Formation and stabilization mechanism of mesoscale clusters in solution

Area of Science:

• Physical Chemistry
• Materials Science
• Chemical Physics

Background:

• Complex meso-sized solute-rich clusters challenge current understanding of phases and phase equilibria.
• The formation and stabilization mechanisms of these clusters during crystal nucleation are not fully understood.
• Oligomer formation between solute molecules is an essential part of cluster nucleation mechanisms.

Purpose of the Study:

• To investigate the formation and stabilization mechanisms of meso-sized solute-rich clusters in solution during crystal nucleation.
• To elucidate the physico-chemical rules governing cluster formation.
• To understand the role of oligomers in the nucleation process.

Main Methods:

• Density functional theory (DFT) simulations were employed to model molecular interactions.
• Nuclear magnetic resonance (NMR) experiments, specifically diffusion-ordered spectroscopy (DOSY), were used to study molecular dynamics.
• Reaction-diffusion kinetics modeling was applied to analyze experimental data and obtain kinetic parameters.

Main Results:

• Oligomers in solution were identified as predominantly π-π stacking dimers.
• Cluster formation was found to be driven by the combined effects of diffusion and monomer-dimer reactions.
• Key quantities like reaction rate constants and diffusion coefficients for monomers and dimers were determined.

Conclusions:

• Long-lived π-π stacking dimers play a critical role in the nucleation and stabilization of solute-rich clusters.
• The study provides a detailed understanding of the formation process, including cluster radius evolution and spatial density distributions.
• These findings offer insights into the fundamental mechanisms underlying phase transitions and solution behavior.