Generation of supramolecular microcapsules by oxidative covalent polymerization of a ditopic supramolecular building block

Abstract

We describe a novel approach to the generation of a supramolecular polymer and its assembly into microcapsules by the aerial oxidation of a supramolecular building block. It involves the initial build-up of a ditopic supramolecular component by hydrogen bonding association of two complementary subunits, followed by its covalent polymerization through oxidative formation of C–C linkages. The supramolecular component itself was selectively formed from a dynamic covalent library of hydrazone isomers by target specific amplification of a single library constituent. The polymer obtained condenses into supramolecular aggregates of micrometric size and capsular-type morphology, presenting multilayered walls, which have been characterized by STEM, SEM and AFM imaging methods. The present design methodology implements the covalent polycondensation of non-covalent monomers towards the formation of supramolecular polymers, in a sequence opposite to the usual non-covalent polyassociation of covalent complementary monomers. It can be envisaged as a proactive step towards forming adaptive smart materials through manipulation of the sequence of supramolecular/non-covalent and molecular/covalent steps for the generation of supramolecular polymers by suitable selection of receptor and substrate moieties.