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−)·H2O, (3); BF4−, (4); CF3SO3−, (5)), {[Cu(pytrz)2](BF4)2·2H2O}n (6), {[Cu3(pytrz)2(OH)2(NO2)2(H2O)2](NO3)2·H2O}n (7), {[Cu3(pytrz)2(OH)2(H2O)2](SO4)2·10H2O}n (8), and {[Cu4(pytrz)4(OH)2(H2O)2](SiF6)3·11.5H2O}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 P212121 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 (327583)(372) topology as 1−4. Complex 6 exhibits a novel two-dimensional (2D) Kagomé topology with bidentate pytrz. The structures of complexes 7 and 8 are based on trinuclear Cu3 clusters, and both display a 2D 44-net when only considering pytrz as bridges. In 7, the NO2− anions act as bridges to connect the 44-nets to form a 3D α-polonium-type network. Complex 9 have four characteristically independent Cu2+ ions and construct a tetranuclear Cu4 cluster, and the Cu4 clusters are bridged by tridentate pytrz to form a 3D porous cationic coordination polymer.