Researchers have developed a luminescent small-molecule system that changes from a solution to a suspension when heated. The solubility change is accompanied by a color change in the photoemission from blue to green. The transition is mediated by oleic acid and methylamine, which aid the reversible reorganization from molecular wires in solution through an intermediate co-crystal and finally into nanoparticles at higher temperatures. This new system could aid the development of new-generation thermo-responsive materials.