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Doctoral Thesis
DOI
Document
Author
Full name
Sheila Gozzo Câmera
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2000
Supervisor
Committee
Toma, Henrique Eisi (President)
de Oliveira Silva, Denise
Franco, Douglas Wagner
Iha, Neyde Yukie Murakami
Oliveira, Luiz Antonio Andrade de
Title in Portuguese
Contribuição à química supramolecular de polipirazinas de rutênio(II)
Keywords in Portuguese
Compostos organometálicos
Química de coordenação
Abstract in Portuguese
Neste trabalho, descreve-se a síntese e caracterização de complexos binucleares derivados de [Ru(bpz)3]2+ e [Ru(bpy)2(bpz)]2+ (bpy = 2,2'-bipiridina; bpz = 2,2'-bipirazina) com os grupos [Fe(CN)5]3- e [Ru(bpy)2Cl]+. As propriedades espectroscópicas e eletroquímicas dos complexos resultantes [RuII(bpz)3RuII(bpy)2Cl]3+, [RuII(bpz)3FeII(CN)5]-, [RuII(bpy)2(bpz)RuII(bpy)2Cl]3+ e [RuII(bpy)2(bpz)FeII(CN)5]- foram investigadas, revelando transições de transferência de carga na faixa do UV-VIS e processos redox centrados no metal e nos ligantes. As espécies binucleares apresentaram tempos de vida na faixa de nanosegundos, não emitindo à temperatura ambiente. Experimentos de determinação da constante de velocidade de supressão (kq) por esfera externa e flash-photolysis indicaram a ocorrência do processo de supressão da emissão da unidade central pela periférica por um mecanismo de transferência eletrônica intramolecular. A separação de cargas foi explorada visando a construção de dispositivos do tipo diad e posteriormente para a elaboração dos triads, [FeIII(CN)5RuII(bpz)3RuII(bpy)2Cl]+ e [FeIII(CN)5Ru(bpy)2(bpz)RuII(bpy)2Cl]+. Estudos paralelos com o complexo [Ru(phen)2(bpz)Cl]+ (phen = 1,10-fenantrolina) também foram efetuados, visando caracterizar a coordenação monodentada do ligante bipirazina. Esse complexo não emite à temperatura ambiente, mas a 77 K exibe bandas de emissão em 628 nm e 680 nm e tempo de vida τr = 8,7 µs. O acoplamento aos grupos [Fe(CN)5]3- e [Ru(edta)H2O]2- levou à formação de complexos binucleares, os quais foram devidamente caracterizados.
Title in English
Contribution to the supramolecular chemistry of ruthenium polypyrines (II)
Keywords in English
Coordination chemistry
Organometallic compounds
Abstract in English
The synthesis and characterization of bimetallic complexes such as [RuII(bpz)3RuII(bpy)2Cl]3+, [RuII(bpz)3FeII(CN)5]-, [RuII(bpy)2(bpz)RuII(bpy)2Cl]3+ and [RuII(bpy)2(bpz)FeII(CN)5]- (bpy = 2,2'-bipyridine; bpz = 2,2'-bipyrazine) were described and their spectroscopic and electrochemical properties investigated. The species showed characteristic charge transfer transitions in the UV-VIS region and redox processes centered on the metal and on the ligands. All of the species exhibited lifetime in the nanosecond range and are not emissive at room temperature. Determination of outer sphere quenching constants and flash-photolysis experiments demonstrated quenching of the emission of central group by an intramolecular electron transfer mechanism. Charge separation was pursued for the construction of dyads and lately triads, such as [FeIII(CN)5RuII(bpz)3RuII(bpy)2Cl]+ and [FeIII(CN)5Ru(bpy)2(bpz)RuII(bpy)2Cl]+. The complex [Ru(phen)2(bpz)Cl]+ (phen = 1,10-phenantroline) was studied in parallel, focusing on the unusual monodentate coordination of bipyrazine. This complex was not emissive at room temperature, but at 77 K it exhibited two emission bands, at 628 nm and 680 nm and lifetime τ = 8,7 µs. The attachment of groups such as [Fe(CN)5]3- e [Ru(edta)H2O]2- led to binuclear complexes that were consistently characterized.
 
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Publishing Date
2019-05-23
 
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