Simulated solvation of organic ions II: Study of linear alkylated - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Physical Chemistry B Année : 2015

Simulated solvation of organic ions II: Study of linear alkylated

(1) , (2, 3) , (4)
1
2
3
4

Résumé

We investigated the solvation of carboxylate ions from formate to hexanoate, in droplets of 50 to 1000 water molecules and neat water, by computations using standard molecular dynamics and sophisticated polarizable models. The carboxylate ions from methanoate to hexanoate show strong propensity for the air/water interface in small droplets. Only the ions larger than propanoate retain propensity for the interface in larger droplets, where their enthalpic stabilization by ion/water dispersion is reduced there by 3 kcal mol–1 per CH2 group. This is compensated by entropy effects over +3.3 cal mol–1 K–1 per CH2 group. On the surface, the anionic headgroups are strongly oriented toward the aqueous core, while the hydrophobic alkyl chains are repelled into air and lose their structure-making effects. These results reproduce the structure-making effects of alkyl groups in solution, and suggest that the hydrocarbon chains of ionic headgroups and alkyl substituents solvate independently. Extrapolation to bulk solution using standard extrapolation schemes yields absolute carboxylate solvation energies. The results for formate and acetate yield a proton solvation enthalpy of about 270 kcal mol–1, close to the experiment-based value. The largest carboxylate ions yield a value smaller by about 10 kcal mol–1, which requires studies in much larger droplets.
Fichier principal
Vignette du fichier
JPC_12094-12107_2015.pdf (3.84 Mo) Télécharger le fichier
Origine : Fichiers produits par l'(les) auteur(s)
Loading...

Dates et versions

hal-01254502 , version 1 (12-01-2016)

Identifiants

Citer

Céline Houriez, Meot-Ner Michael, Michel Masella. Simulated solvation of organic ions II: Study of linear alkylated. Journal of Physical Chemistry B, 2015, 119, pp.12094-12107. ⟨10.1021/acs.jpcb5b04556⟩. ⟨hal-01254502⟩
202 Consultations
80 Téléchargements

Altmetric

Partager

Gmail Facebook Twitter LinkedIn More