Highly electron-deficient 3,6-diaza-9-borafluorene scaffolds for the construction of luminescent chelate complexes

The synthesis and characterization of two fluorinated 2,6-diaza-9-hydroxy-9-borafluorenes oxonium acids featuring improved hydrolytic stability and strong electron-deficient character of diazaborafluorene core is reported. These boracycles served as precursors of fluorescent spiro-type complexes with (O,N)-chelating ligands which revealed specific properties such as delayed emission, white light emission in the solid state and photocatalytic performance in singlet oxygen-mediated oxidation reactions.