Hydrothermal synthesis and crystal structure of four lead(II) coordination polymers with a carboxylate functionalized imidazophenanthroline derivative ligand

Four novel lead(II) metal–organic coordination polymers, [Pb2(Hcpip)4]n (1), [Pb2(Hcpip)2(ox)]n (2), [Pb2(Hcpip)2(suc)]n (3), [Pb2(cpip)2(glu)(H2O)]n·n(H2O) (4) [H2cpip = 2-(2-carboxyphenyl)imidazo(4,5-f)(1,10)-phenanthroline, H2ox = oxalic acid, H2suc = succinic acid, H2glu = glutaric acid], have been hydrothermally synthesized and characterized by elemental analysis, IR, single crystal X-ray diffraction. Complex 1 exhibits a 2D layer structure. Complexes 2 and 3 feature 1D loop-and-chain structures, which are connected by strong π⋯π interaction to result in 2D layer structures. Complex 4 has the dinuclear parallelogram of [Pb2O2] and shows a 2D layer structure. The structural differences of these complexes give some insights into the effect of different auxiliary ligands on the construction of coordination polymers under the same hydrothermal conditions. The fluorescent properties of 1–4 were investigated.