Nuclear Magnetic Resonance: An instrument for characterization of new compounds

Sanjeet Kumar
Ravenshaw university
sanjeet.biotech@gmail.com
 

NMR is one of the principal techniques used to obtain physical, chemical, electronic and structural information about molecules due to either the chemical shift, zeemen effect, or the knight shift, or a combination of both, on the resonant frequencies of the nuclei present in the sample. It is a powerful technique that can provide de

Ø Tailed information on the topology, dynamics and three-dimensional structure of molecular in solution and the solid.

Ø NMR was first described and measured in molecular beams by Isidor Rabi in 1938 and was awarded the Nobel Prize in physics.

Ø There are following types of NMR spectroscopy

o   Continuous wave (CW) spectroscopy

o   Fourier transform spectroscopy

o   Multi-dimensional NMR spectroscopy

o   Solid-State NMR spectroscopy

Hardware of NMR

1.    Magnet

2.    Field Lock

3.    Shim Coils

4.    Sample probe

5.    RF coils

6.    Gradient Coils

7.    Quadranture Detector

8.    Digital Filtering

Carbon-13 NMR

Many of the molecules studied by NMR contain carbon. Unfortunately, the C-12 nucleus does not have a nuclear spin, but the carbon-13 nucleus does due to the presence of an unpaired neutrons. It is less sensitive than Hydrogen NMR spectroscopy.

Applications

Important applications of NMR are:

1.    Molecular structure and conformational changes of molecules can be determined by NMR.

2.    The technique along diffraction data is used in molecular modelling.

3.    High resolution protein structures have been elucidated by NMR.

4.    The technique has been applied to study enzymes kinetics.

5.    Structural studies on both DNA and RNA.

6.    Interactions between proteins and lipid bilayers in membranes have been observed to predict their possible biological functions.

7.    Intracellular and extracellular inorganic phosphate concentrations may be measured in living cells and tissues.