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

Reactions of N,N '- bis (3-methylpyridyl)oxalamide ( L ¹ ), N , N '- bis (3-methylpyridyl)adipoamide ( L ² ) and N , N '- bis (3-methylpyridyl)sebacoamide ( L ³ ) with tricarboxylic acids and Cu(II) salts afforded {[Cu( L ¹ )(1,3,5-HBTC)]·H ₂ O} _n (1,3,5-H ₃ BTC = 1,3,5-benzenetricarboxylic acid), 1 , {[Cu _1.5 ( L ² ) _1.5 (1,3,5-BTC)(H ₂ O) ₂ ]·6.5H ₂ O} _n , 2 , [Cu( L ² ) _0.5 (1,3,5-HBTB)] _n (1,3,5-H ₃ BTB = 1,3,5-tri(4-carboxyphenyl)benzene), 3 , [Cu ₄ ( L ³ )(OH) ₂ (1,3,5-BTC) ₂ ] _n , 4 , {[Cu ₃ ( L ³ ) ₂ (1,3,5-BTB) ₂ ]·2.5MeOH·2H ₂ O} _n , 5 , and {[Cu ₃ ( L ³ ) ₂ (1,3,5-BTB) ₂ ]·DMF·2H ₂ O} _n , 6 , which have been structurally characterized by using single crystal X-ray crystallography. Complexes 1-4 form a 2D layer with the {4 ⁴ .6 ² }- sql topology, a 2D layer with the (4.6 ² ) ₂ (4 ² .6 ² .8 ² )- bex topology, a three-fold interpenetrated 3D net with the (4 ¹² ·6 ³ )- pcu topology and a 3D framework with the (4 ¹⁰ ·6 ³² ·8 ³ )(4 ² ·6) ₂ (4 ³ ·6 ³ ) topology, respectively, whereas 5 and 6 are 3D frameworks with the (6 ³ ) ₂ (6 ⁴ ·8 ² )(6 ⁸ ·8 ⁵ ·10 ² ) 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.