Secondary nucleation as a strategy towards hierarchically organized mesoscale topologies in supramolecular polymerization

Abstract

Developing new generic methodologies for organizing molecules into nano- to mesoscale structures of precise shapes and sizes is a research topic at the forefront of modern chemistry. Creating hierarchical molecular assembly, especially at the mesoscale, is important to realize functions reminiscent of those manifested by biomolecular assemblies in the mesoscopic regime. However, this is challenging due to the difficulty in maintaining stringent controllability over the organization of molecules at higher hierarchical levels, wherein weak non-directional intermolecular interactions rather than strong directional interactions typically play a predominant role. Recent studies have revealed that secondary nucleation, often experienced by one-dimensional assemblies such as supramolecular polymers that grow with spontaneous nucleation, is effective in the hierarchical construction of higher-order structures. Here we illustrate how secondary nucleation can be combined with the well-established precision synthesis of supramolecular polymers to realize precise control over hierarchical structures in the mesoscopic regime. We present a roadmap for creating hierarchical supramolecular polymers by exploiting secondary nucleation–elongation processes and discuss future prospects for the field. Mastering the synthesis of hierarchical molecular assemblies at the mesoscale—mimicking the precision of biomolecular assembly—has been challenging due to the lack of well-defined methodologies for controlling non-covalent interactions at multiple levels. In this Review, secondary nucleation is presented as a promising strategy for constructing mesoscale hierarchical structures.