engleski

Anti-Kasha nitrogen photoelimination from diazoalkanes

Nitrogen elimination from diazoalkanes is a well- known reaction, which can easily be induced both thermally and photochemically.1-2 In this work we present a photochemical study of diazo compound 1. Experimentally, it was observed to have a pronounced anti-Kasha photochemistry, as it gives greater yield of nitrogen elimination after UV excitation than after VIS excitation. Also, an anti-Kasha fluorescence was observed. Nonadiabatic surface hopping dynamics was used to elucidate the photochemical behavior of 1. To simulate VIS and UV excitations, the dynamics was initiated in corresponding energy windows, i.e. in the S1 and S2/S3 states respectively. In both types of simulations, the S1/S0 CI was easily reached by elongation of the CN bond. We identified the anti-Kasha pathway of nitrogen elimination in around 30 % of trajectories initiated by UV excitation. The source of anti- Kasha fluorescence was also identified in around 4 % of UV-initiated trajectories and confirmed by excited-state optimization.

nitrogen photoelimination ; nonadiabatic dynamics ; diazoalkanes

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