Probing the Mechanochemistry of Metal-Organic Frameworks with Low-Frequency Vibrational Spectroscopy

The identification of low-frequency vibrational motions of metal-organic frameworks (MOFs) allows for a full understanding of their mechanical and structural response upon perturbation by external stimuli such as temperature, pressure, and adsorption. Here, we describe the unique combination of an experimental temperature- and pressure-dependent terahertz spectroscopy system with state-of-the-art quantum mechanical simulation to measure and atomistically assign specific low-frequency vibrational modes that directly drive the mechanochemical properties of this important class of porous materials. Our work highlights the complex interplay between structural, vibrational, and mechanochemical phenomena, all of which are key to the effective exploitation of MOFs. We demonstrate the critical importance of terahertz vibrational motions on the function of MOFs, and how this information can be measured and interpreted in a method that can be applied widely to any supramolecular materials.