Exploring the molecular interactions behind light-induced reactions using transition-metal photosensitizers : a cage escape study
(2025)
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- Authors
- Supervisors
- Elias, Benjamin
- Abstract
- The cage escape yield (ФCE), i.e. the ratio of the photoproducts that have escaped the solvent cage over the total amount of excited-state photosensitizers that have reacted, is a key step in photochemical reactions. Indeed, a high quenching combined with a poor cage escape inevitably ends with an overall photoreaction that is unprofitable, and it appears that controlling ФCE, and knowing which experimental factors governs it, is of prime importance. A series of factors have been reported to influence ФCE, such as the solvent viscosity, the presence of noncovalent interactions, the spin multiplicity of the photosensitizer or the distance between the species and the driving force, but the systems studied are often specific and very different. Therefore, it is difficult to extend these results to other systems as the key parameters are yet to be highlighted. In this context, this Ph.D. thesis aimed to bring some insight on several factors influencing cage escape and their respective degree of influence applied in systems containing 21 common transition-metal photosensitizers. This manuscript reports the individual yet intricate studies of several factors influencing the cage escape process i.e. i) the driving force for electron transfer applied to an irreversible oxidative quenching; ii) the counterions, iii) the dielectric constant of the solvent; iv) the spin of the geminate radical pair and v) the nature of the excited state. Taken together, the results obtained in this work helped to create a first scale of impact and a first dichotomous chart to predict the range of ФCE for an unknown quencher with the photosensitizers studied here. Overall, this work highlights the importance of studying mechanistic steps like cage escape, and that determining crucial factors can help to better understand, design and predict a photo-induced chemical reaction.
- Affiliations
Citations
Ripak, A. (2025). Exploring the molecular interactions behind light-induced reactions using transition-metal photosensitizers : a cage escape study.