Solid-state fluorescence of 6-aryl-9-(dibutylamino)benzo[a]phenoxazin-5-ones

6-(9-Anthryl)- and 6-(1-naphthyl)-9-(dibutylamino)benzo[a]phenoxazin-5-ones exhibited fluorescence maximum at around 700 nm in the crystalline form. Their fluorescence quantum yields were significantly higher than that of previously reported 6-perfluoro[4-methyl-3-(1-methylethyl)pent-2-en-2-oxy] derivative due to the isolated dimer-type packing.