TD-DFT study on the sensing mechanism of a fluorescent chemosensor for fluoride: excited-state proton transfer.
An excited-state proton transfer (ESPT) process, induced by both intermolecular and intramolecular hydrogen-bonding interactions, is proposed to account for the fluorescence sensing mechanism of a fluoride chemosensor, phenyl-1H-anthra(1,2-d)imidazole-6,11-dione. The time-dependent density functional theory (TD-DFT) method has been applied to investigate the different electronic states. The present theoretical study of this chemosensor, as well as its anion and fluoride complex, has been conducted with a view to monitoring its structural and photophysical properties. The proton of the chemosensor can shift to fluoride in the ground state but transfers from the proton donor (NH group) to a proton acceptor (neighboring carbonyl group) in the first singlet excited state. This may explain the observed red shifts in the fluorescence spectra in the relevant fluorescent sensing mechanism.
Li
Guang-Yue
GY
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
Zhao
Guang-Jiu
GJ
Liu
Yu-Hui
YH
Han
Ke-Li
KL
He
Guo-Zhong
GZ
D003198:Computer Simulation; D005456:Fluorescent Dyes / Q000032:analysis / Q000737:chemistry*; D005459:Fluorides / Q000032:analysis* / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D011522:Protons; D011789:Quantum Theory; D012984:Software; D013050:Spectrometry, Fluorescence; D013997:Time Factors; D014732:Vibration
D005456:Fluorescent Dyes; D011522:Protons; D005459:Fluorides