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Synthesis, physical properties and processing of multifunctional molecular materials

Sessini, Elisa (2012) Synthesis, physical properties and processing of multifunctional molecular materials. [Doctoral Thesis]

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Abstract

New multifunctional materials (MMMs) where conductivity and magnetism coexist or, in some cases, interact, have been prepared and fully characterized as quality crystals or thin films. [(BDH-TTP)6] [Fe(croc)3] ·CH2Cl2 (1), where paramagnetism is due to isolated Fe(III) metal ions with S = 5/2 ground state of the anionic [Fe(croc)3]3- complexes and conductivity originates from BDH-TTP organic donor in k-type packing, has been obtained. When applying a pressure higher than 7 kbar, (1) behaves as a metal down to low temperature (2 K). The isostructural [(BDH-TTP)6] [Ga(croc)3] ·CH2Cl2 (2) behaves as a metal down to ~ 100 K. [Mn(5-MeOsaltmen)(acetone)]2[Ni(dmit)2]6 (3), where single molecule magnet (SMM) behavior of the Mn(III) dimers coexists with the semiconducting behavior due to the d8 square planar complexes of [Ni(dmit)2]n- (n = 0 or 1), has been obtained. Deviations of the magnetic properties from that of isolated [Mn2]2+ SMMs based, have been found, may be due to interactions such as [Ni(dmit)2]n- ⋯ [Ni(dmit)2]n-, [Mn2]2+ ⋯ [Mn2]2+, [Ni(dmit)2]n- ⋯ [Mn2]2+, demonstrating the tunability of the SMM behavior by changing the combination of both SMMs and conducting building blocks. Processing of these materials has been performed by embedding different magnetic conducting carriers into polymer. the By poly(3,4 ethylenedioxythiophene) potentiostatic and (PEDOT), potentiodynamic electropolymerization, PEDOT films doped with magnetic polyoxometalate (POM) [Co4(H2O)2(PW9O34)2]10- have been obtained; the film obtained by using the potentiodynamic method is more stable than the analogous material obtained by applying a constant potential, when subjected to potential cycles in acetonitrile solutions of LiClO4 and TBAClO4. In situ chemically oxidized PEDOT thin films, doped with [FeIICrIII(ox)3]- anions, have been obtained. These materials show ferromagnetic coupling due to Fe(II)-Cr(III) ions and the presence of some disorder and a superparamagnetic behavior, while the conductivity depends of the EDOT : anion ratio. The PEDOT:PSS (PSS = polystyrenesulfonic acid) aqueous dispersion, has been used for coating negatively charged, Cs0.46Ni[Fe(CN)6]0.94, nanoparticles (NPs) and a high conducting thin film showing superparamagnetic properties due to the NPs has been obtained. Magnetoresistance measurements at low temperature reveal the existence of an interplay between the magnetic and conducting lattices.

Item Type:Doctoral Thesis
Date:29 March 2012
Tutor:Mercuri, Maria Laura, Coronado, Eugenio
PhD classes:Ciclo 24 > Scienze e tecnologie chimiche
Coordinator:Casu, Mariano, Corrias, Anna
Institution:Universita' degli Studi di Cagliari
Divisions:Dipartimenti (fino a dicembre 2011) > Dipartimento di Scienze chimiche
Subjects:Area 03 - Scienze chimiche > CHIM/03 Chimica generale e inorganica
Uncontrolled Keywords:Materiali multifunzionali, magnetismo, conduttività, PEDOT, multifunctional materials, magnetism, conductivity
ID Code:758
Deposited On:30 Mar 2012 12:43

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