Visible-Light-Driven Topological Switching between Nanofibers and Nanotoroids in Fluoroazobenzene–Peptide Assemblies

Abstract Controlling supramolecular assembly pathways is a powerful strategy for encoding complexity and function in soft materials. Here, we introduce a pentafluorinated azobenzene-peptide conjugate that couples visible-light photoisomerization to large-scale topological switching in an aqueous milieu. The E-isomer undergoes cooperative nucleation–elongation into β-sheet nanofibers, whereas conversion to the Z-isomer introduces enhanced through-space Cδ ···Fδ– interactions to stabilize discrete nanotoroidal assemblies with persistent structural memory. Spectroscopy and kinetic analyses confirm a primary nucleation–elongation mechanism, while seeded polymerization bypasses nucleation barriers to achieve seed-guided supramolecular growth from dormant precursors.19F NMR and DFT reveal Cδ ···Fδ–interactions along with other dominant noncovalent interactions, stabilize the Z-form, and molecular dynamics (MD) simulations trace how local dipolar perturbations propagate into curvature-driven reorganization. Microscopy directly visualizes the irreversible fiber-to-toroid transition, establishing light-induced kinetic trapping as a route to nonequilibrium states. Kelvin probe force microscopy further links molecular geometry to nanoscale charge distribution. Taken together, these results demonstrate how molecular conformation, assembly history, and external inputs in tandem dictate supramolecular polymorphism in peptide systems, providing a blueprint for adaptive photoresponsive materials with potential in designing peptide-based hydrogel scaffolds and electroactive biointerfaces.