Investigation of the Excited-State Electron Transfer and Cage Escape Yields Between Halides and a Fe(III) Photosensitizer
(2024) Journal of the American chemical society — Vol. 146, n° 15, p. 10286-10292 (2024)
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- Authors
Ripak, Alexia 
- Abstract
- Excited-state quenching and reduction of [Fe(phtmeimb)2]+, where phtmeimb is phenyl[tris(3-methyl-imidazolin-2-ylidene)]borate, with iodide, bromide and chloride were studied in dichloromethane, acetonitrile, and acetonitrile/water 1:1 mixture by means of steady-state and time-resolved spectroscopic techniques. Quenching rate constants were almost diffu-sion-limited in dichloromethane and acetonitrile and followed the expected periodic trend, i.e. I–>Br–>Cl–. Confirmation of excited-state reductive electron transfer was only unambiguously obtained when iodide was used as quencher. The cage-escape yields, i.e. the separation of the geminate radical pair formed upon bimolecular excited-state electron transfer were determined. These yields were larger in dichloromethane (0.079) than in acetonitrile (0.017) and no photoproduct could be observed in acetonitrile/water 1:1. This study further emphasizes that solvents with low dielectric constant are more suited for productive excited-state electron transfer using Fe(III) photosensitizers with 2LMCT excited-state.
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Citations
De Kreijger, S., Ripak, A., Elias, B., & Troian-Gautier, L. (2024). Investigation of the Excited-State Electron Transfer and Cage Escape Yields Between Halides and a Fe(III) Photosensitizer. Journal of the American chemical society, 146(15), 10286-10292. https://doi.org/10.1021/jacs.4c02808 (Original work published 2024)