Graph Theory and Ion and Molecular Aggregation in Aqueous Solutions

Area of Science:

• Molecular and Cellular Biology
• Physical Chemistry
• Biophysics

Background:

• Dissolved ions and molecules significantly impact biomolecular reactions, stability, and function.
• Understanding the effects of solutes (ions, osmolytes, sugars) on water structure and protein dynamics remains incomplete.

Purpose of the Study:

• To investigate the aggregation behavior of ions and molecules in concentrated aqueous solutions.
• To elucidate the relationship between solute aggregation and water hydrogen-bonding networks.
• To explore the application of graph theory in characterizing aggregate morphology and dynamics.

Main Methods:

• Time-resolved vibrational spectroscopy
• Molecular dynamics (MD) simulations
• Graph-theoretical analysis of MD trajectories

Main Results:

• Ions and solute molecules self-assemble into large, polydisperse aggregates.
• These aggregates significantly alter local and long-range water hydrogen-bonding structures.
• Graph theory effectively characterizes aggregate morphology, revealing percolating behavior with increasing solute concentration.
• An isomorphic relationship exists between percolation transitions of solute aggregates and water hydrogen-bonding networks.

Conclusions:

• The combination of graph theory and MD simulations provides deep insights into solute aggregation and its impact on water structure.
• This approach enhances understanding of dissolution, solute self-aggregation, and water dynamics in complex solutions.