Issue 9, 2018

Understanding light-driven H2 evolution through the electronic tuning of aminopyridine cobalt complexes

Abstract

A new family of cobalt complexes with the general formula [CoII(OTf)2(Y,XPyMetacn)] (1R, Y,XPyMetacn = 1-[(4-X-3,5-Y-2-pyridyl)methyl]-4,7-dimethyl-1,4,7-triazacyclononane, (X = CN (1CN), CO2Et (1CO2Et), Cl (1Cl), H (1H), NMe2 (1NMe2)) where (Y = H, and X = OMe when Y = Me (1DMM)) is reported. We found that the electronic tuning of the Y,XPyMetacn ligand not only has an impact on the electronic and structural properties of the metal center, but also allows for a systematic water-reduction-catalytic control. In particular, the increase of the electron-withdrawing character of the pyridine moiety promotes a 20-fold enhancement of the catalytic outcome. By UV-Vis spectroscopy, luminescence quenching studies and Transient Absorption Spectroscopy (TAS), we have studied the direct reaction of the photogenerated [IrIII(ppy)2(bpy˙)] (PSIr) species to form the elusive CoI intermediates. In particular, our attention is focused on the effect of the ligand architecture in this elemental step of the catalytic mechanism. Finally, kinetic isotopic experiments together with DFT calculations provide complementary information about the rate-determining step of the catalytic cycle.

Graphical abstract: Understanding light-driven H2 evolution through the electronic tuning of aminopyridine cobalt complexes

Supplementary files

Article information

Article type
Edge Article
Submitted
05 Okt. 2017
Accepted
18 Dec. 2017
First published
19 Dec. 2017
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2018,9, 2609-2619

Understanding light-driven H2 evolution through the electronic tuning of aminopyridine cobalt complexes

A. Call, F. Franco, N. Kandoth, S. Fernández, M. González-Béjar, J. Pérez-Prieto, J. M. Luis and J. Lloret-Fillol, Chem. Sci., 2018, 9, 2609 DOI: 10.1039/C7SC04328G

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