Influence of Nitro Group on Solvatochromism, Nonlinear Optical Properties of 3-Morpholinobenzanthrone: Experimental and Theoretical Study

We report the synthesis of 3-morpholino-9-nitrobenzanthrone (NMB) dye. By using FT-IR, 1H NMR, and X-ray crystallography, we characterized the molecular structure of the synthesized dye. The structural features of the dye were compared to those of an identical dye without nitro substituents. The push pull kind of benzanthrone dye (NMB) was examined for solvent-dependent photophysical properties. NMB exhibits a large Stokes shift. The polarity plots indicate that hydrogen-bonding interactions are influential in most of the solvents. Detailed structural analysis as well as one-photon absorption and emission process was computationally investigated for both the molecules. NMB exhibits significant two photon absorption (TPA) activity at various electron transitions ranging from visible to NIR regions. Further, Nonlinear absorption coefficient was calculated for the dye samples from the open aperture Z-scan data. The nonlinear absorption coefficient values were obtained for the dye samples for input laser pulse energies ranging from 5 to 20 mu J. The results decipher that these dye samples are prospective contenders for the fabrication of optical limiter devices. Nitro substituents at the active site enhance charge transfer, thereby enhancing the NLO response.