Optimizing NMR Methods for Structure Elucidation: Characterizing Natural Products and Other Organic Compounds
Chapter 7: Two-dimensional NMR Basics
Published:26 Sep 2018
Special Collection: 2018 ebook collectionSeries: New Developments in NMR
2018. "Two-dimensional NMR Basics", Optimizing NMR Methods for Structure Elucidation: Characterizing Natural Products and Other Organic Compounds, Darcy C Burns, William F Reynolds
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As the title suggests, this chapter covers the basic aspects of acquiring and processing 2D data sets, along with analogous selective 1D experiments. It begins with a historical account of the development of 2D NMR. Next, it compares the advantages and disadvantages of acquiring and processing 2D data using a variety of different techniques. This includes a description of the different appearances of homonuclear and heteronuclear correlation spectra and how they are interpreted, as well as the merits of direct (13C) versus indirect (1H) detection. Then, coherence pathway selection and artifact suppression by phase cycling and gradient selection are discussed. The next section covers the relative merits of alternative ways of processing a 2D data set with the goal of saving time and/or improving f1 resolution, including linear prediction, non-uniform sampling, CRAFT-2D processing and co-variance processing, Next, two alternative ways of rapid acquisition of multiple 2D data sets (simultaneous and sequential acquisition) are compared. The final section discusses the advantages of various types of specialized pulses and pulse sequences that are incorporated into the newer versions of many pulse sequences. This includes adiabatic pulses in place of ‘hard’ pulses, frequency selective and band-selected shaped pulses and broadband decoupling sequences, particularly for 13C decoupling in 1H-detected heteronuclear shift correlation spectra.