Three Novel Cd(II) and Zn(II) Coordination Polymers with O-, N-donor Ligands: Syntheses, Structures, and Photoluminescence Properties

Three new multi-dimensional coordination polymers, namely, [Cd(SIP)(HBPP)(BPP)0.5(H2O)·H2O]n (1), [Zn(L)(BIB)0.5]n (2), and {[Cd2(L)2(BIB)2](H2O)7}n (3) (H3SIP = 5-sulfo-1,3-benzenedicarboxylate, BPP = 1,3-bis(4-pyridyl)propane, H2L = 4-oxyacetate-benzoic acid, and BIB = 1,4-bis(imidazol-1-yl)-butane), were hydrothermally synthesized by self-assembly of the flexible N-donor ligand and the polycarboxylate ligands. Single crystal X-ray analyses reveal that complexes 1–3 possess different structural features. The Cd(II) atom in complex 1 is seven-coordinated by two bidentate chelating carboxylate groups and two nitrogen atoms as well as one water molecule. The adjacent Cd(II) atoms are bridged by two carboxylate groups to form 1D chains running along different directions, which are connected by BPP ligands to generate 2D network. The resulting 2D networks are further linked by hydrogen-bond interactions, affording a 3D supramolecular architecture. In complex 2, the [Zn2(COO)4] units are bridged by L2− ligands to generate 1D double chain structure and then linked by BIB ligands to give 2D grid framework. In complex 3, the [Cd(L2)]n and [Cd(BIB)]n helixes are alternately arranged, leading to the formation of a 2D bilayer structure.