The diffusion of molecules in the liquid phase is of substantial importance to many physical, chemical, and biological processes. It can be the limiting factor for the rate of chemical reactions, and can play a significant role in the details of bimolecular interactions. Pulsed field gradient nuclear magnetic resonance (PFG-NMR) experiments are ideally suited for direct measurement of molecular diffusion. The use of NMR to determine molecular diffusion gives students exposure to modern and relevant chemical instrumentation and fundamental physical chemistry concepts.<br/><br/>A hallmark of physical chemistry is the integration of experiment and computer modeling, simulation and/or theoretical analysis to gain a more complete understanding of complex chemical concepts. However, at the undergraduate physical chemistry laboratory level, the integration of experiment and computer modeling or simulation is rarely done. The two most commonly used computational methods in chemistry are electronic structure calculations and molecular dynamics simulations. Here we introduce molecular dynamics (MD) as a method for simulating and visualizing molecular diffusion. The integration of both experimental NMR and computational MD provides a modern and relevant undergraduate physical chemistry laboratory experience. However, even if only one component is used, students are able to use the computational and experimental data independently and hence can be thought of as modular components.<br/><br/>There are numerous variants that can be done on both the experimental and computational side. We will present the common components used at Arizona State University and briefly discuss simple variants that help accommodate educational institutions with dated NMR and/or computational equipment.

Investigating molecular diffusion in aqueous media using experimental nuclear magnetic resonance (NMR) spectroscopy and computational molecular dynamics (MD): A modular undergraduate physical chemistry laboratory

251st National Meeting (2016)

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