Fluorescence enhancement of terbium(III) perchlorate by 1,10-phenanthroline on acetophenonylcarboxymethyl sulfoxide complex and luminescence mechanism

A novel ligand (L) containing multiple coordinating groups (one sulfinyl group, one carboxyl and carbonyl group), acetophenonylcarboxymethyl sulfoxide, was synthesized by an effective method. Its novel ternary complex, TbL2L− phen(ClO4)2·3 H2O, and the binary complex, TbL3L−(ClO4)2·3 H2O, have been synthesized (using acetophenonylcarboxymethyl sulfoxide as the first ligand L, 1,10-phenanthroline as the second ligand phen). Their compositions and properties were analyzed by element analysis, coordination titration, molar conductivity, IR, TG–DSC, 1HNMR and UV spectra. Their fluorescence intensities, phosphorescence spectra, and fluorescence emission mechanism were also studied. It was shown that the ternary rare-earth complex showed stronger fluorescence intensities than the binary rare-earth complexes in such material. The strongest characteristic fluorescence emission intensity of the ternary system was 3.06 times as strong as that of the binary systems. By fluorescence analysis, it was found that both acetophenonylcarboxymethyl sulfoxide and phen ligands could sensitize the fluorescence intensities of rare-earth ions. In the ternary rare-earth complex, introduction of a phen group was facilitating the fluorescence properties of Tb(III), attributed to the synergistic energy transfer effect. Additionally, the phosphorescence spectra and the luminescence mechanisms of the complexes are studied and explained.