Dynamic Covalent Hydrazone Supramolecular Polymers toward Multiresponsive Self-Assembled Nanowire System

Abstract

Stimuli-responsive polymeric systems are of considerable interest due to their potential applications in environment-adaptive technologies such as smart surfaces. Traditionally, such systems can be constructed either by dynamic noncovalent (supramolecular) or dynamic covalent chemistry, but the use of both chemistries in one system may offer unique opportunities for structural diversity and various controllability. Herein, we report that hydrazone-pyridinum conjugates, which can be dynamically exchanged by transimination, assemble to form one-dimensional nanowires due to direct intermolecular interactions (without metal-ion coordination). The self-assembly process can be controlled not only by dynamic covalent chemistry but also by pH adjustment. The hydrazone-pyridinum conjugates are transformed to merocyanine-type dyes of distinctive negative solvatochromism via deprotonation, which also affects their self-assembly. Such a dual control of the dynamic molecular assembly will provide unique way to develop diverse smart nanomaterials with multistimuli-responsiveness.