Specific spectroscopic behavior of Reichardt's betaine dye in binary mixtures of tetra-n-butylammonium glycinate and tetra-n-butylammonium l-alaninate with molecular solvents

• Published in: Journal of molecular liquids 2014-09, Vol.197, p.315-321
• Main Authors: Harifi-Mood, Ali Reza, Aryafard, Meysam, Minoofar, Babak, Ziyaei-Halimehjani, Azim
• Format: Article
• Language: English
• Subjects: Amino acid ionic liquid; Normalized polarity; Reichardt's dye; Tetrabutylammonium glycinate; Tetrabutylammonium l-alaninate
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2014.05.010

The spectrophotometrical behavior of pyridinium N-phenolate betaine dye used as a solvatochromic indicator of solvent polarity is studied in binary mixtures of tetra-n-butylammonium glycinate and tetra-n-butylammonium l-alaninate with molecular solvents such as acetonitrile, ethyl acetate, and 1-butanol. This study shows that the solvent/solvent interactions, which cause preferential solvation of the dye solute, should not be established for studied amino acid-based ionic liquids with conventional molecular solvent mixtures. After addition of mole fraction of the ionic liquid, the intramolecular charge-transfer absorption spectrum of the betaine dye shows a dual peak structure. Variation of UV–Vis spectra demonstrates the existence of a relationship with the type of the molecular solvent. Molecular dynamic simulations showed clearly different compositions in the solvation shells of betaine dye. [Display omitted] •Reichardt’s dye showed specific behavior in several binary mixtures.•Pereferential solvation model is not established for these mixtures.•Classical molecular dynamics simulations confirm the spectrophotometric findings.