Ultrafast restricted intramolecular rotation in molecules with aggregation induced emission

Xiao Hu; Dongdong Wang; Yanmei Wang; Ye Wang; Song Zhang

doi:10.1063/5.0200622

Ultrafast restricted intramolecular rotation in molecules with aggregation induced emission

J Chem Phys. 2024 Apr 21;160(15):154302. doi: 10.1063/5.0200622.

Authors

Xiao Hu^{1

2}, Dongdong Wang^{1

2}, Yanmei Wang^{1

2}, Ye Wang, Song Zhang^{1

2}

Affiliations

¹ State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Innovation Academy for Precision Measurement Science and Technology, Wuhan 430071, China.
² University of Chinese Academy of Sciences, Beijing 100049, China.

PMID: 38619455
DOI: 10.1063/5.0200622

Abstract

In this work, the ultrafast intramolecular rotation behavior of 1,1,2,3,4,5-hexaphenylsilole has been investigated in several solutions with different viscosities using femtosecond transient absorption spectroscopy combined with density functional theory and time-dependent density functional theory calculations. It is demonstrated that the nonradiative process, which competes with radiative decay, involves two main stages, namely the restricted intramolecular rotation and internal conversion processes. The intramolecular rotation depends on viscosity and presents a significant restriction. The restricted rotational rate is determined to be dozens of picoseconds. The following nonradiative process is strongly dominated by intramolecular rotation. The nonradiative decay rate will decrease with the increase in viscosity, leading to a rise in the radiative probability and photoluminous yield. These results have borne out the mechanism of ultrafast restricted intramolecular rotation of aggregation induced emission and provided a detailed photophysical picture of nonradiative processes.