Synthesis and Photophysical Properties of Alkoxysilyl Derivatives of Dibenzoylmethanatoboron Difluoride

Abstract

Alkoxysilyl derivatives of dibenzoylmethanatoboron difluoride (DBMBF2) are synthesized by the hydrosilylation reaction of the corresponding O-allyl derivatives of DBMBF2 with triethoxysilane. The photophysical properties of the synthesized O-allyl and alkoxysilyl derivatives are investigated. It is found that the absorption and fluorescence spectra of the DBMBF2 derivatives essentially depend on the position of the O-allyl or O-propyl alkoxysilyl substituent. The highest fluorescence quantum yield is obtained for the para-position, whereas the substitution at the meta-position gives the largest bathochromic shift in the fluorescence spectrum. Density functional theory calculations of the structures and time-dependent density functional theory calculations of the gas-phase excitation and emission energies of alkoxysilyl derivatives are performed at the PBE0/SVP level of theory. Some spectral features of para-, ortho-, and meta-substituted derivatives can be adequately explained by the overlapping of two absorption bands.