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Spectral Signatures of Oxidation States in a Manganese-Oxo Cubane Water Oxidation Catalyst |
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| Authors: | Dr. Sebastian Mai Sarah Klingler Dr. Ivan Trentin Julian Kund Marcus Holzer Anastasia Andreeva Dr. Robert Stach Prof. Christine Kranz Prof. Carsten Streb Prof. Boris Mizaikoff Prof. Leticia González |
| Affiliation: | 1. Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Straße 17, 1090 Vienna, Austria;2. Institute of Analytical and Bioanalytical Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany;3. Institute of Inorganic Chemistry I, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany;4. Institute of Analytical and Bioanalytical Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany Hahn-Schickard, Sedanstraße 14, 89077 Ulm, Germany |
| Abstract: | We report IR and UV/Vis spectroscopic signatures that allow discriminating between the oxidation states of the manganese-based water oxidation catalyst [(Mn4O4)(V4O13)(OAc)3]3−. Simulated IR spectra show that V=O stretching vibrations in the 900–1000 cm−1 region shift consistently by about 20 cm−1 per oxidation equivalent. Multiple bands in the 1450–1550 cm−1 region also change systematically upon oxidation/reduction. The computed UV/Vis spectra predict that the spectral range above 350 nm is characteristic of the managanese-oxo cubane oxidation state, whereas transitions at higher energy are due to the vanadate ligand. The presence of absorption signals above 680 nm is indicative of the presence of MnIII atoms. Spectroelectrochemical measurements of the oxidation from [Mn Mn ] to [Mn ] showed that the change in oxidation state can indeed be tracked by both IR and UV/Vis spectroscopy. |
| Keywords: | Density functional calculations IR spectroscopy Polyoxometalates UV/Vis spectroscopy Water splitting |