, with both sulfur end-groups bonding to Au; at increasing exposure the surface coverage presents a saturation and the chemisorbed molecules tend to assume an upright arrangement.

2007 - Development of an electronic tongue based on a PEDOT-modified voltammetric sensor [Articolo su rivista]
V., Martina; K., Ionescu; Pigani, Laura; Terzi, Fabio; Ulrici, Alessandro; Zanardi, Chiara; Seeber, Renato
abstract

Three different electrodes were tested for use as nonspecific amperometric sensors for blind analysis on real matrices, namely different fruit juices from different fruits or different brands. The first two electrodes were traditional Pt and Au electrodes, while the third one was modified with poly(3,4-ethylenedioxythiophene) conducting polymer. The sensors were tested separately, tested coupled to each other, and also tested together. The responses of the electrode system(s) were first screened via PCA and then their discriminant capabilities were quantified in terms of the sensitivities and specificities of their corresponding PLS-DA multivariate classification models. Particular attention was paid to analyzing the evolution of the response over subsequent potential sweeps. The modified electrode demonstrated the most discriminating ability, and it was the only system capable of satisfactorily performing the most complex task attempted during the analysis: discriminating between juices from the same fruit but from different brands. Moreover, the electrode cleaning procedure required between two subsequent potential sweeps was much simpler for the modified electrode than for the others. This electrode system was therefore shown to be a good candidate for use as an informative element in an electronic tongue applied to the analysis of other food matrices.

2007 - Electro-oxidation of chlorophenols on poly (3,4-ethylenedioxythiophene)-poly(styrene sulphonate) composite electrode [Articolo su rivista]
Pigani, Laura; M., Musiani; C., Pirvu; Terzi, Fabio; Zanardi, Chiara; Seeber, Renato
abstract

The electrochemical behaviour of chlorinated phenols on Pt/poly(3,4-ethylenedioxy)thiophene, LiClO4 and on Pt/poly(3,4-ethylenedioxy) thiophene,poly(sodium-4-styrenesulphonate) electrodes has been investigated in phosphate buffer solution. Poly(sodium-4-styrenesulphonate) exerts remarkable effect against the electrode fouling induced by oxidation of chlorophenols, allowing us to record the relevant anodic response even after repeated potential cycles. Hypotheses about the role exerted by poly(sodium 4-styrenesulphonate) are made, on the basis of evidences provided by several techniques, such as cyclic voltammetry, electrochemical impedance spectroscopy, electrochemical microgravimetry and atomic force microscopy. Thanks to the fact that different chlorophenols show differences in the voltammetric responses, depending on number and position of the chloro substituents on the aromatic ring, applications of the modified electrode in the analysis of mixtures of chlorinated phenols are possible. (c) 2006 Elsevier Ltd. All rights reserved.

2007 - Optimization of the DPV Potential Waveform For Determination of Ascorbic Acid on PEDOT-Modified Electrodes [Articolo su rivista]
A., Bello; M., Giannetto; G., Mori; Seeber, Renato; Terzi, Fabio; Zanardi, Chiara
abstract

The electrocatalytic behaviour of poly(3,4-ethylendioxythiophene) (PEDOT) is investigated with respect to detection of ascorbic acid (AA), due to the fundamental importance of such analyte, both for pharmaceutical and food applications.The comparison of the response obtained with ascorbic acid on PEDOT-modified electrodes with Pt-unmodified electrodes resulted particularly interesting: A significant electrocatalytic effect ascribable to the conducting polymer is documented by an anticipated oxidative response of AA, accomplished by a noticeable increase of the anodic peak current. Differential pulse voltammetry (DPV) has been employed as technique for theevaluation of the performance of the CME. The effects of DPV scan parameters on the response of the CME have been studied by means of a 3 factors and 3 levels experimental design. These investigations allowed us to individuate the scan parameters leading to optimal response of the device. The response of CME for AA has been studied by DPV in the optimised conditions, showing good performance in terms of sensitivity and detection limit. A study on the effect of the thickness of the coating has been conducted. The effect of the pH of the solution on the CME response has been also studied.

2007 - Structure and properties of 1,4-benzenedimethanethiol films grown from solution on Au(111): An XPS and NEXAFS study [Articolo su rivista]
Pasquali, Luca; Terzi, Fabio; Zanardi, Chiara; Pigani, Laura; Seeber, Renato; G., Paolicelli; Sm, Suturin; N., Mahne; Nannarone, Stefano
abstract

Core level photoemission and X-ray absorption at the carbon C 1s edge are applied to the study of chemisorption of 1,4-benzenedimethanethiol molecules oil Au(111) and to investigate the effect of the solvent used to prepare the organic films. 1,4-Benzeiledimethanethiol films were prepared in polar and non-polar solvents, i.e. ethanol, methanol and n-hexane. 1,4-Benzenedimethanethiol molecules are anchored to the substrate through a single S-Au bond; the molecules in the films tend to assume an upright orientation, the aromatic ring resulting tilted towards the direction perpendicular to the substrate plane. The films present an effective thickness corresponding to more than a single layer. Only small differences are observed among behaviours in different solvents. It is concluded that the filial properties and conformation of the 1,4-belizenedimethanethiol films are largely determined by the reciprocal interactions between the molecules and with the substrate. (c) 2007 Elsevier B.V. All rights reserved.

2006 - Electrochemical and spectroelectrochemical characterisation of poly(3 '-hydroxymethyl-2,2 ': 5 ',2 ''-terthiophene) [Articolo su rivista]
Zanardi, Chiara; R., Scanu; Pigani, Laura; Mi, Pilo; G., Sanna; Seeber, Renato; N., Spano; Terzi, Fabio; A., Zucca
abstract

The electrochemical polymerisation of 3'-hydroxymethyl-2,2':5',2-terthiophene, afforded a new conducting polymer bearing the nucleophilic-CH2OH substituent in beta-position. The characteristics of the system obtained have been defined through electrochemical and spectroelectrochemical techniques, as a function of the nature of the solvent in which polymerisation has been carried out and in which polymer doping is electrochemically induced. Two different morphological and/or structural fractions are obtained when the polymer is electrogenerated in CH3CN solvent, while a more homogeneous deposit, consisting of molecules with shorter conjugation system, forms in CH2Cl2. Marked differences are also evidenced when the polymer is p-doped in the two different solvents.

2006 - Relaxation phenomena and structural modifications of substituted polythiophenes during the p-doping processes. An electrochemical and morphological study [Articolo su rivista]
Pigani, Laura; Seeber, Renato; Terzi, Fabio; O., Cerri; M., Innocenti; R., Udisti; G., Sanna
abstract

Electrodes modified by polythiophenes bearing different substituents have been prepared and the behaviour of the conducting polymers has been studied with respect to the structural phenomena occurring in the correspondence to the doping and the relevant undoping processes. The effects of experimental parameters, such as undoping potential and time, have been investigated. The steric hindrance of the substituents on the polymer chain is demonstrated to play a fundamental role in determining the extent of compactness of the film, as induced by polarisation of the electrode at potentials at which the previously charged polymer is neutralised. Such a conclusion is in accordance with prediction of the electrochemical stimulated conformational relaxation model. Electrochemical AFM measurements have been performed in order to acquire a direct view of the morphological modifications of the polymer coatings during the reduction.

2006 - Synthesis and electrochemical polymerisation of 3 '-functionalised terthiophenes - Electrochemical and spectroelectrochemical characterisation [Articolo su rivista]
Zanardi, Chiara; R., Scanu; Pigani, Laura; M. I., Pilo; G., Sanna; Seeber, Renato; N., Spano; Terzi, Fabio; A., Zucca
abstract

A new terthienyl derivative, 4-[(2,2:5´,2-terthien-3´-yl)methoxyl-2,2´:6´,2-terpyridine, was synthesised in order to clectrogenerate a new conducting polymer as an electrode coating suitable to complex metal ions. The characteristics of the system obtained have been defined through electrochemical and spectroelectrochernical techniques. The physical and chemical properties of 4´-[(2,2´:5´.2-terthien-3´-yl)methoxy]2,2´: 6´,2-terpyfi dine are compared with those of 3´-hydroxymethyl-2,2´:5´,2-terthiophene, i.e. the corresponding trimer not bearing the terpyridine ligand. Under the same conditions for both monomers, both electrochemical and spectroelectrochentical tests show that 4´-[(2,2´:5´,2-terthien-3´yl)methoxyl-2,2´:6´,2-terpyfidine leads to the formation of a narrower molecular weight distribution, with shorter-conjugated polymer chains.

2005 - 3-methylthiophene Self Assembled Monolayers on planar and nanoparticle Au surfaces [Articolo su rivista]
TERZI, Fabio; SEEBER, Renato; PIGANI, Laura; ZANARDI, Chiara; PASQUALI, Luca; NANNARONE, Stefano; M., FABRIZIO; S., DAOLIO
abstract

In this article the adsorption of 3-methylthiophene on planar and nanoparticle Au surfaces is investigated. The resulting systems are compared with a benchmark system based on 1-decanethiol. The characterization data collected evidence the formation of a packed 3-methylthiophene SAM on the planar surface. In particular, spectroscopic investigations suggest that 3-methylthiophene aromatic system is not adsorbed on the surface through the pi-electron system but rather through the S atom alone. On the other hand, the behavior of 3-methylthiophene on nanoparticle surfaces is notably different from that of the alkanethiol. Only a limited fraction of the surface of Au nanoparticles results to be actually coated after purification; this notwithstanding, the nanoparticle growth seems to be strongly influenced by the presence of such a labile encapsulating agent.

2005 - A poly(3,4-ethylenedioxythiophene)-poly(styrene sulphonate) composite electrode coating in the electrooxidation of phenol [Articolo su rivista]
Ma, Heras; S., Lupu; Pigani, Laura; C., Pirvu; Seeber, Renato; Terzi, Fabio; Zanardi, Chiara
abstract

The effectiveness of using conducting polymers as electrode coating material in order to prevent electrode fouling caused by electrochemical oxidation of phenol is investigated. In particular, the use of poly(3,4-ethylenedioxythiophene) (PEDOT) has been tested. Electrode passivation is dramatically reduced while incorporating surfactants containing hydrophilic groups into the polymeric structure. A significant improvement in performance is obtained using poly(sodium 4-styrenesulfonate); its presence in the solution during electropolymerisation leads to successful formation of the composite material. The influence of polymer thickness and of surfactant nature on phenol oxidation is studied in order to obtain repeatable responses for phenol oxidation.

2005 - Anodic stripping voltammetric determination of traces and ultratraces of thallium at a graphite microelectrode. Method development and application to environmental waters [Articolo su rivista]
N., Spano; A., Panzanelli; P. C., Piu; M. I., Pilo; G., Sanna; Seeber, Renato; A., Tapparo
abstract

A bare graphite microelectrode was used for the anodic stripping voltammetry determination of traces and ultratraces of Tl+ ion in aqueous solutions at pH 3.5, in the presence of a 1×10−3 mol L−1 EDTA solution. The proposed method, validated and tested at ultratrace level in environmental water samples, showed low detection and quantification limits (0.01 and 0.03gL−1, respectively) and excellent capability to determine the analyte also in the presence of a very high excess of interfering ions, i.e. 2200:1 and 10,000:1 (w:w) for Pb2+ and Cd2+, respectively. Furthermore, the wide linearity range, the absence of bias, the low time required for each measurement and the low cost of theinstrumentation needed are additional factors supporting the application of such a method as a screening tool in the direct determination of thallium ionic species in environmental samples.

2005 - In situ atomic force microscopy in the study of electrogeneration of polybithiophene on Pt electrode [Articolo su rivista]
M., Innocenti; F., Loglio; Pigani, Laura; Seeber, Renato; Terzi, Fabio; R., Udisti
abstract

Electrochemical AFM technique has been used for the in situ study of the electrogeneration-deposition process of polybithiophene at varying the polymerisation conditions, such as supporting electrolyte, i.e., LiClO4 or tetrabutylammonium hexafluorophosphate, and polymerisation procedure, i.e., either potentiostatic or potentiodynamic method. In order to better follow the evolution of the morphology of the deposit, particularly during the early stages of the polymer film growth, a suitable home-made electrochemical cell has been used.

2005 - Palladium(II) derivatives of alkylsulfanyl substituted thiophenes as precursors of inorganic polymers: Spectroscopic, electrochemical investigations and X-ray crystal structure of trans-PdCl2[3-(butylsulfanyl)thiophene](2) [Articolo su rivista]
Antolini, Luciano; G., Minghetti; Mucci, Adele; Parenti, Francesca; Pigani, Laura; G., Sanna; Seeber, Renato; Zanardi, Chiara
abstract

Palladium(II) complexes with two thiophene derivatives bearing alkylsulfanyl chains, i.e., 3-(n-butylsulfanyl)thiophene and 4,4´-bis(n-butylsulfanyl)-2,2´-bithiophene, are synthesised and spectroscopically and electrochemically characterised. The molecular structure of PdCl2[3-(n-butylsulfanyl)thiophene]2 was determined by X-ray analysis. The properties of the complexes have been compared with those of PdCl2[3,3´-bis(n-butylsulfanyl)-2,2´-bithiophene] and of a conductive polymer partially coordinated with Pd(II), previously synthesised by us. We found that Pd(11) ions can coordinate sulfanyl sulfur atoms both in cis and trans configuration, leading to a reticulate material, where some kind of interchain bridging may be reasonably supposed to enhance the bulk conductivity.

2005 - Study of ultrathin Prussian Blue films using in situ electrochemical surface plasmon resonance [Articolo su rivista]
S., Lupu; Pigani, Laura; Seeber, Renato; Terzi, Fabio; Zanardi, Chiara
abstract

Characterisation of ultrathin Prussian Blue films has been performed using in situ electrochemical surface plasmon resonance technique. Prussian Blue films have been prepared by potentiostatic method on a gold-coated glass surface plasmon resonance sensor. The electrochemical reduction of Prussian Blue to Prussian White and oxidation to Berlin Green are accompanied by a change of the refractive index; the system shows repeating voltammetric responses over subsequent potential cycles. The surface plasmon resonance signal is capable of evidencing minute electrochemically induced changes in the inorganic film coating the electrode.

2005 - Water-soluble full-length single-wall carbon nanotube polyelectrolytes: Preparation and characterization [Articolo su rivista]
H., Paloniemi; T., Aaritalo; T., Laiho; H., Liuke; N., Kocharova; K., Haapakka; Terzi, Fabio; Seeber, Renato; J., Lukkari
abstract

HiPco single-wall carbon nanotubes (SWNTs) have been noncovalently modified with ionic pyrene and naphthalene derivatives to prepare water-soluble SWNT polyelectrolytes (SWNT-PEs), which are analogous to polyanions and polycations. The modified nanotubes have been characterized with UV-vis-NIR, fluorescence, Raman and X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The nanotube-adsorbate interactions consist of &pi;-&pi; stacking interactions between the aromatic core of the adsorbate and the nanotube surface and specific contributions because of the substituents. The interaction between nanotubes and adsorbates also involves charge transfer from adsorbates to SWNTs, and with naphthalene sulfonates the role of a free amino group was important. The ionic surface charge density of the modified SWNTs is constant and probably controlled by electrostatic repulsion between like charges. The linear ionic charge density of the modified SWNTs is similar to that of common highly charged polyelectrolytes.

2004 - A study of the dielectric behavior and the liquid structure of a ternary solvent system [Articolo su rivista]
Cocchi, Marina; Franchini, Giancarlo; Marchetti, Andrea; Pigani, Laura; Seeber, Renato; Tassi, Lorenzo; Ulrici, Alessandro; Zanardi, Chiara; Zannini, Paolo
abstract

The static dielectric constant of the {DMF(1) + ME(2) + DME(3)} ternary mixtures was measured as a function of temperature (25 less than or equal to t/degreesC less than or equal to 80) and composition, over the whole mole fraction range 0 less than or equal to x(1),x(2),x(3) less than or equal to 1. The experimental values were processed by an empirical equation accounting for the dependence epsilon = epsilon(T, phi(i)), where phi(i) is the volume fraction of the components. A comparison between calculated and experimental data shows that this fitting relationship can be effectively employed to predict epsilon values in correspondence to experimental data gaps. Starting from the experimental measurements, some derived quantities such as molar polarisation (P), and excess counterpart (P-E) were obtained. Both the excess properties, epsilon(E) and P-E, take values partly positive and partly negative under all experimental conditions. The values of the excess quantities are indicative of the presence of specific interactions among different components in the mixtures.

2004 - EQCM study of the p- and n-doping processes of a poly[4,4’-bis(alkylsulphanyl)-2,2’-bithiophene] [Articolo su rivista]
Pigani, Laura; Seeber, Renato; Terzi, Fabio; Zanardi, Chiara
abstract

Electrogenerated deposits of poly[4,40-bis(butylsulphanyl)-2,20-bithiophene] have been characterised in the presence of differentsupporting electrolytes, by coupling current (charge) to microgravimetric measurements from the electrochemical quartz crystal microbalance (EQCM). The simultaneous collection of voltammetric measurements and of data relative to mass changes shows the influence exerted by the nature of the supporting electrolyte on the charge-discharge steps of both p- and n-doping processes. Interestingly, the microgravimetric data collected corresponding to the pre-peaks of both doping processes suggest the occurrence of two opposite motions of ions (ingress into and exit out from the polymer) in the relevant potential region, giving a contribution to the study of the ‘residual charge’ phenomenon.

2004 - Electropolymerisation of 3,4-ethylenedioxythiophene in aqueous solutions [Articolo su rivista]
Pigani, Laura; A., Heras; Á., Colina; Seeber, Renato; J., López Palacios
abstract

The potentiostatic electrosynthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) in aqueous media without addition to the solution of any kind of surfactant has been studied by electrochemical quartz crystal microbalance (EQCM) and by spectroelectrochemistry. These tandem techniques have given valuable new information about the electropolymerisation process, allowing us to relate absorbance-charge and frequency-charge relationships to: (i) oligomers generation and chain propagation, as far as the length leading to precipitation is reached; (ii) growing of the polymer deposit and concomitant p-doping, and even (iii) overoxidation of the polymer film. An analysis of the whole of the data, in fact, shows that the charge spent is not necessarily totally involved in thepolymer deposit formation, growth, and p-doping, so that it is necessary to be particularly careful in the fitting of the experimental data to linear models.

2004 - Influence of the nature of the supporting electrolyte on the formation of poly[4,4'-bis(butylsulphanyl)-2,2'-bithiophene] films. A role for both counter-ion and co-ion in the polymer growth and p-doping processes [Articolo su rivista]
Pigani, Laura; Seeber, Renato; Terzi, Fabio; Zanardi, Chiara
abstract

Electrode deposits of a polythiophene with particularly interesting characteristics, i.e., poly[4,40-bis(butylsulphanyl)-2,20-bithiophene],have been generated in the presence of different supporting electrolytes. The formation of the coatings has been studied bycoupling conventional electrochemical techniques with quartz crystal microbalance measurements. The results of simultaneousvoltammetric or chronoamperometric and microgravimetric experiments allow us to show the influence exerted by the nature of thesupporting electrolyte on the polymerisation and concomitant charging–discharging processes of the conducting polymer.

2003 - Differential pulse techniques on modified conventional-size and microelectrodes. Electroactivity of poly[4,4'-bis(butylsulfanyl)-2,2'-bithiophene] coating towards dopamine and ascorbic acid oxidation. [Articolo su rivista]
S., Lupu; Parenti, Francesca; Pigani, Laura; Seeber, Renato; Zanardi, Chiara
abstract

Poly[4,4'-bis(butylsulfanyl)-2,2'-bithiophene] modified conventional-size and (ultra)microelectrodes are first investigated in acetonitrile and quasi-neutral aqueous solution with respect to the repeatability of the responses obtained both in cyclic voltammetry and in differential pulse voltammetry. The reactivity towards ferrocene and hydroquinone, chosen as benchmark oxidizable substances in the two media, respectively, is considered. Comparison is made with the behavior of poly(3-methylthiophene) as electrode coating, which is one of the most commonly used redox mediators in amperometric sensors based on coatings consisting of conducting polymers. The results confirm the appealing properties of poly[4,4'-bis(butylsulfanyl)-2,2'-bithiophene], previously evidenced by us in different electrochemical studies: it exhibits particularly high stability and the characteristics of the current/potential curves obtained make it particularly suitable for analytical purposes. After performing these tests, the quantitative determination of dopamine by modified microelectrode is examined and the simultaneous voltammetric determination of ascorbic acid and dopamine is considered. The possibility of working profitably with a microelectrode at very low buffer-supporting electrolyte concentration is ascertained.

2003 - Multicomponent Analysis of Electrochemical Signals in the Wavelet Domain [Articolo su rivista]
COCCHI, Marina; J. L., Hidalgo Hidalgo De Cisneros; I., Naranjo Rodruguez; J. M., Palacios Santnder; SEEBER, Renato; ULRICI, Alessandro
abstract

Successful applications of multivariate calibration in the field of electrochemistry have been recently reported, using various approaches such as multilinear regression (MLR), continuum regression, partial least squares regression (PLS) and artificial neural networks (ANN). Despite the good performance of these methods, it is nowadays accepted that they can benefit from data transformations aiming at removing baseline effects, reducing noise and compressing the data. In this context the wavelet transform seems a very promising tool. Here, we propose a methodology, based on the fast wavelet transform, for feature selection prior to calibration. As a benchmark, a data set consisting of lead and thallium mixtures measured by differential pulse anodic stripping voltammetry and giving seriously overlapped responses has been used. Three regression techniques are compared: MLR, PLS and ANN. Good predictive and effective models are obtained. Through inspection of the reconstructed signals, identification and interpretation of significant regions in the voltammograms are possible.

2003 - Multivariate calibration of analytical signals by WILMA (wavelet interface to linear modelling analysis) [Articolo su rivista]
Cocchi, Marina; Seeber, Renato; Ulrici, Alessandro
abstract

A novel algorithm based on coupling of the fast wavelet transform (FWT) with MLR and PLS regression techniques for the selection of optimal regression models between matrices of signals and response variables is presented: wavelet interface to linear modelling analysis (WILMA). The algorithm decomposes each signal into the FWT domain and then, by means of proper criteria, selects the wavelet coefficients that give the best regression models, as evaluated by the leave-one-out cross-validation criterion. The predictive ability of the regression model is then checked by means of external test sets. Moreover, the signals are reconstructed back in the original domain using only the selected wavelet coefficients, to allow for chemical interpretation of the results. The algorithm was tested on different literature data sets: two near-infrared data sets from Kalivas, on which the performances of many calibration algorithms have already been tested, and a data set consisting of lead and thallium mixtures measured by differential pulse anodic stripping voltammetry and giving seriously overlapped responses. Good results were obtained for all the studied data sets; in particular, for the data sets from Kalivas the WILMA models showed improved predictive capability. Copyright

2003 - New rigid conducting composites for electrochemical sensors [Articolo su rivista]
B., Ballarin; MD Cordero, Rando; E., Blanco; JL Hidalgo Hidalgo De, Cisneros; Seeber, Renato; D., Tonelli
abstract

In this work, a novel sonogel-carbon material, obtained via a sonocatalytic procedure, is proposed as a matrix for the preparation of composite electrodes. This material combines the electrical properties of graphite with the mechanical resistance of the sonogel network; an electroactive phase is incorporated inside to give a system with peculiar redox properties. Ni/Al-Cl hydrotalcite and cobalt phthalocyanine complex were used to this end. The electrochemical behaviour of the sonogel-carbon-Ni/Al-Cl and of the sonogel-carbon-cobalt phthalocyanine composites is studied by cyclic voltammetry. These electrodes are stable and lead to repeatable responses. The responses have been compared with those of similar electrodes without added graphite. Key points of the electrochemical behaviour have been identified and discussed and the electrocatalytic capabilities have been investigated on oxidisable substrates, on methanol and on cysteine.

2003 - Radical ions from 3,3 ''',3 ''''-tris(butylsulfanyl)-2,2 ': 5 ',2 '': 5 '',2 ''',5 ''',2 '''': 5 '''',2 '''''-sexithiophene: An experimental and theoretical study of the p- and n-doped oligomer [Articolo su rivista]
A., Alberti; B., Ballarin; M., Guerra; D., Macciantelli; Mucci, Adele; Parenti, Francesca; Schenetti, Luisa; Seeber, Renato; Zanardi, Chiara
abstract

The 3,3',3' tris(butylsulfanyl)-2,2':5,2:5,2',5',2:5, 2'- sexithiophene 1 was investigated through spectroscopic (NMR, EPR, UV/Vis-NIR), electrochemical, spectroelectrochemical and theoretical (DFT) studies. The charged species obtained upon its oxidation and reduction were characterised, showing that 1 can exist in at least five different oxidation states, that is, a neutral species, a radical cation, a dication, a radical anion, and a dianion. The long term stability of the radical cation 1(+circle) was evidenced by the H-1 NMR study in the presence of small quantities of trifluoroacetic acid (TFA). This approach allowed a comparison of the relative broadening of proton signals of 1, induced by the electron exchange process with traces of radical cation 1(+circle), and the hfc (hyperfine coupling) constants obtained from the EPR study and DFT calculations. In the radical cation, all of the heterocyclic sulphur atoms are not significantly involved in the delocalisation of the unpaired electron, whereas the opposite holds for the radical anion. Time-dependent DFT calculations reproduced well the wavelengths of the optical transitions observed in the spectroelectrochemical experiments for all the five oxidation states and support the formation of the dianion 1(2-).

2003 - Synthesis and electrochemical characterisation of novel sonogel–carbon–polythiophene microstructured electrodes [Articolo su rivista]
B., Ballarin; Zanardi, Chiara; Schenetti, Luisa; Seeber, Renato; J. L., HIDALGO HIDALGO DE CISNEROS
abstract

A sonogel–carbon–polythiophene microstructured electrode has been synthesised via sonocatalytic procedure. The composite material was characterised by cyclic voltammetry, atomic force microscopy and optical microscopy. A comparison with a similar polythiophene directly cast on a platinum electrode has been made. In contrast with the degrading behaviour (overoxidation) observed at sufficiently positive potentials for alkylsulphanyl substituted polythiophenes cast on the electrode surface, the entrapment of the polymer inside a composite material drastically enhances the stability of the redox-active phase towards irreversible oxidation. In addition, the sonogel–carbon–polythiophene composite represents a good approach to test and, possibly, exploit the electrochemical properties of the polymer which, due to its complete insolubility in the common organic solvents, cannot be adequately cast on an electrode surface or electrosynthesised.

2003 - The effect of Pd(II) coordination on the properties of an alkylsulfanyl substituted polythiophene. Comparison with the corresponding monomer [Articolo su rivista]
Mucci, Adele; Parenti, Francesca; Pigani, Laura; Seeber, Renato; Zanardi, Chiara; M. I., Pilo; N., Spano; M., Manassero
abstract

The synthesis of a conducting polymer partially coordinated with Pd(II) ions is reported. The aim is to study the influence of the metal on the properties of the material as a whole, which is very appealing for possible applications in the field of amperometric sensors. An alkylsulfanyl substituted polythiophene is used in this first approach, due to the well known affinity of the sulfur atom for soft metals. The interaction between the organic and inorganic moieties results in the easy formation of partially coordinated polymer. The presence of the metal ions is found to affect the chemical, physical, and electrochemical properties of the organicmacromolecules, owing to interactions between the polymer p-conjugation system and the metal d orbitals.Synthesis and characterisation of the relevant monomer complex helps to better understand the behaviour of the complex polymer-metal system.

2002 - Beta-functionalised polythiophenes as microelectrode modifiers in low conductive media [Articolo su rivista]
Cocchi, Marina; Franchini, Giancarlo; M., Manfredini; Marchetti, Andrea; Pigani, Laura; Seeber, Renato; Tassi, Lorenzo; Ulrici, Alessandro; M., Vignali; Zanardi, Chiara; Zannini, Paolo
abstract

A study on polythiophene coated microelectrodes is reported, the goal being that of checking the capability of these electrochemical systems to work in low conductive media. The possibility of electrochemically p-doping the polymer in the presence of very low concentrations or even in the absence of supporting electrolyte in the solution is ascertained, opening the way to the use of similar systems in pure solvent media. This result is obtained in such conditions that the presence of residual charges - and corresponding counterions - trapped inside the film coating can be reasonably hypothesised.

2002 - Bidimensional chronoabsorptometric study of electropolymerisation of 4,4 '-bis(2-methylbutylthio)-2,2 '-bithiophene [Articolo su rivista]
Ruiz, V; Colina, A; Heras, A; Lopez Palacios, J; Seeber, Renato
abstract

Bidimensional chronoabsorptometry is a novel spectroelectrochemical technique that monitors simultaneously three different signals: current and absorbance both normal to the electrode plane and parallel to this plane during a time in which a fixed potential is imposed. This technique is applied in the visible range to the study of the electropolymerisation of 4,4'-bis(2-methylbutylthio)2,2'-bithiophene (MBTBT). Experiments are performed in a spectroelectrochemical cell under finite diffusion conditions (thin layer cell) with the aim of interpreting the processes taking place both at the electrode surface and in the adjacent solution during the potentiostatic electrogeneration and deposition of the polymer. Correlations are drawn out among the trends of the oligomers concentration in solution, the polymer electrodeposition and charging, and the current flow, on the time scales of the different steps of the process. (C) 2002 Elsevier Science B.V. All rights reserved.

2002 - Electrocatalytic activity of cobalt phthalocyanine stabilized by different matrixes [Articolo su rivista]
Ballarin, B; Gazzano, M; de Cisneros, Jlhh; Tonelli, D; Seeber, Renato
abstract

The behavior of cobalt phthalocyanine complexes incorporated inside an hydrotalcite-like clay (HT) or a sonogel-carbon composite has been investigated in order to develop chemically modified electrodes suitable for use as amperometric defectors. The electrocatalytic oxidation process of cysteine at this new electrode has been studied by cyclic voltammetry. For comparison, the oxidation of cysteine catalyzed by the cobalt phthalocyanine complex as a redox mediator, either dissolved in solution or entrapped inside the HT structure, has been followed by polarography. The sonogel-carbon composite electrode is stable and its response is repeatable. Cysteine oxidation is actually induced by the electrogenerated Co(III) complex, and the relevant anodic peak current varies linearly with cysteine concentration within the range 9.0x10(-4) to 1.0X10(-2) mol L-1.

2002 - Electrochemical preparation and characterisation of bilayer films composed by Prussian Blue and conducting polymer [Articolo su rivista]
S., Lupu; C., Mihailciuc; Pigani, Laura; Seeber, Renato; N., Totir; Zanardi, Chiara
abstract

Preparation and electrochemical behaviour of bilayer films consisting of iron(Ill) hexacyanoferrate, well known as Prussian Blue, and of poly[4,4´-bis(butylsulphanyl)-2,2´-bithiophene], on a platinum electrode, are reported. The electrochemical features of the Prussian Blue/conducting polymer bilayer system are examined in aqueous and acetonitrile solutions. Cyclic voltammetric studies show that, in acetonitrile solvent, the inner layer Prussian Blue is electroactive to some extent, though the electrochemical response of the system is mainly accounted for by poly[4,4´-bis(butylsulphanyl)-2,2´-bithiophene] outer layer. On the other hand, in aqueous solution Prussian Blue exhibits good electroactivity. Under specific experimental conditions, the individual redox behaviour of each constituent of the bilayer is evidenced in the two solvents separately, i.e., that of PB and that of poly[4,4´-bis(butylsulphanyl)-2,2´bithiophene] in aqueous and in organic solvent, respectively. However, interesting reciprocal influences are evident in the current/potential curves recorded under conditions which are discussed.

2002 - Microelectrodes for the determination of heavy metal traces in physiological conditions. Hg, Cu and Zn ions in synthetic saliva [Articolo su rivista]
Sanna, G; Pilo, Mi; Piu, Pc; Spano, N; Tapparo, A; Seeber, Renato
abstract

The present article reports an introductory study aimed to define voltammetric methodologies employing microelectrodes for the quantitative evaluation of Hg and other heavy metals in physiological-like matrices as synthetic saliva. The utilization of graphite, Pt and Au microdisc electrodes as voltammetric sensors in the differential-pulse stripping analysis of Hg, Cu, Ag, Sn and Zn (the main constituents of the well-known dental or silver amalgams, largely used for the dental restoration) has been studied in different artificial saliva. The best analytical performances, in terms of detection limit, repeatability and width of the potential window available, have been shown by graphite electrodes. Co-deposition effects (e.g., Pb or Cd) play an important role in improving detection limit and repeatability of the responses of graphite electrodes in the determination of Hg. The conditions for contemporary determination of Hg, Cu and Zn in a single re-oxidation step are also established and selected experimental conditions are proposed by virtue of the absence of Cu-Zn intermetallic interference in the deposition step. On the other hand, the study has shown that no possible combination of experimental conditions, i.e., nature of electrode and saliva, presence or absence of other reducible ions, allows the detection of Ag and Sn at mug dm(-3) levels.

2002 - Polimeri conduttori coordinati con ioni metallici come nuovi materiali per sensori elettrocatalitici [Abstract in Atti di Convegno]
Mucci, Adele; Parenti, Francesca; Pigani, Laura; M. I., Pilo; P., Piu; G., Sanna; Schenetti, Luisa; Seeber, Renato; N., Spano; Zanardi, Chiara
abstract

v. allegato

2002 - Polythiophene derivative conducting polymer modified electrodes and microelectrodes for determination of ascorbic acid. Effect of possible interferents [Articolo su rivista]
S., Lupu; Mucci, Adele; Pigani, Laura; Seeber, Renato; Zanardi, Chiara
abstract

Conventional-size electrodes and microelectrodes coated by electrogenerated poly[4,4'-bis(butylsulfanyl)-2,2'-bithiophene] have been tested with respect to the electrocatalytic oxidation of a particularly interesting analyte, i.e., ascorbic acid, in different concentrations of phosphate buffer, aqueous solution. Linear sweep and cyclic voltammetry have been used and the quantities related to the analyte concentration were the peak current and the diffusion (t(-1/2)) deconvoluted peak current in the case of conventional-size and of microelectrode, respectively. Fairly good linear correlation could be found; a particularly wide linearity range was obtained by working with the microelectrode. It showed to give good results also at a very low (10(-4) M) phosphate buffer-supporting electrolyte concentration. The actual interference on the analysis of compounds often coupled with ascorbic acid in natural or pharmaceutical products has been studied.

2002 - Study of the short-term release of the ionic fraction of heavy metals from dental amalgam into synthetic saliva, using anodic stripping voltammetry with microelectrodes [Articolo su rivista]
Sanna, G; Pilo, MI; Piu, PC; Spano, N; Tapparo, A; Campus, GG; SEEBER, Renato
abstract

The present paper describes a fast and reproducible procedure, employing differential pulse stripping analysis technique with graphite microelectrodes, for the quantitative evaluation of the ionic fraction of heavy metals (namely Hg, Cu, and Zn) released from dental amalgams into synthetic saliva during 6-90 h contact between amalgam and saliva, after completion of the dental restoration (short-term release). The Zn2+ concentration was evaluated by linear calibration, whereas Cu2+ and Hg2+ contents were estimated by the standard additions method. While the concentration of Zn2+ ion does not increase significantly anymore after a 6-h contact (values from 288+/-12 to 346+/-12 mug dm(-3) at time of contact from 6 to 90 h, respectively), in the same time interval the concentration of both Cu2+ and Hg2+ ions progressively increases (from 38+/-6 to 197+/-4 mug dm(-3) and from 15+/-3 to 101+/-2 mug dm(-3), respectively). The results of the release tests reveal that Hg concentration is at the highest level of risk (HBM III), as identified by the three human biomonitoring categories suggested by the Institut fur Wasser-, Boden- und Lufthygiene des Umweltbundesamtes (Germany) for the estimation of potential harmful effects on health due to exposure to heavy metals. (C) 2002 Elsevier Science B.V. All rights reserved.

2002 - Temperature and composition dependence of the refractive indices of the 2-chloroethanol + 2-methoxyethanol binary mixtures [Articolo su rivista]
Cocchi, Marina; M., Manfredini; Marchetti, Andrea; Pigani, Laura; Seeber, Renato; Tassi, Lorenzo; Ulrici, Alessandro; M., Vignali; Zanardi, Chiara; Zannini, Paolo
abstract

AbstractMeasurements of the refractive index n for the binary mixtures 2-chloroethanol + 2-methoxyethanol in the 0 ≤ T/°C ≤ 70 temperature range have been carried out with the purpose of checking the capability of empirical models to express physical quantity as a function of temperature and volume fraction, both separately and together, i.e., in a two independent variables expression. Furthermore, the experimental data have been used to calculate excess properties such as the excess refractive index, the excess molar refraction, and the excess Kirkwood parameter Ag over the whole composition range. The quantities obtained have been discussed and interpreted in terms of the type and nature of the specific intermolecular interactions between the components.

2002 - Viscosity of (ethane-1,2-diol+1,2-dimethoxyethane + water) at temperatures from 263.15 K to 353.15 K [Articolo su rivista]
Cocchi, Marina; M., Manfredini; Marchetti, Andrea; Pigani, Laura; Seeber, Renato; Tassi, Lorenzo; Ulrici, Alessandro; Zanardi, Chiara
abstract

AbstractThe kinematic viscosity ν for (ethane-1,2-diol + 1,2-dimethoxyethane + water) was measured at 14 different ternary compositions covering the whole miscibility field, and at 19 temperatures in the range 263.15 T / K 353.15. The experimental values were fitted using empirical equations of the type ν = ν (T) and ν = ν (xi), respectively, in order to provide reliable models to account for the behaviour of the system. The excess kinematic viscosity νEhas been determined and interpreted in terms of the type and nature of the interactions among the components of the mixture. Using the experimental ν data, the thermodynamic properties ( ΔG * , ΔH * ,ΔS * ) of the viscous flow have been obtained from the Eyring’s approach and standard thermodynamic equations. Furthermore, excess mixing functions, such asΔG * E , have been determined, and found to evidence the existence of quite strong specific interactions among the components, probably due to the formation of hydrogen bonds and dipolar networks. However, all the calculated excess mixing properties suggest the absence of stable three-component adducts.

2001 - Bidimensional spectroelectrochemistry applied to the electrosynthesis and characterization of conducting polymers: Study of poly[4,4 '-bis(butylthio)-2,2 '-bithiophene] [Articolo su rivista]
V., Ruiz; A., Colina; A., Heras; J., Lopez Palacios; Seeber, Renato
abstract

The electropolymerization mechanism of 4,4'-bis(butylthio)-2,2'-bithiophene (1) was studied by means of bidimensional spectroelectrochemistry. Simultaneous electrochemical and spectroscopic signals were analyzed with the aim of obtaining information about the role of the low-molecular-weight oligomers in the polymerization process. Experiments in electrochemical cells with finite (thin layer) and semi-infinite diffusion geometries were carried out to elucidate the role the oligomeric species play, both in the nucleation step and in the subsequent growth of the polymer deposited onto the electrode surface.

2001 - Electrochemical behaviour of cyclometallated gold(III) complexes. Evidence of transcyclometallation in the fate of electroreduced species [Articolo su rivista]
G., Sanna; M. I., Pilo; N., Spano; G., Minghetti; M. A., Cinellu; A., Zucca; Seeber, Renato
abstract

The electrochemical behaviour of a series of neutral and cationic N-C and N-N-C cyclometallated gold(III) species: ([Au(py(1))(Cl)(2)], Hpy(1) = 2-benzylpyridine; [Au(bipy(n))(Cl)][PF6], Hbipy(1) = 6-benzyl-2,2'-bipyridine, Hbipy(2) = 6-(1-methylbenzyl)-2,2'-bipyridine, Hbipy(3) = 6-(1,1-dimethylbenzyl)-2,2'-bipyridine, Hbipy(4) = 6-phenyl-2,2'-bipyridine) has been investigated in different solvent systems using cyclic voltammetry and controlled-potential coulometry. All the species considered show, in cyclic voltammetry, an irreversible one-electron reduction in the potential range -0.9/-1.2 V versus Fc(+/0), using a Pt electrode. On the other hand, exhaustive coulometries have shown the consumption of a number of Faraday per mole within the range 1-2. The very complex decomposition of the electrogenerated species affords elemental gold and significant amounts of different gold by-products. In some situations (e.g. reduction of [Au(bipy(4))(Cl)][PF6]), working with 0.1 mol dm(-3) Na[PF6], CH3C solvent system, it has been possible to characterise the most abundant gold(III) compound, by NMR, FAB-MS, and elemental analysis. The analytical and spectroscopic data provide evidence for the N-C bis-cyclometallated gold(III) derivative (e.g. [Au(bipy(4))(2)][PF6]); the result entails quite an unusual transcyclometallation process. The same compound can also be obtained, albeit in very minor yield, by chemical reduction of [Au(bipy(4))(Cl)][PF6]. (C) 2001 Elsevier Science B.V. All rights reserved.

2001 - Electrochemical characterization of polythiophene derivatives modified electrodes using differential pulse techniques [Articolo su rivista]
Lupu, Stelian; Pigani, Laura; Seeber, R.; Zanardi, Chiara
abstract

The electrochemical behavior of poly[4,4′-bis(butylsulfanyl)-2,2′-bithiophene] (PBSBT) modified conventional-size and microelectrodes in acetonitrile and aqueous solutions has been investigated using differential pulse voltammetry and cyclic voltammetry. The differential pulse voltammograms of both conventional-size and microelectrodes modified with PBSBT in acetonitrile containing 0.1 M TBAPF6 show the appearance of two peaks, when the electrode potential is scanned from 0.0 to +1.0 V, which correspond to the polaron formation (peak at ca. +0.50 V), and to bipolaron formation (peak at ca. +0.90 V), respectively. This behavior of the polymer when submitted to differential pulse measurements is similar to that exhibited in cyclic voltammetric tests. The modified electrodes present good stability under repetitive scanning of the electrode potential.

2001 - Electropolymerisation and characterisation of poly[4,4 '-bis(butylsulphanyl)-2,2 '-bithiophene] [Articolo su rivista]
B., Ballarin; F., Costanzo; F., Mori; Mucci, Adele; Pigani, Laura; Schenetti, Luisa; Seeber, Renato; D., Tonelli; Zanardi, Chiara
abstract

Electrochemical properties of electrogenerated poly[4,4'-bis(butylsulphanyl)-2.3'-bithiophene] have been studied. with particular attention to the charge-discharge processes. The possibility of both p- and n-doping is indicated. Doping and relevant de-doping processes of the specific polymer have also been considered in the context of the more general, still un-solved problem of the analysis of the mechanisms that al-e operative in the case of simple polythiophenes. In situ spectroelectrochemical measurements have been used to support the electrochemical results and both in situ UV-visible NIR spectroscopy on neutral, p- and n-doped forms of the polymer, and ex situ IR measurements have been performed. (C) 2001 Elsevier Science Ltd. All rights reserved.

2001 - Impedance Characteristics of Poly(4,4’- Bis(butylsulfanyl)-2,2’-bithiophene) Film Electrode as a Function of Different Oxidation Levels [Articolo su rivista]
Hongbo, Ding; Zhongxiao, Pan; Laura, Pigani; Seeber, Renato; Pigani, Laura
abstract

The impedance characteristics of poly[4,4 ' -bis(butylsulfanyl)-2,2 ' -bithiophene] film electrode are studied at different p-doping levels. The impedance features can be coherently described modeling the polymer deposit by a 'generalized transmission line circuit', using different simplifications when dealing with different oxidation states. Through these simplifications, the parameters of the equivalent circuit can be calculated The deviation of the impedance plots of the oxidized state from the Warburg-impedance 45 degrees slope in the mid-frequency domain is attributed to a non-uniform ionic conductivity profile within the polymer film. The analysis of the plots suggests the high-frequency semicircle, detectable in the case of both the neutral and the p-doped polymer to be due to the ion transfer barrier at the polymer/solution interface.

2001 - Mass Transport Properties in Solvent Liquid Mixtures [Articolo su rivista]
Cocchi, Marina; Manfredini, Matteo; A., Marchetti; Tassi, Lorenzo; Seeber, Renato; A., Ulrici
abstract

The study of mass transport properties, such as density and viscosity of mixed solvent systems (both aquomixed and nonaqueous liquids), have proven to be a very useful tool in investigating specific intermolecular interactions and structural effects in condensed phases of real components. The knowledge of these properties and of some related quantities is of strategic importance for a lot of technical and scientific applications, and the availability of correlation models with temperature and chemical composition, which can be employed both for interpretative and predictive calculations, is extremely useful for chemists, physics, biologists, practising engineers and research workers devoted to material sciences. Here, some of the most significant descriptive relationships will be summarised (together with their graphical representations), and some new concepts will be introduced to reach a better understanding about some Newtonian and pseudo-rheological complex systems. The chosen species for these studies pertain to the class of 1,2-ethanedyil-derivatives, such as 1,2-ethanediol (ED), 2-methoxyethanol (ME), 1,2-dimetho-xyethane (DME), di-ethylen-glycol (DEG), 1,2-propa- nediol (12PD), 2-butanone (MEK), in addition to water (W) and to DMF among other solvents, in order to construct a suitable data-base. Emphasis has been given to some aspects related to the peculiar hydrodynamic behaviour of water and to its binary and ternary mixtures. Furthermore, some aspects of excess mixing properties (YE) of multicomponent solvent systems are focused.

2001 - P- and n-doping processes in polythiophene with reduced bandgap. An electrochemical impedance spectroscopy study [Articolo su rivista]
H., Ding; Z., Pan; Pigani, Laura; Seeber, Renato; Zanardi, Chiara
abstract

Electrochemical impedance spectroscopy has been used for the characterisation of electrodes modified with different polythiophenes, namely poly[4,4 ' -bis(butylsulfanyl)-2,2 ' -bithiophene], poly[4,4 ' -bis(methylsulfanyl)-2,2 ' -bithiophene] and poly( 3-methylthiophene), at different applied potentials, using different supporting electrolytes. By comparison of the results obtained under experimental conditions in which n-doping is prevented and those obtained from tests where it does occur, some general features have been deduced. all of them being coherently described by a recently proposed 'generalised transmission line circuit' model: impedance plots at different applied potentials exhibit progressive changes which are well accounted for by the 'evolving' model. The results obtained on the n-doping process of S-alkyl substituted polymers suggest a behaviour interestingly similar to that exhibited in the p-doping: this supports a symmetry that was also found by us in a previous work, with respect to the incorporation and release of counterions during the n- and p-charge-discharge processes.

2001 - Politiofeni funzionalizzati con gruppi alchilsulfanilici [Abstract in Atti di Convegno]
Mucci, Adele; Parenti, Francesca; Schenetti, Luisa; Seeber, Renato; Zanardi, Chiara
abstract

v.allegato

2001 - Refractive properties of binary mixtures containing N,N-dimethylformamide+2-methoxyethanol or 1,2-dimethoxyethane [Articolo su rivista]
Franchini, Giancarlo; Marchetti, Andrea; Seeber, Renato; Tassi, Lorenzo; Zannini, Paolo
abstract

Refractive index (n) and related properties such as molar refraction (R) have been investigated for DMF+ME and DMF+DME binary mixtures over the entire composition range, at 15 different temperatures in the range 0 less than or equal to t/degreesC less than or equal to 70. Some relationships have been applied to study the dependence of the measured and derived quantities by temperature and composition. Furthermore, the excess functions n(E), R-E and the excess Kirkwood correlation parameters Deltag have been examined, in order to identify the presence of solvent-cosolvent adducts in these binary mixtures. The results obtained have been interpreted on the basis of specific intermolecular interactions between different species.

2001 - Substituent effect on the redox potential of substituted(aryl)(2-nitrobenzo [b]thiophen-3-yl) amines [Articolo su rivista]
B., Cosimelli; D., Spinelli; F., Costanzo; D., Tonelli; L., Lamartina; M. C., Sarvà; Seeber, Renato
abstract

The electronic effect of some meta- or para-substituents on the reduction of the title compounds has been investigated. The reversible reduction potential values of these compounds have been evaluated by cyclic voltammetry at a mercury electrode in 0.1 M tetraethylammoniumtetrafluoroborate, dimethylsulfoxide solutions. The substituent effect depends on both its nature and its position. The reduction potential Values of the derivatives studied have been correlated with the Hammett substituent constants.

2001 - Synthesis and Spectroscopic and Electrochemical Characterisation of a Conducting Polythiophene Bearing a Chiral β-Substituent: Polymerisation of (+)-4,4′-Bis[(S)-2-methylbutylsulfanyl]-2,2′-bithiophene [Articolo su rivista]
Iarossi, Dario; Mucci, Adele; Parenti, Francesca; Schenetti, Luisa; Seeber, Renato; Zanardi, Chiara; Forni, Arrigo; Tonelli, Massimo
abstract

A regioregular head-to-head/tail-to-tail poly(b,b'-disubstituted bithiophene) P1 was synthesised by chemical and electrochemical polymerisation of 2,2'-bithiophene that bears (S)-2-methylbutylsulfanyl chains in the b and b'-positions. The polymer was characterised by GPC, NMR and UV/Vis spectroscopy,CD, AFM and by electrochemical and conductivity measurements.The CD spectra of P1 in solutions in which poor solvents are present show interesting features and allow the presenceof different optically active species to be distinguished. Upon varying the casting conditions of P1, different relativeamounts of grainy and homogeneous aggregated phases were observed in AFM micrographies of films and correspondingnegative or positive first Cotton effects were found in the CD spectra. AFM, CD and UV/Vis characterisations were also performed on an electrogenerated optically active polymerPE1, in order to make a comparison with the chemically synthesised one. The interesting, small band gap of P1 allowsfor easy p- and n-electrochemical doping.

2001 - The 2-Methoxyethanol + 1,2-Dimethoxyethane + Water Ternary System: Static Relative Permittivity from -10 to 80 °C [Articolo su rivista]
Cocchi, Marina; DE BENEDETTI, Pier Giuseppe; Marchetti, Andrea; Menziani, Maria Cristina; Seeber, Renato; Tassi, Lorenzo; Ulrici, Alessandro
abstract

Static relative permittivities of the 2-methoxyethanol + 1,2-dimethoxyethane + water ternary solvent system were measured as a function of temperature (-10 less than or equal to t/degreesC less than or equal to 80) and of composition, over the whole molar fractions range 0 less than or equal to x(1), x(2), x(3) less than or equal to 1. The experimental values have been used to test some empirical relationships accounting for the dependence of epsilon on T. x(i), and on T, x(i) couples of values. A comparison between calculated and experimental data shows that these relationships can be profitably employed to predict E values in correspondence to experimental data gaps. The excess dielectric permittivity, epsilon (E), assumes, in the most cases, negative values for any compositions of the mixtures. while the values of the excess molar polarization, PE, are positive. The large values of the excess quantities are indicative of the strong specific interactions among similar, as well as different molecules in the mixtures. Discussion of the data in terms of Kirkwood correlation factor also gives information on the short-range intermolecular interactions among the components. suggesting the formation of two-components adducts rather than of than mure complex moieties involving all three molecular species.

2001 - WPTER: Wavelet packet transform for efficient pattern recognition of signals [Articolo su rivista]
Cocchi, Marina; Seeber, Renato; Ulrici, Alessandro
abstract

In the present work, we propose a novel algorithm based on the Wavelet Packet Transform WPT for pattern recognition of signals, which operates both feature selection and classification at the same time: Wavelet Packet Transform for Efficient pattern Recognition of signals WPTER . The distinctive characteristics of WPTER with respect to the previously proposed algorithms for the WPT-based classification of signals consist mainly of two aspects: 1 a Classification Ability criterion is introduced into the procedure for selection of the best discriminant basis; 2 the signals are reconstructed in the original domain by using only the selected wavelet coefficients, which allow for chemical interpretation of the results. The algorithm was first tested on an artificial simulated set of signals, consisting of a number of subsequent peaks, par- tially overlapped to each other, with added noise and baseline drift, simulating a three-class system. Then, it was applied to a data set consisting of X-ray diffractograms on fired tiles subjected to different firing cycles, aiming at discriminating the different firing methods on the basis of the phase composition. In both cases, satisfactory classifications were achieved.

2001 - [Ni/Al-Cl]-based hydrotalcite electrodes as amperometric sensors: Preparation and electrochemical study [Articolo su rivista]
Scavetta, E; Berrettoni, M; Seeber, Renato; Tonelli, D.
abstract

A study has been carried out to develop electrochemical devices based on the hydrotalcite (HT) [Ni/Al-Cl] suitable for the amperometric determination of oxidisable species. The amperometric sensors have been tested on methanol, mannitol and glucose substrates. The measured signal is an electrocatalytic current due to the oxidation of Ni(II) centres present in the brucite layers of HT to Ni(III) or NI(IV). Different kinds of electrodes have been studied in terms of chemical and mechanical stability, lifetime, and simple regenerability of the surface. Cyclic voltammetry has been used to evaluate the electrochemical responses. The best performances have been achieved when HT particles were entrapped into an epoxy resin and the electrical contact was guaranteed by a carbon-based material. (C) 2001 Elsevier Science Ltd. All rights reserved.

2000 - A Study on Stochastic Resonance for the Process of Active-passive Transition of Iron in Sulfuric Acid [Articolo su rivista]
Ding, H. B.; Xia, B.; Yin, C.; Pan, Z.; Seeber, Renato
abstract

Passivation of iron in sulphuric acid is studied by stochastic resonance method.

2000 - Anionic clay modified electrode for detection of alcohols. An electrocatalytic amperometric sensor [Articolo su rivista]
B., Ballarin; Seeber, Renato; D., Tonelli; Zanardi, Chiara
abstract

The mechanism of the electrocatalytic oxidation towards a wide series of alcohols, by an electrode covered with the [Ni/Al-Cl] hydrotalcyte-like clay, has been analyzed in the different steps it consists of. Such a clay has been reported to be electrically conductive via a mechanism that shows similarities with that of the redox polymers. The overall process occurs in quite a complicated physical system that is completely different both from a classical electrode-solution one and from an electrode covered with a film of heterogeneous catalyst. By varying the characteristics of the substrate, in terms of steric hindrance and dipole moment of the molecule, the factors affecting the redox mediator-substrate reaction have been studied. The concentration ranges where the amperometric response varies linearly have been determined for the different substrates considered.

2000 - Determination of heavy metals in honey by anodic stripping voltammetry at microelectrodes [Articolo su rivista]
Sanna, G; Pilo, Mi; Piu, Pc; Tapparo, A; Seeber, Renato
abstract

A methodology for the determination of Cu, Pb, Cd and Zn by differential pulse anodic stripping voltammetry (DPASV) at Hg microelectrodes in honey samples is proposed. The simultaneous quantification of the four metals in the mineralised matrix is prevented by the formation of Cu-Zn intermetallic species during the deposition step. However, the addition of Ga(III) salt to the measurement solution and the metal deposition at a potential lower than that required for Zn reduction allow the determination of the four metals by two DPASV experiments, consecutively performed on the same sample solution. High levels of repeatability (uncertainty better than 2% for metal concentrations higher than 0.2 mu g g(-1), independent of the kind of metal) and not significantly biased results make the proposed method accurate. The detection limits, computed by following the procedure suggested by IUPAC, do not show any significant differences from one another, allowing the computation of a common value equal to 0.0123 mu g g(-1). Although the complete procedure is optimised for the mineralised honey samples, the possibility to obtain speciation information by a direct stripping analysis in raw honey, i.e. a highly viscous real sample, has also been investigated and is discussed. (C) 2000 Elsevier Science B.V. All rights reserved.

2000 - Electroanalytical determination of heavy metals in artificial saliva. In vitro study [Articolo su rivista]
G., Sanna; M. I., Pilo; L., Ciotti; Seeber, Renato; A., Lumbau; G., Campus
abstract

The heavy metals are determined in synthetic saliva by polarographuc method

2000 - Electrochemical Oscillations during Cathodic Polarizatioon Process of Aluminum Covered with Talc Coatings [Articolo su rivista]
Hb, Ding; Zx, Pan; Fy, Zheng; Gm, Wen; Seeber, Renato
abstract

Talc coatings were produced with chemical method on the surface of pure aluminum. The characteristics of cathodic polarization in a 3.5% NaCl solution have been studied through the observation of the 'current oscillations' phenomenon.

2000 - Electrochemical properties of gold(III) complexes with 2,2 '-bipyridine and oxygen ligands [Articolo su rivista]
Sanna, G; Pilo, Mi; Minghetti, G; Cinellu, Ma; Spano, N; Seeber, Renato
abstract

The electrochemical behavior of a series of five cationic species containing the Au(bipy)(3+) moiety and additional oxygen-donor ligands, and of the relevant common precursor, i.e. the dichloride [Au(bipy)Cl-2][PF6] species, have been investigated using cyclic voltammetry and controlled-potential coulometry. All the compounds with oxygen-containing ligand(s) (2-6) undergo an easy, irreversible one-electron reduction process. The first reduction process of the dichloride consists of an equally easy but quasi-reversible charge transfer, as evidenced by voltammetric tests at a very high scan rate, followed by an irreversible second-order chemical reaction. Correlations between the relative values of the reduction potentials and the corresponding molecular structure are made and hypotheses on the nature of the reduction mechanisms are advanced. (C) 2000 Elsevier Science B.V. All rights reserved.

2000 - Electrochemical synthesis and characterisation of polythiophene conducting polymers functionalised by metal-containing porphyrine residue [Articolo su rivista]
B., Ballarin; Seeber, Renato; Tassi, Lorenzo; D., Tonelli
abstract

Two different copolymers of 2,2'-bitthiophene and of new thiophene derivatives, bearing in the beta position a porphyrin macrocycle, either free or complexed with Ni(II), have been electrogenerated and studied. The electrochemical behaviour of the relevant coatings has been compared, and the complexing ability of the macrocycle with respect to Ni(II) ion has been investigated. Moreover, the possibility of growing the metal-containing polymer on a micro Pt disk has been checked. The resulting modified microelectrode has been characterised and tested. (C) 2000 Elsevier Science S.A. All rights reserved.

2000 - Hydrotalcite-like compounds as ionophores for the development of anion potentiometric sensors [Articolo su rivista]
Ballarin, B; Morigi, M; Scavetta, E; Seeber, Renato; Tonelli, D.
abstract

A double layered hydroxide anionic clay containing chloride or nitrate as the interlayer anion has been used to prepare ion-selective electrodes (ISE) for potentiometric sensing of the intercalated anionic species. The electrodes exhibited a linear range for the potential response to logarithm of concentration: from 5.0 x 10(-5) to 2.0 x 10(-1) M with an average slope equal to - 54.2 mV decade(-1) for chloride and from 2.0 x 10(-4) to 1.0 M with an average slope equal to - 48.3 mV decade-1 for nitrate. The response time was from 1 to 6 min, depending on the analyte concentration; the stability of the signal was quite satisfactory. The effect of interfering ions has been investigated and the values of the relevant selectivity constants have been determined. The lifetime of the sensors was at least 2 weeks. (C) 2000 Elsevier Science B.V. All rights reserved.

2000 - P- and n-doping of electrochemically formed poly(4,4 '-bisbutylsulfanyl-2,2 '-bithiophene). A novel material with reduced bandgap [Articolo su rivista]
H., Ding; Pigani, Laura; Seeber, Renato; Zanardi, Chiara
abstract

Electrodes covered by stable electron conducting polymer films which exhibit easy p- and relatively easy n-doping have been successfully prepared by electrochemical polymerisation of symmetrical 4,4'-bisbutylsulfanyl-2,2'-bithiophene. The whole of the cyclic voltammetric behaviour has been explained based on the concept of 'electrostatically stabilised polarons'.

2000 - Platinum complexes with N-N-C ligands. Syntheses, electrochemical and spectroscopic characterisations of platinum(II) and relevant electroreduced species [Articolo su rivista]
G., Sanna; G., Minghetti; A., Zucca; Seeber, Renato; Mi, Pilo; F., Laschi
abstract

A series of cyclometallated platinum(II) species with N-N-C ligands (N-N-C = ortho-C-deprotonated form of 6-benzyl-substituted 2,2'-bipyridines) and different fourth monodentate ligands (Cl-, I-, CN-, CO, PPh3, Py, MeCN) has been investigated electrochemically, with particular emphasis to the analysis of the relatively st;able one-electron reduced species. EPR spectra have been recorded at different temperatures on the electroreduced solutions. The :analyses were supported by a systematic comparison with simulated spectra and allowed a definition of the interaction of the additional unpaired electron with the Pt-195, N-14, and H-1 nuclei present in the molecule. Attention has been also paid to the effects of the ligands on the thermodynamics (E-1/2,E-r) of the reduction, as well as to some reactivity aspects of the substrates that could be shown by voltammetric tests. A number of these compounds have been synthesised for the first time, so that a full characterisation has been performed. (C) 2000 Elsevier Science S.A. All rights reserved.

2000 - X-ray Absorption Spectroscopy Study on the Electrochemical Reduction of Co((DO)DOH)pn)Br2 [Articolo su rivista]
M., Giorgetti; M., Berrettoni; I., Ascone; S., Zamponi; Seeber, Renato; R., Marassi
abstract

The reduction process of Co-III((DO)(DOH)(pn))Br-2 has been studied by X-ray absorption spectroscopy. A structural rearrangement takes place during the first reduction step, from Co-III to Co-II. It involves the cleavage of both axial bromide ligands. However, the reduction from Co-II to Co-I proceeds with retaining of the coordination geometry. These findings have also been confirmed by an 'ad hoc' electrochemical experiment. (C) 2000 Elsevier Science Ltd. All rights reserved.

1999 - Development of Quantitative Structure-Property Relationships (QSPR) using calculated descriptors for the prediction of the physico-chemical properties (nD, r, bp, e and h) of a series of organic solvents. [Articolo su rivista]
Cocchi, Marina; DE BENEDETTI, Pier Giuseppe; Seeber, Renato; Tassi, Lorenzo; Ulrici, Alessandro
abstract

Quantitative structure-property relationship (QSPR) models were derived for predicting boiling point (at 760 mmHg), density (at 25 °C), viscosity (at 25 °C), static dielectric constant (at 25 °C), and refractive index (at 20 °C) of a series of pure organic solvents of structural formula X-CH2CH2-Y. A very large number of calculated molecular descriptors were derived by quantum chemical methods, molecular topology, and molecular geometry by using the CODESSA software package. A comparative analysis of the multiple linear regression techniques (heuristic and best multilinear regression) implemented in CODESSA, with the multivariate PLS/GOLPE method, has been carried out. The performance of the different regression models has been evaluated by the standard deviation of prediction errors, calculated for the compounds of both the training set (internal validation) and the test set (external validation). Satisfactory QSPR models, from both predictive and interpretative point of views, have been obtained for all the studied properties.

1999 - Electrocatalytic Properties of Nickel(II) Hydrotalcyte-type Anionic Clay. Application to Methanol and Ethanol Oxidation. [Articolo su rivista]
Ballarin, B.; Seeber, Renato; Tonelli, D.; Vaccari, A.
abstract

Glassy carbon electrodes modified with a [Ni/Al-Cl] hydrotalcite-type anionic clay have been studied with respect to the electrochemical oxidation of the NI(II) centres. The oxidation of Ni(II) is quasi-reversible and the presence in the hydrotalcite lattice of nickel with mixed oxidation states increases the conductivity of the coverage strongly. It has been verified that these nickel redox systems may act as redox mediators for the oxidation of alcohol substrates (methanol and ethanol have been tested) which are not oxidised at the bare electrode in the potential window available. For both alcohols the height of the current responses in linear sweep voltammetry is roughly linear with varying concentration in solution up to a limit of ca. 3000 ppm, with a detection limit of 3-4 ppm.

1999 - Electropolymerization of tetrakis(o-aminophenyl)porphyrin and relevant transition metal complexes from aqueous solution. The resulting modified electrodes as potentiometric sensors [Articolo su rivista]
E. M., Bruti; M., Giannetto; G., Mori; Seeber, Renato
abstract

The mechanism of electrogeneration of polyporphyrin from ortho-substituted phenylporphyrins, either free or complexing transition metals, is different when performed in aqueous solution from that operative in organic solvents, that has been reported in the literature. Polymerization occurs through the amino phenyl substituents, leading to a three dimensional 'cage' structure. The polymer is sensitive to morphology and nature of the surface it grows on. The mass deposited on a gold electrode was about 2 x 10(-4) g/cm(2). If the polymerization is performed under potentiodynamic conditions, the polymer forms essentially during the first scan, while no significant further growth is observed in subsequent potential cycles, from both free and metallated porphyrins. All polyporphyrin films, except the one obtained from CoTAPP, exhibit poor electrical conductivity, due to the three dimensional growth of the polymer chain that does not allow the necessary conjugation of pi orbitals inside the macromolecules. On the other hand, interesting properties are shown by the unmetallated as well as by metallated polymer films as possible coverages for 'coated wire' ion selective electrodes. The results obtained with respect to different ions and in particular, a selectivity study carried out on iodide ions are reported.

1999 - High-performance size exclusion chromatography in the evaluation of molecular size distributions of humic acids fractionated by ultrafiltration [Articolo su rivista]
B., Ballarin; Seeber, Renato; D., Tonelli; S., Zappoli
abstract

The distribution of the molecular weights in humic acid fractions are evaluated by HPLC

1999 - Polymerization and Characterization of 4,4’-bis(alkylsulfanyl)-2,2’-bithiophenes [Articolo su rivista]
Iarossi, Dario; Mucci, Adele; Schenetti, Luisa; Seeber, Renato; F., Goldoni; Affronte, Marco; Nava, Filippo
abstract

Regioregular polymers poly[4,4'-bis(butylsulfanyl)-2,2'-bithiophene] (P1)and poly[4,4'-bis(octylsulfanyl)-2,2'-bithiophene] (P2) were prepared from 4,4'-bis(butylsulfanyl)- and 4,4'-bis(octylsulfanyl)-2,2'-bithiophene, by oxidative polymerization with FeCl3, and characterized by 1-H, and 13-C NMR, FT-IR, ad UV-vis spectroscopies, atomic force microscopy (AFM) , electrical conductivity, and cyclic voltammetry measurements. They exhibit weight-average molecular weights of 8 and 70 kDa, respectively, and are both readily soluble in CHCl3, CH2Cl2, CS2, toluene, and THF. P1 has a lamellar structure, and P2 is a flexible and compact film that can be easily processed and manipulated. In the neutral state, they show UV-vis absorption maxima at about 470 nm in CHCL3 solution and exhibit marked solvatochromism and thermochromism. Furthermore, thay can be cast from orange-red solution to form a violet film. The p-doping potentials have been determined, and the possibility of electrogenerating corresponding polymers has been checked. First comparative characterizations of the electrogenerated polymers bave been carried out.

1999 - Transform Methods in the Synthesis and Elaboration of Signals [Articolo su rivista]
Seeber, Renato; Ulrici, Alessandro
abstract

Different transform methods, from Fourier Transform to Wavelet Transform, are discussed and exemplified

1998 - Dependence on molecular weight of acid-base properties of humic and fulvic acids [Articolo su rivista]
A., Falzoni; Seeber, Renato; D., Tonelli; C., Ciavatta; C., Gessa; D., Montecchio
abstract

The organic matter of Irish peat of Sphagnum was extracted with 0.1 M NaOH and separated into humic (HA) and fulvic (FA) acids. Afterwards, HA and FA fractions were obtained at different nominal molecular weight using a tangential ultrafiltration system. The behaviour of such fractions has been studied both in acid and alkaline solutions. Solutions at different ionic strength have been titrated under different conditions and the resulting curves have been elaborated through a computer program based on a bimodal Gaussian distribution. The typical parameters (pK$_{\rm A}$ mean value and dispersion degree) of the two main groups of HA and FA acidic functionalities have been determined.

1998 - Electrodes Coated by Hydrotalcite-like Clays. Effect of the Metals and the Intercalated Anions on Ion Accumulation and Retention Capability [Articolo su rivista]
Ballarin, B.; Gazzano, M.; Seeber, Renato; Tonelli, D.; Vaccari, A.
abstract

The influence of the nature of the di- and trivalent metals and of the interlayer anion of different hydrotalcite-like (HT) clays on the anion-exchange ability is investigated. In view of the application of similar clays as electrode coatings in electroanalysis and electrocatalysis, the responses of electrodes modified with the different HT to electroactive species in solution constitute the primary source of information. However, XRD measurements have proved to be invaluable tools when coupled with the electrochemical data. Two organic and one inorganic anion with reversible redox behaviour, i.e. anthraquinone mono-and disulphonates and hexacyanoferrate(II), have been chosen as electroactive species.

1998 - Modification of Electrodes with Porphirin-functionalysed Conductive Polymers [Articolo su rivista]
Ballarin, B.; Masiero, S.; Tonelli, D.; Seeber, Renato
abstract

A new thiophene derivative has been synthesised, in which a porphyrin moiety has been inserted in the beta position of the heterocyclic ring. The homopolymer deriving from this monomer has been prepared by chemical oxidation and subsequently deposited on a glassy carbon electrode, while the copolymer with dithiophene has been generated electrochemically directly on the electrode surface. Both materials have been characterised by SEM, and by UV-visible and IR spectroscopies. The electrochemical behaviour of the relevant coatings has been studied and the complexing ability of the polymer chains has been investigated with respect to the Ni(II) ion.

1997 - Electrosynthesis and Characterisation of Alkylester-substituted Polythiophenes [Articolo su rivista]
Ballarin, B.; Tonelli, D.; Andreani, F.; COSTA BIZZARRI, P.; DELLA CASA, C.; Salatelli, E.; Seeber, Renato
abstract

Thiophenes containing alkylester groups in the beta position of the ring have been electropolymerized on Pt. The fraction of the polymer films that became soluble in chloroform has been analysed by spectroscopic techniques and by size exclusion chromatography, with the aim of comparing them with the chemically prepared corresponding macromolecules. The electrochemical behaviour, i.e., the charge process of the polythiophene coatings, has been studied and the relevant parameters have been discussed.

1997 - Extraction of humic acids from a natural matrix by alkaline pyrophosphate. Evaluation of the molecular weight of fractions obtained by ultrafiltration [Articolo su rivista]
Tonelli, D; Seeber, Renato; Ciavatta, C; Gessa, C.
abstract

 Fractions of humic acids, resolved by ultrafiltration of extracts from a sample of peat treated with alkaline pyrophosphate solution, have been submitted to high-performance size-exclusion chromatography, with the aim of determining the molecular weight distributions. Anomalous peaks, located at retention volumes higher than those corresponding to the main signal, are present in the elution profiles relative to the lightest fractions. These peaks are more intense when using a refractive index detector rather than a UV detector. Elemental analysis data for the lightest fractions suggested that the spurious peaks are due to the presence of inorganic material. The hypothesis that pyrophosphate interacts with humic acids in the course of the extraction has been confirmed by colorimetric determination of the phosphorus content in the different fractions. As a consequence, the extraction procedure has been modified by using 0.1 mol/L NaOH as extractant.The average molecular weights of the various fractions, following NaOH extraction, result in substantial agreement with those obtained following pyrophosphate solution extraction (if the ‘pyrophosphate peaks’ present in the chromatographic profile are discarded in the calculations).

1997 - Gli amminoacidi di mosti base-spumante del Trentino in correlazione con paramentri geografici: rilievi su tre annate [Articolo su rivista]
G., Sferlazzo; G., Versini; Seeber, Renato; M. A., Franco; F., Congiu
abstract

Metodi chemiometrici sono impiegati per correlare le caratteristiche di mosti per spumante alla loro origine geografica.

1997 - Potentiometric and spectroscopic study of ternary complexes of copper(II), substituted 1,10-phenanthrolines and oxidised glutathione [Articolo su rivista]
Paola, Piu; Gavino, Sanna; Andreina, Masia; Maria Antonietta, Zoroddu; Seeber, Renato
abstract

A series of ternary systems consisting of copper(II), oxidised glutathione (a S–S′ bonded hexapeptide) and five differently substituted 1,10-phenanthrolines has been studied in aqueous solvent in the range pH 3–8. The stability constants of the complexes formed, together with the relevant distributions as a function of pH, have been evaluated by elaboration of data from acid–base potentiometric titrations. Electron paramagnetic resonance and electronic spectroscopy have been used to identify the chromophore in the 1 : 1 : 1 complexes, i.e. the ternary species are in all cases the predominant ones at pH close to the physiological values. The data from the spectroscopic measurements, when considered together with the trend in stability constant values, allowed reasonable hypotheses about the effect of the substituents on the phenanthroline ring on the stability and configuration of the complexes.

1996 - Resolution of Partially Overlapped Signals by Fourier Analysis. Application to Differential Pulse Polarographic Responses [Articolo su rivista]
Allegri, D.; Mori, G.; Seeber, Renato
abstract

An analysis of the first harmonic components of the sequence resulting from a suitable deconvolution operation on a response composed of single partially overlapped signals allows the resolution of the over-all response into the individual signals, Ideally, it is possible to reduce the original response to single impulses with suitable height and location. If the number, n, of single signals is known, the first n - 1 harmonic components of the spectrum of the deconvoluted response, plus the continuous term, need only be computed, On the other hand, if the over-all response includes an unknown number of single signals, a method is suggested that requires the calculation of only a few harmonic components in order to build up a suitable form of the whole spectrum of the deconvoluted signal, The effectiveness of the proposed procedures, which are suitable for the treatment of responses from different analytical techniques, was tested on simulated responses, both in the absence and presence of noise, and on experimental data, viz,, differential-pulse polarographic responses recorded on solutions containing two metals that were reduced at similar potentials.

1995 - Potentiometric and spectroscopic study of ternary complexes of copper(II), 1,10-phenanthroline and oxidised glutathione [Articolo su rivista]
Paola, Piu; Gavino, Sanna; Maria Antonietta, Zoroddu; Seeber, Renato; Riccardo, Basosi; Rebecca, Pogni
abstract

The ternary system consisting of oxidised glutathione (a S–S′ bonded dimeric hexapeptide), 1,10-phenanthroline (phen) and copper(II) has been studied in aqueous solution in the range pH 3–8 by potentiometry, electronic spectroscopy and electron paramagnetic resonance. Potentiometric titrations have allowed the evaluation of stoichiometry and formation constants of the complexes in the system; EPR and electronic spectroscopy were used to define the chromophore of one particularly important adduct predominant at physiological pH, [Cu(HL)(phen)]–(H6L2+= completely protonated oxidised glutathione). The results obtained suggest that in the stable conformation of this complex only one glutamyl moiety is involved, the other two positions in the plane being occupied by two nitrogen atoms from phenanthroline.

1995 - Stability Constants of Metal-Humate Complexes: Titration Data Analyzed by Bimodal Gaussian Distribution Model [Articolo su rivista]
B., Manunza; S., Deiana; V., Maddau; C., Gessa; Seeber, Renato
abstract

Different metal-humate complexes are considered and the relevant formation constants are computed on the basis of potentiometric data.

1994 - Aroma Compounds of Arbustus Distillates [Capitolo/Saggio]
G., Versini; Seeber, Renato; A., Dalla Serra; G., Sferlazzo; B., de Carvalho; F., Reniero
abstract

The compounds constiuting the aroma of arbustus distillates are determined analytically.

1994 - Electrochemical reduction of 1,1-diaryl-substituted ethenes in dimethylformamide [Articolo su rivista]
Michelina, Fruianu; Mauro, Marchetti; Giovanni, Melloni; Gavino, Sanna; Seeber, Renato
abstract

The cathodic behaviour of 1,1-diaryl-substituted ethenes (Ar)PhC[double bond, length half m-dash]CH2(where Ar = phenyl-, 2-naphthyl-, 2-pyridyl-, 2-thienyl-, 2-furyl-) at a Hg cathode in N,N-dimethylformamide (DMF) and 0.1 mol dm–3 tetraethylammonium tetrafluoroborate (TEAF), was investigated by cyclic voltammetry and controlled potential electrolysis experiments. In cyclic voltammetry, at a potential scan rate of 0.2 V s –1, all substrates showed an irreversible reduction peak [(Ep,c) between –2.27 and –2.54 V vs. saturated calomel electrode (SCE)]. Controlled potential coulometries indicated that the apparent charge number of the process involved ranges from 1 to 2. The reduction products were characterised as (Ar)PhCH–Me (1-aryl-1-phenylethanes) and (Ar)PhCH–[CH2]2–CHPh(Ar)(1,4-diaryl-1,4-diphenylbutanes). The charge number of the process and the ratio between the two different reduction products depended strongly on the structure and concentration of the substrate. Exhaustive electrolyses performed in the presence of variable amounts of D2O or in [2H7]DMF allowed us to suggest that two distinct pathways are involved in the reduction process, leading to the monomeric and dimeric product, respectively. Hypotheses on the nature of the two reduction mechanisms are discussed.

1993 - Electrochemical and spectroelectrochemical study of copper complexes with 1,10-phenanthrolines [Articolo su rivista]
G., Sanna; M. I., Pilo; M. A., Zoroddu; Seeber, Renato; S., Mosca
abstract

The redox behaviour of a series of copper(II) complexes with different phenanthrolines (1:2 metal to ligand) in dimethylformamide solvent is reported. Cyclic voltammetry, controlled potential coulometry and spectroelectrochemistry in the visible region have been used. Accurate values for the formal potential of the copper(II)/ copper(I) couples could be computed by spectroelectrochemistry, also in those cases in which the systems are poorly reversible. Two further reductions lead to neutral and anionic copper species, respectively. The nature of the substituents on the phenanthroline ligands has been found to affect strongly the redox potential of the former couples, while a less marked influence on the latter ones has been evidenced. On the other hand, differences in the ligands induce very different kinetic stability of the copper complexes formed in the more cathodic processes.

1993 - Electrochemical and spectroelectrochemical study of cyclometallated platinum derivatives with nitrogen ligands. electrogeneration of monomeric reduced platinum species [Articolo su rivista]
G., Minghetti; M. I., Pilo; G., Sanna; Seeber, Renato; S., Stoccoro; F., Laschi
abstract

The cathodic reduction of the complexes [LPtCl] and [LPtL′] (BF4) [HL  6-(1-methylbenzyl)-2,2′-bipyridine and L′ triphenylphosphine, pyridine, or acetonitrile] has been studied in acetonitrile and dichloromethane solvents. The main goal has been that of defining the nature and reactivity of the corresponding relatively stable one-electron reduced forms. In particular, X-band EPR spectrometry has allowed us to get information about the character (metal- or ligand-based) of the unpaired extra electron of the reduced species.

1993 - Numerical Methods in Synthesis and Analysis of Electrochemical Responses [Relazione in Atti di Convegno]
Seeber, Renato; M. I., Pilo; G., Sanna
abstract

Performances of different explicit and implicit methods, with constant and nonuniform discretisation for the space time grid are discussed, with reference to digital simulation of electrode processes

1993 - Thiolato-technetium complexes. 4(1): Synthesis, characterization and electrochemical properties of bis(1,2-bis(dimethylphosphino)-ethane)technetium(III) complexes with arene-thiolato ligands [Articolo su rivista]
Takumi, Konno; Seeber, Renato; Jon R., Kirchhoff; William R., Heineman; Edward, Deutsch; Mary Jane, Heeg
abstract

The reaction of trans-[Tcv(OH)(O)(DMPE)2]2+ (DMPE = 1,2-bis(dimethylphosphino)ethane) with a series of arenethiols in base produces the novel complexes cis-[TcIII-(SC6H4X-p)2 (DMPE)2]+ for X = H, Cl, Me, OMe, t-Bu. One of the complexes has been characterized by X-ray crystallography: cis-[Tc(SPh)2(DMPE)2]PF6, chemical formula Tc1S2P5F6C24H42, crystallizes in the orthorhombic space group P21nb with Z = 4 and lattice parameters a = 9.311(1) Å, b=11.190(2) Å, c = 31.936(4) Å, Vol = 3327.3(8) Å3. The final weighted R-value was 0.033. Averaged structural parameters are Tc—S = 2.29(2) Å, Tc—P (trans to P) = 2.42(1) Å, Tc—P (trans to S) = 2.49(3) Å, Tc—S—C = 118.5(5)°. The complexes have been characterized by FAB mass spectrometry and u.v.-vis. spectroscopy. The visible region charge transfer bands are diagnostic for cis geometry in the [Tc(SR)2(DMPE)2]+ complexes. Electrochemical and spectroelectrochemical measurements show reversible TcIII/II redox couples in the range -0.19V to -0.38V versus Ag/AgCl (3 M NaCl). Irreversible couples are exhibited at ca. -1.1 V to -1.2 V for TcII/I and +0.7V to +0.9V for TcIV/III. Variation in redox potential is discussed in terms of sulphur nucleophilicity.

1992 - Analysis of cyclic voltammetric responses by Fourier transform-based deconvolution and convolution procedures [Articolo su rivista]
Maria I., Pilo; Gavino, Sanna; Seeber, Renato
abstract

Numerical procedures for processing linear sweep and cyclic voltammetric responses are suggested in order to (1) deconvolve a sequence accounting for diffusion from the original signals; (2) convolve these with the same sequence. Deconvolution and convolution operations are performed via the Fourier transform method. Responses obtained by simulation of uncomplicated reversible, quasi-reversible and irreversible charge transfers are considered. The values of the parameters characterizing deconvolution and convolution responses are computed and discussed; a comparison is made with the corresponding parameters of the original current/potential curves, as well as with data reported in the literature for nernstian and totally irreversible charge transfers, obtained by following different mathematical procedures.

1992 - Synthesis, crystal structure, electrochemistry and molecular-orbital analysis of the piano-stool dimer [Mo2(?-C5H5)2(CO)4(NC5H4PPh2-2)2] [Articolo su rivista]
Carmela G., Arena; Felice, Faraone; Marco, Fochi; Maurizio, Lanfranchi; Carlo, Mealli; Seeber, Renato; Antonio, Tiripicchio
abstract

The addition of 2-(diphenylphosphino)pyridine (NC5H4PPh2-2) to an in situ prepared m-xylene solution of [Mo2(η-C5H5)2(CO)4](molar ratio 2 : 1), at room temperature, yields the complex [Mo2(η-C5H5)2(CO)4(NC5H4PPh2-2)2]1. Compound 1 is easily converted into the cationic molybdenum(II) mononuclear complex [Mo(η-C5H5)(CO)3(NC5H4PPh2-2)]PF62 by reaction with AgPF6. Reduction of 1 with Na or Na/Hg, in tetrahydrofuran, affords an air-sensitive solution containing Na[Mo(η-C5H5)(CO)2(NC5H4PPh2-2)]3, together with minor products. Electrochemical measurements show that 1 undergoes a reversible one-electron oxidation followed by relatively slow decomposition of the electrogenerated species. The molecular structure of the diethyl ether solvate of 1 was determined by X-ray diffraction methods: monoclinic, space group P21/c, with a= 13.218(4), b= 19.485(6), c= 11.019(4)Å, β= 110.10(2)° and Z= 2. The centrosymmetric complex 1 is a typical piano-stool dimer in which two units share the leg coinciding with the Mo–Mo vector. Similarly to other compounds of this type, the M–M separation is quite long [Mo–Mo 3.276(3)Å], ca. 0.5 Å longer than the sum of the metal radii. The evidence for the single metal–metal bond (predicted by counting rules) and its role in providing the system's stability is discussed in terms of qualitative molecular orbital theory. The extended-Hückel method used appears sufficiently reliable as the total electronic energy minimizes for an intermetal separation close to the experimental one. The loss of σ bonding, on elongating Mo–Mo, is counterbalanced by the diminished repulsion between metal lone pairs (filled xy orbitals), thus the intermetallic distance is an evident compromise between attractive and repulsive electronic forces. Steric factors may not be so important. The theoretical implications for the eventual homolytic cleavage of the dimer are also underlined. A rationale is provided for the effects that follow the removal of one electron from the system.

1991 - Analytical study of the reduction of chromium(VI) by d-galacturonic acid [Articolo su rivista]
S., Deiana; C., Gessa; M., Usai; P., Piu; Seeber, Renato
abstract

The reduction of chromium (VI) to chromium(III) by d-galacturonic acid takes place to a significant extent only in the presence of metal ions such as copper(II) or chromium(III) itself. These metals can form stable complexes in which the opening of the sugar ring leads to a reducing free aldehydic group. The stoichiometry of the reaction, the dependence of the yield on the nature of the metal ion and the pH of the solution and the products formed, were studied. Stoichiometries and stability constants of the complexes present in the system chromium(III)-d-galacturonic acid were evaluated.

1991 - EPR and electrochemical study of copper complexes with phenanthrolines and cinnamate ligands [Articolo su rivista]
M., Antonietta Zoroddu; Maria I., Pilo; Seeber, Renato; Rebecca, Pogni; Riccardo, Basosi
abstract

Solid state and solution EPR and electrochemical studies have been carried out on a series of complexesof copper(H) with differently substituted phenanthrolines and cinnamate Iigands. Spectra were recordedon binary complexes with cinnamate ligand and on a series of ternary complexes with the same anionand 1,10-o-phenanthroline, 2,9-dimethyl-1,10-o-phenanthroline or 4,7-dimethyl-1,10-o-phenanthrolineadditional ligands, respectively. The electrochemistry of the same copper complexes was studied inN,N-dimethylformamide solvent. The results of both EPR and electrochemical experiments can becorrelated with electronic and steric effects attributable to the methyl substituents on the phenanthrolineligand.

1991 - Electrochemical properties of copper complexes with unsubstituted and substituted 1,10-o-phenanthrolines in N,N-dimethylformamide solvent [Articolo su rivista]
Maria I., Pilo; Gavina, Manca; M., Antonietta Zoroddu; Seeber, Renato
abstract

The electrochemical reduction of a series of copper(II) complexes with 1,10-o-phenanthrolines, namely the 1:1 and 1:2 metal:ligand complexes with 2,9-dimethylphenanthroline, 4,7-dimethylphenanthroline and unsubstituted phenanthroline, respectively, has been studied in N,N-dimethylformamide using platinum electrodes. As to the 1:2 complexes, the effect of the presence of substituents with different electronic and steric effects on the phenanthroline ligands has been studied with the aim of rationalizing the different values of the standard potentials which have been measured. Furthermore, the possibility of electrogenerating neutral species, with a formally zerovalent copper centre, exhibiting different stability depending on the nature of the ligands, has been ascertained. In out solvent medium, 1:1 complexes have been found to be in equilibrium with the corresponding 1:2 complexes. A scheme for the reduction of solutions of these compounds, including the different equilibria associated to the electrode charge transfers, has been outlined.

1991 - Electrochemistry of the pyrazolate-bridged dirhodium(I) complex Rh2(CO)2(PPh3)2(μ-3,5-Me2pz)2 [Articolo su rivista]
Seeber, Renato; Giovanni, Minghetti; Maria I., Pilo; Guido, Banditelli; Silvia, Zamponi
abstract

The dirhodium(I) complex Rh2(CO)2(PPh3)2(mu-3,5-Me2pz)2 undergoes two consecutive oxidation processes at a platinum electrode in dichloromethane. The first oxidation gives the corresponding cationic species, [Rh2(CO)2(PPh3)2(mu-3,5-Me2pz)2]+, as inferred from the electrochemical (voltammetric and coulometric) and spectroelectrochemical data and from spectroscopic (IR, ESR and visible) examination of the oxidized product. The more anodic process involves poisoning adsorptions on the electrode surface, which rules out any effective study. Suggestions concerning the electronic charge distribution inside the monocationic compound are advanced on the basis of the voltammetric and ESR data.

1991 - Iron(III) reduction by D-galacturonic acid. Part 3. Influence of the presence of additional metal ions and of 2-amino-2-deoxy-D-gluconic acid [Articolo su rivista]
Salvatore, Deiana; Carlo, Gessa; Paola, Piu; Seeber, Renato
abstract

The effects of the presence of an aminosugar, namely 2-amino-2-deoxy-D-gluconic acid, on the reduction of iron(III) to iron(II) by D-galacturonic acid when copper(II), uranyl(VI), lead(II), nickel(II) or cadmium(II) ions are also present in the solution have been investigated. Lowering of the yield in iron(III) reduction has been found at any time in the cases of those metals whose addition to the system iron(III)–D-galacturonic acid favours iron(II) formation. Stoichiometries and stability constants of the complexes formed in the binary systems comprising one of the above- mentioned metal ions and the aminosugar ligand, as well as in the ternary systems with D-galacturonic acid as additional ligand, have been preliminarily determined by potentiometry. Relations between the compositions of the systems and the results of the kinetic tests have been suggested. The importance of similar reduction–complexation processes in the mobilization and consequent bioavailability of iron in biological systems, in particular at the root–soil interface, is emphasized.

1991 - Multivariate data analysis in classification of musts and wines of the same variety according to vintage year [Articolo su rivista]
Seeber, Renato; Gianvito, Sferlazzo; Riccardo, Leardi; Anita Dalla, Serra; Giuseppe, Versini
abstract

Multivariate analysis has been used to discriminate among different vintage years (1986, 1987,1988)of Chardonnay musts and wines from 31 growing areas in a relatively small geographical region ofTrentino (Italy). Musts have been analyzed as to their content of amino acids and wines with respectto amino acids, volatile compounds (i.e., alcohols, esters, amides, acids, and others), and metal ions.Principal component analysis has been used as a display technique. To identify the most significantparameters for discrimination, an appropriate stepwise procedure for feature selection was carried outbefore linear discriminant analysis was applied, which led to quite satisfactory classification and predictionrates. Biochemical and oenological arguments have been proposed to account for the significance ofthe selected sets of variables. On the other hand, unsatisfactory results were obtained by univariateapproach based upon calculation of Fisher weights.

1990 - ANALYTICAL AND SPECTROSCOPIC CHARACTERIZATION OF HUMIC ACIDS EXTRACTED FROM SEWAGE SLUDGE, MANURE, AND WORM COMPOST [Articolo su rivista]
S., Deiana; C., Gessa; B., Manunza; R., Rausa; Seeber, Renato
abstract

Humic acids from difgferent origin/source have been characterised, particularly by using spectroscopic techniques

1990 - Classification and prediction ability of pattern recognition methods applied to sea-water fish [Articolo su rivista]
M. A., Franco; Seeber, Renato; G., Sferlazzo; R., Leardi
abstract

The capabilities of the principal components, linear discriminant, quadratic discriminant and SIMCA methods in discriminating between two different species of fish (mullet), and between samples of one species caught in different seasons, were checked with a set of 13 biometric and chemical variables. Promising results were obtained, particularly by linear discriminant analysis after proper feature selection.

1990 - Electrochemical behavior of ‘costa-type’ organocobalt coenzyme B12 models [Articolo su rivista]
Seeber, Renato; Roberto, Marassi; Wallace O., Parker; G., Kelly
abstract

The cathodic reduction of nine ‘Costa-type’ organocobalt B12 model compounds, [RCo(III)L]C1O4 (where R = alkyl ligand; L = N2,N2′-propanediylbis- (2,3-butanedione 2-imine 3-oxime) and a neutral base), was studied in acetonitrile solvent, using cyclic voltammetry, controlled potential coulometry, and spectroelectrochemical techniques. The effect of the alkyl substituents, namely i-C3H7, neo-C5H11, i-C4H9, CH3CH2, C6H5CH2, CH3, HO(CH2)2, CH3- COOCH2 and CF3CH2, on the relevant cobalt reduction mechanisms and potentials was investigated. A marked infiuence of axial group bulk on the reactivity of the low oxidation state cobalt derivatives formed in the reduction process has been evidentiated. The reactivity of these electrogenerated compounds is conditioned for the most part by their ability to form stable bisalkyl complexes.

1990 - Iron(III) reduction by D-galacturonic acid. Part I. Influence of Copper(II) complexes formation [Articolo su rivista]
S., Deiana; C., Gessa; B., Manunza; P., Piu; Seeber, Renato
abstract

The addition of copper(II) ions to the system iron(III)-D-galacturonic acid strongly enhances the yield of the reduction of iron(III) to iron(II). In a copper(II)-iron(III)-D-galacturonic acid system with initial quantities in 4:1:5 relative ratios, iron reduction occurs almost quantitatively. The results found are explained by the formation of stable copper(II)-D-galacturonate complexes that leads to opening of the sugar molecule ring, with consequent formation of reducing aldehydic functional groups.

1990 - Iron(III) reduction by D-galacturonic acid. Part II. Influence of uranyl(VI), lead(II), nickel(II), and cadmium(II) complexes formation [Articolo su rivista]
S., Deiana; C., Gessa; P., Piu; Seeber, Renato
abstract

As a part of our study on iron reduction-mobilization in biological systems, in particular at root-soil interface, the effect of the addition of different metal ions to the iron(III)-D-galacturonic acid system has been investigated. The ions which are found to form particularly stable complexes with the galacturonate ligand strongly increase the yield of the reduction of iron(III) to iron(II). These findings are in agreement with the capability of some metal ions to form stable complexes through interaction both with the carboxylate group and with the ring oxygen atom of the sugar molecule, inducing opening of the ring and formation of a free aldehydic group. The importance of these processes in availability of iron to plant roots is emphasized.

1990 - Use of microelectrodes and spectroelectrochemical techniques in the study of redox properties of organometallic complexes [Articolo su rivista]
J., Chlistunoff; S., Zamponi; R., Marassi; Seeber, Renato
abstract

The electrochemical behaviour of the “Costa-type” coenzyme B12 model neopentyl-N2,N2'-propane-diylbis (2,3-butanedione-2-imine-3-oxime) Co(III) perchlorate complex has been studied using a platinum inlaid disk microelectrode techniques over a wide range of supporting electrolyte concentrations, and thin-layer absorption spectroelectrochemistry. In the former case, the separation of the two single electron transfers leading to Co(I) increased with decreasing supporting electrolyte concentration and, at the same concentration of the supporting electrolyte, with increasing radius of the cation. The likely explanation for this behaviour is the influence of ion-pair formation on the reduction potential of the redox couple involved in the second electron transfer that leads to a Co(I) complex bearing a negative charge.It has been demonstrated that the plot of the derivative of the steady-state current with respect to the electrode potential vs. E is morphologically identical to the derivative of the absorbance in thin-layer spectroelectrochemistry, and that the correlation between the results obtained using the two different techniques is useful for a better understanding of the electrochemical process.

1989 - Analytical Study of the Interactions of D-galacturonic Acid with Iron(III) in Solution and with Iron(III)-bentonite [Articolo su rivista]
S., Deiana; C., Gessa; V., Solinas; P., Piu; Seeber, Renato
abstract

The reduction of Fe(III) to Fe(II) to bioavailability to plants roots is studied both from a thermodynamic and a kinetic point of view.

1989 - Complexing and redox properties of the system D-galacturonic acid-iron(III) [Articolo su rivista]
S., Deiana; C., Gessa; V., Solinas; P., Piu; Seeber, Renato
abstract

The stoichiometry of the reduction reaction and D-galacturonic acid with iron(III) has been determined, leading to a 4:1 ratio between the quantities of reduced iron and oxidized D-galacturonic acid, respectively. This last molecule is oxidized to formic acid, and the residue is thought to present a further terminal carboxylic group. The reducing predominant species appears to be the FeGal3 complex.

1989 - Electrochemical synthesis of Costa-type cobalt complexes [Articolo su rivista]
Seeber, Renato; Wallace O., Parker; Patricia A., Marzilli; Luigi G., Marzilli
abstract

Due to the difficulty encountered in chemical preparations, [LCo( (DO)(DOH)pn)R]X species [whereL = neutral ligand, R = alkyl group, (DO)(DOH)pn = IP,P'-propanediylbis(2,3-butanedione 2-imine3-oxime)l have been prepared previously with only a limited range of alkyl ligands in comparison to othermodel systems. In this connection, the feasibility of electrochemical methods in the synthesis of theseorganocobalt Costa-type B12 model complexes was examined. The Co(1) species produced from cathodicreduction of Co((DO)(DOH)pn)Brza t ca. -0.8 to -0.9 V (versus SCE) in acetonitrile at 25 "C reacted quicklywith methyl iodide and more slowly with 2,2-bis(ethoxycarbonyl)propyl bromide (C2H5O2CC(CH3)-(CH2Br)CO2CzH6d,i ester bromide). Although the product of the reaction with the diester bromide couldbe reduced at only slightly more negative potentials, we were able to prepare [H,OCo((DO)(DOH)pn)-diesterlClO,, a useful synthon, by controlled potential electrolysis of Co((DO)(DOH)pn)Br2a t -0.8 V. Thisaqua complex, which we could not prepare by NaBH, reduction, was isolated and characterized. Theelectrochemical results are consistent with the view that both reduction of the organocobalt product andthe slowness of the alkylation of the Co(1) species are responsible for previously observed difficulties instandard chemical preparations. The 1,5,6-trimethylbenzimidazole(M e3Bzm)a nd pyridine (py) adductswere prepared by ligand substitution of the aqua complex and were characterized by NMR spectroscopyand elemental analysis. Rates of ligand dissociation of these adducts were found to be - 10 times fasterthan for the corresponding Me3Bzm and py complexes in which R = methyl. In contrast, the y-13C pyshifts of the two py derivatives were similar. These results can be rationalized if the alkyl ligands areelectronically similar but sterically different, with the more bulky diester group favoring L dissociation.

1989 - Linear Sweep and Cyclic Voltammetry [Articolo su rivista]
G., Bontempelli; F., Magno; G. A., Mazzocchin; Seeber, Renato
abstract

La review esamina criticamente come prove di voltammetria a scansione lineare e ciclico del potenziale possano discriminare i diversi meccanismi, più o meno complessi, alla base del trasferimento di carica all'elettrodo

1989 - The standard redox potential in the study of solute—solvent interactions. Dirhodium complexes [Articolo su rivista]
Seeber, Renato; Paola, Piu; Pasquale, Piraino; Piero, Zanello
abstract

A wide series of empirical parameters of solvents are employed in the study of the dependence of the redox potentials of some dirhodium(II) derivatives [namely, Rh2(O2CCF3)2(form)2, Rh2(form)4, Rh2(ONHCF3)4] upon the solvent nature. A statistical approach is proposed which analyzes the influence of solvent basicity, acidity and polarizability both independently and jointly. This has proved to be useful in rationalizing the solvent effects on the redox potentials, as well as in suggesting different solvation models.

1988 - Electrochemical study of triscyclopentadienyluranium complexes [Articolo su rivista]
F., Ossola; P., Zanella; P., Ugo; Seeber, Renato
abstract

The electrochemical behaviour of Cp3UBH4 and Cp3UNEt2 in THF has been studied using cyclic voltammetry and chronoamperometry. Cp3UBH4 undergoes a simple one-electron quasi-reversible reduction, while chemical reactions between the product of the charge-transfer reaction and the starting electroactive species occur both after oxidation and reduction of Cp3UNEt2.

1988 - Electrochemistry of oxo-technetium(V) complexes containing Schiff base and 8-quinolinol ligands [Articolo su rivista]
Fiorenzo, Refosco; Ulderico, Mazzi; Edward, Deutsch; Jon R., Kirchhoff; William R., Heineman; Seeber, Renato
abstract

The electrochemistry of six-coordinate, monooxo technetium(V) complexes containing Schiff base ligands has been studied inacetonitrile and N,N'-dimethylformamide solutions. The complexes have the general formula TcOCl(LB)Z or TcO(L,)(L& whereLB represents a bidentate-N,O Schiff base ligand or a bidentate-N,O 8-quinolinol ligand and LT represents a tridentate-O,N,OSchiff base ligand. Cyclic voltammetry at a platinum-disk electrode, controlled-potential coulometry, and thin-layer spectroelectrochemistrywere used to probe both the oxidation and the reduction of these complexes. The results of these studies, andpreviously reported results on the analogous Re(V) complexes, can be understood within a single general reaction scheme. Thesalient features of this scheme are (i) one-electron reduction of Tc(V) to Tc(IV), (ii) subsequent loss of a ligand situated cis tothe Tc=O linkage, and (iii) subsequent isomerization of this unstable Tc(IV) product to a more stable complex in which the sitetrans to the Tc=O linkage is vacant. The Tc(IV) complexes can also be reduced to analogous Tc(II1) species, which appear toundergo the same ligand loss and isomerization reactions. The technetium complexes are 400-500 mV easier to reduce than aretheir rhenium analogues. The 8-quinolinol ligands, and especially the 5-nitro derivative, both thermodynamically and kineticallystabilize the Tc(IV) and Tc(II1) oxidation states. These electrogenerated species are unusual in that they constitute the bulk of the known examples of monomeric Tc(IV) and Tc(II1) complexes containing only N- and 0-donating ligands.

1988 - Oxidation potentials of electrolyte solutions for lithium cells [Articolo su rivista]
F., Ossola; G., Pistoia; Seeber, Renato; P., Ugo
abstract

The oxidation potentials, Eox, of several solutions of interest for nonaqueous Li cells have been measured by linear sweep voltammetric experiments. A correlation is found between Eox and the basicity of the solvents, expressed by their donor numbers (DN). Esters and sulfones have higher resistance to oxidation than ethers, which possess the highest DN values. All solutions have Eox > 4 V vs Li/Li+. However, some reactivity between positive electrodes and solutions has been observed below this potential.

1988 - Unusually long-lived cobalt(II) and cobalt(I) species identified during electrochemical reduction of neopentyl B12 costa-type models [Articolo su rivista]
Seeber, Renato; Marassi, R. o. b. e. r. t. o.; Wallace O., Parker; Luigi G., Marzilli
abstract

Unusually long-lived complexes, which areformally in cobalt(I1) and cobalt(1) oxidation states, areidentified spectrally and electrochemically during thecathodic reduction in acetonitrile of a Costa-type organocobatt(II1) B,2 model with a particularly bulky alkyl axialligand, namely, neopentyl. The solution behavior is differentfrom that reported for other similar complexes inthat intermolecular alkyl transfer processes are essentiallyprevented by the bulky neopentyl axial ligand

1987 - Electrochemistry of rhenium(V) complexes with N-(2-hydroxyphenyl)salicylideneiminate as schiff base ligand [Articolo su rivista]
Seeber, Renato; Gian Antonio, Mazzocchin; Fiorenzo, Refosco; Ulderico, Mazzi; Francesco, Tisato
abstract

The anodic and cathodic behaviour of the rhenium(V) complexes nBu4N[ReOCl3(HOPhSal)], nBu4N[ReOCl2(OPhSal)], [ReOCl(OPhSal)(MeOH)] and [ReOCl(OPhSal)(PMe2Ph)] in acetonitrile was studied using platinum and mercury electrodes. Cyclic voltammetry and controlled potential coulometry were the main electroanalytical techniques employed. The nature of the electrolysis products as well as the mechanisms of the electrode oxidation and reduction processes were investigated. In particular a complex of rhenium(VI) containing the group ReO4+ and complexes of rhenium(IV) with ReO2+ core were electrochemically synthesized. They were characterized by elemental analysis, IR spectroscopy, magnetic susceptibility and conductivity measurements.

1986 - Complexes of magnesium(II) and other divalent metal ions with adenosine 5′-triphosphate and 2,2′-dipyridylamine in aqueous solution [Articolo su rivista]
Renzo, Cini; Arnaldo, Cinquantini; Seeber, Renato
abstract

Binary and ternary systems involving adenosine 5′-triphosphate (ATP), 2,2′-dipyridylamine (DPA) and magnesium, calcium, strontium, manganese, cobalt, copper, and zinc(II) metal ions have been investigated in aqueous media by potentiometric titrations. The analysis of the titration curves shows the existence of M(ATP)2−, M(ATP)(H)−, and M(ATP)2(H)24− species for alkaline-earth metal ions, while no ternary complex can be detected. For transition metal ions both binary and ternary species are found. Binary M(ATP)2(H)24− complexes are present in solutions containing manganese and cobalt(II) metal ions but these species cannot be revealed in the case of copper and zinc(II). Ternary complexes as M(ATP)(DPA)2− and M(ATP)(DPA)(H)− are common to all transition metals. Binuclear and hydroxo complexes as M2(ATP)(OH)− and M(ATP)(OH)3− are found only for copper and zinc(II). A hypothesis on the possible role of the species M-ATP in 1:2 ratio in the dephosphorylation mechanism is advanced on the basis of a comparison between the equilibrium data in the solution phase and the solid state structures of the magnesium, calcium, and manganese(II)- ATP-DPA systems.

1986 - Electrochemistry of rhenium(V) complexes with bidentate-bidentate and tridentate-bidentate schiff base ligands [Articolo su rivista]
Seeber, Renato; Gian Antonio, Mazzocchin; Ulderico, Mazzi; Fiorenzo, Refosco; Francesco, Tisato
abstract

The cathodic and anodic behaviour of rhenium(V) complexes, characterized by the ReO3+ core, with bidentate and tridentate Schiff base ligands, has been studied in acetonitrile solvent. Cyclic voltammetry and controlled potential coulometry were the main electroanalytical techniques employed to define the electrode processes. Electrolyses were also carried out with the aim to identify the nature of the reduced and oxidized products. In particular, it was possible to isolate and characterize new rhenium(VI) complexes, containing the group ReO4+, and the possibility of obtaining stable rhenium(IV) complexes has also been proved.

1986 - Minicomputer-based instrumentation for electroanalytical techniques [Articolo su rivista]
S., Stefani; Seeber, Renato
abstract

The system comprises a PDP 11/23 PLUS (16-bit) computer and a home-made electrochemical interface which includes digital/analog and analog/digital conversion circuits, a potentiostat, and programmable timers allowing fast data transfer. The software developed includes operating system routines and user-level programs for cyclic voltammetry and chronoamperometry. The whole system provides the user with a computer-aided execution of experiments, including potential waveform synthesis and collection and evaluation of responses.

1985 - Cyclic Staircase Voltammetry as a dc and ac Electroanalytical Technique [Articolo su rivista]
Seeber, Renato; S., Stefani
abstract

Fourier analysis is used to deconvolve,from a square wave voltammogram, the continuous current response to the alternating one.

1985 - Solvent effects on the redox potential of the uranium(VI)?uranium(V) couple [Articolo su rivista]
Seeber, Renato; Piero, Zanello
abstract

Binary and ternary systems involving adenosine 5′-triphosphate (ATP), 2,2′-dipyridylamine (DPA) and magnesium, calcium, strontium, manganese, cobalt, copper, and zinc(II) metal ions have been investigated in aqueous media by potentiometric titrations. The analysis of the titration curves shows the existence of M(ATP)2−, M(ATP)(H)−, and M(ATP)2(H)24− species for alkaline-earth metal ions, while no ternary complex can be detected. For transition metal ions both binary and ternary species are found. Binary M(ATP)2(H)24− complexes are present in solutions containing manganese and cobalt(II) metal ions but these species cannot be revealed in the case of copper and zinc(II). Ternary complexes as M(ATP)(DPA)2− and M(ATP)(DPA)(H)− are common to all transition metals. Binuclear and hydroxo complexes as M2(ATP)(OH)− and M(ATP)(OH)3− are found only for copper and zinc(II). A hypothesis on the possible role of the species M-ATP in 1:2 ratio in the dephosphorylation mechanism is advanced on the basis of a comparison between the equilibrium data in the solution phase and the solid state structures of the magnesium, calcium, and manganese(II)- ATP-DPA systems.

1984 - La Trasformata Discreta di Fourier. Applicazioni in Chimica Analitica [Articolo su rivista]
Seeber, Renato; S., Stefani
abstract

Nella serie Rassegne di Scienza e Tecnologia è presentata la definizione di FT e DFT, le operazioni di filtraggio - convoluzione e deconvoluzione - e alcune applicazioni strumentali, nonché di elaborazione dati

1984 - Voltammetric behaviour of rhenium(I) complexes with phosphine and carbon monoxide ligands in acetonitrile solvent [Articolo su rivista]
Seeber, Renato; Gian Antonio, Mazzocchin; Ulderico, Mazzi; Edoardo, Roncari; Fiorenzo, Refosco
abstract

Reacting Re(CO)5Cl with the azopyridine ligand (1) (L) in boiling benzene afford the complex Re(CO)3Cl(L), (2) in excellent yield [L=2-(p-Cl-C6H4NN)C5H4N]. The chelation of the azopyridine ligand accompanied by displacement of the two carbon monoxide ligands furnish a five-membered chelate ring. Structure determination of complex (2) has revealed a distorted octahedral ReC3N2Cl coordination sphere. The Re–N(pyridine) and, Re–N(azo) distances are 2.158(3) and 2.153(6) Å respectively, and the N–N length [1.273(4) Å], implicate relatively weak Re-azo(π*) back–bonding. The Re(CO)3Cl(L) lattice consists of C–H...Cl hydrogen bonding and Cl...O non-bonded interactions constituting a supramolecular network. Extended Hückel calculations reveal that the LUMO of Re(CO)3Cl(L) is Ca. 57% azo in character. One-electron quasireversible electrochemical reduction of the complex occurs near −0.3 V versus Saturated Calomel electrode(s.c.e.) The redox orbital is believed to belong to the above noted LUMO. Electrogenerated Re(CO)3Cl(L•–) underwent spontaneous solvolytic chloride displacement in MeCN, resulting in the isolation of Re(CO)3(MeCN)(L•–). The latter complex in turn reacted with imidazole and triphenylphosphine, furnishing Re(CO)3(C3H4N2)(L•–) and Re(CO)3(PPh3)(L•–), respectively. The pattern of carbonyl stretching frequencies of these radical anion complexes is similar to that of Re(CO)3Cl(L) but with shifts to lower frequencies by 10–20 cm−1. All three radical anion systems are one-electron paramagnetic (1.7–1.8 μB). The unpaired electron is primarily localized on the azoheterocycle ligand in a predominantly azo-π* orbital, but a small metal contribution (185, 187Re, I=5/2) is also present. Thus Re(CO)3(MeCN)(L•–) and Re(CO)3(C3H4N2)(L•–) display six-line e.p.r. spectra (A ˜ 28 G). The line shapes and intensities are characteristic of the presence of g-strain. In the case of Re(CO)3(PPh3)(L•–) seven nearly equispaced lines are observed due to virtually equal coupling between the metal and 31P (I=&frac;) nuclei. The g-values of the radical species are slightly higher than the free-electron value of 2.0023.

1983 - Square Wave Voltammetry as an Electroanalytical Technique for Measuring Pure Faradic Currents [Articolo su rivista]
S., Stefani; Seeber, Renato
abstract

A theory is elaborated in order to extract from a square wave voltammteric curve the relevant cyclic voltammetric responses, purged by the capacitive curve. The analysis of the response results much easier.

1982 - Electrochemical behaviour of complexes of copper(II) with 14-membered saturated tetra-aza macrocycles [Articolo su rivista]
Piero, Zanello; Seeber, Renato; Arnaldo, Cinquantini; Gian Antonio, Mazzocchin; Luigi, Fabbrizzi
abstract

The electrochemistry of copper(II) with three 14-membered saturated tetra-aza macrocyclic ligands (L) is reported. Both anodic and cathodic electrode processes involve complicated mechanisms; nevertheless cyclic voltammetry at high potential scan rates allowed evaluation of the E½ values for the couples [CuL]3+–[CuL]2+ and [CuL]2+–[CuL]+. Reduction and oxidation mechanisms have been studied and the half-life of the species [CuL]3+ anodically electrogenerated has been evaluated. The thermodynamic data are discussed.

1982 - Electrochemical behaviour of dinitrosylbis(triethyl phosphite)-cobalt(I) tetraphenylborate in acetonitrile [Articolo su rivista]
Seeber, Renato; Gabriele, Albertin; Gian Antonio, Mazzocchin
abstract

The electrochemical behaviour of the complex [Co{P(OEt)3}2(NO)2][BPh4] has been studied in acetonitrile, using platinum and mercury electrodes. It undergoes two subsequent reduction processes and a single oxidation process. In particular, the less cathodic one-electron reduction leads to the formation of the corresponding neutral species which is fairly stable in carefully deaerated solution.

1982 - Electrochemical investigation on the phosphine rhenium complexes [ReCl3(PMe2Ph)3] and [ReCl4(PMe2Ph)2] in an aprotic medium [Articolo su rivista]
Edoardo, Roncari; Ulderico, Mazzi; Seeber, Renato; Piero, Zanello
abstract

The cathodic and anodic behaviour of the complexes [ReCl3(PMe2Ph)3] and [ReCl4(PMe2Ph)2] has been studied at platinum and mercury electrodes in acetonitrile solvent. The reduction and oxidation products have been identified and both thermodynamic and kinetic aspects of the involved electrode mechanisms have been studied. In particular, new rhenium derivatives such as [ReCl3(PMe2Ph)3]+. [ReCl4(PMe2Ph)2]− and [ReCl3(PMe2Ph)2(MeCN)]+, have been prepared. In addition the species [ReCl4(PMe2Ph)2] has been obtained in a yield higher than that obtained by conventional chemical methods. The EView the MathML source values of several redox couples of rhenium complexes have been calculated and compared with the corresponding values of the technetium ones; the stability of analogous rhenium and technetium compounds has been also discussed.

1982 - Electrochemical investigations on pentagonal bipyramidal complexes of manganese(II), iron(II), and cobalt(II) with a heptadentate Schiff-base ligand in non-aqueous solvents [Articolo su rivista]
Arnaldo, Cinquantini; Seeber, Renato; Renzo, Cini
abstract

The voltammetric properties of the complexes formed by manganese(II), iron(II), and cobalt(II) ions with a heptadentate Schiff-base ligand have been investigated by cyclic voltammetry and controlled-potential coulometry at mercury and platinum electrodes in acetonitrile and dimethyl sulfoxide solvents.All the species undergo a single one-electron oxidation process leading to the corresponding stable metal(III) complexes which have been isolated and characterized.The cathodic behaviour of manganese(II) and iron(II) derivatives is very similar, in that the less cathodic process occurs at nearly equal potential values, indicating that the ligand moiety is reduced rather than the metal centre. The one-electron reduction process of the cobalt(II) complex leads to the corresponding cobalt(I) derivative, stable in the electrolysis solution.

1982 - Polarographic investigations on uranyl(VI) complexes in dimethylsulphoxide. V. 14-membered tetra-aza macrocycles [Articolo su rivista]
P., Zanello; Seeber, Renato; A., Cinquantini
abstract

The redox potentails of the complex between Uranyl(VI)/(V) redox couple and tetraazamacrocycles in organbic solvenbts is determined by polarogtraphic methods.

1982 - Theory of staircase voltammetry for simple electrode reactions [Articolo su rivista]
Stefani, S. t. e. f. a. n. o.; Seeber, Renato
abstract

Stalrcase voltammetry has been proposed as an electroanalyticaltechnlque which allows the obsarvatlon of pure faradaiccurrent. In the present paper the staircase wave form Isregarded as a hear sweep wlth a superlmposed perlodlcsawtooth perturbatlon. Wlth the sawtooth represented by aFowler serles, under sultable condltlons the theory of theclassical ac voltammetry can be applled. In thls way theoutput due to the sawtooth perturbatlon can be computed andits zeroes identified. The current at these polnts, whose locationdepends on electrode potentlal and klnetlc parametersof the charge transfer, Is that of the underlylng linear sweep,unaffected by the charging current. We describe a methodto flnd these points In an experimental stalrcase voltammogram,without knowlng a prior1 the klnetlc parameters of theprocess. These points descrlbe completely the linear sweepvoltammogram, so much so that It can be drawn by trlgonometriclnterpolatlon.

1982 - Voltammetric behaviour of transition metal complexes with extended - systems schiff base ligands [Articolo su rivista]
A., Cinquantini; Seeber, Renato; R., Cini; P., Zanello
abstract

The redox properties of complexes of Pd(II), Cu(II) and Ni(II) with the N,N′-ethylenebis(acetylacetoniminate) ligand, [(acac)2en]2−, have been investigated by cyclic voltammetry, chronoamperometry and controlled potential coulometry in acetonitrile solvent at platinum and mercury electrodes. The one-electron oxidation product of [Pd{(acac)2en}] has been identified as the dimeric cation [Pd{(acac)2en}]22+; the cathodic reduction of the starting complex originates the corresponding Pd1 species, stable only in the voltammetric time-scale. The electrooxidation process of [Cu{(acac)2en}] leads to the short-lived corresponding [CuL]+ species, from which free Cu+ or Cu2+ ions generate, depending on the working potential; the overall cathodic process appears to be rather complicated. The [Ni{(acac)2en}] complex undergoes an irreversible one-electron oxidation in the voltammetric time-scale, while the overall anodic process gives rise to a doubly charged cationic species, from which the parent compound can be electrolytically regenerated. Comparisons with the previously reported voltammetric properties of N,N′-ethylenebis(monothioacetylacetoniminato) metal complexes have been done; the effect on EView the MathML source values of substitution of oxygen for sulphur in the atom donor set is outlined.

1981 - ELECTROANALYTICAL STUDY OF THE KINETICS OF THE FAC-MER ISOMERIZATION OF [RECL(CO)3(PME2PH)2]+ IN ACETONITRILE [Articolo su rivista]
Seeber, Renato; G. A., Mazzocchin; E., Roncari; U., Mazzi
abstract

The isomerization offac-[ReCl(CO)3(PMe2Ph)2]+ to the corresponding meridional-trans isomer has been studied by electroanalytical techniques in MeCN solvent. Chronoamperometric and cyclic voltammetric data relative to the oxidation offac- andmer-[ReCl(CO)3(PMe2Ph)2] allow the accurate determination of the very high kinetic rate constant for the isomerization and permit discussion of thermodynamic aspects of redox homogeneous chemical reactions involving species of the different redox couples arising from the anodic processes.

1981 - Electrochemical synthesis of the N,N′-ethylenebis-(monothioacetylacetominiminato)cobalt(II), copper(II), nickel(II) and zinc(II) complexes [Articolo su rivista]
Arnaldo, Cinquantini; Seeber, Renato; Renzo, Cini; Piero, Zanello
abstract

Cobalt(II), copper(II), nickel(II) and zinc(II) complexes are synthesised via electrochemistry, by anodic polarisation of the corresponsding metal in a solution containing the ligand. The resulting complexed are then purified and characterised.

1981 - Explicit finite difference method in simulating electrode processes [Articolo su rivista]
Seeber, Renato; Stefani, S. t. e. f. a. n. o.
abstract

The expllclt flnite dlfference method is widely used In slmulatingelectroanalytical experiments; however, In many casesthe required computation amount becomes too large. Twomeans of overcomlng Nhls dlfflculty are descrlbed In this paper.In the first, a nonunlform space-tlme grld ls built up. Ifthe slre of space elements Increases at Increasing dlstancefrom the electrode according to a geometrlcal progression,It Is posslble to achieve also a nonunlform tlme dlscretlzatlon,such that the species concentratlons are modlfled wlth avarlable frequency decreaslng at Increasing distance from theelectrode. In the second, the transient behavior of theelectrode boundary Is improved leading to accurate values inthe computed response even at the early polnts after a suddenchange In equilibrium conditions. Efficlency and accuracyof the model are tesUed in simulating different electrodemechanlsms wlth different electroanalytical techniques.

1981 - Synthesis, reactivity, and electrochemical behaviour of new five-co-ordinate nitrosyl cobalt complexes [Articolo su rivista]
Gabriele, Albertin; Emilio, Bordignon; Gian Antonio, Mazzocchin; Angelo A., Orio; Seeber, Renato
abstract

The synthesis and characterization of some new five-co-ordinate mononitrosyl cobalt complexes of the type [CoL4(NO)][BPh4]2[L = P(OMe)3, P(OEt)3, or PPh(OEt)2] is described. The reactivity of these compounds with π-acceptor ligands such as NO, CO, phosphite, and isocyanide is discussed. Furthermore, the reaction with molecular oxygen and with halide ions (X–) has been investigated and a new method of obtaining the cations [CoXL3(NO)]+ has been achieved. The cathodic and anodic behaviour of the complex [Co{P(OEt)3}4(NO)][BPh4]2 at a platinum electrode in acetonitrile is also reported.

1981 - The equilibrium between monomeric and dimeric benzyl- and cyanobenzylpalladium(II) complexes in aprotic media [Articolo su rivista]
P., Zanello; Seeber, Renato; A., Cinquantini; R., Ros
abstract

The existence of an equilibrium between benzytchlorobistriphenylphosphinepalladium(II) and di - /* - chlorodibenzylbistriphenylphosphinepalladium(II) complex species,as well as between the corresponding cyanobenzylpalladium(ll) derivatives llas been already evidentiated [1, 2], butequilibrium constant values have not been measured

1981 - Voltammetric behaviour of transition metal complexes with extended π system schiff base ligands. N,N′-ethylenebis(monothioacetylacetoniminato)cobalt(II) and -palladium(II) complexes [Articolo su rivista]
A., Cinquantini; R., Cini; Seeber, Renato; P., Zanello
abstract

Redox properties of the complexes of Co(II) and Pd(II) with the extended π system N,N′-ethylenebis(monothioacetylacetoniminate) ligand are studied in acetonitrile solvent at platinum and mercury electrode by cyclic voltammetry and controlled potential coulometry. The Co(II) complex undergoes a reduction process giving rise to the corresponding Co(I) species, stable in the electrolysis solution; the oxidation product, [Co{(sacac)2en}]+, stable in solid state, decomposes in solution phase.The electroreduction of the Pd(II) complex occurs by two subsequent cathodic processes, originating the unstable species [Pd{(sacac)2en}]− and [Pd{(sacac)2en}]2−. The anodic oxidation product is the species [Pd{(sacac)2en}]2+, from which the starting complex can be electrolytically regenerated.

1981 - Voltammetric behaviour of transition metal complexes with extended π systems schiff base ligands [Articolo su rivista]
A., Cinquantini; R., Cini; Seeber, Renato; P., Zanello
abstract

The cathodic and anodic behaviour of the complex formed by Cu(II) and the extended π-system ligand N,N′-ethylenebis(monothioacetylacetonimine), [Cu{(sacac)2en}], was investigated in acetonitrile solvent at platinum and mercury electrodes by cyclic voltammetry, chronoamperometry and controlled potential coulometry. The first reduction process gives rise to the corresponding Cu(I) complex, stable in the electrolysis solution; the one at more negative potentials leads to unstable species. The oxidation products are a cationic compound with z=2, from which the starting ligand can be regenerated electrolytically, and free Cu(I) or Cu(II) ions, depending on the working potential.

1980 - Electrochemical behaviour of five-co-ordinate nitrosyl cobalt complexes in an aprotic medium [Articolo su rivista]
Seeber, Renato; Gian Antonio, Mazzocchin; Gabriele, Albertin; Emilio, Bordignon
abstract

The cathodic and anodic behaviour of some five-co-ordinated nitrosyl cobalt complexes of the type [CoXL3(NO)][BPh4][X = Cl or I, L = P(OEt)3 or P(OMe)3] has been investigated at platinum electrodes in acetonitrile solvent. Four-co-ordinated mononitrosyl cobalt compounds of formula [CoL3,(NO)] are formed via an e.c.e. type reduction mechanism (electron transfer followed by a chemical reaction followed by electron transfer). The anodic oxidation of these [CoL3(NO)] compounds has also been studied. The [CoXL3(NO)][BPh4] complexes with L = P(OEt)3 undergo a complicated oxidation process leading to the dinitrosyl [CoL2(NO)2][BPh4] and [CoXL(NO)2] compounds and to species containing no nitrosyl ligand. The chemical reactions associated with the charge-transfer steps involve traces of water.

1980 - Electrochemical behaviour ofcis-dichloro(arylisocyanide)(tertiaryphosphine) platinum (II) and palladium(II) complexes in an aprotic solvent [Articolo su rivista]
Piero, Zanello; Seeber, Renato; Arnaldo, Cinquantini; Bruno, Crociani
abstract

The electrochemical behaviour of neutral platinum(II) and palladium(II) isocyanide complexes has been investigated in an aprotic medium at platinum and mercury electrodes. Platinum(II) derivatives are reduced to platinum(0) species, Palladium(II) compounds give rise to palladium(0) species at room temperature, while at 0° it is possible to obtain palladium(I) compounds.

1980 - Electrochemical investigations of cationictrans-haloarylisocyanidebis(tertiaryphosphino)platinum (II) complexes [Articolo su rivista]
Piero, Zanello; Seeber, Renato; Bruno, Crociani; Marino, Nicolini
abstract

The electrochemical behaviour of a series of cationic platinum(II) isocyanide complexes has been studied in acetonitrile. All the tested compounds are oxidized at a platinum electrode via a two-electron process and reduced at a platinum or mercury electrode via two successive one-electron steps. The anodic step involves the formation of platinum(IV) complexes. The main reduction product formed in correspondence to the first cathodic process is a stable dimer platinum(I) containing bridging isocyanide ligands. Platinum(0) species are formed in the subsequent reduction step.

1980 - Voltammetric behaviour of technetium99 complexes with π-acceptor ligands in aprotic medium. III. Oxidation of technetium(I) complexes with phosphine and carbon monoxide ligands [Articolo su rivista]
U., Mazzi; E., Roncari; Seeber, Renato; G. A., Mazzocchin
abstract

The anodic behaviour of TcCl(CO)2(PMe2Ph)3 and TcCl(CO)3(PMe2Ph)2 complexes has been studied in acetonitrile solvent. Both the complex undergo an overall two-electron oxidation process with the formation of Tc(III) species; the electrode mechanism leading to their formation has been studied. In particular the [TcCl(CO)(MeCN)2(PMe2Ph)3][ClO4]2 compound has been isolated and characterized.

1980 - Voltammetric behaviour of transition metal complexes with extended π systems schiff base ligands The N,N′-ethylenebis(monothyoacetylaceton-iminato)nickel(II) complex [Articolo su rivista]
A., Cinquantini; R., Cini; Seeber, Renato; P., Zanello
abstract

Cyclic voltammetry, chronoamperometry and controlled potential coulometry are employed to study the cathodic and anodic behavior of the complex between Ni(II) and the extended rr system N,N'-ethylenebis(monothioacetylacetonimine) in cetonitrile solvent at platinum and mercury electrodes The reduction process leads to the corresponding Ni(I) complex, stable in the electrolysis solution;the oxidation product proves to be a fourcharged cationic complex with structural features very similar to those of the starting compound.The initial complex species can be electrolytically regenerated both from the oxidized and reduced species in a quantitative yield

1979 - Voltammetric investigations on mercury(II) and silver(I) polyamine complexes in dimethyl sulphoxide solution [Articolo su rivista]
Seeber, Renato; Piero, Zanello; Arnaldo, Cinquantini; Gian Antonio, Mazzocchin
abstract

he formation of mercury(II) and silver(I) complexes with polyamines in dimethyl sulphoxide solvent has been studied by anodic dissolution of mercury and silver electrodes in the presence of ethylenediamine, sym-dimethyl-ethylenediamine, NNN′N′-tetramethylethylenediamine, propane-1,3-diamine, and triethylenetetramine. D.c. polarography at a dropping mercury electrode, d.c. voltammetry at a solid electrode with periodical renewal of the diffusion layer, cyclic voltammetry, and controlled-potential coulometry has allowed a determination of electrode reaction orders, the complexation steps, and the stability constants of the complex species arising at the electrode surface. Short-lived species have been detected by cyclic voltammetry and the species formed in the bulk of the solution have been identified by coulometry.

1978 - Anodic Oxidation of Diphenylselenide in Aprotic Solvent [Articolo su rivista]
Seeber, Renato; A., Cinquantini; P., Zanello; G. A., Mazzocchin
abstract

The cathodic reduction of diphenylselenide in aprotic medium is studied with respect to reaction mechanism and final electrolysis products

1978 - Electroanalytical investigation on the stability of tetracoordinate nickel(I) complexes [Articolo su rivista]
Seeber, Renato; Gian Antonio, Mazzocchin; Gino, Bontempelli; Franco, Magno
abstract

The stability of tetracoordinate nickel(I) complexes, of the type [Ni(CN)2P2]− (P=substituted phosphine), generated by cathodic reduction of the parent nickel(II) complexes, has been studied by cyclic voltammetry and double potential step techniques. Evidence has been obtained that nickel(I) complexes decay to the dimeric species Ni2(CN)2P4 via a first order chemical reaction the rate determining step being the release of a cyanide ion leading to the radical species [Ni(CN)P2]. The experimental trend obtained for the first order kinetic constants has been explained on the basis of the different “trans-effect” induced by a cyanide ligand in comparison with that induced by a phosphine group and taking into account the different basic character of the phosphine ligands.

1978 - Electrochemical Reduction of Benzenesulphenyl Chloride in Aprotic Solvent [Articolo su rivista]
G., Bontempelli; F., Magno; Seeber, Renato; G. A., Mazzocchin
abstract

The reduction mechanism of benxenesulphenyl chloride at a Pt electrode in aprotic solvent is studied and elucidated

1978 - Polarographic Investigation on Uranyl(VI) Complexes in Dimethylsulfoxide. Part IV. Ammonia and Polyamines [Articolo su rivista]
P., Zanello; A., Cinquantini; Seeber, Renato; G., Pieri
abstract

Complex formation of uranyl(VI) ion with ammonia and some polyamines has been studied by the polarographic technique at 25 °C in 0.1 M TBAP-DMSO solutions. The polarographic data could be explained in terms of the formation of the following complexes: [UO2(L)n]2+ where L = NH3, en, dmen and n = 2, 3; L = tn, hexn and n = 1, 2; L = tmen and n = 3; L = trien and n = 2. The relative coordinating abilities of the ligands have been discussed on the basis of the calculated βOx/βRed values.

1978 - Voltammetric Behaviour of Technetium99 Complexes with -Acceptor Ligands in Aprotic Medium. Part I. Oxidation of TcCl3(PMe2Ph2) [Articolo su rivista]
G. A., Mazzocchin; Seeber, Renato; U., Mazzi; E., Roncari
abstract

The redox properties of a Tc complex are studied in order to the define the electrode mechanisms and the stability potential range

1978 - Voltammetric Behaviour of Technetium99 Complexes with -Accptor Ligands in Aprotic Medium. Part II. Reduction of TcCl3(PMe2Ph)3 and of TcCl4(PMe2Ph)2 [Articolo su rivista]
G. A., Mazzocchin; Seeber, Renato; U., Mazzi; E., Roncari
abstract

The electrode processes relative to oxidation and reduction of Tc99 compounds, together with the relevant stability potential range are studied, aiming at defining the characteristics suitable for application in diagnostics.

1978 - Voltammetric Investigations on the Interaction between Thorium(IV) and Electrogenerated Superoxide Ion [Articolo su rivista]
P., Zanello; A., Cinquantini; Seeber, Renato; G. A., Mazzocchin
abstract

Short-living superoxide ion is electrogenerated in aprotic solvent and its reactivity towards Thorium (IV) ion is studied

1978 - Voltammetric behaviour of cis-diarylbis(triethylphosphine)platinum(II) complexes [Articolo su rivista]
Seeber, Renato; G. A., Mazzocchin; D., Minniti; R., Romeo; P., Uguagliati; U., Belluco
abstract

The voltammetric behaviour of cis-[Pt(PEt3)2(YC6H4)2] complexes in acetonitrile has been investigated by cyclic voltammetry and controlled potential coulometry. The oxidation potential increases linearly with increasing electron-withdrawing ability of the Y substituent in the platinum-bonded aryl ligand. The data are related to studies of electrophilic Pt—C bond cleavage.

1977 - A Study of the Reaction Kinetics of Electrogenerated Superoxide Ion with Benzylbromide [Articolo su rivista]
F., Magno; Seeber, Renato; S., Valcher
abstract

The decay kinetics of the unstable superoxide ion in the presence of a reactant is studied in aprotic medium

1976 - An Investigation on the Cathodic Behaviour of Phenylbenzoate in Dimethylformamide Solution [Articolo su rivista]
Seeber, Renato; F., Magno; G., Bontempelli; G. A., Mazzocchin
abstract

The wide cathodic range of dimethylformamide is exploited to study the reduction mechanism, at a Pt electrode, for the reduction of phenylbenzoate

1976 - Electroanalytical Evidences for the Instability of Hydrogen Tetrafluoroborate in Acetonitrile [Articolo su rivista]
G., Bontempelli; Seeber, Renato; S., Zecchin; G., Schiavon
abstract

HBF4 is demontrated to decompose to HF and BF3 in acetonitrile solvent. Electrochemistry is used for demonstration

1976 - Electrochemical Reduction of Triphenyltin Chloride in Aprotic Medium [Articolo su rivista]
G. A., Mazzocchin; Seeber, Renato; G., Bontempelli
abstract

The electrode mechanism for the reduction of theSnPh3Cl organometallic species in aprotic solvent is defined

1975 - Cathodic Reduction of Carbon Disulfide in Aprotic Medium [Articolo su rivista]
G., Bontempelli; F., Magno; G. A., Mazzocchin; Seeber, Renato
abstract

The electrode mechanism of cathodic reduction of CS2 in aprotic solvent is studied

1974 - Anodic Oxidation of Diphenylsulphoxide in Aprotic Solvent [Articolo su rivista]
G., Bontempelli; F., Magno; G. A., Mazzocchin; Seeber, Renato
abstract

Mechanism and products of the oxidation of diphenylsulphoxide at a Pt electrode are studied

1974 - Electrode Processes of Oxygenated Nitrogen Compounds in Acetonitrile Medium. Part II. Nitrite Ion [Articolo su rivista]
G., Bontempelli; G. A., Mazzocchin; F., Magno; Seeber, Renato
abstract

The electrochemical behaviour of nitrite ions in acetonitrile medium has been investigated at platinum electrodes. The nitrite ion undergoes three consecutive oxidation steps with the formation of NO and NO3−, of N2O4 and of NO2+ respectively.