Intramolecular rearrangements studied by two-dimensional nuclear magnetic resonance line shape analysis

Abstract

The usual theory of nuclear magnetic resonance (NMR) line shapes in the presence of molecular rearrangements has been extended to two-dimensional (2D) NMR in liquids using an explicitly superoperator formalism. Advantages of the proposed 2D method include a clearer ‘‘signature’’ for the presence of a chemical reaction (even at a single temperature), peak shapes providing more information about the underlying NMR parameters, and (in favorable cases) the presence of off-diagonal peaks with characteristic shapes which can be analyzed even in cluttered spectra. Detailed calculations are shown for a single spin 1/2 and for a group of two strongly coupled spins 1/2, jumping between two different spin Hamiltonians. The agreement between the predicted peak shapes and the corresponding experimental results on simple molecules is excellent.