The photophysical properties of Nile red and Nile blue in ordered anisotropic media

The absorption and fluorescence spectra of a highly fluorescent laser dye, Nile red, were investigated in nematic solvents and isotropic liquids as a function of the solvent polarity and type. The interaction of the dye with the anisotropic surrounding and with that of the isotropic solvents was investigated and compared using optical spectroscopy. The spectral behavior of the cationic oxazine dye, Nile blue, was also investigated in anisotropic and isotropic environments for comparison. The spectral shifts were correlated by the solvent polarity and nature. The electro-optical effect of the guest–host systems was also investigated in an electro-optical system using polarized spectroscopic method and the dichroic ratios R and degree of anisotropies S of these dyes in the liquid crystalline hosts were investigated.