Diagonal free homonuclear 2D correlation using heteronuclei

Original · EN

Homonuclear correlation spectroscopy has played a crucial role in elucidating structure of molecules in solution. In all kinds of homonuclear correlation, the most intense peaks appear in the diagonal, and quite often due to its broad dispersive tails obscure the useful cross peaks close to the diagonal. Herein, we demonstrate that by editing the 1H magnetization by a C-13 nucleus in natural abundance before starting the t1 evolution, it is possible to discriminate the inphase 1H magnetizations that leads to the diagonal peaks from the antiphase 1H magnetizations that generates the cross peaks. The 1H magnetization is edited by a C-13 nucleus in natural abundance before starting the t1 period in COSY. After the coherence transfer, the inphase transverse magnetization directly attached to C-13 evolves under one bond heteronuclear coupling for a time period 2τ tuned to one bond heteronuclear coupling while the antiphase transeverse magnetization directly attached to remote C-12 evolves under negligible long range heteronuclear couplings. As a result the inphase magnetization can be eliminated as an unobservable heteronuclear multiple quantum coherence leading to a diagonal free correlated spectrum. The method is demonstrated for COSY.