Porous materials are becoming increasingly popular because they are highly functional and readily produced. There are numerous applications involving porous materials, such as catalysis, gas separation and water purification. However, in order to more effectively use porous materials in advanced applications, it is critical that accurate information related to host-guest interactions be well-understood with atomic-level precision. In this work, two applications of porous materials are investigated, focusing on the nature and dynamics of guest molecules within the porous solid. In the first case, the stabilization of disordered active pharmaceutical ingredients through interactions with mesoporous silica was explored. In the study, the guest-host interaction is characterized experimentally and theoretically, with focus on monolayer formation in the porous silica. Using solid-state density functional theory (DFT), the binding energy, molecular conformations, and atomic dynamics were all obtained. The results show that loading drug molecules into porous silica did increase the stability of the amorphous state, by allowing the drug molecules to maximize favorable intermolecular interactions. However, this simultaneously results in a more highly stranded intramolecular conformation, revealing the complex energetic interplay between conformational strain and external stabilization. In a second application, the gas-capture and sequestration phenomena in porous materials was studied in hydroquinone (HQ) clathrate materials. A series of gases were studied, including the noble gases (He, Ne, Ar, Kr, Xe, Rn) as well as carbon dioxide (CO<sub>2</sub>). By using the terahertz spectroscopy, the dynamics of the gas – HQ interaction were uncovered as a function of temperature and pressure. Solid-state DFT simulations help to assign the terahertz spectra and uncover the interaction mechanism. The results also indicate that porous HQ adsorbs the guest gas molecules selectively based on the various energetic forces present within the pores, and that low-frequency vibrations are linked to the adsorption process in these materials.<br/>

Terahertz spectroscopy as a tool to investigate guest-host interactions in porous materials

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.