Theoretical study of chemosensor for fluoride and phosphate anions and optical properties of the derivatives of 2-(2-hydroxyphenyl)-1,3,4-oxadiazole

Abstract

The interactions between chemosensor, 2-(2-hydroxyphenyl)-5-phenyl-1,3,4-oxadiazole (HOXD1), and different halides (F −, Cl −, and Br −) and phosphate ( H 2 PO 4 - ) anions were theoretically investigated. It turned out that the unique selectivity of HOXD1 for F - / H 2 PO 4 - is ascribed to its ability of deprotonating the hydroxy group of host sensor. Optical spectra of neutral and deprotonated sensors were simulated using TD-DFT method. It was found that intermolecular proton transfer is responsible for the colorimetric and fluorescent signaling of chemosensor for F - / H 2 PO 4 - . Seven derivatives of HOXD1 have been designed. All the mono-electron-donating (–CH 3, –OCH 3, and –N(CH 3) 2) substituted derivatives are expected to be promising candidates for ratiometric fluorescent F - / H 2 PO 4 - chemosensors as well as chromogenic chemosensors, while para-N(CH 3) 2 substituted derivative can serve as chromogenic F - / H 2 PO 4 - chemosensor only. Furthermore, the mono-electron-withdrawing (–CN and –COCH 3) derivatives are promising electron transport and luminescent materials for OLEDs as well.