Mechanistic insights into the influence of subtle structural variations on photophysical properties and desilication reaction.

Fluoride ions (F-), an important trace element in the natural environment, and excessive intake may cause potential health risks. Fluorescent probes are always used for the detection of F-, and previous studies focused on modifying probes with various substituents to improve F- detection efficiency. However, most studies ignore the influence of the subtle differences in molecular structure on detection. Herein, we investigate the influence of the structural variations in polycyclic aromatic hydrocarbon (PAH) of 3-Hydroxy-2-naphthalene formaldehyde (HPNI) on the detection of F- by the DFT/TD-DFT methods. Our simulation results indicate that the subtle structural variations in PAH can regulate the energy barrier of the excited state intramolecular proton transfer (ESIPT) and photophysical properties, and the strength of hydrogen bonds is proved to be the main influencing factor for ESIPT. Moreover, based on the mechanistic analysis of the desilication reaction, a candidate probe is identified that exhibits superior F- detection performance compared to that reported in experimental studies. Our study will provide theoretical support for enhancing the sensitivity of F- detection and present a novel fluorescent probe with improved performance.