Aerobic oxidation of alcohols on Au/TiO2 catalyst: new insights on the role of active sites in the oxidation of primary and secondary alcohols

Abstract

Cyclobutane thymine dimerization is the most prominent DNA photoinduced damage. While the ultrafast mechanism that proceeds in the singlet manifold is nowadays well established, the triplet-state pathway is not completely understood. Here we report the underlying mechanism of the photosensitized dimerization process in the triplet state. Quantum chemical calculations, combined with wavefunction analysis, and nonadiabatic molecular dynamics simulations demonstrate that this is a stepwise reaction, traversing a long-lived triplet biradical intermediate, which is characterized as a Frenkel exciton with very small charge-transfer character. The low yield of the reaction is regulated by two factors: (i) a relatively large energy barrier that needs to be overcome to form the exciton intermediate, and (ii) a bifurcation of the groundstate potential-energy surface that mostly leads back to the Franck-Condon region because dimerization requires a very restricted combination of coordinates and velocities at the event of non-radiative decay to the ground state. Graphical abstract

Metal–Support Interaction in Gold Zeolitic Octahedral Metal Oxide and the Catalytic Activity for Low-Temperature Alcohol Oxidation

“…The selectivities to benzaldehyde and benzyl benzoate were 21 and 76%, respectively (Table , entry 1). Benzyl benzoate was derived from the oxidative esterification of benzyl alcohol, , which was the major product of benzyl alcohol oxidation catalyzed by Au 1% /o-MoVO-N400. Oxidation of benzyl alcohol catalyzed by Au 1% /o-MoVO-N400 was carried out to understand the influence of the reaction conditions on the selectivities to benzaldehyde and benzyl benzoate.…”