Macroscopic handedness inversion of terbium coordination polymers achieved by doping homochiral ligand analogues

Abstract

Inspired by natural biological systems, chiral or handedness inversion by altering external and internal conditions to influence intermolecular interactions is an attractive topic for regulating chiral self-assembled materials. For coordination polymers, the regulation of their helical handedness remains little reported compared to polymers and supramolecules. In this work, we choose the chiral ligands R-pempH₂ (pempH₂ = (1-phenylethylamino)methylphosphonic acid) and R-XpempH₂ (X = F, Cl, Br) as the second ligand, which can introduce C–H⋯π and C–H⋯X interactions, doped into the reaction system of the Tb(R-cyampH)₃·3H₂O (cyampH₂ = (1-cyclohexylethylamino)methylphosphonic acid) coordination polymer, which itself can form a right-handed superhelix by van der Waals forces, and a series of superhelices R-1H-x, R-2F-x, R-3Cl-x, and R-4Br-x with different doping ratios x were obtained, whose handedness is related to the second ligand and its doping ratio, indicating the decisive role of interchain interactions of different strengths in the helical handedness. This study could provide a new pathway for the design and self-assembly of chiral materials with controllable handedness and help the further understanding of the mechanism of self-assembly of coordination polymers forming macroscopic helical systems.