Inside the pores of metal–organic frameworks
Dr. Constanze Neumann and her team at the Max-Planck-Institut für Kohlenforschung have developed a new method to map the internal pore environments of MOFs.
Metal–organic frameworks (MOFs) are crystalline materials that have garnered considerable attention in recent years due to their chemical tunability. Researchers can tailor them precisely for a wide range of applications, from harvesting water from desert air to capturing carbon dioxide. Dr. Constanze Neumann and her team at the Max-Planck-Institut für Kohlenforschung have now developed a new method to map the internal pore environments of MOFs. Their findings were published in the journal Chem.
“MOFs are part of what we call reticular materials. We use a chemical toolbox of pre-designed building blocks and combine them according to our needs,” Neumann explains. “Pores of various sizes and shapes can thus be created, and we already have great tools to experimentally verify the dimensions of MOF pores. Our new approach allows us to determine how the shape and size of pores affects their chemical environment. We can also find out where chemical modifications have taken place within the framework, and what kind of defects are present. The chemical environment inside pores is critical for a wide range of MOF applications – from gas storage and separation to catalysis.”
The team’s idea was to use nuclear magnetic resonance spectroscopy (NMR) to ‘map’ MOF pores. Small chemical groups containing hydrogen or fluorine atoms are introduced into the MOF, where they extend into the pores and act as local reporters. These atoms are particularly easy to detect by NMR, so a few minutes of measurement time suffice to reveal the chemical environment the reporters experience inside the pore. When the researchers compared MOFs built from the same chemical components but featuring different pore sizes, the NMR signals clearly differed depending on the pore in which the reporter group was located. The method also responds sensitively to changes inside the pores. When gases or solvents enter the pores, the NMR signals shift, revealing how guest molecules alter the local environment.
The importance of this research field was underlined in 2025, when the Nobel Prize in Chemistry was awarded for the development of metal–organic frameworks. The prize recognized MOFs as a versatile materials platform with enormous potential for addressing challenges in energy, sustainability and resource efficiency. By providing a new way to look inside these materials, Neumann’s work adds an important piece to the growing toolbox needed to turn MOFs into reliable, application-ready systems.
