A crystalline bisindolylmaleimide with strong solid-state fluorescence of red color and its analogous cross-linked polymer without fluorescence

A crystalline bisindolylmaleimide (BIM) 3 with strong fluorescence in the solid state was prepared and studied. Its analogous cross-linked polymer 4 with the same BIMs fluorophore was designed and characterized. The investigation of the covalent bonding networking effect on the solid-state fluorescence was carried out by the comparison between 3 and 4.