Is excited state intramolecular proton transfer frustrated in 10-hydroxy-11H-benzo[b]fluoren-11-one?

Dapeng Yang; Tianjie Zhang; Xiaoyan Song; Haiyan Gao

doi:10.1016/j.saa.2019.117734

Is excited state intramolecular proton transfer frustrated in 10-hydroxy-11H-benzo[b]fluoren-11-one?

Spectrochim Acta A Mol Biomol Spectrosc. 2020 Mar 5:228:117734. doi: 10.1016/j.saa.2019.117734. Epub 2019 Nov 2.

Authors

Dapeng Yang¹, Tianjie Zhang², Xiaoyan Song², Haiyan Gao²

Affiliations

¹ College of Physics and Electronics, North China University of Water Resources and Electric Power, Zhengzhou, 450046, PR China; State Key Laboratory of Molecular Reaction Dynamics, Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, PR China. Electronic address: dpyang_ncwu@163.com.
² College of Physics and Electronics, North China University of Water Resources and Electric Power, Zhengzhou, 450046, PR China.

PMID: 31718974
DOI: 10.1016/j.saa.2019.117734

Abstract

Recently, Piechowska and coworker found that hydroxybenzofluorenone 10-hydroxy11H-benzo[b]fluoren-11-one (10-HHBF) does not show dual fluorescence, which is in contrast to its well-known analogue 1-hydroxy-11H-benzo[b]fluoren-11-one (1-HHBF) [Dyes Pigm. 2019, 165, 346-353.]. Based on the increased donor-acceptor distance and the lower stability of the excited state tautomer of former, they believe that different from 1-HHBF, ESIPT is not occurring in 10-HHBF. In the preset work, in order to clarify whether ESIPT would take place in 10-HHBF, we have optimized the four-state geometrical structures (ground state S₀, first singlet excited state S₁, transition state S_1-TS and after proton transfer S_1-PT), carried out the Natural Population Analysis and scanned the ground-state and excited-state potential energy curves of 1-HHBF and 10-HHBF at TD-CAM-B3LYP/6-311 + g(2d,2p)/IEFPCM (cyclohexane) theory level. It is found that ESIPT should take place in both 1-HHBF and 10-HHBF and the Gibbs free energy diagram further indicates that the ESIPT process is more favorable in 10-HHBF than in 1-HHBF.

Keywords: Excited state intramolecular proton transfer (ESIPT); Gibbs free energy; Infrared vibrational spectra; Natural population analysis; Potential energy curves.