Self-Assembly of a Series of Metal-Organic Frameworks Based on 4-Pyridyl-1,2,4-triazole and Copper(II) Ion

Using 4-pyridyl-1,2,4-triazole (pytrz) as ligand and a variety of copper(II) salts, nine copper(II) coordination polymers, {[Cu(pytrz)(OH)]X}(n) (X = Cl-, (1); Br-, (2); (NO3-)center dot H2O, (3); BF4-, (4); CF3SO3-, (5)), {[Cu(pytrz)(2)](BF4)(2)center dot 2H(2)O}(n) (6) {[Cu-3(pytrz)(2)(OH)(2)(NO2)(2)(H2O)(2)](NO3)(2)center dot H2O}(n) (7), {[Cu-3(pytrz)(2)(OH)(2)(H2O)(2)](SO4)(2)center dot 10H(2)O}(n) (8), and {[Cu-4(pytrz)(4)(OH)(2)(H2O)(2)](SiF6)(3)center dot 11.5H(2)O}(n) (9), were prepared and their crystal structures were determined via single-crystal X-ray diffraction. Complexes 1-3 crystallize in a chiral space group P2(1)2(1)2(1) and exhibits a three-dimensional (3D) chiral framework constructed by left-handed (CuO)(n) helixes (L). Complex 4 consists of (CuO)(n) helixes with the opposite chirality (R) and have the analogous cationic framework as 1. The structure of 5 is constructed through (CuO)(n) zigzag chains and represents the same (3(2)7(5)8(3))(37(2)) topology as 1-4. Complex 6 exhibits a novel two-dimensional (2D) Kagome topology with bidentate pytrz. The structures of complexes 7 and 8 are based on trinuclear Cu-3 clusters, and both display a 2D 4(4)-net when only considering pytrz as bridges. In 7, the NO2- anions act as bridges to connect the 4(4)-nets to form a 3D alpha-polonium-type network. Complex 9 have four characteristically independent Cu2+ ions and construct a tetranuclear Cu-4 cluster, and the Cu-4 clusters are bridged by tridentate pytrz to form a 3D porous cationic coordination polymer.