Mechanosensitive non-equilibrium supramolecular polymerization in closed chemical systems

Abstract

Abstract Inspired by biofuel-driven dissipative self-assembly in nature, chemical fuel-driven supramolecular systems have been developed showing out-of-equilibrium functions such as transient gelation and oscillations. However, these systems suffer from undesired waste accumulation and they function only in open systems. Herein, we report non-equilibrium supramolecular polymerizations in closed chemical systems. The system is built by viologens and pyranine in the presence of hydrazine hydrate. On shaking, the viologens were quickly activated by oxidation by air followed by self-assembly of pyranine into micrometer-sized nanotubes. The self-assembled nanotubes disassembled spontaneously over time by the reduced agent, with nitrogen as the only waste product. The dissipative supramolecular polymerization could be repeated at least 6 times even in a closed system. Our mechanosensitive dissipative self-assembly process could be extended to fabricate a chiral transient supramolecular helix by introducing chiral charged small molecules into the system. More specifically, we show that shaking could induce transient fluorescence enhancement or quenching depending on substitution of viologens. Ultrasound was introduced as a specific shaking way to generate template-free reproducible patterns.