Investigation of the ultrafast dynamics occurring during unsensitized photocatalytic H2 evolution by an [FeFe]-hydrogenase subsite analogue

Frederix, P. W. J. M., Adamczyk, Katrin, Tuttle, Tell, Wright, Joseph A. ORCID: https://orcid.org/0000-0001-9603-1001, Ulijn, Rein V., Pickett, Christopher J. and Hunt, Neil T. (2014) Investigation of the ultrafast dynamics occurring during unsensitized photocatalytic H2 evolution by an [FeFe]-hydrogenase subsite analogue. Organometallics, 33 (20). pp. 5888-5896. ISSN 0276-7333

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Abstract

Biomimetic compounds based upon the active subsite of the [FeFe]-hydrogenase enzyme system have been the focus of much attention as catalysts for hydrogen production: a clean energy vector. Until recently, use of hydrogenase subsite systems for light-driven hydrogen production has typically required the involvement of a photosensitizer, but the molecule [(μ-pdt)(μ-H)Fe2(CO)4(dppv)]+, (1; dppv = cis-1,2-C2H2(PPh2)2; pdt = 1,3-propanedithiolate) has been reported to catalyze the evolution of hydrogen gas under sensitizer-free conditions. Establishing the molecular mechanism that leads to photohydrogen production by 1 is thus an important step that may enable further development of this family of molecules as solar fuel platforms. Here, we report ultrafast UVpump–IRprobe spectroscopy of 1 at three different excitation wavelengths and in a range of solvents, including under the conditions required for H2 production. Combining spectroscopic measurements of the photochemistry and vibrational relaxation dynamics of 1 with ground-state density functional theory (DFT) calculations shows that, irrespective of experimental conditions, near-instantaneous carbonyl ligand loss is the main photochemical channel. No evidence for a long-lived excited electronic state was found. These results provide the first time-resolved data for the photochemistry of 1 and offer an alternative interpretation of the underlying mechanism of light-driven hydrogen generation.

Item Type: Article
Uncontrolled Keywords: sdg 7 - affordable and clean energy ,/dk/atira/pure/sustainabledevelopmentgoals/affordable_and_clean_energy
Faculty \ School: Faculty of Science > School of Chemistry
Depositing User: Pure Connector
Date Deposited: 04 Nov 2014 12:00
Last Modified: 21 Oct 2022 00:14
URI: https://ueaeprints.uea.ac.uk/id/eprint/50632
DOI: 10.1021/om500521w

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