Crystal structure and spectral properties of vitamin K3 based nitrobenzo[a]phenoxazines

Abstract Benzo[ a ]phenoxazines are the planar polycyclic fluorescent compounds, find a variety of applications in biological sciences and are of growing interest. In the present work we synthesized heterocyclic aromatic fluorescent benzo[ a ]phenoxazines namely, 6-methyl-9-nitro-5H-benzo[ a ]phenoxazin-5-one ( 1 ) and 6-methyl-10-nitro-5H-benzo[ a ]phenoxazin-5-one ( 2 ) which are characterized in terms of the 1 H and 13 C chemical shifts from 2D gHSQCAD NMR experiments. Single crystal X-ray experiments revealed both 1 and 2 possess the C H⋯O interactions. Moreover the π∙∙∙π stacking interactions between planar polycycles have been noticed only in 1 . The structural and vibrational spectral inferences obtained from experiments are corroborated through the ωB97xD based density functional theory.