Two 2-D 4-connected lanthanide coordination framework based on benzimidazole-5,6-dicarboxylate and acetate mixed ligands

Two 2-D polymers, [Ln(bidc)(Ac)·H2O]n (Ln=Tb(1), Dy(2) H2bidc=benzimidazole-5,6-dicarboxylic acid, HAc=acetic acid), have been successfully synthesized under hydrothermal conditions at 150°C and characterized by elemental analysis, infrared spectra and single-crystal X-ray diffraction. Single crystal X-ray diffraction analyses reveal that the two compounds are isomorphous and exhibit one new (4,4)-connected 2-nodal (44·62)(44·62) layer-like net, stabilized by the interchain hydrogen bonding N–H⋯O, O–H⋯O and π⋯π stacking interactions between two benzimidazole rings. 2-D layers are further connected by the interlayer O–H⋯O hydrogen-bonding interactions to form a 3-D supermoleculaer network. Moreover, the luminescent property of compound 1 and thermogravimetric analyses of the two complexes 1–2 are discussed in detail.