Collaborative Research: Tracking Reactivity in Porous Materials with Terahertz Spectroscopies

About This Grant

With support from the Chemical Structure and Dynamics (CSD) program in the Division of Chemistry, Professor Daniel Mittleman of Brown University and Professor Michael Ruggiero of the University of Rochester are investigating guest-host molecule interactions in porous materials using a combination of vibrational spectroscopies and computational methods. This project aims to uncover the atomic-level mechanisms that drive the adsorption of gases in porous materials such as metal-organic frameworks (MOFs) and clathrates. A key challenge is that the intermolecular forces are often weak, requiring probes in the terahertz range. The team will apply low-frequency infrared and Raman spectroscopies, exploiting a unique capability to obtain such measurements in a custom-designed pressure cell, to reveal how gas loading alters the vibrational dynamics in real time. Quantum mechanical simulations will help to interpret these spectral changes, linking them to structural information. The combination of computational and experimental results will clarify important open questions in the field, such as the impact of structural disorder on adsorption dynamics. These new insights will inform the rational design of materials optimized for particular applications such as hydrogen storage or toxic chemical remediation. These efforts are linked to a hands-on week-long summer course developed for high school students in Rochester and Providence, which will further the pedagogical training of the graduate students participating in the project. This project integrates state-of-the-art experimental and theoretical techniques to study the vibrational dynamics of porous media under gas-loading conditions. Vibrational spectroscopy, including terahertz time-domain and Raman measurements, will be used to monitor subtle structural changes, through changes in the low-frequency modes, which reflect shifts in the intermolecular forces during gas adsorption. A gas-dosing manifold with stoichiometric control will enable precise quantification of guest molecule uptake and its impact on vibrational spectra. These data will be compared to solid-state density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations to interpret experimental results and uncover structure–dynamics relationships. The results will reveal the role of host framework flexibility, host/guest molecule disorder, and cooperative phase transformations on the gas loading mechanisms and associated kinetics. The ultimate goal of this project is the development of predictive models that link spectroscopic signatures to molecular-scale mechanisms. This project will establish a new paradigm for characterizing and designing functional porous materials using laboratory-based spectroscopic methods. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.