Polymeric Frameworks Constructed from Bulky Carboxylates and 4,4′-Bipyridine Linkages: Synthesis, Crystal Structures, and Properties

Six novel coordination polymers, {[M-2(L1)(2)(mu(2)-L1)(2)(4,4'-bipy)(2)]center dot CH3OH}(n) (HL1 = 3-(4-carboxylphenylamino)-1-ferrocenyl-2-butylen-1-one, 4,4'-bipy = 4,4'-bipyridine) (M = Zn (1) or Cd (2)), {[Cd-2(eta(2)-L2)(2)(mu(2)-eta(2)-L2)(2)(4,4'-bipy)(2)]center dot CH3OH}(n) (HL2 = N-phenylanthranilic acid) (3), {[Cd-2(mu-L3)(mu(2)-L3)(eta(2)-L3)(4,4'-bipy)(2)(H2O)(2)]center dot NO3}(n) (HL3 = cinnamic acid) (4), {[Cd-2(mu(2)-L4)(4)(4,4'-bipy)(2)]center dot 2H(2)O}(n) (HL4 = hippuric acid) (5), and {[Cd-2(mu(2)-center dot eta(2)-L5-eta(2))(2)(SO4)(4,4'-bipy)(2)(H2O)(2)]center dot 5H(2)O}(n) (HL5 = 1-(carboxymethyl)-1,3-benzimidazol-3-ium-3-acetate) (6), have been synthesized and structurally characterized by single-crystal X-ray diffraction method. Polymers 1-4 exhibit one-dimensional (I-D) ladder-like structures, in which carboxylate ligands bridge two metal ions forming dinuclear cores, and 4,4'-bipy ligands link these cores. In polymers 5 and 6, the carboxylate-linked chains [Cd-2(mu(2)-L4)(4)](n) or mixed carboxylate and SO42- linked [Cd-2(mu(2)-eta(2)-L5-eta(2))(2)(SO4)](n) chains are bridged by 4,4'-bipy ligands to form two-dimensional (2-D) sheet structures. In addition, the solution-state differential pulse voltammetries of polymers 1 and 2 were determined, and the photoluminescence properties of polymers 3-6 were investigated. The thermal properties of polymers 1-6 were determined as well.