Sunlight-Driven Dehydrogenative Oxidation Photocatalysis by a Mononuclear Complex Acting as both Chromophore and Catalyst

Journal of the Brazilian Chemical Society

article

Rocha, Francisca R.¹  Chen, Weizhong¹  Scott, Brian L.¹  Rocha, Reginaldo C.¹ 

[1] Los Alamos National Laboratory

关键词: photochemistry;    photooxidation;    proton-coupled electron transfer;    ruthenium;    solar catalysis;   

DOI  :  10.21577/0103-5053.20200161

学科分类：内科医学

来源: SciELO

【 摘 要 】

Under simulated solar irradiation in the visible spectral region, the catalytically active Ru IV -oxo species [Ru(O)(bpy)(tppz)] 2+ (tppz = tetrapyridylpyrazine, a strongly π-accepting tridentate N, N, N -ligand) is produced directly from a single metal-to-ligand charge-transfer (MLCT) photoexcitation of the resting Ru II -aquo complex [Ru(H 2 O)(bpy)(tppz)] 2+ in aqueous media containing an electron acceptor. This photoinduced path to 2-electron/2-proton activation of a mononuclear catalyst (i.e., without a paired chromophoric unit) is enabled by the thermodynamic instability of the intermediate Ru III -hydroxo species [Ru(OH)(bpy)(tppz)] 2+ , which promptly disproportionates into the Ru IV -oxo and Ru II -aquo states as electrochemically observed by cyclic and pulse voltammetries in a wide range of pH. The proton-coupled multielectron photocatalytic capability of the complex in neutral aqueous solutions, at room conditions, was demonstrated through the dehydrogenative oxidation of benzyl alcohol into benzaldehyde with a product selectivity of about 100%. The performance of this mononuclear complex acting as chromophore/catalyst is comparable to that of the previously reported dinuclear complex [(tpy)Ru(tppz)Ru(H x O)(bpy)] 4+ . In addition to the characterization of redox and spectroscopic properties for the [Ru(L)(bpy)(tppz)] n+ derivatives with L = Cl - or H x O, structural analysis of the precursor chloro complex [RuCl(bpy)(tppz)](PF 6 ) was also performed by single-crystal X-ray diffraction in this work.

【 授权许可】

CC BY