New two-dimensional metal–organic frameworks constructed from 1H-benzimidazole-5,6-dicarboxylic acid with luminescent studies

New two-dimensional metal–organic frameworks [Pb(Hbidc)]n (1) and [Cd(Hbidc)]n (2), constructed from multidentate ligand 1H-benzimidazole-5,6-dicarboxylic acid (Hbidc), have been synthesized under hydro/solvothermal conditions and fully characterized. Compound 1 is the first lead–organic framework based on Hbidc, and displays a 5-connected SnS network which contains 2D [Pb(CO2)]n layers. The Hbidc ligand exhibits a novel coordination mode (μ5:η2:η2:η2:η1), which is reported for the first time in M-bidc frameworks. Compound 2 has a two-dimensional layer structure constructed of rod-shaped building blocks. Both the two 2D compounds are further assembled by hydrogen bonds and π–π stacking interactions into 3D supramolecular networks. Luminescent studies show that the title compounds exhibit different fluorescence emission activity at room temperature in the solid state.