Synthesis, photophysical and electrochemical properties of aza-boron-diquinomethene complexes

Abstract A series of aza-boron-diquinomethene (aza-BODIQU) complexes with different aryl-substituents ( B1–B6 ) were synthesized and characterized. Their photophysical properties were investigated systematically via spectroscopic and theoretical methods. All complexes exhibit strong 1 π–π * absorption bands and intense fluorescent emission bands in the visible spectral region at room temperature. The fluorescence spectra in solution show the mirror image features of the S 0 →S 1 absorption bands, which can be assigned to the 1 π–π */ 1 ICT (intramolecular charge transfer) emitting states. Except for B6 , all complexes exhibit high photoluminescence quantum yields ( Φ PL  = 0.47–0.93). The spectroscopic studies and theoretical calculations indicate that the photophysical properties of these aza-BODIQUs can be tuned by the appended aryl-substituents, which would be useful for rational design of boron–fluorine complexes with high emission quantum yield for organic light-emitting applications.