Thermodynamics of anion binding to zwitterionic sulfobetaine micelles.

Autor: Patiño-Agudelo ÁJ; Instituto de Química, Universidade de São Paulo, 05508-000, São Paulo, SP, Brazil. Electronic address: patinoagudeloaj@gmail.com., Quina FH; Instituto de Química, Universidade de São Paulo, 05508-000, São Paulo, SP, Brazil. Electronic address: quina@usp.br.
Jazyk: angličtina
Zdroj: Journal of colloid and interface science [J Colloid Interface Sci] 2022 Apr; Vol. 611, pp. 39-45. Date of Electronic Publication: 2021 Dec 11.
DOI: 10.1016/j.jcis.2021.12.062
Abstrakt: One of the most intriguing aspects of zwitterionic surfactant micelles is their propensity to exhibit selectivity in the binding of the anions of added salts. In this work we examine the thermodynamics of the interaction of the strongly bound perchlorate ion and the more weakly bound bromide ion with micelles of N-tetradecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (SB3-14) in aqueous solution employing enthalpies derived from isothermal titration calorimetry combined with Gibbs free energies derived from literature data for the binding equilibria. In both cases, the binding is exothermic and enthalpy driven, but entropically unfavorable, with only modest changes in the Gibbs free energy as a function of the extent of anion binding. Likewise, perchlorate ion binding was found to have little or no effect on the aggregation numbers of SB3-14 micelles determined by time-resolved fluorescence quenching of pyrene by the N-hexadecylpyridinium cation. The results are interpreted within the context of the factors involved in the ion-pairing between the anions and the positive charge center of the zwitterion headgroup and the interplay between electrostatics, solvent reorganization and a net loss of translational degrees of freedom that accompany anion binding.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2021 Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
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