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Submitted by Lucas Cesar Gomes Squillante null (lucasquillante@hotmail.com) on 2018-01-19T17:39:44Z No. of bitstreams: 1 Dissertação de Mestrado Lucas Cesar Gomes Squillante.pdf: 13112928 bytes, checksum: b4a4e7a0bc1cbdc48db3b829714e912d (MD5) / Approved for entry into archive by Ana Paula Santulo Custódio de Medeiros null (asantulo@rc.unesp.br) on 2018-01-22T13:15:43Z (GMT) No. of bitstreams: 1 squillante_lcg_me_rcla.pdf: 13113103 bytes, checksum: ee63e961b931fa78df69438fc268b5f2 (MD5) / Made available in DSpace on 2018-01-22T13:15:43Z (GMT). No. of bitstreams: 1 squillante_lcg_me_rcla.pdf: 13113103 bytes, checksum: ee63e961b931fa78df69438fc268b5f2 (MD5) Previous issue date: 2017-11-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O fenômeno da supercondutividade atualmente um dos mais relevantes tópicos na Física da Matéria Condensada, tornando os sistemas fortemente correlacionados um tópico de grande interesse devido à possibilidade de estudar os aspectos fundamentas da interação elétron-elétron, que são o âmago da supercondutividade. Desta forma, a classe de condutores moleculares (TMTTF)2X (onde TMTTF é tetrametiltetratiafuvaleno e X é um contra-ânion) desempenha um papel sistemático e fundamental no estudo de tais aspectos de correlação. Nesta tese de mestrado, os materiais de interesse foram o (TMTTF)2PF6-H12 e o (TMTTF)2PF6-D12, onde uma anomalia na constante dielétrica diferente para os dois sais foi observada na transição ferroelétrica de Mott-Hubbard através de medidas de constante dielétrica quasi-estática no eixo c* (contribuição iônica) e o comportamento tipo relaxor da variante hidrogenada foi analisado com base na teoria de campo médio. Uma revisão de transições de fase clássicas e quânticas também foi realizada com o objetivo de estudar o chamado efeito magneto-calórico para o modelo do paramagneto de Brillouin (o parâmetro de Grüneisen magnético), que é uma grandeza Física única e poderosa para detectar experimentalmente uma transição de fase quântica induzida por campo magnético em um sistema real. Ainda, um estudo comparativo entre as fases delta (hexagonal) e delta' (tetragonal) da liga binária FeSe1-x foi realizado e monocristais foram sintetizados utilizando o método de síntese de estado sólido visando atingir a fase delta. / The phenomenon of superconductivity is currently one of the most relevant topics in Solid State Physics, making strongly correlated systems a very highattractive topic due to the possibility of studying the fundamental aspects of the electron-electron interaction that are the core of superconductivity. Thus, the class of molecular conductors (TMTTF)2X (where TMTTF is tetramethyltetrathiafuvalene and X is a counter-anion) plays a systematic and fundamental role to study such correlation aspects. In this Master Thesis, the materials of interest were the (TMTTF)2PF6-H12 and (TMTTF)2PF6-D12, where a different dielectric anomaly at the Mott-Hubbard ferroelectric transition was observed for the two salts and the relaxor behavior of the hydrogenated variant was analysed based on the mean-field theory. A review of classical and quantum phase transitions was performed aiming to study the so-called magneto-caloric effect (the magnetic Grüneisen parameter) for the Brillouin paramagnet model, which is a powerful and unique physical quantity to experimentally detect a quantum phase transition induced by magnetic field in a real system. Also, a comparative study between the (hexagonal) and (tetragonal) phases of the binary alloy FeSe1-x was performed and single-crystals were synthesized employing the solid-state reaction method in order to achieve the phase.

Research in the fields of molecular conductors and magnets over the past four decades has involved collaborative efforts of chemists and physicists whose common goal is to design useful materials composed of molecular building blocks. Of particular interest are materials whose properties can be tuned by electronic or steric changes in the molecular sub-units. The research on TCNQ derivatives described in this thesis was inspired by the observation that, although a vast amount of research has been directed at understanding binary M(TCNQ•-) materials, analogous compounds based on substituted TCNQ acceptors are surprisingly scarce. Single crystals of a new structure type for the M+(TCNQ)•- binary family were isolated from reactions of two dihalogenated TCNQ derivatives with Cu(I) ions, namely Cu(TCNQX2) (X = Cl, Br). The new 3-D compound Cu(TCNQCl2) exhibits the highest conductivity of the M+(TCNQ)•- series to date, despite the greater separation of TCNQCl2 units as compared to other derivatives. Compounds of lower dimensionality were also obtained, namely the 2-D Cu(TCNQBr2)(CH3CN) and 1-D Cu(TCNQI2)(CH3CN)2 phases. Several 2p-3d heterospin molecular magnets were also synthesized. For example a “magnetic sponge” material based on a 2-D hexagonal framework of composition {[Mn2(TCNQF4)(CH3OH)7.5(H2O)0.5]-(TCNQF4)2•7.5CH3OH}∞, as well as molecular magnets based on first row metal ions and TCNQF4 ligands of composition MII(TCNQF4)-•(TCNQF42-)0.5(CH3CN) (M = Mn, Co) were prepared. In addition, unprecedented isostructural 2-D frameworks based on combinations of first row metal ions with TCNQBr2 radicals of composition [M(TCNQBr2)2(H2O)2]∞ (M = Mn, Zn) were synthesized. Lanthanide chemistry is also described in this dissertation. A series of mononuclear Ln-TCNQF4 heterospin complexes of composition {MIII[TCNQF4]2[H2O]x}(TCNQF4)(3H2O) (M = La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er and Yb) was also obtained which exhibit remarkable properties. In this family of compounds there exists an unprecedented subtle interplay between single molecule magnetic behavior and phonon bottleneck effect behavior for the Tb analogue. Magnetic ordering was observed for the Sm analogue. A homologous series of 1-D materials based on alternating lanthanide ions and hexacyanometallates of formula {[Ln(tptz)(H2O)4Fe(CN)6]•8H2O}∞ (Ln = Pr, Nd, Sm, Eu, Gd, Tb) was obtained and a detailed magnetic study provided incontrovertible evidence that the SmIII-[FeIII(CN)6]3- compound exhibits ferromagnetic and not antiferromagnetic coupling as had been reported for related 1-D chains.

Ce travail de thèse explore la capacité des ligands anilates d’être employés pour la préparation de nouveaux matériaux moléculaires fonctionnels avec des propriétés magnétiques et de conduction électrique. Les anilates, qui sont les dérivés du 2,5-dihydroxy-1,4- benzoquinone substitués sur les positions 3 et 6, ont été sélectionnés comme ligands puisque leurs caractéristiques électroniques et structurales, leurs modalités de coordination et leur capacité de médiation des interactions de super-échange magnétique en font d’excellents ligands pour la préparation de ces matériaux. Plusieurs ligands anilates ont été utilisés pour le design et la préparation d'une nouvelle classe de complexes paramagnétiques octaédriques tris-chélates de formule générale [MIII(X2An)3]3- (MIII = Cr, Fe; X = Cl, Br, I, H, Cl/CN, An = C6O4 2- = anilate). Ces complexes métalliques paramagnétiques ont été complètement caractérisés et utilisés comme briques moléculaires pour la préparation de i) une nouvelle classe de ferriaimants moléculaires, dans laquelle la modification des substituants sur le ligand permet de modifier les interactions entre les centres métalliques, et, par conséquent, les propriétés magnétiques, ii) des conducteurs paramagnétiques moléculaires obtenus par combinaison avec le donneur organique BEDT-TTF, iii) une série de conducteurs moléculaires chiraux obtenus par combinaison du donneur organique TM-BEDT-TTF avec des couches hétéro-bimétalliques anioniques obtenues par association in situ de complexes tris(chloranilate)ferrate(III) et des ions potassium. En outre, ont été synthétisés de nouveaux dérivés anilates avec des propriétés electroactives et de luminescence, afin de démontrer la capacité du motif anilate d’être fonctionnalisé avec différents substituants comme porteurs de propriétés physiques spécifiques. / This work explores the potential of anilate-based ligands in the synthesis of new rational designed functional molecular materials exhibiting improved magnetic and conducting properties. Anilates, namely 3,6-disubstitued 2,5-dihyroxy-1,4- benzoquinones in their dianionic form, have been selected as ligands since their electronic/structural features, coordination modes and ability to mediate magnetic exchange interactions between coordinated metal centers make them potential candidates for the preparation of theabove-mentioned materials. Various anilate derivatives have been used for the preparation of a family of rationally designed tris-chelated octahedral paramagnetic metal complexes of general formula [MIII(X2An)3]3- (MIII = Cr, Fe; X = Cl, Br, I, H, Cl/CN, An = C6O4 2- = anilate). These paramagnetic metal complexes have been thoroughly characterized and used, in turn, as molecular building blocks for the preparation of i) a family of molecule-based magnets, where subtle changes in the nature of the substituents on the anilate moiety were employed as “adjusting screws” in tuning the magnitude of the magnetic interaction between the metals, and thus, the magnetic properties, ii) hybrid paramagnetic molecular conductors in combination with the BEDT-TTF organic donor, iii) a complete series of isostructural chiral molecular conductors obtained by combining the TMBEDT- TTF chiral donor with 2D heterobimetallic anionic layers obtained in situ by the self-assembling of tris (chloranilato)ferrate(III) metal complexes and potassium cations.Moreover, novel anilate derivatives showing electroactive and luminescent properties have been further synthesized, highlighting the versatility of the anilate moiety to be functionalized with suitable substituents carrying selected physical properties.

Ce travail a concerné la préparation des premières nanoparticules de supraconducteurs moléculaires dont la croissance en solution a pu être contrôlée par l'ajout de molécules amphiphiles neutres (amines, imines, acides carboxyliques). Notre étude s'est principalement focalisée sur les sels de Bechgaard (TMTSF)2X (TMTSF : tétraméthyltétrasélénafulvalène, X = ClO4 ou PF6) et sur le dérivé (BEDT-TTF)2I3 (BEDT-TTF : bis(éthylènedithio)tétrathiafulvalène). La taille, la morphologie et l'état de dispersion des nanoparticules ont été contrôlés par la nature et la concentration du structurant amphiphile. Ces nanoparticules ont été caractérisées par des méthodes spectroscopiques (IR, Raman, UV-visible, spectrométrie de photoélectrons), diffractométriques et microscopiques (microscopie électronique à transmission et AFM). Elles présentent une transition vers un état supraconducteur mise en évidence par des mesures de résistivité électrique ou de susceptibilité magnétique. Finalement, le pouvoir thermoélectrique des nano-objets de (BEDT-TTF)2I3 a été évalué. Des mesures préliminaires de facteur de mérite thermoélectrique (ZT) en font des candidats potentiels pour la réalisation de modules thermoélectriques organiques. / In this work, we described the preparation of the first nanoparticles of molecule-based superconductors for which the growth has been controlled by the addition of neutral amphiphilic molecules (such as amines, imines, carboxylic acids). Our study focused on Bechgaard salts (TMTSF)2X (TMTSF: tetramethyltetraselenafulvalene, X = ClO4 or PF6) and (BEDT-TTF)2I3 (BEDT-TTF: bis(ethylenedithio)tetrathiafulvalene). The size, the morphology and the state of dispersion of the nanoparticles have been controlled by the nature and the concentration of the amphiphilic structuring agent. The particles have been characterized by spectroscopic methods (IR, Raman, UV-visible, photoelectron spectroscopy), X-Ray diffraction and microscopy (TEM and AFM). Small particles underwent a transition to a superconducting state, as evidenced by electrical resistivity or magnetic susceptibility measurements. Finally, the thermoelectric power of nano-objects of (BEDT-TTF)2I3 has been evaluated. Preliminary measurements of the thermoelectric figure of merit (ZT) make them potential candidates for future organic-based thermoelectric generators.