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

• Published in: Journal of luminescence 2012-04, Vol.132 (4), p.931-937
• Main Authors: Zakerhamidi, M.S., Moghadam, M., Ghanadzadeh, A., Hosseini, S.
• Format: Article
• Language: English
• Subjects: Atomic and molecular physics; Dipole moment; Exact sciences and technology; Fluorescence and phosphorescence; radiationless transitions, quenching (intersystem crossing, internal conversion); Linear solvation energy relationships; Molecular properties and interactions with photons; Physics; Rhodamine dyes; Solvent polarity scale; Solvent–solute interactions
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/j.jlumin.2011.11.027

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. ► Solvation mechanism of R6G and RB in different solvent media is dissimilar. ► Three types of variation with solvent can be identified for R6G and RB. ► These dyes show unlike mesomeric resonance structure. ► Mesomeric structures of these dyes are related to solvation interactions. ► Charge transfer process of R6G and RB in liquid crystal media might be facilitated.