Researchers have invented and demonstrated a computational technique that allows them to map the atomic-level structural pathways of reversible phase changes in flexible Metal-Organic Frameworks (MOFs). The research was performed by teams of students and senior investigators with the Computational Material Science centered at North Carolina State University in partnership with the McGuirk experimental group at the Colorado School of Mines.

Rational design of materials is a critical societal and technological imperative. MOFs are a class of porous adsorbates, recognized in the 2026 Nobel Prize in Chemistry, that perform ubiquitous tasks like water harvesting, dehumidification and chemical separations – these activities alone represent roughly 30% of global energy use. Such technologies will dominate our energy and sustainability future, providing widely available clean energy and potable water for drinking and agriculture.

Researchers resolved complex structural transitions in the framework CdIF-13 that were previously impossible to understand through experiments alone.

By leveraging High Performance Computing and Graphics Processing Units, an iterative unloading scheme that mimics the real-world desorption process, researchers resolved complex structural transitions in the framework CdIF-13 that were previously impossible to understand through experiments alone. A significant finding is that these phase changes are “chaperoned” by specific adsorbates, meaning the energetic and structural path the material takes is highly dependent on the identity of the gas molecule being captured.

Ultimately, the research provides the microscopic resolution needed to move the field away from accidental discovery and toward the rational, deliberate design of materials for advanced gas storage and separation applications.

The paper “Combining Theory and Experiment to Map the Atomic-Level Structure–Energy Pathways of Adsorbate-Mediated Phase Changes in a Cooperatively Flexible Metal–Organic Framework” appears in the Journal of the American Chemical Society (JACS). JACS is the flagship publication of the American Chemical Society and is globally recognized as one of the most prestigious and influential journals in the chemical sciences. Established in 1879, it serves as the gold standard for reporting significant fundamental research and groundbreaking discoveries that impact all disciplines of chemistry.

Forrest and Space gratefully acknowledge the computing resources provided by North Carolina State University High Performance Computing Services Core Facility (RRID: SCR_022168), as well as the support from the Hydrogen and Fuel Cell Technologies and Vehicle Technologies Office within the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (Award No. DE-EE0008812).

Space acknowledges the National Science Foundation (NSF) (Grant No. 2154882) as well as the Bridges-2 at Pittsburgh Supercomputing Center through allocation CHE230105 from the Advanced Cyberinfrastructure Coordination Ecosystem: Services & Support (ACCESS) program, which is supported by the NSF grants #2138259, #2138286, #2138307, #2137603 and #2138296.

“Combining Theory and Experiment to Map the Atomic-Level Structure–Energy Pathways of Adsorbate-Mediated Phase Changes in a Cooperatively Flexible Metal–Organic Framework“

DOI: 10.1021/jacs.5c06728

Authors: Katherine A. Forrest, Brian Space*, NC State University and Arijit Halder, C. Michael McGuirk*, Colorado School of Mines

Published:  June 11, 2025

Abstract: An important subclass of metal–organic frameworks (MOFs) exhibits cooperative flexibility, wherein individual crystallites undergo global structural phase changes in response to external stimuli. Where cooperative flexibility results in reversible changes between crystalline states of distinct accessible porosity, these frameworks can exhibit rare yet desirable behaviors that cannot be explained by local dynamics alone. Yet, the chemical and structural origins of cooperative flexibility and how frameworks undergo these reversible phase changes at the atomic level remain poorly understood. Deliberate design for specific applications is therefore exceedingly difficult, and there is great impetus to develop a fundamental understanding of this phenomenon. Here, an effective and widely accessible computational approach is developed, which is designed to provide microscopic resolution via direct comparison to experimental data along the desorption-guided pathway. The strategy is applied to explain the desorption-induced phase change in an experimentally well-characterized framework, CdIF-13 (sod-Cd(benzimidazolate)₂), where experiment alone was unable to resolve the atomistically detailed phase change landscape. Our findings reveal that the cooperative phase change pathways are adsorbate dependent with thermodynamics of intermediate structural states dictated by a nuanced interplay of ligand orientation, skeletal symmetry, and modes of surface adsorption. The results reveal that this isotropically flexible framework is “chaperoned” through a complex energy landscape by specific adsorbates, revealed by the reported computational approach with atomic-level insight and validated by experimentally determined structures. Thus, this work facilitates both understanding and future design of flexible materials for applications in gas storage, transport, delivery, and separation technologies.