Structural transformations in cobalt(II) coordination polymers constructed from flexible N,N′-bis(3-pyridylmethyl)sebacoamide and benzene-1,3,5-tricarboxylic acid

Hydro(solvo)thermal reactions of cobalt(n) salts, N,N'-bis(3-pyridylmethyl)sebacoamide (L), and benzene-1,3,5-tricarboxylic acid (1,3,5-H3BTC) in water afforded {[Co(L)(1,3,5-HBTC)]center dot H2O}(n) 1 and {[Co-2(L)(2)(1,3,5-HBTC)(2)(H2O)(4)]center dot 9H(2)O}(n) 2, whereas those in MeOH and MeOH/H2O gave {[Co-3 (L)(1,3,5-BTC)(2)(CH3OH)(5)]center dot 5CH(3)OH}(n) 3 and {[Co-1.5(L)(0.5)(1,3,5-BTC)(CH3OH)(H2O)(3)]center dot H2O}(n) 4, respectively, which have been structurally characterized by using single-crystal X-ray diffraction. Complex 1 displays a two-dimensional (2D) network with the {4(2)center dot 6(7)center dot 8}{4(2)center dot 6}-3,5L2 topology, and complexes 2 and 3 are three-dimensional (3D) frameworks with the (6(5)center dot 8)-cds topology and a new topology with a point symbol of {5 center dot 6 center dot 7}{5 center dot 6 center dot 8}(2){5(2)center dot 6(2)center dot 7 center dot 8(2)center dot 9(3)}, respectively, while 4 shows a 2D layer with the {6(3)}-hcb topology, demonstrating that the concentration of the reagent and the solvent system are important in determining the structural diversity. Irreversible structural transformations from 1 to 3 and 2 to 3 under hydro(solvo)thermal conditions are observed and discussed, showing that the flexible nature of the spacer ligands is important in promoting the structural transformations.