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Competent Electrocatalytic and Photocatalytic Proton Reduction by a Dechelated [Co(tpy) 2 ] 2+ Scaffold
Author(s) -
Ahmad Ejaz,
Majee Karunamay,
Patel Jully,
Das Babulal,
Padhi Sumanta Kumar
Publication year - 2017
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201700628
Subject(s) - chemistry , denticity , photochemistry , overpotential , ligand (biochemistry) , photocatalysis , pyridine , electrochemistry , terpyridine , proton , catalysis , visible spectrum , ascorbic acid , medicinal chemistry , metal , organic chemistry , physics , electrode , quantum mechanics , biochemistry , receptor , food science , optoelectronics
The complexes [Co II (QCl‐tpy) 2 ]Cl 2 ( 1 ) and [Co III (QCl‐tpy) 2 ](PF 6 ) 3 [where QCl‐tpy = 2‐chloro‐3‐(2,6‐di(pyridin‐2‐yl)pyridine‐4‐yl) quinoline] have been synthesised and characterised by various spectroscopic techniques. Complex 1 acts as a hydrogen‐evolving catalyst under electrochemical and photochemical conditions. It exhibits photochemical proton reduction by irradiation with visible light in the presence of [Ru(bpy) 3 ]Cl 2 as a photosensitiser and ascorbic acid as a sacrificial electron donor. The formation of [Co II (QCl‐tpy)( 2 QCl‐tpyH)DMF] 3+ was detected after 24 h, due to the dechelation of one of the QCl‐tpy ligands in DMF/H 2 O (95:5 v/v, where 2 QCl‐tpy is a bidentate ligand). The introduction of 2‐chloroquinoline into the terpyridine framework reduces the overpotential by 300 mV for proton reduction, as compared with the parent [Co(tpy) 2 ] 2+ complex. Considering the spectroscopic studies, the possible involvement of the active species are depicted and mechanistic paths are proposed.