1. Investigation of Excited-State Intramolecular Proton Transfer and Structural Dynamics in Bis-Benzimidazole Derivative (BBM)
- Author
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Junhan Xie, Ziyu Wang, Ruixue Zhu, Jiaming Jiang, Tsu-Chien Weng, Yi Ren, Shuhua Han, Yifan Huang, and Weimin Liu
- Subjects
excited-state intramolecular proton transfer ,structural dynamics ,transient absorption ,femtosecond fluorescence upconversion ,femtosecond stimulated Raman spectroscopy ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
The bis-benzimidazole derivative (BBM) molecule, consisting of two 2-(2′-hydroxyphenyl) benzimidazole (HBI) halves, has been synthesized and successfully utilized as a ratiometric fluorescence sensor for the sensitive detection of Cu2+ based on enol–keto excited-state intramolecular proton transfer (ESIPT). In this study, we strategically implement femtosecond stimulated Raman spectroscopy and several time-resolved electronic spectroscopies, aided by quantum chemical calculations to investigate the detailed primary photodynamics of the BBM molecule. The results demonstrate that the ESIPT from BBM-enol* to BBM-keto* was observed in only one of the HBI halves with a time constant of 300 fs; after that, the rotation of the dihedral angle between the two HBI halves generated a planarized BBM-keto* isomer in 3 ps, leading to a dynamic redshift of BBM-keto* emission.
- Published
- 2023
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