Designing Order: Crystal polymorphism in Soft and Functional Materials

This Collection supports and amplifies research related to SDG 3 and SDG 9.

                                                        Crystal polymorphism, the ability of a compound to crystallise in multiple distinct forms, often separated by small differences in thermodynamic free energies, influences physical properties, stability, and functions. Recent advances in experimental, computational, and data-driven techniques have opened new avenues for exploring the underlying principles governing polymorphism. This spans a wide range of materials, including pharmaceutical compounds; soft systems such as colloidal assemblies and liquid crystals; nanomaterials such as nanocrystals, 2D materials, and framework materials (for example, MOFs, COFs). The phenomenon of disappearing or late-appearing polymorphs provides insights into the connections between structure, interaction potentials, and free energy landscapes, which are relevant for a deeper understanding of the stability, formation pathways, and functional performance of specific polymorphs across multiple length scales.

Designing crystalline materials with targeted functionalities is a fundamental challenge in materials research and drug development. A dramatic and instructive example is the HIV drug ritonavir, introduced into medical use and then unexpectedly withdrawn when a more stable, lower free-energy polymorph was discovered, whose reduced solubility resulted in markedly diminished bioavailability. The inevitable ramifications of this single example underscore the importance of a nuanced understanding of the principles that dictate crystalline form and function.

This cross-journal collection welcomes Original Research, Perspectives, and Review Articles that focus on the rational design of materials with tailored functionalities in both fundamental scientific and industrial contexts. Submissions that bridge disciplines are especially encouraged. Topics of interest include, but are not limited to the following:
 

• Thermodynamic principles in crystal structure predictions and polymorphic transitions
• Nucleation and kinetics of polymorphism in colloidal or liquid crystals
• Polymorphic transformations in pharmaceutically relevant materials
• Polymorphism in nanomaterials, including nanocrystals, 2D materials, framework materials, and nanostructured hybrids
• Experimental techniques or simulation algorithms based on first-principles or multiscale approaches to understand polymorphism
• Advanced imaging and spectroscopy techniques for studying polymorphism and structure evolution
• Machine learning for enhancing efficiency and generalizability of interatomic potentials
• Machine learning in polymorphism prediction, crystal structure analysis, and property prediction