Refining a Generic Force Field for Predicting Phase Transitions in Wine-Rack Metal–Organic Frameworks

Metal-organic frameworks (MOFs) are versatile materials with tunable properties, enabling their application in diverse fields. Flexible MOFs, characterized by their dynamic response to external stimuli, have gained significant attention for their gas storage and energy storage capabilities. However, predicting their flexibility, especially in wine-rack frameworks undergoing phase transitions, remains challenging. In this study, we developed a refined force field (UFF4WR-MOF) based on UFF4MOF to predict flexibility in wine-rack MOFs. We introduced key enhancements to accurately model metal coordination environments and π-π interactions, with a focus on MIL-53 and DMOF-1 frameworks as representative wine-rack MOFs. The UFF4WR-MOF showed superior performance compared to the UFF4MOF, achieving lower mean absolute errors (MAEs) in energy and volume predictions while accurately reproducing phase transitions relative to DFT results. Validation using experimentally synthesized MOFs confirmed its predictive accuracy and emphasized the importance of refining the force field to capture flexibility. Despite some limitations in systems with strong hydrogen bonding, the UFF4WR-MOF offers a robust and transferable tool for modeling flexibility in diverse wine-rack MOF structures.