Pre-Nucleation Clusters Predict Crystal Structures in Models of Chiral Molecules.

Area of Science:

• Computational chemistry
• Materials science
• Chemical physics

Background:

• Polymorphism, the ability of molecules to form multiple crystal structures, is influenced by crystallization kinetics.
• Current crystal structure prediction methods primarily focus on thermodynamic stability, neglecting kinetic factors like nucleation and growth.
• Accurate kinetic rate calculations are complex and computationally intensive.

Purpose of the Study:

• To investigate the role of kinetics in molecular crystallization using computer simulations.
• To develop improved computational methods for crystal structure prediction that incorporate kinetic factors.
• To model the crystallization behavior of chiral molecules, including enantiopure and racemic forms.

Main Methods:

• Utilized molecular dynamics computer simulations on simple molecular models.
• Studied crystallization behavior under varying supersaturation conditions.
• Correlated oligomeric species in solution with molecular motifs in crystal structures.

Main Results:

• A significant portion of molecules formed crystals that were not the most thermodynamically stable.
• Crystal formation at high supersaturation was accurately predicted by comparing solution species to crystal motifs.
• Kinetic considerations alone were sufficient to predict spontaneous chiral separation in racemic mixtures.

Conclusions:

• Kinetic factors are essential for accurate crystal structure prediction and understanding polymorphism.
• Incorporating kinetic insights can improve current crystal structure prediction methodologies.
• This approach offers a conceptually simpler way to enhance predictive power in crystallization studies.