Structural Elucidation of Small Organic Molecules by 1D, 2D and Multi Dimensional-Solution NMR Spectroscopy

Structural Elucidation of Small Organic Molecules by 1D, 2D and Multi Dimensional-Solution NMR Spectroscopy

For the last fifty years nuclear magnetic resonance spectroscopy, generally referred as NMR, is one of the most versatile techniques for elucidation of structure of organic compounds. Among all available spectrometric methods, NMR is the only technique which offers a complete analysis and interpretation of the entire spectrum. Due to improved experimental technology and novel approaches, over the last decade nuclear magnetic resonance (NMR) has shown a tremendous progress. Generally, NMR spectroscopy makes use of three approaches; those are one dimension (1D), two dimensions (2D) and three dimensions (3D). Usually, the first approach of 1D-NMR (1H DEPT, 13C, 15N, 19F, 31P, etc.) generates good information about the structure of simple organic compounds, but in case of larger molecules the 1D-NMR spectra are generally overcrowded. Hence, the second approach of 2D-NMR (COSY, DQFCOSY, MQFCOSY, HETCOR, HSQC, HMQC, HMBC, TOCSY, NOESY, EXSY, etc.) is used for the further larger molecules, but 2D-NMR spectra also becomes complex and overlapping when used for further very large molecules like proteins. Hence, so as to achieve high resolution and reduced overlapping in spectra of very large molecules, Multi Dimensional-NMR (Homonuclear and Heteronuclear) are generally used. This paper supports interpretation of structure of different organic compounds by different NMR techniques. Introduction NMR spectroscopy was discovered after the second world war and was developed from experiments performed to accurately measure the nuclear magnetogyric ratio about seventy years ago [1]. Purcell et al. at Harvard and Bloch et al. at Stanford in 1945 reported the first observation of nuclear magnetic resonance in bulk matter for which they were jointly awarded with Nobel Prize for physics in 1952. Since... read more