Anisotropic and isotropic solvent effects on the dipole moment and photophysical properties of rhodamine dyes

Absorption and emission spectra of two rhodamine dyes with same molecular skeletons and different functional groups have been studied in various isotropic and anisotropic media. The solute photo-physical behavior depends strongly on the solvent–solute interactions and solvent microenvironment as well as resonance structures of the rhodamine dyes. In order to understand the effect of intermolecular interactions on spectral behaviors of these dyes and to conceive nature and extend of solvent–solute interactions the spectral variations were analyzed by the linear solvation energy relationships concept. In addition, by means of solvatochromic method the dyes dipole moments variations, from ground to excited states, were investigated in isotropic and anisotropic solvents media.