421-821-chapter-19

421-821-chapter-19 - Nuclear Magnetic Resonance A.)...

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Unformatted text preview: Nuclear Magnetic Resonance A.) Introduction : Nuclear Magnetic Resonance (NMR) measures the absorption of electromagnetic radiation in the radio-frequency region (~4-900 MHz)- nuclei (instead of outer electrons) are involved in absorption process- sample needs to be placed in magnetic field to cause different energy states NMR was first experimentally observed by Bloch and Purcell in 1946 (received Nobel Prize in 1952) and quickly became commercially available and widely used. Probe the Composition, Structure, Dynamics and Function of the Complete Range of Chemical Entities: from small organic molecules to large molecular weight polymers and proteins. NMR is routinely and widely used as the preferred technique to rapidly elucidate the chemical structure of most organic compounds. One of the One of the MOST MOST Routinely used Analytical Techniques Routinely used Analytical Techniques 1937 Rabi predicts and observes nuclear magnetic resonance 1946 Bloch, Purcell first nuclear magnetic resonance of bulk sample 1953 Overhauser NOE (nuclear Overhauser effect) 1966 Ernst, Anderson Fourier transform NMR 1975 Jeener, Ernst 2D NMR 1985 Wthrich first solution structure of a small protein (BPTI) from NOE derived distance restraints 1987 3D NMR + 13C, 15N isotope labeling of recombinant proteins (resolution) 1990 pulsed field gradients (artifact suppression) 1996/7 new long range structural parameters:- residual dipolar couplings from partial alignment in liquid crystalline media- projection angle restraints from cross-correlated relaxation TROSY (molecular weight > 100 kDa) Nobel prizes 1944 Physics Rabi (Columbia) 1952 Physics Bloch (Stanford), Purcell (Harvard) 1991 Chemistry Ernst (ETH) 2002 Chemistry Wthrich (ETH) 2003 Medicine Lauterbur (University of Illinois in Urbana ), Mansfield (University of Nottingham) NMR History NMR History NMR History NMR History First NMR Spectra on Water Bloch, F.; Hansen, W. W.; Packard, M. Bloch, F.; Hansen, W. W.; Packard, M. The nuclear induction experiment. The nuclear induction experiment. Physical Review (1946), 70 474-85. Physical Review (1946), 70 474-85. 1 H NMR spectra of water H NMR spectra of water NMR History NMR History First Observation of the Chemical Shift 1 H NMR spectra ethanol H NMR spectra ethanol Modern ethanol spectra Modern ethanol spectra Arnold, J.T., S.S. Dharmatti, and M.E. Packard, J. Chem. Phys., 1951. Arnold, J.T., S.S. Dharmatti, and M.E. Packard, J. Chem. Phys., 1951. 19 19 : p. 507. : p. 507. Typical Applications of NMR: 1.) Structural (chemical) elucidation Natural product chemistry Synthetic organic chemistry- analytical tool of choice of synthetic chemists- used in conjunction with MS and IR 2.) Study of dynamic processes reaction kinetics study of equilibrium (chemical or structural) 3.) Structural (three-dimensional) studies Proteins, Protein-ligand complexes DNA, RNA, Protein/DNA complexes Polysaccharides 4.) Drug Design S tructure A ctivity R elationships by...
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This note was uploaded on 05/09/2010 for the course CHEM 221 taught by Professor Dr.robertpowers during the Fall '07 term at San Diego.

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421-821-chapter-19 - Nuclear Magnetic Resonance A.)...

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