title: Heteroleptic Copper Photosensitizers: Why an Extended π-System Does Not Automatically Lead to Enhanced Hydrogen Production.
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.
authors: Institute of Organic Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany.
authors: Martin
authors: M
authors: Heberle
authors: Institute of Organic Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany.|Institute of Physics, University of Rostock, Albert-Einstein-Str. 23, 18059 Rostock, Germany.
authors: Stefanie
authors: 0000-0001-9441-7904
authors: S
authors: Tschierlei
authors: Leibniz-Institute for Catalysis at the, University of Rostock (LIKAT), Albert-Einstein-Str. 29a, 18059, Rostock, Germany.
authors: Nils
authors: 0000-0001-6925-8577
authors: N
authors: Rockstroh
authors: Institute of Inorganic Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany.
authors: Mark
authors: 0000-0001-7585-5757
authors: M
authors: Ringenberg
authors: Institute of Organic Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany.
authors: Wolfgang
authors: W
authors: Frey
authors: Leibniz-Institute for Catalysis at the, University of Rostock (LIKAT), Albert-Einstein-Str. 29a, 18059, Rostock, Germany.
authors: Henrik
authors: H
authors: Junge
authors: Leibniz-Institute for Catalysis at the, University of Rostock (LIKAT), Albert-Einstein-Str. 29a, 18059, Rostock, Germany.
authors: Matthias
authors: M
authors: Beller
authors: Institute of Physics, University of Rostock, Albert-Einstein-Str. 23, 18059 Rostock, Germany.
authors: Stefan
authors: 0000-0001-9729-8277
authors: S
authors: Lochbrunner
authors: Institute of Organic Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany.
authors: Michael
authors: 0000-0002-6755-0002
authors: M
authors: Karnahl
keywords: copper complexes; hydrogen production; photocatalysis; photophysics; transient absorption