Substituent Effect on Difluoroboron β-diketonate Complexes: Synthesis, Photophysical and Electrochemical Properties, and Application as Nitro-Explosive Chemosensors

Abstract

In this study, three difluoroboron dibenzoylmethane compounds that have substituents at the peripheral phenyl groups varying from electron-withdrawing to electron-donating, BF 2 dbm-F, BF 2 dbm-H, and BF 2 dbm-OMe, were prepared. The photophysical and electrochemical properties of these compounds, along with density functional theory and time-dependent density functional theory calculations, were systematically investigated to study the structure-property relationships of these compounds. The energy band gaps were systematically controlled, and the emission colors were tuned by the choice of substituent. In addition, the excited state behaviors of these compounds were significantly different, which resulted in variations in the fluorescence quantum yield and radiative/non-radiative decay rate constants. The BF2dbm compounds were employed as selective chemosensors for the detection of nitro explosives by fluorescence quenching, and BF 2 dbm-OMe showed the most efficient sensing ability for ortho-nitroaniline.