Porphyrin-ionic liquid coassembly polymorphism controlled by liquid-liquid phase separation.

Understanding and controlling multicomponent coassembly is of primary importance in different fields, such as materials fabrication, pharmaceutical polymorphism and supramolecular polymerization, but these aspects have been a long-standing challenge. Herein, we discover that liquid-liquid phase separation (LLPS) into ion cluster-rich and ion cluster-poor liquid phases is the first step prior to coassembly nucleation based on a model system of water-soluble porphyrin and ionic liquids. The LLPS-formed droplets serve as the nucleation precursors, which determine the resulting structures and properties of coassemblies. Coassembly polymorphisms and tunable supramolecular phase transition behaviors can be achieved by regulating the intermolecular interactions at the LLPS stage. These findings elucidate the key role of LLPS in multicomponent coassembly evolution and enable it to be an effective strategy to control coassembly polymorphisms as well as supramolecular phase transitions.