Chemical Exchange in NMR

This lecture covers the basic steps in magnetic resonance, focusing on chemical exchange effects in NMR arising from chemical and conformational equilibria. It explains how NMR lines are broadened by slow exchange and how differences in NMR frequencies of exchanging spins can be averaged by fast exchange. Examples include the motion of tyrosine side-chains in proteins, ethanol NMR multiplets at neutral pH, cis-decalin NMR spectra at different temperatures, bullvalene NMR spectra, cyclooctatetraene NMR spectra, and t-butyl carbon NMR spectra. The magnitude of the chemical shift relative to the exchange rate constant determines whether the exchange is slow or fast, providing insights into chemical reactions, molecular rearrangements, and internal motions.