Syntheses, Structures and Photoluminescent Properties of Two New Pb(II) and Cd(II) Coordination Polymers Constructed from 1,10-Phenanthroline-derived and 1,4-Naphthalenedicarboxylate Ligands

Two new related coordination polymers, namely, [Pb(L)(1,4-ndc)] · 0.5H2O (1) and [Cd(L)(1,4- ndc)] · 0.5H2O (2), where L = 2-(3-fluorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline and 1,4- ndc = 1,4-naphthalenedicarboxylate, were synthesized under hydrothermal conditions. Crystal data for 1: C62H36F2N8O9Pb2, monoclinic space group C2/c, a = 15.874(3), b = 19.982(4), c = 16.045(3) Å, β = 94.26(3), V = 5075.3(18) Å3, Z = 4. Crystal data for 2: C62H36Cd2F2N8O9, monoclinic space group P21/n, a = 12.622(2), b = 14.038(3), c = 14.938(3) Å , β = 100.81(2), V = 2600.0(8) Å3, Z = 2. In compound 1, the 1,4-ndc ligands connect the Pb(II) atoms to yield a chain structure. The L ligands are attached on the same side of the chain. The π-π interactions between L ligands of neighboring chains result in a 2D supramolecular architecture of 1. In compound 2, 1,4-ndc ligands link the Cd(II) atoms to generate a layer structure. The L ligands from adjacent layers are paired to furnish strong π-π interactions. Further, these layers are extended into 3D supramolecular architectures through these π-π interactions. The structural differences of 1 and 2 suggest the importance of the metal centers in the construction of the coordination polymers. The luminescent properties of the compounds were also investigated.