Water-Assisted Concerted Proton-Electron Transfer at Co(II)-Aquo Sites in Polyoxotungstates With Photogenerated RuIII (bpy)33+ Oxidant.
Chemphyschem
; 22(12): 1208-1218, 2021 06 16.
Article
en En
| MEDLINE
| ID: mdl-33851772
ABSTRACT
The cobalt substituted polyoxotungstate [Co6 (H2 O)2 (α-B-PW9 O34 )2 (PW6 O26 )]17- (Co6) displays fast electron transfer (ET) kinetics to photogenerated RuIII (bpy)33+ , 4 to 5 orders of magnitude faster than the corresponding ET observed for cobalt oxide nanoparticles. Mechanistic evidence has been acquired indicating that (i) the one-electron oxidation of Co6 involves Co(II) aquo or Co(II) hydroxo groups (abbreviated as Co6(II)-OH2 and Co6(II)-OH, respectively, whose speciation in aqueous solution is associated to a pKa of 7.6), and generates a Co(III)-OH moiety (Co6(III)-OH), as proven by transient absorption spectroscopy; (ii) at pH>pKa , the Co6(II)-OHâRuIII (bpy)33+ ET occurs via bimolecular kinetics, with a rate constant k close to the diffusion limit and dependent on the ionic strength of the medium, consistent with reaction between charged species; (iii) at pH Palabras clave
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MEDLINE
Asunto principal:
Compuestos Organometálicos
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Polímeros
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Protones
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Compuestos de Tungsteno
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Electrones
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Complejos de Coordinación
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En
Revista:
Chemphyschem
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BIOFISICA
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QUIMICA
Año:
2021
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Article