Molecular-based smart hybrid material through in situ sol-gel process: Artificial assembly of terbium with modified bridge ligand and luminescence

A kind of functional monomer (abbreviated as BIMA-APMS) was synthesized by means of the amidation reaction of benzimidazole-5-carboxylic acid (BIMA) with a cross-linking molecule (3-aminopropyl)trimethoxysilane (APMS). Then, the composite materials were obtained by reaction of this kind of monomer (BIMA-APMS), tetraethoxysilane (TEOS) and Tb(NO3)3·6H2O by an in situ sol-gel process, resulting in a novel molecular composite material (named as Tb-BIMA-APMS) with double chemical bonds (Tb-O coordination bond and Si-O covalent bond). Ultraviolet absorption, phosphorescence and fluorescence spectra were applied to characterize the photophysical properties of the obtained composite material. The strong luminescence of Tb3+ substantiates optimum energy match and effective intramolecular energy transfer between the triplet state energy of modified ligand bridge and emissive energy level of Tb3+.