Highly Emissive Boron Ketoiminate Derivatives as a New Class of Aggregation-Induced Emission Fluorophores



A series of boron ketoiminate derivatives that exhibited clear aggregation-induced emission (AIE) characteristics (in THF: ΦPL≤0.01; in the solid state: ΦPL=0.30–0.76) were prepared by the reactions of 1,3-enaminoketone derivatives with boron trifluoride–diethyl etherate. The structures and optical properties were investigated by UV-visible spectroscopy, photoluminescent (PL) spectroscopy, and X-ray single-crystal measurements. These results indicate that the AIE characteristics were derived from molecular motions of the boron-chelating rings with a boron[BOND]nitrogen (B[BOND]N) bond. Furthermore, the optical properties were controllable by steric hindrance of the substituted groups on the nitrogen atom.