Theoretical study on the sensing mechanism of an ON1-OFF-ON2 type fluoride fluorescent chemosensor

Sha Ding; Aixiang Xu; Mengyao Li; Aokui Sun; Zhe Zhang; Yong Xia; Yuejun Liu

doi:10.1016/j.saa.2020.118397

Theoretical study on the sensing mechanism of an ON¹-OFF-ON² type fluoride fluorescent chemosensor

Spectrochim Acta A Mol Biomol Spectrosc. 2020 Aug 15:237:118397. doi: 10.1016/j.saa.2020.118397. Epub 2020 Apr 23.

Authors

Sha Ding¹, Aixiang Xu², Mengyao Li³, Aokui Sun³, Zhe Zhang², Yong Xia⁴, Yuejun Liu³

Affiliations

¹ Key Laboratory of Advanced Packaging Materials and Technology of Hunan Province, School of Packaging and Materials Engineering, Hunan University of Technology, Zhuzhou 412007, China; School of Civil Engineering, Hunan University of Technology, Zhuzhou 412007, China.
² School of Civil Engineering, Hunan University of Technology, Zhuzhou 412007, China.
³ Key Laboratory of Advanced Packaging Materials and Technology of Hunan Province, School of Packaging and Materials Engineering, Hunan University of Technology, Zhuzhou 412007, China.
⁴ Key Laboratory of Advanced Packaging Materials and Technology of Hunan Province, School of Packaging and Materials Engineering, Hunan University of Technology, Zhuzhou 412007, China; College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China. Electronic address: [email protected].

PMID: 32361321
DOI: 10.1016/j.saa.2020.118397

Abstract

A density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations have been used to study the sensing mechanism of an ON¹-OFF-ON² type fluoride anion fluorescent chemosensor (Bis[[7-(diethylamino)-2-oxo-2H-chromene]methyl-ene]‑carbonothioic dihydrazide (CTC). The current theoretical calculation presents a different sensing mechanism from the experimentally proposed one (Sensor and Actuators B 2016, 222, 823-828). Instead of the combination of CTC deprotonation and poorly emissive excited state tautomer or ICT mechanism, the theoretical results predict the sensing mechanism based on dissociation reaction and excited-state proton transfer (ESPT). The calculated vertical excitation energies both in the ground states and first excited states of different forms of CTC, as well as the potential-energy curves, have completely reproduced the experimental results, providing powerful evidence for our proposed CTC sensing mechanism for fluoride anion.

Keywords: Fluorescence; Fluoride anion; Sensing mechanism; TDDFT.