Anisotropic Rotational Diffusion Studied by Nuclear Spin Relaxation and Molecular Dynamics Simulation: An Undergraduate Physical Chemistry Laboratory

Abstract

Laboratories studying the anisotropic rotational diffusion of bromobenzene using nuclear spin relaxation and molecular dynamics simulations are described. For many undergraduates, visualizing molecular motion is challenging. Undergraduates rarely encounter laboratories that directly assess molecular motion, and so the concept remains an abstraction. Spin relaxation and molecular dynamics simulations are complementary tools in studying molecular motion in solution. Simulations allow direct visualization of motion. Comparison of simulation results to experimental spin relaxation results enables discussion of the strengths and weaknesses of each technique. Performance of spin relaxation experiments in addition broadens undergraduate perceptions of the utility of NMR spectroscopy. Laboratories which enable the study of the motion of small molecules by both techniques are presented.