Synthesis, structure, redox activity and luminescence of sterically crowded 6,8-di-(tert-butyl)-3H-phenoxazin-3-one

[Display omitted] •New method for preparation of derivatives of 3H-phenoxazin-3-one was studied.•The condensation reaction of 3H-phenoxazin-3-one with arylamines was studied.•Redox activity of 3H-phenoxazin-3-one studied by cyclic voltammetry.•Reduction of 3H-phenoxazin-3-one affords its stable radical anion and dianion.•Very rare for radical anions intense fluorescence was detected. A sterically crowded 6,8-di-(tert-butyl)-3H-phenoxazin-3-one 3 was prepared by coupling 3,5-di-(tert-butyl)-o-benzoquinone with p-aminophenol. The molecular structure of 3 was established with the aid of X-ray crystallography and the redox activity studied using cyclic voltammetry and ESR spectroscopy. The reduction of 3 with a potassium mirror led to the formation of persistent radical anion 3a and dianion 3b which were characterized by their absorption and luminescence spectra.