Ana B. Muñoz-García, Benjamin Dietzek, Sebastian Bold, Murielle Chavarot-Kerlidou, Michele Pavone, Vincent Artero, Tatiana Straistari, Solar fuels, hydrogen and catalysis (SolHyCat), Laboratoire de Chimie et Biologie des Métaux (LCBM - UMR 5249), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich-Schiller-Universität = Friedrich Schiller University Jena [Jena, Germany], Leibniz Institute of Photonic Technology Jena, Department Functional Interfaces, Albert-Einstein-Straße 9, 07745 Jena, Germany, Dipartimento di Fisica 'Ettore Pancini', University of Naples Federico II = Università degli studi di Napoli Federico II, Department of Chemical Sciences, Complesso Universitario Monte Sant'Angelo, Center for Energy and Environmental Chemistry (CEEC Jena), Università degli studi di Napoli Federico II, Bold, Sebastian, Straistari, Tatiana, Muñoz García, Ana Belen, Pavone, Michele, Artero, Vincent, Chavarot-Kerlidou, Murielle, and Dietzek, Benjamin
The light-induced processes occurring in two dye-catalyst assemblies for light-driven hydrogen production were investigated by ultrafast transient absorption spectroscopy. These dyads consist of a push-pull organic dye based on a cyclopenta[1,2-b:5,4-b&rsquo, ]dithiophene (CPDT) bridge, covalently linked to two different H2-evolving cobalt catalysts. Whatever the nature of the latter, photoinduced intramolecular electron transfer from the excited state of the dye to the catalytic center was never observed. Instead, and in sharp contrast to the reference dye, a fast intersystem crossing (ISC) populates a long-lived triplet excited state, which in turn non-radiatively decays to the ground state. This study thus shows how the interplay of different structures in a dye-catalyst assembly can lead to unexpected excited state behavior and might open up new possibilities in the area of organic triplet sensitizers. More importantly, a reductive quenching mechanism with an external electron donor must be considered to drive hydrogen production with these dye-catalyst assemblies.