title: A Molecular Tetrad That Generates a High-Energy Charge-Separated State by Mimicking the Photosynthetic Z-Scheme.
abstract: The oxygenic photosynthesis of green plants, green algae, and cyanobacteria is the major provider of energy-rich compounds in the biosphere. The so-called "Z-scheme" is at the heart of this "engine of life". Two photosystems (photosystem I and II) work in series to build up a higher redox ability than each photosystem alone can provide, which is necessary to drive water oxidation into oxygen and NADP(+) reduction into NADPH with visible light. Here we show a mimic of the Z-scheme with a molecular tetrad. The tetrad Bodipy-NDI-TAPD-Ru is composed of two different dyes-4,4-difluoro-1,3,5,7-tetramethyl-2,6-diethyl-4-bora-3a,4a-diaza-s-indacene (Bodipy) and a Ru(II)(bipyridine)3 (Ru) derivative-which are connected to a naphthalene diimide (NDI) electron acceptor and tetraalkylphenyldiamine (TAPD) playing the role of electron donor. A strong laser pulse excitation of visible light where the two dye molecules (Ru and Bodipy) absorb with equal probability leads to the cooperative formation of a highly energetic charge-separated state composed of an oxidized Bodipy and a reduced Ru. The latter state cannot be reached by one single-photon absorption. The energy of the final charge-separated state (oxidized Bodipy/reduced Ru) in the tetrad lies higher than that in the reference dyads (Bodipy-NDI and TAPD-Ru), leading to the energy efficiency of the tetrad being 47% of the sum of the photon threshold energies. Its lifetime was increased by several orders of magnitude compared to that in the reference dyads Bodipy-NDI and TAPD-Ru, as it passes from about 3 ns in each dyad to 850 ns in the tetrad. The overall quantum yield formation of this extended charge-separated state is estimated to be 24%. Our proof-of-concept result demonstrates the capability to translate a crucial photosynthetic energy conversion principle into man-made molecular systems for solar fuel formation, to obtain products of higher energy content than those produced by a single photon absorption.
authors.affiliation: CEISAM, Chimie et Interdisciplinarité, Synthèse, Analyse, Modélisation, CNRS, UMR CNRS 6230, Université de Nantes , 2 rue de la Houssinière, BP 92208, Nantes 44322 Cedex 3, France.
authors.forename: Ludovic
authors.initials: L
authors.lastname: Favereau
authors.affiliation: Department of Chemistry-Ångström Laboratory, Uppsala University , Box 523, Uppsala, SE75120 Sweden.
authors.forename: Abhinandan
authors.initials: A
authors.lastname: Makhal
authors.affiliation: CEISAM, Chimie et Interdisciplinarité, Synthèse, Analyse, Modélisation, CNRS, UMR CNRS 6230, Université de Nantes , 2 rue de la Houssinière, BP 92208, Nantes 44322 Cedex 3, France.
authors.forename: Yann
authors.initials: Y
authors.lastname: Pellegrin
authors.affiliation: CEISAM, Chimie et Interdisciplinarité, Synthèse, Analyse, Modélisation, CNRS, UMR CNRS 6230, Université de Nantes , 2 rue de la Houssinière, BP 92208, Nantes 44322 Cedex 3, France.
authors.forename: Errol
authors.initials: E
authors.lastname: Blart
authors.affiliation: Department of Chemistry-Ångström Laboratory, Uppsala University , Box 523, Uppsala, SE75120 Sweden.
authors.forename: Jonas
authors.initials: J
authors.lastname: Petersson
authors.affiliation: Department of Chemistry-Ångström Laboratory, Uppsala University , Box 523, Uppsala, SE75120 Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Göransson
authors.affiliation: Department of Chemistry-Ångström Laboratory, Uppsala University , Box 523, Uppsala, SE75120 Sweden.
authors.forename: Leif
authors.initials: L
authors.lastname: Hammarström
authors.affiliation: CEISAM, Chimie et Interdisciplinarité, Synthèse, Analyse, Modélisation, CNRS, UMR CNRS 6230, Université de Nantes , 2 rue de la Houssinière, BP 92208, Nantes 44322 Cedex 3, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Odobel
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry*; D001896:Boron Compounds / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D003959:Diamines / Q000737:chemistry*; D055668:Photochemical Processes; D056951:Photoelectron Spectroscopy; D045331:Photosystem I Protein Complex / Q000737:chemistry* / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000378:metabolism; D010944:Plants / Q000378:metabolism; D012428:Ruthenium / Q000737:chemistry*
chemical_list: C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D001896:Boron Compounds; D056831:Coordination Complexes; D003959:Diamines; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D012428:Ruthenium