Red emissive diarylboron diketonate crystals: aggregation-induced color change and amplified spontaneous emission

Two novel diarylboron diketonates 1 and 2 were synthesized by the reaction of 1,3-diaryl-β-diketone with triphenylborane or fluorobis(pentafluorophenyl)borane. The synthesized boron-containing compounds exhibit intense greenish-blue or green emissions in solution but red fluorescence in crystals, showing an aggregation-induced colour change characteristic. Notably, the flake-like crystals of 1 and 2 show an evidently narrowed emission when irradiated by a pulsed laser beam and thus provide the first example of amplified spontaneous emission based on four-coordinate organoboron solids. This finding indicates the potential of four-coordinate boron species in organic solid lasing and thus may expand the application area of boron-containing materials.