The aggregation-induced emission enhancement properties of BF2 complex isatin-phenylhydrazone: Synthesis and fluorescence characteristics

Abstract Isatin-phenylhydrazone derivatives and their corresponding BF 2 complexes were efficiently synthesised by a three-step reaction starting from isatin and phenylhydrazine hydrochloride. The fluorescence properties of the isatin-phenylhydrazone derivatives and derived BF 2 complexes were investigated in different organic solvents, in the solid state and in mixed solvent solutions of THF and H 2 O. These fluorescent dyes exhibited low fluorescent intensity in solution but a high fluorescent intensity as aggregates and in their solid state due to the interesting aggregation-induced emission enhancement characteristics which were caused by the inhibition of intramolecular rotation in the single molecule state. Information supporting this inference was supported by single crystal X-ray analysis.