Cu(II) Coordination Polymers Containing Mixed Ligands with Different Flexibilities: Structural Diversity and Iodine Adsorption

Reactions of N,N '-bis(3-methylpyridyl)oxalamide (L1), N,N'-bis(3-methylpyridyl)adipoamide (L2) and N,N'-bis(3-methylpyridyl)sebacoamide (L3) with tricarboxylic acids and Cu(II) salts afforded {[Cu(L1)(1,3,5-HBTC)]center dot H2O}n (1,3,5-H3BTC = 1,3,5-benzenetricarboxylic acid), 1, {[Cu1.5(L2)1.5(1,3,5-BTC)(H2O)2]center dot 6.5H2O}n, 2, [Cu(L2)0.5(1,3,5-HBTB)]n (1,3,5-H3BTB = 1,3,5-tri(4-carboxyphenyl)benzene), 3, [Cu4(L3)(OH)2(1,3,5-BTC)2]n, 4, {[Cu3(L3)2(1,3,5-BTB)2]center dot 2.5MeOH center dot 2H2O}n, 5, and {[Cu3(L3)2(1,3,5-BTB)2 ]center dot DMF center dot 2H2O}n, 6, which have been structurally characterized by using single crystal X-ray crystallography. Complexes 1-4 form a 2D layer with the {44.62}-sql topology, a 2D layer with the (4.62)2(42.62.82)-bex topology, a three-fold interpenetrated 3D net with the (412 center dot 63)-pcu topology and a 3D framework with the (410 center dot 632 center dot 83)(42 center dot 6)2(43 center dot 63) topology, respectively, whereas 5 and 6 are 3D frameworks with the (63)2(64 center dot 82)(68 center dot 85 center dot 102) topology. Complex 5 shows a better iodine adsorption factor of 290.0 mg g-1 at 60 degrees C for 360 min than the other ones, revealing that the flexibility of the spacer ligand governs the structural diversity and the adsorption capacity.