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

Six novel coordination polymers, {[M2(L1)2(μ2-L1)2(4,4′-bipy)2]·CH3OH}n (HL1 = 3-(4-carboxylphenylamino)-1-ferrocenyl-2-butylen-1-one, 4,4′-bipy = 4,4′-bipyridine) (M = Zn (1) or Cd (2)), {[Cd2(η2-L2)2(μ2-η2-L2)2(4,4′-bipy)2]·CH3OH}n (HL2 = N-phenylanthranilic acid) (3), {[Cd2(μ-L3)(μ2-L3)(η2-L3)(4,4′-bipy)2(H2O)2]·NO3}n (HL3 = cinnamic acid) (4), {[Cd2(μ2-L4)4(4,4′-bipy)2]·2H2O}n (HL4 = hippuric acid) (5), and {[Cd2(μ2-η2-L5-η2)2(SO4)(4,4′-bipy)2(H2O)2]·5H2O}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 (1-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 [Cd2(μ2-L4)4]n or mixed carboxylate and SO42− linked [Cd2(μ2-η2-L5-η2)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.