Synthesis, structure and luminescent property of a binuclear terbium complex [Tb 2(Hsal) 8(H 2O) 2][(Hphen) 2]·2H 2O

Abstract

A binuclear terbium complex [Tb 2(Hsal) 8(H 2O) 2][(Hphen) 2]·2H 2O 1 (Hsal= o-HOC 6H 4CO 2 −, phen=1,10-phenanthroline) was synthesized and characterized by elemental analysis, molar conductance, IR, UV–VIS, X-ray powder diffraction, Thermogravimetric analysis and fluorescence. Its structure was determined by X-ray single crystal diffraction. In the dimeric anion [Tb 2(Hsal) 8(H 2O) 2] 2−, two terbium atoms are connected by four bidentate bridging carboxylate groups. Each Tb atom is eight-coordinated to four bidentate bridging carboxylate groups, one bidentate chelating carboxylate groups, one monodentate carboxylate group as well as one water molecule. The mono-protonated phen does not coordinate to the Tb atom directly. Hydrogen bonds, π–π stacking interactions and electrostatic attractions result in the formation of a two-dimensional supramolecular structure. The solid-state luminescence behavior of 1 was studied. Compared with binary terbium salicylate Tb(Hsal) 3(H 2O) 2·2H 2O, it emits a relatively weak green light under the excitation of UV light, which may be attributed to the formation of extensive π-electron conjugation systems in the structure.