Recent Advances in Editing and Selective Detection Methods for 1 H NMR Spectroscopy

In complex organic molecules, macromolecules and biological samples, 1 H NMR spectra can be very complex and assignments of resonances can be difficult. Thus NMR pulse sequence methods to edit and simplify spectra have been introduced. During the last few years, there have been a number of reports on the use of heteronuclear multiple-quantum filtration to simplify 1 H NMR spectra. The method is known as inverse-detected or 1 H-detected NMR spectroscopy. These pulse sequences start and end with 1 H single-quantum coherence, and heteronuclear single- or multiple-quantum coherence is generated and allowed to evolve in the middle stage of the pulse sequence. In addition, we have developed a family of NMR pulse sequences, known generically as MAXY, for the provision of separate one-, two- and three-dimensional 1 H NMR spectra of CH, CH 2 and CH 3 groups. These methods utilize the natural abundance of 13 C spins and are based upon the selection of the different possible maximum multiple-quantum coherences of the various groups. These approaches have been applied to the measurement of chemical shifts, coupling constants, relaxation rates and molecular diffusion coefficients. These recent results are summarized in this article. Possibilities for the future are also outlined.