Anion-dependent assemblies of two unprecedented copper(II) polymers with four-fold screw axes and trapped sodium chains

Three Cu(II) coordination polymers [Cu(taa)2]n (1), [Cu(taa)2 · (H2O)4 · Na0.5 · (ClO4)0.5]n (2) and [Cu(taa)2 · (H2O)4 · Na0.5 · (BF4)0.5]n (3) have been synthesized by the reaction of 1H-1,2,4-triazol-1-acetic acid (Htaa) with different Cu(II) salts. Polymer 1 features a 2-D grid-like network structure constructed by crossed zigzag chains. In both of polymers 2 and 3, there exist rare four-fold 1-D helical chains, which are induced by image or image anions. Besides, trapped sodium chains are found to be nested in the channels formed by the intertwist of the helical chains of 2 and 3.