Molecular Properties of Caffeine Explored by NMR: A Benchtop NMR Experiment for Undergraduate Physical-Chemistry Laboratories

NMR is a fundamental part of any undergraduate chemistry degree, and training students how to measure and interpret NMR spectra is essential for postgraduate research or chemistry-based careers. Traditionally, the undergraduate laboratory experience with NMR is restricted to sample submission for NMR analysis, which is typically conducted by a technician. However, instant access to NMR instrumentation is now possible because of the development of benchtop NMR spectrometers. These can be placed on the lab bench alongside other spectroscopic equipment. The simplicity of operation and variety of experiments available allows the development of new undergraduate experiments across organic-, inorganic-, and physical-chemistry laboratories. Here we describe a new experiment for undergraduate physical-chemistry laboratories that incorporates relaxation measurements to understand the behavior of caffeine in a variety of conditions. The experiment uses the T1 and T2 experiments available on most benchtop spectromet...