Crystallographic elucidation of chiral and helical Cu(II) polymers assembled from a heterodifunctional 1,2,3-Triazole ligand

Abstract

A left-handed homochiral [CuCl2(L1)]n (1) and two solvated heterochiral [CuCl2(L1)]nn(H2O) (2) and [CuBr2(L1)]nn(MeOH) (3) one-dimensional helical copper(II) coordination polymers have been self-assembled from Cu(II) with an achiral functionalized 1,2,3-triazole (L1) (L1 = 1-(2-picolyl)-4-(1-(methoxyl)- benzotriazole)-1H-1,2,3-triazole) under different conditions. They have been characterized by single-crystal X-ray diffraction (XRD) analysis. Complexes 2 and 3 have been further analyzed by powder XRD, thermogravimetric analysis, and electron paramagnetic resonance. Different conformational twists of the ligand skeleton result in different chiral organizations ' a large torsional twist (C'C'O'N) of ~59.4 in 1 results in a large screw-pitch of ~45.2 , whereas a small twist of ~6.2 in 2 and 6.7 in 3 results in a short screw-pitch of ~7.6 and 8.1 , respectively. The effect of the lattice solvates (H2O and MeOH) on the change of helical structures has also been described. © 2010 American Chemical Society.