Free Space and Natural Tilings in Metal-Organic Frameworks

Area of Science:

• Materials Science
• Crystallography
• Computational Chemistry

Background:

• Metal-organic frameworks (MOFs) possess complex porous structures.
• Understanding the topology of free space within MOFs is crucial for material design.
• Systematic classification of these spaces has been challenging.

Purpose of the Study:

• To systematically classify the free space in highly porous metal-organic frameworks (MOFs) using a natural-tiling model.
• To develop a comprehensive database of topological types for MOF pores.
• To establish a topological basis for reticular chemistry-driven design of novel porous materials.

Main Methods:

• Application of the natural-tiling model to 898 highly porous MOFs.
• Rigorous algorithm for simplification of atomic nets to build natural tilings.
• Introduction of a stiffness scale based on the sphericity criterion (G3).
• Creation of the Topological Types of Tiles (TTT) collection.

Main Results:

• Unambiguous construction of natural tilings across diverse crystal structures.
• Ligand coordination affects tile topology and ring geometry, not tile volume.
• Developed a database of 2030 natural tiles in 202 topological types.
• Demonstrated model universality on low-porosity coordination frameworks.

Conclusions:

• The natural-tiling model provides a unified and consistent topological approach for analyzing atomic networks and free space.
• Automated processing of crystallographic data yields valuable datasets for material discovery.
• The TTT collection serves as a foundation for designing new porous materials using AI and machine learning.