Stereospecific supramolecular polymerization of nanoclusters into ultra-long helical chains and enantiomer separation
Zexi Zhu, Guohua Zhang, Bao Li, Minghua Liu, Lixin Wu
Abstract
During the construction of supramolecular polymers of smaller nanoparticles/nanoclusters bearing hierarchy and homochirality, the mechanism understanding via intuitive visualization and precise cross-scale chirality modulation is still challenging. For this goal, a cooperative self-assembly strategy is here proposed by using ionic complexes with uniform chemical composition comprising polyanionic nanocluster cores and surrounded chiral cationic organic components as monomers for supramolecular polymerization. The single helical polymer chains bearing a core-shell structure at utmost length over 20 μm are demonstrated showing comparable flexibility resembling covalent polymers. A nucleation-elongation growth mechanism that is not dealt with in nanoparticle systems is confirmed to be accompanied by strict chiral self-sorting. A permeable membrane prepared by simple suction of such supramolecular polymers displays high enantioselectivity (e.e. 98% after four runs) for separating histidine derivatives, which discloses a benefiting helical chain structure-induced functionalization for macroscopic supramolecular materials in highly efficient racemate separation. Understanding the mechanism for supramolecular polymer assembly from nanoclusters bearing hierarchy and homochirality is challenging. Here, the authors report a cooperative self-assembly strategy using ionic complexes with chiral surfactants through a nucleation-elongation growth mechanism with chiral self-sorting and prepare a permeable membrane for the separation of histidine derivatives.