Molecular dyad exhibiting strong multi-resonance blue fluorescence

A multi-resonance (MR) fluorophore exhibiting circularly polarized luminescence (CPL) holds a significant promise for enhancing the utility of organic light-emitting devices. To meet this demand, we have devised molecular dyads having azaoxaborin MR emitters based on homochiral (R)- and (S)-1,1′-bi-2-naphthol. The synthesized 12,12′-di-tert-butyl-9,9′-bi(8,8′-dioxa-4b,4′b-diaza-14b,14′b-diborafluorantheno[1,2,3-de]tetracene) products (TBNBOCz) exhibit strong blue fluorescence, with a remarkable 100% fluorescence quantum yield and an extremely narrow full width at half-maximum of 22 nm. However, unexpectedly, TBNBOCz exhibits negligible electric circular dichroism and CPL activities. Chiroptical investigations into the reaction precursors reveals an occurrence of racemization in the borylation step. This result emphasizes the importance of understanding synthetic processes and their impact on the chiroptical properties.