Proton transport in a binary biomimetic solution revealed by molecular dynamics simulation.

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Biophysics

Background:

• Proton transport in aqueous solutions is crucial for many chemical and biological processes.
• The role of amphiphilic molecules, like tetramethylurea (TMU), in modulating proton mobility is not fully understood.
• Previous studies suggested amphiphiles universally suppress proton mobility by affecting water reorientation.

Purpose of the Study:

• To investigate the mechanisms of proton transport in water-TMU mixtures.
• To determine how TMU concentration influences proton transport efficiency.
• To clarify the complex interplay between amphiphiles, water structure, and proton mobility.

Main Methods:

• Molecular dynamics simulations were employed to model proton transport.
• Analysis focused on the formation of water-wire structures and hydrogen bond connectivity.
• Simulations examined varying concentrations of TMU in a binary mixture with water.

Main Results:

• Proton transport is influenced by concentration-dependent mechanisms.
• Low TMU concentrations facilitate proton transfer via water-wire structures.
• High TMU concentrations retard proton transfer by reducing hydrogen bond connectivity.

Conclusions:

• The effect of amphiphilic molecules on proton transport is more complex than previously thought.
• Water-wire formation and hydrogen bond network disruption are key mechanisms.
• TMU concentration critically determines whether proton mobility is enhanced or reduced.