Synthesis, Crystal Structure and Luminescent Property of a One-dimensional Europium Citrate Complex

A new compound, Eu(Hcit)(H2O)2]·H2O]n (1, Hcit3- = C(OH)(COO-)(CH2COO-)2),has been synthesized under hydrothermal reactions of europium oxide, MnCl2-4H2O and citric acid at 120 ℃ for three days. The compound was characterized by single-crystal X-ray diffraction analyses, IR and TGA. Complex 1 crystallizes in monoclinic, space group P21/n with a = 6.179(1),b = 9.688(2), c= 16.990(3) (A), β = 91.98(3)°, Z= 4, V= 1016.4(3) (A)3, C6H11EuO10, Mr = 395.11,Dc = 2.582 g/cm3, μ = 6.218 mm-1, F(000) = 760, R = 0.0183 and wR = 0.0411. Single-crystal X-ray analysis reveals that complex 1 displays lD ladder chains along the a axis, with dinuclear Eu2O2units serving as "steps" and carboxylate groups as "uprights", which are connected by hydrogen bonds. The solid-state luminescent property of complex 1 was investigated at room temperature.Upon excitation at 394 nm, compound 1 exhibits interesting luminescent properties with several intense bands in the visible region and the most intense and sharp emission being in the red region at 615 nm. The TGA and XRD results prove that complex 1 undergoes facile thermal decomposition to form Eu2O3 at about 870 ℃.