Reflection on Medium Effects on Photochemical Reactivity

• Published in: Accounts of chemical research Vol. 38; no. 5; pp. 396 - 403
• Main Authors: Liu, Robert S. H, Hammond, George S
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 01-05-2005
• Subjects: Bacterial Proteins - chemistry; Bacterial Proteins - metabolism; Isomerism; Models, Molecular; Molecular Structure; Photochemistry; Photoreceptors, Microbial - chemistry; Photoreceptors, Microbial - metabolism; Protein Structure, Tertiary; Rhodopsin - chemistry; Rhodopsin - metabolism; Solutions
• ISSN: 0001-4842; 1520-4898
• DOI: 10.1021/ar040246z

In reexamining medium effects on photochemical reactions, we have emphasized those on unequilibrated excited species such as the Franck−Condon species. Despite recent advances in femtochemistry, such a discussion in molecular photochemistry is uncommon, and the problem remains challenging on account of the extremely short-lived excited species. However, in such cases, a small perturbation resulting from, for example, weak guest−host interactions could turn into a determining factor in dictating the course of a photochemical channel of deactivation. Examples of medium-directed diabatic processes have been examined with this idea in mind. A modified view on rhodopsin photoisomerization is presented along with the consideration that confinement does not necessarily lead to inhibition of reactions of the trapped substrate.