Valence tautomerism in cobalt o-dioxolene complexes

• Ano de defesa: 2021
• Autor(a) principal: Ludmila Maria Diniz Leroy
• Orientador(a): Carlos Basílio Pinheiro
• Banca de defesa: Ângelo Malachias de Souza, Javier Alcides Ellena, Klaus Krambrock, Eduardo Granado Monteiro da Silva
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Minas Gerais
• Programa de Pós-Graduação: Programa de Pós-Graduação em Física
• Departamento: ICX - DEPARTAMENTO DE FÍSICA
• País: Brasil
• Palavras-chave em Português: Bistability; Valence tautomerism; Cobalt complexes
• Link de acesso: http://hdl.handle.net/1843/39096; https://orcid.org/0000-0002-4272-0298

Bistability in the form of valence tautomerism (VT), that is, the combination of mixed valence and spin crossover processes, is present in numerous metal complexes that candidate to be used as electronic and magnetic switchers. For cobalt metallic complexes in which a redox- active ligand participates in the electron transfer, the cobalt atom alternates between the low- spin (d6 CoIII) and high-spin (d7 CoII) states as a function of external stimuli in a reversible fashion. There has been an effort to understand, stimulate and control the VT in solid state and even to design complexes that candidate to be engineered as devices. In this work, two cobalt complexes and their VT properties are investigated. The controlled light-induced VT in single crystals of Co(dioxolene)2(Cyan-pyridine)2 is demonstrated, for the first time with an 80% interconversion yield of metastable states induced by visible light irradiation at low temperature. Additionally, Co(dioxolene)2(pyridine)2 was investigated for three different crystal forms and in solution, benchmarking key environmental conditions that modulate the VT for such complex. The results presented in this thesis for solid state and solutions illustrate the robustness and versatility of cobalt metal complexes as electronic labile materials.