title: Study of preferential solvation of 2,6-diaminoanthraquinone in binary mixtures by absorption and fluorescence studies.
abstract: The role of solute-solvent and solvent-solvent interaction on the preferential solvation characteristics of 2,6-diaminoanthraquinone (DAAQ) has been analysed by monitoring the optical absorption and fluorescence emission spectra. Binary mixtures consist of dimethylformamide (DMF)-ethanol (EtOH), DMF-dimelthylsulfoxide (DMSO), benzene (BZ)-DMF and acetonitrile (ACN)-DMF. The optical absorption spectra maximum and emission spectra maximum of DAAQ show the changes with varying the solvents and change in the composition in the case of binary mixtures. Non-ideal solvation characteristics are observed in all binary mixtures. It is found that at certain concentrations two mixed solvents interact to form a common structure with a nu(12) (wave number in cm(-1)) value not always intermediate (nu(1) and nu(2)) between the values of the solvents mixed. Synergistic effect is observed in the case of DMF-EtOH mixtures. The preferential solvation parameters local mole fraction X(2)(L), solvation index delta(S2), exchange constant K(12) are calculated in all binary mixtures expect in the case of DMF-BZ mixture and DMF-EtOH mixture in the ground state. We have also monitored excitation wavelength effect on the probe molecule in aprotic polar and protic polar solvents.
authors.affiliation: Department of Laser Studies, School of Physics, Madurai Kamaraj University, Madurai 625021, India. saserekha@yahoo.co.in
authors.forename: V
authors.initials: V
authors.lastname: Sasirekha
authors.forename: V
authors.initials: V
authors.lastname: Ramakrishnan
mesh_terms: D000042:Absorption; D000097:Acetonitriles / Q000737:chemistry; D000880:Anthraquinones / Q000737:chemistry*; D001554:Benzene / Q000737:chemistry; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D004126:Dimethylformamide / Q000737:chemistry; D006860:Hydrogen Bonding; D012997:Solvents / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
chemical_list: D000097:Acetonitriles; D000880:Anthraquinones; D012997:Solvents; C116107:2,6-diaminoanthraquinone; D004126:Dimethylformamide; D001554:Benzene; D004121:Dimethyl Sulfoxide; C032159:acetonitrile