Light-Induced H2 Evolution with a Macrocyclic Cobalt Diketo-Pyrphyrin as a Proton-Reducing Catalyst

Evelyne Joliat-Wick; Nicola Weder; Daniel Klose; Cyril Bachmann; Bernhard Spingler; Benjamin Probst; Roger Alberto

doi:10.1021/acs.inorgchem.7b02992

Light-Induced H₂ Evolution with a Macrocyclic Cobalt Diketo-Pyrphyrin as a Proton-Reducing Catalyst

Inorg Chem. 2018 Feb 5;57(3):1651-1655. doi: 10.1021/acs.inorgchem.7b02992. Epub 2018 Jan 25.

Authors

Evelyne Joliat-Wick¹, Nicola Weder¹, Daniel Klose², Cyril Bachmann¹, Bernhard Spingler¹, Benjamin Probst¹, Roger Alberto¹

Affiliations

¹ Department of Chemistry, University of Zürich , Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
² Laboratory of Physical Chemistry, Department of Chemistry, ETH Zürich , Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland.

PMID: 29368926
DOI: 10.1021/acs.inorgchem.7b02992

Abstract

Cobalt complexes are well-known catalysts for photocatalytic proton reduction in water. Macrocyclic tetrapyridyl ligands (pyrphyrins) and their Co^II complexes emerged in this context as a highly efficient class of H₂ evolution catalysts. On the basis of this framework, a new macrocyclic Co^II complex consisting of two keto-bridged bipyridyl units (Co diketo-pyrphyrin) is presented. The complex is synthesized along a convenient route, is well soluble in water, and shows high activity as a water reduction catalyst (WRC). In an aqueous system containing [Ru(bpy)₃]Cl₂ as a photosensitizer and NaAscO as a sacrificial electron donor, turnover numbers (TONs) of 2500 H₂/Co were achieved. Catalysis is terminated by a limited electron supply and decomposition of the photosensitizer but not of the WRC, highlighting the distinct stability of Co diketo-pyrphyrin.