Lanthanide (Tb3+, Eu3+) functionalized MCM-41 through modified meta-aminobenzoic acid linkage: Covalently bonding assembly, physical characterization and photoluminescence

Novel luminescent organic–inorganic mesoporous materials were synthesized by linking lanthanide (Tb3+, Eu3+) complexes to the functionalized ordered mesoporous MCM-41 with modified meta-aminobenzoic acid (MABA-Si) by co-condensation of tetraethoxysilane (TEOS) in the presence of the cetyltrimethylammonium bromide (CTAB) surfactant as template. meta-Aminobenzoic acid (MABA) grafted to the coupling agent 3-(triethoxysilyl)-propyl isocyanate (TEPIC) was used as the precursor for the preparation of mesoporous materials. The luminescence properties of these resulting materials (denoted as Ln-MABA-MCM-41, Ln = Tb, Eu) were characterized in detail, and the results reveal that luminescent mesoporous materials have high surface area, uniformity in the mesopore structure and good crystallinity. Moreover, the mesoporous material covalently bonded Tb3+ complex (Tb-MABA-MCM-41) exhibits the stronger characteristic emission of Tb3+ and longer lifetime than Eu-MABA-MCM-41 due to the triplet state energy of organic ligand MABA-Si matches with the emissive energy level of Tb3+ very well. Compared with pure Tb(MABA)3 complex, the increase of luminescence intensity in Tb-MABA-MCM-41 shows that the mesoporous MCM-41 is an excellent host for the luminescence Tb(MABA)3 complex. In addition, the luminescence lifetime and emission quantum efficiency of 5D0 Eu3+ excited state also indicates that a more efficient intramolecular energy transfer process in Tb-MABA-MCM-41 than in Eu-MABA-MCM-41.