title: Spectroscopic study of association of a hemicyanine dye in mixed aqueous binary solvents.
abstract: Electronic absorption and steady state emission properties of a hemicyanine dye [4-[4-(dimethylamino)styryl]-1-docosylpyridinium bromide], have been studied in several pure solvents and two mixed binary solvents (water+ethanol and water+acetonitrile). In pure solvents the band-width of the absorption spectrum correlates well with the Stoke's shift. In mixed aqueous solvents two different molecular forms of the solute, viz. the monomer and the dimer of the solute exists in equilibrium. Thermodynamic parameters (e.g. the Delta G degrees and Delta H degrees ) characterizing the equilibrium have been determined. While the value of Delta G degrees changes very slightly with the composition of the binary mixture, the value of Delta H degrees has been observed to depend significantly with solvent composition.
authors.affiliation: Department of Chemistry, T.D.B. College, Raniganj, West Bengal 713347, India.
authors.forename: Parimal Kumar
authors.initials: PK
authors.lastname: Das
authors.forename: Debashis
authors.initials: D
authors.lastname: Banerjee
authors.forename: Sanjib
authors.initials: S
authors.lastname: Bagchi
mesh_terms: D000438:Alcohols; D000814:Aniline Compounds / Q000737:chemistry*; D002232:Carbocyanines / Q000737:chemistry*; D002725:Chloroform; D005663:Furans; D007700:Kinetics; D009570:Nitriles; D016011:Normal Distribution; D011726:Pyridinium Compounds / Q000737:chemistry*; D012996:Solutions; D012997:Solvents; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D014867:Water
chemical_list: C522492:4-(4-(dimethylamino)styryl)-1-docosylpyridinium; D000438:Alcohols; D000814:Aniline Compounds; D002232:Carbocyanines; D005663:Furans; D009570:Nitriles; D011726:Pyridinium Compounds; D012996:Solutions; D012997:Solvents; D014867:Water; C018674:tetrahydrofuran; D002725:Chloroform