title: Photoisomerization of Arylazopyrazole Photoswitches: Stereospecific Excited-State Relaxation.
abstract: Electronic structure calculations and nonadiabatic dynamics simulations (more than 2000 trajectories) are used to explore the Z-E photoisomerization mechanism and excited-state decay dynamics of two arylazopyrazole photoswitches. Two chiral S1/S0conical intersections with associated enantiomeric S1relaxation paths that are barrierless and efficient (timescale of ca. 50 fs) were found. For the parent arylazopyrazole (Z8) both paths contribute evenly to the S1excited-state decay, whereas for the dimethyl derivative (Z11) each of the two chiral cis minima decays almost exclusively through one specific enantiomeric S1relaxation path. To our knowledge, the Z11 arylazopyrazole is thus the first example for nearly stereospecific unidirectional excited-state relaxation.
authors.affiliation: Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, 100875, China.
authors.forename: Ya-Ting
authors.initials: YT
authors.lastname: Wang
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. ganglong.cui@bnu.edu.cn.
authors.forename: Ganglong
authors.initials: G
authors.lastname: Cui
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: Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany. thiel@mpg.kofo.de.
authors.forename: Walter
authors.initials: W
authors.lastname: Thiel
keywords: arylazopyrazoles; conical intersections; nonadiabatic dynamics; photoisomerization; photoswitches