Competitive solvent-molecule interactions govern primary processes of diphenylcarbene in solvent mixtures

作者：Johannes Knorr, Pandian Sokkar, Sebastian Schott, Paolo Costa, Walter Thiel, Wolfram Sander, Elsa Sánchez‐García, Patrick Nuernberger · 发表于：Nature Communications · 年份：2016 · DOI：10.1038/ncomms12968 · 被引用次数：50 · 研究领域：Radical Photochemical Reactions、Chemical Reactions and Mechanisms、Photochemistry and Electron Transfer Studies

Photochemical reactions in solution often proceed via competing reaction pathways comprising intermediates that capture a solvent molecule. A disclosure of the underlying reaction mechanisms is challenging due to the rapid nature of these processes and the intricate identification of how many solvent molecules are involved. Here combining broadband femtosecond transient absorption and quantum mechanics/molecular mechanics simulations, we show for one of the most reactive species, diphenylcarbene, that the decision-maker is not the nearest solvent molecule but its neighbour. The hydrogen bonding dynamics determine which reaction channels are accessible in binary solvent mixtures at room temperature. In-depth analysis of the amount of nascent intermediates corroborates the importance of a hydrogen-bonded complex with a protic solvent molecule, in striking analogy to complexes found at cryogenic temperatures. Our results show that adjacent solvent molecules take the role of key abettors rather than bystanders for the fate of the reactive intermediate.