Synthesis, crystal structures, and luminescence properties of lanthanide(III) complexes with 1-(1H-benzimidazol-1yl-methyl)-1H-benzotriazole

Ligand 1-(1H-benzimidazole-1yl-methyl)-1H-benzotriazole (L) was used for the synthesis of five new lanthanide compounds with the composition [LnL2(H2O)(NO3)3]n (Ln = Eu3+, Sm3+, Tb3+, Dy3+, Gd3+). The obtained complexes were characterized by elemental and powder X-ray diffraction analysis, as well as IR-spectroscopy. The structures of the coordination compounds were determined by single-crystal X-ray diffraction analysis. The ligand exhibits both bidentate-bridging coordination via nitrogen atoms of the benzimidazole and benzo-triazole rings and monodentate coordination via nitrogen atom of the benzimidazole ring. The photoluminescent properties of the obtained complexes were investigated in the solid state. The energy transfer from the ligand triplet state to the central atom takes place in Eu(III), Sm(III), Tb(III) and Dy(III) compounds and, the charac-teristic bands of lanthanide ions were observed in the emission spectra. Luminescence quantum yield of Tb(III) complex was high enough (32%), therefore L is a good energy donor for sensitization of Tb(III) photo-luminescence in the solid state. Photoluminescence lifetimes were in the submillisecond range (0.015-1.14 ms) for all coordination compounds under the study.