Predicting the Thermodynamic Limits of Metal-Organic Framework Metastability

Area of Science:

• Materials Science
• Computational Chemistry
• Chemical Engineering

Background:

• Metal-organic frameworks (MOFs) offer vast potential due to their tunable structures.
• Understanding the thermodynamic stability of MOFs is crucial for their practical applications.
• Predicting MOF stability and synthesizability remains a significant challenge.

Purpose of the Study:

• To computationally determine the thermodynamic stability of over 20,000 MOFs and coordination polymers.
• To investigate factors influencing MOF metastability, including composition and constituent elements.
• To establish the energy above hull as a metric for MOF synthesizability and to create a comprehensive database.

Main Methods:

• Density functional theory (DFT) calculations were employed to compute formation energies.
• Convex hull phase diagrams were constructed to assess thermodynamic stability.
• The energy above hull (E_above_hull) was calculated as a primary stability indicator.

Main Results:

• All investigated MOFs were found to be thermodynamically metastable.
• Permanent porosity was associated with an inherent energetic penalty, increasing metastability.
• MOF composition and metal/linker identity significantly influence the degree of metastability.

Conclusions:

• The energy above hull serves as a reliable metric for predicting MOF synthesizability.
• The QMOF-Thermo Database provides accessible thermodynamic data for MOFs and coordination polymers.
• Machine learning interatomic potentials can be benchmarked and improved using this database for predicting MOF stability.