Fluorescent enhancement effect in heterometallic terbium–lanthanum hybrid molecular materials obtained by functional bridge grafting to silica network

A new monomer, TBBA–APMES, has been synthesized by grafting 3-aminopropyl-methyl-diethoxylsiliane (APMES) to 4-tert-butylbenzoic acid (TBBA) and characterized by H NMR, C NMR and Fourier transform infrared (FT-IR). The monomer acts as a functional ligand for Tb and La ion and as a sol–gel precursor. Luminescent hybrid materials consisting of terbium–lanthanum complex covalently bonded to a silica-based network have been obtained in situ via a sol–gel approach. Through the co-hydrolysis and polycondensation, Tb3+ and La3+ can be introduced in the same molecular hybrids through the chemical Si–O network and fluorescent enhancement is observed. The luminescent behavior has been studied with the different ratios of Tb3+–La3+, suggesting that the luminescence intensities of hybrids can be enhanced obviously by the existence of La3+. The enhanced fluorescence effect may be due to the strengthening of intramolecular energy transfer efficiency by La3+.