Química de complexos de (etilenodiaminatetraacetato)rutenato(III/II)

Rein, Francisca N.; Rocha, Reginaldo C.; Toma, Henrique E.

doi:10.1590/s0100-40422004000100021

Cited by 5 publications

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“…Complexos metal-catecol podem exibir efeitos eletrônicos interessantes associados à distribuição de carga variável entre o metal e o ligante, em função do delicado balanço de energia entre os orbitais de fronteira do dioxoleno e do metal [11,12] .…”

Section: Catecolunclassified

“…maior que 59/n (mV) , atribuindo a um processo quase-reversível [32] (Tabela 7 e 8). , 1086 cm -1 e 516 cm -1 [11,12] . Também Embora haja vários estudos a respeito do comportamento eletroquímico dos fenóis, ainda é difícil a comparação dos dados obtidos com o da literatura devido a grande variedade de solventes, eletrodos e condições de pH empregados [33] .…”

Section: Síntese Do Complexo Com O Ligante 3-hidroxiflavonaunclassified

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Síntese e caracterização de complexos de rutênio com ligantes fenólicos

Araujo¹

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Universidade de São Paulo, como parte das exigências para a obtenção do título de Mestre em Ciências, Área: Química.RIBEIRÃO PRETO -SP The electrochemical behavior of the free ligands 1, 2-dihydroxybenzene and 3,5-di-terc-butylcatechol presented quite interesting profile in relation to the influence of the substituent in the aromatic ring; 1,2-dihydroxybenzene shows reduction peak and the 3,5-di-terc-butylcatechol is not observed.The complex formed with the 3-hydroxyflavone shows influence of several factors related to the structure of the flavonoid.vi

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Section: Catecolunclassified

Section: Síntese Do Complexo Com O Ligante 3-hidroxiflavonaunclassified

Síntese e caracterização de complexos de rutênio com ligantes fenólicos

Araujo¹

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Homogeneous Photocatalytic Oxidation of Alcohols by a Chromophore–Catalyst Dyad of Ruthenium Complexes

2009

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A common challenge in the molecular photocatalysis of water splitting toward artificial photosynthesis [1] has been the realization of modular, multicomponent chromophore-catalyst assemblies that can meet the kinetic and thermodynamic requirements whilst successfully integrating both 1) the charge-transfer photoexcitation and accompanying stepwise transfer of a single electron to/from an acceptor/donor at the chromophoric end, and 2) the proton-coupled, multielectron redox buildup and chemical reactivity of the catalytic unit. Of particular interest to us is the potential utilization of visible sunlight energy to photochemically drive the catalytic oxidation of water into dioxygen. This reaction is highly endergonic and mechanistically complex, and involves a four-electron/ four-proton transformation that has been recognized as the bottleneck for the overall water splitting leading to H 2 and O 2 evolution. The photocatalysis of this process remains to be demonstrated in (supra)molecular chemistry.As a step toward this goal, we have designed and prepared a structurally simple dyad assembly of ruthenium complexes that is capable of catalytically performing the homogeneous visible-light photooxidation of organic compounds at ambient conditions in aqueous solution. As a proof of concept, we chose the dehydrogenation of alcohols, which is a thermodynamically uphill conversion involving a two-electron/twoproton coupled process. Besides their practical importance in organic processes, [2] such transformations are also of relevance to hydrogen-based energy technologies because the anodic liberation of protons and electrons [Eq. (1)] can be coupled with recombination on a cathode for H 2 fuel production in an integrated photoelectrochemical cell. [3] R 1 CHðÀOHÞR 2 hn H2O, 25 C, 1 atmThe photocatalyst was constructed from ruthenium polypyridyl building blocks using the synthetic strategy shown in Scheme 1. A key consideration in the design of this assembly was the fact that the [Ru II (tpy)(bpy)(OH 2 )] 2+ /[Ru IV (tpy)-(bpy)(O)] 2+ couple has been extensively explored [4,5] in proton-coupled electron-transfer (PCET) reactions [6] and oxidation of organic substrates upon redox activation by either electrochemistry or chemical oxidants, that is, H 2 O-Ru II QO = Ru IV + 2 H + + 2e À . The [Ru(tpy) 2 ] 2+ unit is a well known chromophore [7] , owing to its efficient metal-to-ligand charge transfer (MLCT) "pump", with a strong absorption in the visible region. [Ru(tpy) 2 ] 2+ is a more appealing alternative to the bipyridine [Ru(bpy) 3 ] 2+ analogue because substitution at the 4-position of terpyridine can be used to afford linear, rigid structures favoring electron-transfer directionality. [7, 8] Scheme 1. Synthetic strategy for the preparation of the dyad assembly and its monometallic precursors/components: A) [Ru(tpy)(dmso)Cl 2 ] (0.8 equiv) in N,N-dimethylformamide, reflux; isolation, then NH 4 PF 6 (excess) in water. B) cis-[Ru(bpy)(dmso) 2 Cl 2 ] (1.0 equiv) in methanol, reflux; then NH 4 PF 6 (excess). C) cis...

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Homogeneous Photocatalytic Oxidation of Alcohols by a Chromophore–Catalyst Dyad of Ruthenium Complexes

2009

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A common challenge in the molecular photocatalysis of water splitting toward artificial photosynthesis [1] has been the realization of modular, multicomponent chromophore-catalyst assemblies that can meet the kinetic and thermodynamic requirements whilst successfully integrating both 1) the charge-transfer photoexcitation and accompanying stepwise transfer of a single electron to/from an acceptor/donor at the chromophoric end, and 2) the proton-coupled, multielectron redox buildup and chemical reactivity of the catalytic unit. Of particular interest to us is the potential utilization of visible sunlight energy to photochemically drive the catalytic oxidation of water into dioxygen. This reaction is highly endergonic and mechanistically complex, and involves a four-electron/ four-proton transformation that has been recognized as the bottleneck for the overall water splitting leading to H 2 and O 2 evolution. The photocatalysis of this process remains to be demonstrated in (supra)molecular chemistry.As a step toward this goal, we have designed and prepared a structurally simple dyad assembly of ruthenium complexes that is capable of catalytically performing the homogeneous visible-light photooxidation of organic compounds at ambient conditions in aqueous solution. As a proof of concept, we chose the dehydrogenation of alcohols, which is a thermodynamically uphill conversion involving a two-electron/twoproton coupled process. Besides their practical importance in organic processes, [2] such transformations are also of relevance to hydrogen-based energy technologies because the anodic liberation of protons and electrons [Eq. (1)] can be coupled with recombination on a cathode for H 2 fuel production in an integrated photoelectrochemical cell. The photocatalyst was constructed from ruthenium polypyridyl building blocks using the synthetic strategy shown in Scheme 1. A key consideration in the design of this assembly was the fact that the [Ru 2+ couple has been extensively explored [4,5] in proton-coupled electron-transfer (PCET) reactions [6] and oxidation of organic substrates upon redox activation by either electrochemistry or chemical oxidants, that is, H 2 ORuunit is a well known chromophore [7] , owing to its efficient metal-to-ligand charge transfer (MLCT) "pump", with a strong absorption in the visible region. [Ru(tpy) 2 ]2+ is a more appealing alternative to the bipyridine [Ru(bpy) 3 ] 2+ analogue because substitution at the 4-position of terpyridine can be used to afford linear, rigid structures favoring electron-transfer directionality. [7,8] Scheme 1. Synthetic strategy for the preparation of the dyad assembly and its monometallic precursors/components: A) [Ru(tpy)(dmso)Cl 2 ] (0.8 equiv) in N,N-dimethylformamide, reflux; isolation, then NH 4 PF 6 (excess) in water. B) cis-[Ru(bpy)(dmso) 2 Cl 2 ] (1.0 equiv) in methanol, reflux; then NH 4 PF 6 (excess). C) cis-[Ru(bpy)(dmso) 2 Cl 2 ] (0.7 equiv) in N,N-dimethylformamide, reflux; isolation, then NH 4 PF 6 (excess) in water. D) cis-[Ru(tpy)(dmso)Cl 2 ] (1.0...

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Química de complexos de (etilenodiaminatetraacetato)rutenato(III/II)

Cited by 5 publications

References 21 publications

Síntese e caracterização de complexos de rutênio com ligantes fenólicos

Síntese e caracterização de complexos de rutênio com ligantes fenólicos

Homogeneous Photocatalytic Oxidation of Alcohols by a Chromophore–Catalyst Dyad of Ruthenium Complexes

Homogeneous Photocatalytic Oxidation of Alcohols by a Chromophore–Catalyst Dyad of Ruthenium Complexes

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