Water wires in aqueous solutions from first-principles calculations

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Biophysics

Background:

• Water wires, chains of water molecules, are crucial in biological and chemical processes.
• Understanding their structure and dynamics is key to elucidating proton transfer mechanisms.
• Previous studies have debated whether water wires are stable structures or transient phenomena.

Purpose of the Study:

• To elucidate the structural and dynamical properties of water wires in aqueous solutions.
• To investigate the influence of probe molecules on water wire formation and length.
• To analyze the impact of water wires on proton transfer mechanisms.

Main Methods:

• First-principles molecular dynamics (MD) simulations were employed.
• Hydroxyquinoline derivatives (heteroaromatic fluorescent dyes) were used as probe molecules.
• Analysis focused on hydrogen bond networks, water wire length, and proton transfer pathways.

Main Results:

• Water wire length is dependent on the initial/final coordinates set by the chromophore.
• Water wires exhibit persistence on the picosecond time scale.
• The presence of water wires can shift proton transfer from concerted to stepwise mechanisms.

Conclusions:

• Water wires can be considered characteristic structural motifs, not just transient phenomena.
• The study provides insights into the role of water wires in mediating proton transfer.
• This research clarifies the long-standing debate on the nature of water wires.