Syntheses, Crystal Structures and Thermal Stabilities of Two New Mixed Ligated Coordination Polymers with Rigid Dicarboxylate and Flexile N-donor Ligands

Two new coordination polymers, [Co(BIPA)(bpp)] (1) and [Zn(BIPA)(bpp)(H2O)] (2) (H(2)BIPA = 5-bromoisophthalic acid, bpp = 1,3-di(4-pyridyl)propane) have been synthesized via hydrothermal reactions. The two compounds were characterized by elemental analysis, IR spectra, TG analysis and single-crystal X-ray determination. Compound 1 crystallizes in triclinic, space group P (1) over bar with a = 9.0316(13), b = 10.1179(14), c = 11.8884(17) angstrom, alpha = 68.022(2), beta = 84.749(2), gamma = 77.791(2)degrees, V = 984.5(2) angstrom(3), Z = 2, C21H17BrN2O4Co, M-r = 500.21, D-c = 1.687 g.cm(-3), mu = 2.932 mm(-1), S = 0.981, F(000) = 502, R = 0.0440 and wR = 0.1357 for 3773 observed reflections with I > 2 sigma(I). Compound 2 crystallizes in the monoclinic system, space group P2(1)/c with a = 7.8466(10), b = 27.483(4), c = 9.6583(13) angstrom, beta = 96.663(3)degrees, V = 2068.8(5) angstrom(3), Z = 4, C21H19BrN2O5Zn, M-r = 524.66, D-c = 1.685 g.cm(-3), mu = 3.155 mm(-1), S = 0.969, F(000) = 1056, R = 0.0441 and wR = 0.0517 for 4058 observed reflections with I > 2 sigma(I). The two compounds are constructed from the BIPA(2-) and bpp ligands but they exhibit different kinds of one-dimensional chain structures. In 1, the chains are composed of the Co(II) ions and BIPA(2-) ligands, and the chains are further extended into a 2D framework structure by pi center dot center dot center dot pi interactions of the benzene rings from the BIPA(2-) ligands between the adjacent chains. In 2, the chains are made up of Zn(II) ions and BIPA(2-) ligands through another fashion, and the chains are further linked via hydrogen bonding interactions to yield a two-dimensional supramolecular layer structure. Furthermore, the bpp ligand features two kinds of different coordination modes in the two compounds.