Foundations and Strategies of Multidimensional NMR

Abstract

Two-dimensional (and higher-order) NMR spectroscopy provides new levels of structural, and/or dynamical, information that cannot be extracted directly from conventional one-dimensional(1D) spectra, because the information is not displayed in a ID format or because of debilitating spectral overlaps. This is accomplished by correlating the information of two separate 1D-type experiments in a 2D pattern, which often spreads out otherwise overlapping spectral information and generates a new level of knowledge via the correlation itself. In this chapter, the concept of correlation is introduced via magnetization transfer concepts of relevant 1D experiments and of the popular 2D COSY technique. Correlation via dipolar interactions in the NOESY experiment are valuable for providing proximity information in the closely related EXSY technique. The use of multiple quantum coherence for simplifying, or “filtering”, the spectrum is discussed, especially for the INADEQUATE experiment, which is so useful for establishing carbon-carbon connectiveties -- i.e., the carbon framework. The behavior of J couplings in spin echo segments can be exploited in a variety of “J-spectroscopy” techniques and for achieving the long-awaited “Broadband Decoupled” proton spectra.