Nuclear magnetic resonance papers read like a veritable alphabet soup. There's NOESY, COSY, TOESY, and ROESY; HMQC, HMBC, HSQC, and DEPT. And let's not forget INEPT, INADEQUATE, EXSY, and SECSY.
It's enough to make a biologist squirm. Yet fundamentally, these experiments all take advantage of a relatively simple physical phenomenon. Anybody who has ever turned a nail into a magnet by wrapping it with electrical wire knows magnetism and electricity are inextricably linked. NMR spectroscopists exploit that fact to derive structural and dynamic information about the molecules they study.
Certain nuclei, including 1H, 13C, and 15N, tend to behave like tiny magnets. In the absence of a magnetic field, these nuclei orient themselves randomly (A). But when a strong magnetic field is applied, they snap into place along the magnetic field lines, either with the field (parallel) (B) or against it (antiparallel); of the two, the parallel state is more ...
