The fabrication of rare earth covalent luminescent hybrid materials with potential molecular bridge by in situ sol-gel process

1,2,4-Benzenetricar boxylic acid (abbreviated as TMA) was modified to achieve a functional molecular bridge (TMA-APMES) with double reactivity by the reaction with a cross-linking molecule (3-aminopropyl-methyl-diethoxylsiliane, APMES). The modified functional ligand further behaves as a bridge both coordinates to Ln3+ through oxygen atom and occurs in situ sol-gel process with matrix precursor (tetraethoxysilane, TEOS) through co-hydrolysis and co-polycondensation reaction. Then a novel molecular hybrid material (named as hybrid Ln3+) with double chemical bond (TbO coordination bond and SiO covalent bond) resulted. Ultraviolet absorption, phosphorescence, and fluorescence spectra were applied to characterize the photophysical properties of the obtained hybrid material. The strong luminescence of Tb3+ substantiates optimum energy couple and effective intramolecular energy transfer between the triplet state energy of modified ligand bridge and emissive energy level of Tb3+.