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+.