An unusual way to luminescent terbium molecular-level hybrid materials: Modified methyl benzoic acid covalently bonded with silica as a bridge

Abstract

The syntheses of modified ortho or meta methylbenzoic acid by (3-aminopropyl)triethoxysilane and the preparation of their corresponding organic–inorganic molecular-based hybrid material with the two components equipped with covalent bonds are described. The organic part is a derivative of methyl benzoic acid, which is used to coordinate to Tb3+ and further introduced into silica matrices by Si–O bonds after hydrolysis and polycondensation processes. The Judd–Ofelt theory proves that covalency increases along with increasing reciprocal energy difference between the 4fN and 4fN−15d1 configurations. Ultraviolet absorption, phosphorescence spectra, and luminescence spectra were applied to characterize the photophysical properties of the obtained hybrid material, and the above spectroscopic data reveal that the triplet energy of modified methyl benzoic acid matches with the emissive energy level of Tb3+. In this way, the intramolecular energy transfer process took place within these molecular-based hybrids, and strong green emission of Tb3+ was obtained.