Crystallographic Elucidation of Chiral and Helical Cu(II) Polymers Assembled from a Heterodifunctional 1,2,3-Triazole Ligand

A left-handed homochiral [CuCl2(L1)](n) (1) and two solvated heterochiral [CuCl2(L1)](n)center dot n(H2O) (2) and [CuBr2(L1)](n)center dot n(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 similar to 59.4 degrees in 1 results in a large screw-pitch of similar to 45.2 angstrom, whereas a small twist of similar to 6.2 degrees in 2 and 6.7 degrees in 3 results in a short screw-pitch of similar to 7.6 and 8.1 angstrom, respectively. The effect of the lattice solvates (H2O and MeOH) on the change of helical structures has also been described.