Terahertz Vibrational Motions Mediate Gas Uptake in Organic Clathrates

Clathrates, supramolecular materials that contain guest molecules trapped within a framework of a host lattice, are important in many areas of science and technology. However, despite much research, fundamental questions concerning the mechanism and kinetics associated with the enclathration process remain unanswered. Here, through a combination of terahertz spectroscopy, density functional theory, and molecular dynamics simulations, we demonstrate that the gas-capture process is mediated by a single terahertz vibrational mode and then use this mode to track the uptake of gas. This result provides a critical molecular-level understanding of this key kinetic process in clathrate science.