Enhanced Mechanical and Helical Properties with Achiral Calix[4]arene in a Co-Assembled Hydrogel with a Helical Structure

Abstract

A mixture of the building blocks 1A and 2G, featuring d-alanine moieties and glycine-functionalized calix[4]arene moieties, respectively, formed a co-assembled hydrogel. In particular, the remarkable enhancement of helical intensity of co-assembled gel was controlled by achiral calix[4]arene 2G, which was attributed to the bridging effect between 1A and 2G, similar to a helical structure. Furthermore, the improvement of the mechanical strength (G and G values) of the co-assembled hydrogel prepared with 1.0 equivalent of 2G were around 7000% and 4400% stronger, respectively, compared to the gel prepared from the 0.25 equivalents of 2G. The improved mechanical strength was attributed to the formation of a network structure with a H-bonding interaction between 1A and 2G. The results indicate that the enhanced helical and mechanical strength of the co-assembled gel could be controlled by achiral component 2G.