Light-intensity-dependent out-of-equilibrium processes toward dimensionally distinct nanopolymorphs

Molecular assemblies that form distinct out-of-equilibrium states in response to varying energy inputs represent a promising platform for designing advanced, autonomous adaptive materials capable of flexibly and diversely responding to environmental stimuli. Herein, we describe a supramolecular polymer system that integrates azobenzene photoisomerization with hydrogen-bond-directed supramolecular polymorphism, enabling the formation of distinct out-of-equilibrium states under varied light intensities. t rans isomers of an azobenzene derivative featuring a barbituric acid merocyanine unit self-assemble into lamellar crystals via two-dimensional nanosheet stacking. Ultraviolet light irradiation of a nanosheet dispersion in nonpolar media at different intensities modulates the proportion of cis isomers, eliciting unique out-of-equilibrium states. Specifically, a strong light facilitates the coassembly of trans and cis isomers into one-dimensional nanofibers through hydrogen bond rearrangement, whereas weaker light drives Ostwald ripening, transforming two-dimensional nanosheets into three-dimensional multilayered structures. High-speed atomic force microscopy reveals the intricate dynamic processes driving these transitions.