Structural Design and Application of Azo-based Supramolecular Polymer Systems

This article presents a brief overview of recent advances in azo-containing supramolecular systems. In literature, it has been shown that azo supramolecular polymers and their composite materials exhibit fast and intelligent responses to various external stimuli, such as temperature, pH change, redox reagents, ligands, coupling reagents, etc. In applications, these systems are widely used for molecular motors, shape memory, liquid crystal, solar thermal energy storage, signal transmission, intelligent encryption, and other purposes. Furthermore, these systems can function as key components for device upgrade processing. However, the design and rules of azo supramolecular polymers are still not supported by an exact theory. Information about the relationship between the spatial structure and behavior is lacking, and new supramolecular materials cannot be designed by adding functional moieties to known azo polymers. Based on the current research status, this review mainly summarizes the structural design principles as well as structures and applications of known azo supramolecules; meanwhile, it highlights the emerging development fields, recent advances, and prospects in fabricating self-assembling intelligent supramolecular systems with azo supramolecular polymers as responsive units. The goal of this review is to bring new inspiration to researchers who want to optimize the chemical structure, steric conformation, electrostatic environment, and specific molecular functionalization.