title: The Position of the N Atom Plays a Significant Role for Excited-State Decay of Heterocycles.
abstract: We have employed combined electronic structure calculations and nonadiabatic dynamics simulations to study the S1radiationless deactivation mechanism of pyrazole. In terms of MS-CASPT2 computed results, we propose that the1πσ* state-driven nonadiabatic N-N dissociation is a major relaxation path; the ring-puckering deformation path as well as the1πσ* state-driven N-H dissociation are less favorable. This excited-state decay mechanism is supported by MS-CASPT2 nonadiabatic dynamics simulations. The present study demonstrates that pyrazole has a different excited-state radiationless deactivation mechanism compared with its structural isomer imidazole, in which the1πσ* state-driven nonadiabatic N-H dissociation plays a more important role. However, such a channel is suppressed in pyrazole; instead, the1πσ* state-driven nonadiabatic N-N dissociation is dominant.
authors.affiliation: Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University , Beijing 100875, China.
authors.forename: Bin-Bin
authors.initials: BB
authors.lastname: Xie
authors.affiliation: Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University , Beijing 100875, China.
authors.forename: Xiang-Yang
authors.initials: XY
authors.lastname: Liu
authors.affiliation: Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University , Beijing 100875, China.
authors.forename: Qiu
authors.initials: Q
authors.lastname: Fang
authors.affiliation: Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University , Beijing 100875, China.
authors.forename: Wei-Hai
authors.initials: WH
authors.lastname: Fang
authors.affiliation: Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University , Beijing 100875, China.
authors.forename: Ganglong
authors.identifier: http://orcid.org/0000-0002-9752-1659
authors.initials: G
authors.lastname: Cui