Surface behavior of N-dodecylimidazole at Air/Water Interfaces

RODRIGUEZ, J; LARIA, D

JOURNAL OF PHYSICAL CHEMISTRY B

American Chemical Society

Lugar: Washington DC; Año: 2007 vol. 111 p. 908 - 915

1089-5647

Using Molecular Dynamics techniques, we investigate surface states of the surfactantN-Dodecylimidazole (DIm) in its basic and acid forms adsorbed at the water/air interface.Two different surface coverages were examined: an infinitely diluted detergent and asaturated monolayer. Spatial and orientational correlations of the surfactants andthe aqueous substrate are presented. At large surface coverages, DIm presents two solvationstates with well differentiated structural and dynamical characteristics.Superficial solvation of the protonated surfactant becomes unstable at large concentrations, whilethe relative stability of the surface states of DImH$^+$ with respect to bulk statesincreases at infinite dilution.The surface acidic behavior of N-Dodecylimidazolium was investigated using amultistate empirical valence bond Hamiltonian model.Our simulation results suggest that the acidic characteristicsof DIm are enhanced at the surface. The differences are rationalized in terms ofthe distinctive features in the overall solvation structure of the reactive complex.