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)]·H₂O}_n (1,3,5-H₃BTC = 1,3,5-benzenetricarboxylic acid), 1, {[Cu_1.5(L²)_1.5(1,3,5-BTC)(H₂O)₂]·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]·2.5MeOH·2H₂O}_n, 5, and {[Cu₃(L³)₂(1,3,5-BTB)₂ ]·DMF·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 (4¹²·6³)-pcu topology and a 3D framework with the (4¹⁰·6³²·8³)(4²·6)₂(4³·6³) topology, respectively, whereas 5 and 6 are 3D frameworks with the (6³)₂(6⁴·8²)(6⁸·8⁵·10²) topology. Complex 5 shows a better iodine adsorption factor of 290.0 mg g⁻¹ at 60 °C for 360 min than the other ones, revealing that the flexibility of the spacer ligand governs the structural diversity and the adsorption capacity. [ABSTRACT FROM AUTHOR]