Crystallization-induced red emission of a facilely synthesized biodegradable indigo derivative

We report a new class of crystallization-induced red-emitting luminogen based on a synthetic biodegradable indigo derivative, Indigoid-B. This compound, upon an ultrasonic treatment, formed well-defined microcrystals that showed striking crystallization-induced emission (CIE) in mixed solvents of tetrahydrofuran-water.