Quantum Chemical Study of the Monomethoxylated Derivative of the Boron Difluoride Dibenzoylmethanate Dye and Its Exciplexes with Benzene and Toluene on a Silica Surface

Abstract TDDFT calculations of exciplexes of monomethoxylated dibenzoylmethanate boron difluoride (CH3O-DBMBF2) with benzene and toluene in the gas phase and on a silica surface have been performed. The energies of exciplex formation and dye adsorption on silica, as well as the fluorescence wavelengths of isolated and adsorbed exciplexes, have been calculated. Spectral shifts upon exciplex adsorption on silica have been evaluated. The Mulliken charges on atoms, the electron density transfer in exciplexes, and its change upon exciplex adsorption on silica have been calculated. It has been shown that the introduction of an electron-donating methoxyl substituent into the DBMBF2 molecule at the para-position of the phenyl ring leads to a decrease in both the energy of dye adsorption on silica and the formation energies of exciplexes with benzene and toluene, lessens electron density transfer in exciplexes, and reduces bathofluoriic shifts in the exciplex fluorescence spectra compared to the spectrum of the free dye. These results can be used to design new sensor materials.