Issue 48, 2017

A pentadentate nitrogen-rich copper electrocatalyst for water reduction with pH-dependent molecular mechanisms

Abstract

The new pentadentate 3d9 complex [CuII(LN2Py3)](PF6)2 (1) based on a nitrogen-rich framework acts as an electrocatalyst toward dihydrogen production from water. This species is active at pHs 7 and 2.5 yielding respective TON3h values of 1670 and 3900. Comparison of the molecular structure of 1 with that of the reduced [CuI(LN2Py3)]PF6 (2) evidences elongated Cu–N bond lengths resulting from an increased electron density around the 3d10 CuI center. The absence of nanoparticulate formation indicates that molecular mechanisms prevail at both pHs. Furthermore, experimental and DFT data support that distinct mechanisms are operative: while the metal center plays a key role at pH 7, one dangling pyridine moiety gets protonated at pH 2.5 and becomes actively involved in a relay mechanism. In both cases the CuIII–H intermediate seems to be bypassed by PCET processes.

Graphical abstract: A pentadentate nitrogen-rich copper electrocatalyst for water reduction with pH-dependent molecular mechanisms

Supplementary files

Article information

Article type
Paper
Submitted
25 Jul 2017
Accepted
30 Aug 2017
First published
31 Aug 2017

Dalton Trans., 2017,46, 16812-16820

A pentadentate nitrogen-rich copper electrocatalyst for water reduction with pH-dependent molecular mechanisms

D. M. Ekanayake, K. M. Kulesa, J. Singh, K. K. Kpogo, S. Mazumder, H. Bernhard Schlegel and C. N. Verani, Dalton Trans., 2017, 46, 16812 DOI: 10.1039/C7DT02711G

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