Solvent control of charge transfer excited state relaxation pathways in [Fe(2,2′-bipyridine)(CN)4]2−
| Autor: | Martin Nielsen, Kristoffer Haldrup, Kristjan Kunnus, James M. Glownia, Marcin Sikorski, Pavel Chábera, Yizhu Liu, Zoltán Németh, Henrik T. Lemke, Kasper S. Kjær, Mads G. Laursen, Tim Brandt van Driel, Kathryn Ledbetter, Sophie E. Canton, Dorottya Sárosiné Szemes, Petter Persson, Frederik B. Hansen, Jens Uhlig, Kenneth Wärnmark, Sergey Koroidov, H. Tatsuno, Lin Li, Marco Reinhard, György Vankó, Peter Vester, Silke Nelson, Roberto Alonso-Mori, Elisa Biasin, Tobias Harlang, Dimosthenis Sokaras, Cornelia Timm, Amy A. Cordones, Morten Christensen, Robert W. Hartsock, Éva G. Bajnóczi, Villy Sundstöm, Kelly J. Gaffney |
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| Rok vydání: | 2018 |
| Předmět: |
chemistry.chemical_classification
Materials science 010405 organic chemistry Ligand Relaxation (NMR) General Physics and Astronomy Electronic structure 010402 general chemistry 01 natural sciences 2 2'-Bipyridine 0104 chemical sciences Coordination complex chemistry.chemical_compound chemistry Excited state Picosecond Physical chemistry Lewis acids and bases Physical and Theoretical Chemistry |
| Zdroj: | Kjær, K S, Kunnus, K, Harlang, T C B, Van Driel, T B, Ledbetter, K, Hartsock, R W, Reinhard, M E, Koroidov, S, Li, L, Laursen, M G, Biasin, E, Hansen, F B, Vester, P, Christensen, M, Haldrup, K, Nielsen, M M, Chabera, P, Liu, Y, Tatsuno, H, Timm, C, Uhlig, J, Sundstöm, V, Nemeth, Z, Szemes, D S, Bajnoczi, E, Vanko, G, Alonso-Mori, R, Glownia, J M, Nelson, S, Sikorski, M, Sokaras, D, Lemke, H T, Canton, S E, Warnmark, K, Persson, P, Cordones, A A & Gaffney, K J 2018, ' Solvent control of charge transfer excited state relaxation pathways in [Fe(2,2 '-bipyridine)(CN) 4 ] 2-', Physical Chemistry Chemical Physics, vol. 20, no. 6, pp. 4238-4249 . https://doi.org/10.1039/c7cp07838b |
| ISSN: | 1463-9084 1463-9076 |
| Popis: | The excited state dynamics of solvated [Fe(bpy)(CN)4]2-, where bpy = 2,2'-bipyridine, show significant sensitivity to the solvent Lewis acidity. Using a combination of optical absorption and X-ray emission transient spectroscopies, we have previously shown that the metal to ligand charge transfer (MLCT) excited state of [Fe(bpy)(CN)4]2- has a 19 picosecond lifetime and no discernable contribution from metal centered (MC) states in weak Lewis acid solvents, such as dimethyl sulfoxide and acetonitrile. 1,2 In the present work, we use the same combination of spectroscopic techniques to measure the MLCT excited state relaxation dynamics of [Fe(bpy)(CN)4]2- in water, a strong Lewis acid solvent. The charge-transfer excited state is now found to decay in less than 100 femtoseconds, forming a quasi-stable metal centered excited state with a 13 picosecond lifetime. We find that this MC excited state has triplet (3MC) character, unlike other reported six-coordinate Fe(II)-centered coordination compounds, which form MC quintet (5MC) states. The solvent dependent changes in excited state non-radiative relaxation for [Fe(bpy)(CN)4]2- allows us to infer the influence of the solvent on the electronic structure of the complex. Furthermore, the robust characterization of the dynamics and optical spectral signatures of the isolated 3MC intermediate provides a strong foundation for identifying 3MC intermediates in the electronic excited state relaxation mechanisms of similar Fe-centered systems being developed for solar applications. |
| Databáze: | OpenAIRE |
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