Action-at-a-Distance via Ice-Like point Defects: Relating Catalytic Gas-Hydrate Formation and Antifreeze Protein Action to Epitaxial Growth of Gas Hydrates

Oklahoma State University, Stillwater OK

Investigators

Abstract

Paul Devlin of Oklahoma State University is supported by the Chemical Structure, Dynamics and Mechanisms Program of the Chemistry Division to understand and modify the basic physical and chemical properties of crystalline hydrates that contain trapped gas molecules. These gas hydrates are ice-like lattices of water molecules with incorporated small cages that serve as molecule-size traps for other species. Gas hydrates are abundant in nature and have significant technological roles. Much is known about their occurrence and physical properties; but less about their participation in hydrogen-bond chemistry and catalytic processes during their formation. A better understanding of these processes may have implications with respect to the suppression of ice formation by adsorbed antifreeze-proteins (AFP) as observed in fish and other species. This project provides research opportunities for a number of undergraduate students, and involves collaboration with a researcher from Turkey. This research includes both experimental and theoretical studies. Lattice defects, common in ice and readily generated in much greater abundance by hydrogen-bonding guests, facilitate rapid hydrate formation by inducing solid-state molecular mobility. With a proper guest catalyst included (for example, the ether tetrahydrofuran (THF)), droplets instantly crystallize as gas-hydrate particles. This catalytic action of defects at micron distances within gas hydrates is of more general interest. In this project, Prof. Devlin and his undergraduate research assistants are using Fourier Transform Infrared (FTIR) spectroscopy to explore how the behavior of ice-like point defects that underlie molecular actions that may influence the formation of clathrate hydrates (CH), as well as the function of antifreeze proteins. Insights are also being gained through ab initio and molecular dynamics (MD) calculations on the CH systems being studied experimentally. The computational work is being done in collaboration with Professor Nevin Uras-Aytemiz, of Karabuk University, Turkey.