Solvation effect on photophysical properties and ESIPT behaviours for 2-benzooxazol-2-yl-6-thiophen-2-yl-phenol fluorophore: a theoretical study

Abstract

Inspired by its potential applications of organic luminescence and fluorescence probe materials for 2-(2′-hydroxyphenyl)benzazoles (HBX) derivatives, this study mainly investigates the excited-state behaviours of a novel 2-benzooxazol-2-yl-6-thiophen-2-yl-phenol (BYTYP) fluorophore. Theoretical exploration has been conducted on the solvent-dependent interactions of excited-state intramolecular hydrogen bonding and the process of excited-state intramolecular proton transfer (ESIPT) for BYTYP. By combining optimised geometrical modifications, infrared (IR) vibrational spectra and the core-valence bifurcation (CVB) index, hydrogen bonding strengthening can be confirmed. Predicting the bond energy (E_HB), we assert that nonpolar solvents are more conducive to enhancing hydrogen bonding interactions. The ESIPT tendency of BYTYP is further elucidated by charge reorganisation resulting from photoexcitation. By exploring potential energy surfaces (PESs) and identifying transition states (TS), we have uncovered the solvent-polarity-controlled ESIPT behaviours. We hope these insights into excited-state dynamics will facilitate the design and development of novel fluorescent sensors in future.

GRAPHICAL ABSTRACT

KEYWORDS:

• Hydrogen bonding interaction
• solvent polarity
• charge redistribution
• frontier molecular orbital
• excited-state intramolecular proton transfer

Acknowledgements

The authors are grateful to the Innovative Entrepreneurship Training Program for college students (grant number S202310166011), the General Program of the Education Department of Liaoning Province (grant number LJKMZ20221473) and the Major Incubation Program of Shenyang Normal University (grant number ZD202304).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Data are available on request from the corresponding author.

Additional information

Funding

This work was supported by the Major Incubation Program of Shenyang Normal University [grant number ZD202304]; Innovative Entrepreneurship Training Program for college students [grant number S202310166011]; General Program of the Education Department of Liaoning Province [grant number LJKMZ20221473].