Synthesis, structures and luminescent properties of novel coordination polymers constructed by lanthanide salts and benzimidazole-5,6-dicarboxylic acid

Abstract Two three-dimensional (3D) novel lanthanide complexes with the H 2 L benzimidazole-5,6-dicarboxylate [Ln 2 L 3 (H 2 O)] [Ln = Eu ( 1 ), Tb ( 2 )] and one two-dimensional (2D) novel lanthanide complex [Pr(L)(HL)H 2 O]·H 2 O ( 3 ) were synthesized by hydrothermal reaction at 180 °C and characterized by elemental analysis, infrared spectra and single-crystal X-ray diffraction. The result showed that complexes 1 and 2 are isostructural and build porous 3D networks by L 2− groups linking Ln(III) atoms via tetradentate (bridging and bridging) and pentadentate (bridging/chelating and bridging) coordination modes. Complex 3 is a eight-coordinated Pr(III) chain complex, exhibiting a 2D polymeric network with parallel Pr-carboxylate chains along the crystallographic c -axis. In addition, it is found that in these structures, coordination modes of L 2− and HL − are versatile and can adopt different conformations according to distinct dimensions of polymeric structures. The photoluminescent properties of 1 , 2 and thermogravimetric analyses of the three complexes were discussed in detail.