Crystallization of molecular systems from solution: phase diagrams, supersaturation and other basic concepts

Area of Science:

• Physical Chemistry
• Materials Science
• Chemical Engineering

Background:

• Crystallization is a fundamental process in chemistry and materials science.
• Understanding crystallization pathways is crucial for controlling crystal properties.
• Current models often simplify the complex thermodynamics of crystallization from solution.

Purpose of the Study:

• To demonstrate that all solution crystallization is directed by stable or metastable equilibria.
• To provide a framework for rationalizing crystallization using phase diagrams.
• To explain the driving forces and transient metastable states in crystallization.

Main Methods:

• Review of crystallization principles guided by phase diagrams.
• Analysis of crystallization pathways under cooling, evaporation, and anti-solvent addition.
• Quantification of the driving force for crystallization.

Main Results:

• Crystallization phenomena can be consistently explained through stable and metastable equilibrium concepts.
• Phase diagrams offer a rational approach to understanding and controlling crystallization.
• Transient metastable states arise from specific crystallization pathways and system heterogeneity.

Conclusions:

• Solution crystallization is fundamentally governed by thermodynamic equilibria.
• Phase diagrams are essential tools for rationalizing and predicting crystallization behavior.
• A deeper understanding of crystallization pathways clarifies the formation of metastable states.