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Heteroleptic Copper Photosensitizers: Why an Extended π‐System Does Not Automatically Lead to Enhanced Hydrogen Production
Author(s) -
Heberle Martin,
Tschierlei Stefanie,
Rockstroh Nils,
Ringenberg Mark,
Frey Wolfgang,
Junge Henrik,
Beller Matthias,
Lochbrunner Stefan,
Karnahl Michael
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201604005
Subject(s) - diimine , homoleptic , photochemistry , excited state , copper , ligand (biochemistry) , chemistry , nanosecond , triethylamine , spectroscopy , photocatalysis , ultrafast laser spectroscopy , electrochemistry , laser , metal , electrode , catalysis , organic chemistry , optics , atomic physics , biochemistry , physics , receptor , quantum mechanics
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 [Fe 3 (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.