Heteroleptic Copper Photosensitizers: Why an Extended π-System Does Not Automatically Lead to Enhanced Hydrogen Production

Martin Heberle, Stefanie Tschierlei, Nils Rockstroh, Mark Ringenberg, Wolfgang Frey, Henrik Junge, Matthias Beller, Stefan Lochbrunner, Michael Karnahl

Research output: Contribution to journalArticlepeer-review

88 Scopus citations

Abstract

A series of heteroleptic copper(I) photosensitizers of the type [(P^P)Cu(N^N)]+ with an extended π-system in the backbone of the diimine ligand has been prepared. The structures of all complexes are completely characterized by NMR spectroscopy, mass spectrometry, and X-ray crystallography. These novel photosensitizers were assessed with respect to the photocatalytic reduction of protons in the presence of triethylamine and [Fe3(CO)12]. Although the solid-state structures and computational results show no significant impact of the π-extension on the structural properties, decreased activities were observed. To explain this drop, a combination of electrochemical and photophysical measurements including time-resolved emission as well as transient absorption spectroscopy in the femto- to nanosecond time regime was used. Consequently, shortened excited state lifetimes caused by the rapid depopulation of the excited states located at the diimine ligand are identified as a major reason for the low photocatalytic performance.

Original languageEnglish
Pages (from-to)312-319
Number of pages8
JournalChemistry - A European Journal
Volume23
Issue number2
DOIs
StatePublished - 5 Jan 2017
Externally publishedYes

Keywords

  • copper complexes
  • hydrogen production
  • photocatalysis
  • photophysics
  • transient absorption

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