Supramolecular substrate preorganization at tailored oligonuclear transition metal complexes for improved artificial photosynthesis Muhammad Abubakar-Sidiq, Sven Rau Institute of Inorganic Chemistry I, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany The limitations in harnessing and converting solar energy through photosynthesis create boundaries in the photocatalytic process. For artificial photosynthesis, ruthenium-centered photosensitizer are frequently studied. Ruthenium (II) polypyridyl sensitizers usually absorb visible light with molar absorption coefficients surpassing 10000 M −1 cm −1 in the visible region and demonstrate relatively long-lived excited states. 1 To overcome efficiency limitations due to electron donor diffusion towards the photocatalyst, pre-arrangement of these donors is desirable. Initial experiments involved [(Rbpy) 2 Ru(tpphz)PtI 2 ] 2+ alongside various pre-arranged electron donor materials to enhance hydrogen production. By altering solvent combinations and temperature settings, a notably higher turnover number (TON) was achieved. Maximizing the ratio of the desired forward electron transfer processes to unintended back electron transfer is crucial for an efficient photocatalytic process. Introducing competitive binders on the tpphz surface, as illustrated in Figure 1, presents an additional molecular solution to enhance cage escape yields (CEYs) and thereby improve photocatalysis. 2 Figure 1: Acceleration of NADH •+ loss from tpphz binding site for competitive binder (shown in red)-improved CEY using [(Rbpy) 2 Ru(tpphz)PtI 2 ] 2+ and NADH References 1. Cerfontaine, Simon; Wehlin, Sara A. M.; Elias, Benjamin; Troian-Gautier, Ludovic. Photostable Polynuclear Ruthenium (II) Photosensitizers Competent for Dehalogenation Photoredox Catalysis at 590 nm . In: Journal of the American Chemical Society , Vol. 142, no.12, p. 5549-5555 (2020). doi:10.1021/jacs.0c01503. 2. Wintergerst, K. Witas, D. Nauroozi, M. A. Schmid, E. Dikmen, S. Tschierlei, S. Rau, Zeitschrift fur Anorganische und Allgemeine Chemie 2020, 646 , 842–848.
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