α,β-Diarylation on β-Diketo-BF₂ Complexes: Strong Intrinsic Aggregation-Induced Emission and Organic Self-Recovering Electrochromism

A novel one-step synthetic strategy was developed to synthesize α,β-diaryl β-diketone-BF₂ complexes (<b>2a</b>-<b>2g</b>) using readily available building blocks (1,2-diarylethanones). The complexes were further transformed to π-extended α,β-diaryl-β'-styryl-β-diketo-BF₂ (<b>3a</b>-<b>3c</b>) via Knoevenagel condensation with aromatic aldehydes. All the complexes exhibit strong intrinsic aggregation-induced emission, with fluorescence colors tuning from cyan (λ_em = 470 nm) to red (λ_em = 652 nm) and the quantum yields reaching up to 90%. The complexes were demonstrated for electrochromism, which exhibits a drastic color change from colorless to purple upon applying a reduction potential of -1.3 V with spontaneous self-oxidation from the reduced state.