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Surfactant binary systems: Ab initio calculations, preferential solvation, and investigation of solvatochromic parameters

Kohantorabi, M ; Sharif University of Technology

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  1. Type of Document: Article
  2. DOI: 10.1021/acs.jced.5b00522
  3. Publisher: American Chemical Society
  4. Abstract:
  5. Solvatochromic UV-vis shifts of three probes 4-nitroaniline, 4-nitroanisol, and Reichardt's dye in binary mixtures of polyethylene glycol p-(1,1,3,3-tetramethylbutyl)-phenyl ether (Triton X-100 or TX-100) with methanol, ethanol, 1-propanol, and water have been investigated at 298 K. Structural and intermolecular interactions of solvatochromic probes were determined in these systems. Solvatochromic parameters, including normalized polarity (ETN), dipolarity-polarizability (π∗), hydrogen-bond donor (α), and hydrogen-bond acceptor (β) abilities, were measured at a wide range of mole fraction (0 ≤ X ≤ 1) with 0.1 increment. Interestingly, a similar behavior of ETN and α is observed in alcohols/TX-100 mixtures. The ETN parameters obtained from absorbance of Reichardt's dye within various mixtures of surfactant were observed to be lower than predicted values from ideal additive behavior. A negative deviation from ideality is shown by ETN parameter in all alcohols/TX-100 mixtures, while a fluctuated behavior for other probes can be seen. The optimized geometries exhibit that the hydroxyl ('OH) group on the side chain of TX-100 significantly affects the arrangement of the selected solvents around TX-100. All binary systems show complex behavior for chosen probes. The results demonstrate that 4-nitroanisole and Reichardt's dye have stronger interactions with binary mixtures of alcohols/TX-100 systems. Synergistic solvation behavior for water/TX-100 was observed. Preferential solvation model was applied for the first time in the surfactant binary mixtures and from this model information solute-solvent and solvent-solvent interactions were interpreted. Preferential solvation (specific solute-solvent interactions) or the solvent-solvent interaction is the reason for deviation from ideal behavior of probes. As a main result, alkyl chain length of alcoholic solvents does not have impressive effects on predicted trends of solvatochromic parameters. Ab initio calculations of solvents/TX-100 mixtures demonstrate the following trend for magnitude order of interactions: water > methanol > ethanol >1-propanol. Electrostatic potential map is another confident evidence for predicted order
  6. Keywords:
  7. Bins ; Calculations ; Ethanol ; Hydrogen bonds ; Methanol ; Mixtures ; Organic solvents ; Probes ; Solvation ; Solvents ; Surface active agents ; Systems (metallurgical) ; Ab initio calculations ; Electrostatic potential maps ; Hydrogen bond acceptors ; Intermolecular interactions ; Preferential solvation ; Solute-solvent interaction ; Solvatochromic parameters ; Solvent-solvent interactions ; Binary mixtures
  8. Source: Journal of Chemical and Engineering Data ; Volume 61, Issue 1 , 2016 , Pages 255-263 ; 00219568 (ISSN)
  9. URL: http://pubs.acs.org/doi/abs/10.1021/acs.jced.5b00522