Synthesis, Structures, Fluorescence Properties, and Natural Bond Orbital (NBO) Analysis of Two Metal [EuIII, CoII] Coordination Polymers Containing 1, 3-Benzenedicarboxylate and 2-(4-methoxyphenyl)-1H-imidazo[4, 5-f][1,10]phenanthroline Ligands

Two new metal-organic coordination polymers[Eu(m-BDC)(1.5)(MOPIP)center dot 1/2H(2)O](n) (1) and [Co(m-BDC)(MOPIP)(2)center dot 2H(2)O](n) (2) [m- H2BDC = benzene-1, 3-dicarboxylic acid, MOPIP = 2-(4-methoxyphenyl)-1H-imidazo[4, 5-f][1,10]phenanthroline] were hydrothermally synthesized and structurally characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. The coordination polymers crystallize in monoclinic space group P2(1)/m for 1 (2: P2(1)/n), with a = 9.779(2), b = 18.242(4), c = 17.146(3) angstrom, beta = 106.41(3)degrees for 1, and with a = 8.2153(16), b = 27.974(6), c = 17.974(4) angstrom, beta = 100.40(3)degrees for 2. The crystal structure of complex 1 is a zipper-like chain of octacoordinate Eu3+ ions, in which Eu3+ ions are bridged in two coordination modes by m-BDC2+ ligands and decorated by MOPIP ligands. The molecular structure of complex 2 consists of a hexacoordinte Co2+ atom, which generates a slightly distorted octahedral arrangement, and assembles into three-dimensional supramolecular nets by pi center dot center dot center dot pi stacking interactions. Additionally, these two compounds show strong fluorescence in the solid state at room temperature. Natural bond orbital (NBO) analysis is performed by using the NBO method built in Gaussian 03 Program. The calculation results show a weak covalent interaction between the coordinated atoms and metal ions.