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MANUEL IMPERATO

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Pubblicazioni

2024 - Dual Structure of a Vanadyl-Based Molecular Qubit Containing a Bis(β-diketonato) Ligand [Articolo su rivista]
Imperato, Manuel; Nicolini, Alessio; Boniburini, Matteo; Sartini, Daniele; Benassi, Enrico; Chiesa, Mario; Gigli, Lara; Liao, Yu-Kai; Raza, Arsen; Salvadori, Enrico; Sorace, Lorenzo; Cornia, Andrea
abstract

We designed [VO(bdhb)] (1′) as a new electronic qubit containing an oxovanadium(IV) ion (S = 1/2) embraced by a single bis(β-diketonato) ligand [H2bdhb = 1,3-bis(3,5-dioxo-1-hexyl)benzene]. The synthesis afforded three different crystal phases, all of which unexpectedly contain dimers with formula [(VO)2(bdhb)2] (1). A trigonal form (1h) with a honeycomb structure and 46% of solvent-accessible voids quantitatively transforms over time into a monoclinic solvatomorph 1m and minor amounts of a triclinic solventless phase (1a). In a static magnetic field, 1h and 1m have detectably slow magnetic relaxation at low temperatures through quantum tunneling and Raman mechanisms. Angle-resolved electron paramagnetic resonance (EPR) spectra on single crystals revealed signatures of low-dimensional magnetic behavior, which is solvatomorph-dependent, being the closest interdimer V···V separations (6.7−7.5 Å) much shorter than intramolecular V···V distances (11.9−12.1 Å). According to 1H diffusion ordered spectroscopy (DOSY) and EPR experiments, the complex adopts the desired monomeric structure in organic solution and its geometry was inferred from density functional theory (DFT) calculations. Spin relaxation measurements in a frozen toluene-d8/CD2Cl2 matrix yielded Tm values reaching 13 μs at 10 K, and coherent spin manipulations were demonstrated by Rabi nutation experiments at 70 K. The neutral quasi-macrocyclic structure, featuring nuclear spin-free donors and additional possibilities for chemical functionalization, makes 1′ a new convenient spin-coherent building block in quantum technologies.

2024 - Quantum Spin Coherence and Electron Spin Distribution Channels in Vanadyl-containing Lantern Complexes [Articolo su rivista]
Imperato, Manuel; Nicolini, Alessio; Borsari, Marco; Briganti, Matteo; Chiesa, Mario; Liao, Yu-Kai; Ranieri, Antonio; Raza, Arsen; Salvadori, Enrico; Sorace, Lorenzo; Cornia, Andrea
abstract

We herein investigate the heterobimetallic lantern complexes [PtVO(SOCR)4] as charge neutral electronic qubits based on vanadyl complexes (S = 1/2) with nuclear spin-free donor atoms. The derivatives with R = Me (1) and Ph (2) give highly resolved X-band EPR spectra in frozen CH2Cl2/toluene solution, which evidence the usual hyperfine coupling to the 51V nucleus (I = 7/2) and an additional superhyperfine interaction with the I = 1/2 nucleus of the 195Pt isotope (natural abundance ca. 34%). DFT calculations ascribe the spin-density delocalization on the Pt2+ ion to a combination of π and δ pathways, with the former representing the predominant channel. Spin relaxation measurements in frozen CD2Cl2/toluene-d8 solution between 90 and 10 K yield Tm values (1-6 μs in 1 and 2-11 μs in 2) which match or even outperform those of known vanadyl-based qubits in similar matrices. Coherent spin manipulations indeed prove possible at 70 K, as shown by the observation of Rabi oscillations in nutation experiments. The results indicate that the heavy Group 10 metal is not detrimental to the coherence properties of the vanadyl moiety and that Pt-VO lanterns can be used as robust spin-coherent building blocks in materials science and quantum technologies.

2021 - Development of Graphite-Epoxy Composites for Bipolar Plates in PEM Fuel Cells [Abstract in Atti di Convegno]
Roncaglia, Fabrizio; Spinelli, Luca; Imperato, Manuel; Biagi, Roberto; Romagnoli, Marcello; di Bona, Alessandro; Mucci, Adele
abstract

Graphite-Epoxy composites can be a good alternative to metals and metal alloys to build Bipolar Plates (BPs),1 that are important components of Proton Exchange Membrane Fuel Cells (PEMFC), mainly used in hydrogen-powered electric vehicles. We are currently working2 on the preparation of graphite-epoxy composites, suitable for manufacturing BPs meeting the technical targets for 2025.3 Among the overall properties expected for BPs, we are mainly focussing on conductivity, flexural strength and permeability and we are tuning the preparation steps, i.e. composite formulation, mixing and molding, trying to optimize these properties. We compared different resin to filler ratios, dry and wet mixing, mechanical and magnetic stirring and different temperature and pressure ranges. A two-level full factorial Design Of Experiment (DOE) approach was performed to analyze the molding parameters. We observed substantial changes in the properties of the composites, depending on the type of graphite, the mixing method, the epoxy resin to filler ratio and the molding pressure, temperature and time. The results of these studies will be presented.

2021 - Graphite-epoxy composites for fuel-cell bipolar plates: Wet vs dry mixing and role of the design of experiment in the optimization of molding parameters [Articolo su rivista]
Roncaglia, Fabrizio; Romagnoli, Marcello; Incudini, Simone; Santini, Elena; Imperato, Manuel; Spinelli, Luca; di Bona, Alessandro; Biagi, Roberto; Mucci, Adele
abstract

Bipolar plates (BPs) are key components of Proton Exchange Membrane Fuel Cells mainly employed in hydrogen-powered electric vehicles. Here, a reliable and detailed experimental method to prepare graphite-epoxy composites suitable for manufacturing BPs is reported. Dry and wet mixing procedures were compared and a simple composition was optimized, with regard to electrical conductivity. The adoption of wet mixing of the components and the choice of the conductive filler were the main factors that contributed to the achievement of good electrical and mechanical properties. The addition of a small percentage of carbon black as a secondary filler was also advantageous. The effects of molding parameters (pressure, temperature, and time) on a graphite-epoxy composite of fixed-composition were modeled using a Design Of Experiments approach, which provided valuable information for future improvements. Conductivity values well above the US DOE requirements were obtained

2020 - Copper-Catalysed “Activators Regenerated by Electron Transfer” “Atom Transfer Radical Polymerisation” of Styrene from a Bifunctional Initiator in Ethyl Acetate/Ethanol, Using Ascorbic Acid/Sodium Carbonate as Reducing System [Articolo su rivista]
Braidi, Niccolo'; Buffagni, Mirko; Ghelfi, Franco; Imperato, Manuel; Menabue, Alberto; Parenti, Francesca; Gennaro, Armando; Isse, Abdirisak A.; Bedogni, Elena; Bonifaci, Luisa; Cavalca, Gianfranco; Ferrando, Angelo; Longo, Aldo; Morandini, Ida
abstract

2019 - EFFECT OF COMPRESSION MOLDING PARAMETERS ON GRAPHITE/EPOXY COMPOSITE BIPOLAR PLATES [Poster]
Roncaglia, Fabrizio; DI BONA, Alessandro; Imperato, Manuel; Biagi, Roberto; Romagnoli, Marcello; Mucci, Adele
abstract

2019 - Optoelectronic Properties of A‐π‐D‐π‐A Thiophene‐Based Materials with a Dithienosilole Core: An Experimental and Theoretical Study [Articolo su rivista]
Parenti, Francesca; Caselli, Monica; Vanossi, Davide; Buffagni, Mirko; Imperato, Manuel; Pigani, Laura; Mucci, Adele
abstract

Two A‐π‐D‐π‐A thiophene based small molecules, with a central dithienosilole core and dicyanovinyl end groups were synthesized. These compounds differ only for the presence of alkyl and alkylsulfanyl chains, respectively, on thiophene beta positions. The computational data together with the spectroscopic and electrochemical findings (obtained by means of absorption, steady‐state/time‐resolved emission techniques and cyclic voltammetry) revealed that both molecules possess low electronic and optical band gaps, broad absorption spectra and a good stability both in p and n‐doping states, properties that make them suitable for optoelectronic applications. In either compounds the HOMO‐LUMO transition involves an intramolecular charge transfer from the electron‐donor dithienosilole unit to the two terminal electron‐acceptor DCV groups. A marked positive emission solvatochromism was observed for both molecules and was interpreted on the basis of the symmetry breaking in the S1 excited state. The two synthesized compounds were also compared to their shorter precursors and to similar oligothiophenes to understand how the nature of the building block influences the characteristics of the final materials. Furthermore, it was possible to better understand the contribution of the sulfur atom in modulating the optical properties of the small molecules studied.