Formation of Multiple Supramolecular Helices for Spontaneous Resolution

Abstract

Relating supramolecular helices to the spontaneous resolution that generates conglomerate crystals is meaningful to the production of enantiopure compounds and to the understanding of natural homochirality as well. While homochiral elongation is favored along the axis of 1D supramolecular helical chains, conglomerate crystallization requires a 3D homochiral framework. This inspires us to explore new avenues to the spontaneous resolution through the formation of multiple supramolecular helices during crystallization. This Concept outlines and reviews multiple supramolecular helices found in the conglomerate crystals, i. e. three supramolecular helices along one crystallographic axis and two or three supramolecular helices along different crystallographic axes, followed by our observations of homochiral elongation of the helicity of the helical building blocks, the azapeptides, during the formation of supramolecular helices, as well as the spontaneous resolution of amino acid alanine that is made into a helical azapeptide derivative via the formation of supramolecular helices along two different crystallographic axes.