Tuning the emission properties of luminescent 1,2,3-diazaborinates.

B-Aryl-based 1,2,3-diazaborinates (DABates), derived from neutral 1,2,3-diazaborines (DABs), are a promising class of unexplored fluorophores which show an intriguing high optical performance. This work systematically investigates previously unexplored factors that govern their photoluminescence. We strategically designed and synthesized a diverse library of DABate derivatives, modifying the exocyclic boron and N-substituents, the N-lone pair, and the fused π system. All compounds were fully characterized by conventional NMR, HRMS and XRD techniques, as well as UV-vis and fluorescence spectroscopy. Our results allow the identification of key molecular attributes which enhance or quench the fluorescence. Complementary supporting time-dependent DFT calculations provide further insights into the excitation process. In addition, we also performed modifications to render the DABates air- and moisture-stable, expanding potential future applications of this novel class of potent fluorophores beyond inert conditions.