Plasmon-assisted transformations of organic compounds represent a novel opportunity for conversion of light to chemical energy at room temperature. However, the mechanistic insights of interaction between plasmon energy and organic molecules is still under debate. Herein, we proposed a comprehensive study of the plasmon-assisted reaction mechanism using unsymmetric iodonium salts (ISs) as an organic probe. The experimental and theoretical analysis allow us to exclude the possible thermal effect or hot electron transfer. We found that plasmon interaction with unsymmetrical ISs led to the intramolecular excitation of electron followed by the regioselective cleavage of C-I bond with the formation of electron-rich radical species, which cannot be explained by the hot electron excitation or thermal effects. The high regioselectivity is explained by the direct excitation of electron to LUMO with the formation of a dissociative excited state according to quantum-chemical modeling, which provides novel opportunities for the fine control of reactivity using plasmon energy.

Department of Chemistry University of Helsinki Helsinki FIN 00014 Finland

Institute of Chemical Technology Technicka 5 Prague 16628 Czech Republic

Institute of Chemistry Saint Petersburg State University Universitetskaya Nab 7 9 Saint Petersburg Russian Federation

Research School of Chemistry and Applied Biomedical Sciences National Research Tomsk Polytechnic University Lenin Avenue 30 Tomsk 634050 Russia

University Paris Est Créteil 61 Avenue du Général de Gaulle 94000 Créteil France

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Establishing plasmon contribution to chemical reactions: alkoxyamines as a thermal probe