Coordination geometry in metallo-supramolecular polymer networks

Abstract

Nature employs a wide library of transient interaction to operate adaptively on various time and length scales. Inspired by such elegant designs, combinations of different supramolecular assemblies have been extensively introduced in synthetic material platforms to obtain biomimetic functions. Among the most widely used transient bond, metal–ligand coordination performs a distinct role in designing robust and stimuli-responsive metallo-supramolecular polymer networks (MSPNs). The functionality of the metal–ligand complex, in addition to the technological benefits of the polymer backbone, provides novel materials with outstanding potentials to be used in a wide range of applications. Although the correlation between bulk macroscopic properties of such systems to the microscopic characteristics of the polymer precursor and transient bonds is frequently studied, the importance of coordination geometry of the metal complex is often overlooked. Despite that, the knowledge of controlling the spatial configuration of supramolecular coordination complexes (SCCs) has been extremely advanced in recent years. Notable outcomes include but are not limited to the development of highly ordered SCCs arcing from 1D nanofibers to 3D metal–organic frameworks or the advent of reversible molecular rearrangement as employed in molecular machines. This wealth of knowledge has been rarely employed in the field of polymer science, while it could provide a new approach to build highly ordered model-type networks or even induce novel structural rearrangements upon the application of external stimuli. Accordingly, we classify existing reports on the coordination geometry of MSPNs and review relevant self-sorting mechanisms of SCCs to lay out general directions for employing coordination geometry as a new design parameter in polymeric systems.