Light-Controlled Supramolecular Reconfiguration Enables Sustainable Crop Protection.

Bacterial biofilms fuel antimicrobial resistance, a pressure amplified by repeated deployment of structurally uniform bactericides. Photoswitchable azobenzenes offer light-driven structural diversity that may temper resistance evolution, but their small-molecule form limits foliar adhesion. Although supramolecular materials show promise as biofilm inhibitors, photoresponsive supramolecular polymers for this purpose remain largely unexplored. This study reports Azo@CB[8], a multifunctional supramolecular polymer that self-assembles in water from a de novo azobenzene (Azo) and cucurbit[8]uril (CB[8]). CB[8]-mediated association preserves photoisomerization, improves cycling stability, and integrates membrane disruption, redox imbalance, biofilm inhibition, sessile-cell killing, and enhanced foliar affinity. In pot assays, Azo@CB[8] outperforms free Azo and thiodiazole copper against rice bacterial leaf blight, without detectable biosafety penalties, and likewise exceeds both controls against kiwifruit bacterial canker. Notably, photoisomerization perturbs azobenzene-mediated host-guest interactions while largely retaining bipyridinium-CB[8] association, thereby reducing supramolecular connectivity and driving reconfiguration of the extended architecture into a smaller, less-connected supramolecular ensemble. The photoirradiated supramolecular state retains antibacterial efficacy comparable to that of the initial assembly. Together, these findings outline a supramolecular polymer-based, photoregulated route to greener management of bacterial plant diseases.