Weak Dewar bond modulates protonated azaindole photodynamics

Abstract

Recent experimental work revealed that the lifetime of the S3 state of protonated 7-azaindole is about ten times slower than that of protonated 6-azaindole. We simulated the nonradiative decay pathways of these molecules using trajectory surface hopping dynamics after photoexcitation into S3 to elucidate the reason for this difference. Both isomers mainly follow a common pp* relaxation pathway involving multiple state crossings while coming down from S3 to S1 in the subpicosecond time scale. However, the simulations reveal that the excited-state topographies are such that while the 6-isomer can easily access the region of nonadiabatic transitions, the internal conversion of the 7-isomer is delayed by a pre-Dewar bond formation with a boat conformation.

Pre-Dewar structure modulates protonated azaindole photodynamics

“…The initial conditions sampling, absorption spectra calculations, and DC-FSSH simulations were carried out with Newton-X (version 2.2 build 12) 43 interfaced with Turbomole. The dataset of all the trajectories 44 and processed data 45 for each azaindole isomer are available to download.…”