Syntheses, Structures and Optical Band Gaps of Two Coordination Polymers with 2D → 3D Polythreaded and Interdigitated Structures

Two coordination polymers [Cu(phen)(L)(0.5) (H2O)] (1) and [Ni-2(phen)(2)(L)(H2O)(0.5)]center dot 0.5H(2)O (2), where phen = 1,10-phenanthroline and H4L = 5,5'-(ethane-1,2-diyl)-bis(oxy)diisophthalic acid, have been synthesized under hydrothermal conditions. In complex 1, the L anions and the phen ligands connect the Cu(II) ions to form a layer. The phen ligands act as arms and thread into the adjacent layer, forming a 2D -> 3D polythreaded architecture. In complex 2, the L anions and the phen ligands link the Ni(II) ions to form a layer. Further, the adjacent layers interdigitate each other through intermolecular pi - pi interactions to generate a 2D -> 3D interdigitated architecture. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by infrared spectra (IR) and elemental analyses. The thermal properties and optical band gaps of complexes 1 and 2 have also been investigated.