title: Unusual hydrophobic interactions in acidic aqueous solutions.
abstract: Hydrophobic interaction, which is believed to be a primary driving force for many fundamental chemical and biological processes such as nanostructure self-assembly, micelle formation, and protein folding, is different in acidic aqueous solutions compared to salt solutions. In this study, the aggregation/dispersion behavior of nonpolar hydrophobic molecules in aqueous solutions with varying acid (HCl) concentrations is investigated using novel molecular dynamics simulations and compared to the hydrophobic behavior in corresponding salt (NaCl) solutions. The formation of unusual weakly bound hydrophobe-hydrated proton solvation structures is observed and can be attributed to the unique "amphiphilic" characteristic of hydrated protons. This molecular-level mechanism for the acid-enhanced dissolution of hydrophobic particles also provides a novel interpretation for the apparent anomaly of the hydronium cation in the Hofmeister series.
authors.affiliation: Center for Biophysical Modeling and Simulation and Department of Chemistry, University of Utah, 315 South 1400 East, Room 2020, Salt Lake City, Utah 84112-0850, USA.
authors.forename: Hanning
authors.initials: H
authors.lastname: Chen
authors.forename: Jianqing
authors.initials: J
authors.lastname: Xu
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Voth
mesh_terms: D003198:Computer Simulation; D006851:Hydrochloric Acid / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D008968:Molecular Conformation; D010420:Pentanes / Q000737:chemistry; D011522:Protons; D012965:Sodium Chloride / Q000737:chemistry; D012996:Solutions; D014867:Water / Q000737:chemistry*
chemical_list: D010420:Pentanes; D011522:Protons; D012996:Solutions; D014867:Water; D012965:Sodium Chloride; C039752:neopentane; D006851:Hydrochloric Acid