Narrowband Blue Circularly Polarized Luminescence Emitter Based on BN-Doped Benzo[6]helicene with Stimuli-Responsive Properties

Graphical Two 1,4-azaborinine [6]helicenes, H[6]BN1 and H[6]BN2 , exhibit blue fluorescence with narrow FWHMs below 31 nm and high PLQY up to 92 %. Desirable circularly polarized luminescence with g lum reaching 4~5×10 −4 and good configurational stability are relized for H[6]BN1 and H[6]BN2 . Mechanochromism occurs between H[6]BN1 ′s crystalline and amorphous states by modulationg π-π intermolecular interanctions. An turquoise OLED based H[6]BN1 is manufactured with the external quantum efficiency (EQE) of 3.18 %. Boron-doped helicenes, known for their unique electronic and photophysical properties, are of great interest for numerous applications. This research introduces two new azabora[6]helicenes, H[6]BN1 and H[6]BN2 , synthesized through an efficient method. These molecules have boron and nitrogen atoms in opposing positions, enhancing their distinctive attributes. Both helicenes show excellent emission properties, with H[6]BN1 and H[6]BN2 exhibiting narrowband blue fluorescence and circularly polarized luminescence (CPL), achieving g lum values of 4~5×10 −4 which is beneficial for chiroptical applications. The addition of a donor group, 3, 6-di-tert-butyl-9H-carbazole, in H[6]BN2 improves luminescence, likely due to enhanced molecular orbital overlap and electron delocalization. H[6]BN1 ′s needle-like single crystals exhibit mechanochromism, changing luminescent color from yellow to green under mechanical stress, which is promising for stimulus-responsive materials. In conclusion, this study presents a novel class of BN[6]helicenes with superior chiroptical properties. Their combination of electronic features and mechanochromism makes them ideal for advanced chiroptical materials, expanding the potential of helicene-based compounds and offering new directions for the synthesis of molecules with specific chiroptical characteristics.