Co-luminescence effect of heterometallic terbium-gadolinium hybrid molecular materials constructed by covalent grafting.

In this paper, 2-chlorobenzoic acid (CBA) and 2-chloronicotinic acid (CNA) were modified by 3-aminopropyl-trimethoxysilane (APMS) to afford corresponding organic-inorganic monomers (CBA-APMS and CNA-APMS) with two components equipped with covalent bonds which not only can coordinate to RE ions (Tb(3+) and Gd(3+)) but also act as a sol-gel precursor. Luminescent hybrid materials consisting of terbium-gadolinium complex covalently bonded to silica-based network have been obtained in situ via a sol-gel approach. Through co-hydrolysis and polycondensation, Tb(3+) and Gd(3+) can be introduced in the same organic-inorganic hybrid monomer and then formed Si-O backbones. The co-luminescence effect can be found by studying the luminescence spectra of different ratios of Tb(3+)-Gd(3+), which means that the existence of Gd(3+) can enhance the luminescence intensity, which may be due to the intramolecular energy transfer between Gd(3+) and Tb(3+).