Nuclear Magnetic Resonance
History and overview
Nuclear Magnetic Resonance Spectroscopy is one of the most powerful spectroscopic techniques available to chemists in the world.
Some atoms, when placed in a strong magnetic field, can absorb radio waves at particular frequencies. This phenomenon has been known since 1938 and led to the development of magnetic resonance spectroscopy as an analytical technique It was refined by Bloch and Purcell who received the Nobel Prize for Physics in 1952. Further work to transform the technique into what it is today was centred on the development of Fourier Transform NMR and related pulsed techniques pioneered by Ernst, for which he received the Nobel Prize for Chemistry in 1991. Of particular interest to chemists are the NMR effects of hydrogen (the proton) and carbon, which the most important element in organic chemistry. More recently Kurt Wüthrich was awarded the Nobel prize for his contributions to biological NMR.
Uses of NMR Spectroscopy
NMR spectrometers generate a spectrum of energies that can be used to identify the structure of molecules we are studying through its dependence on their molecular properties. For example, by noting the interactions between the atomic nuclei in the sample (such as phosphorus and carbon) and running various pulse sequences to alter the properties of the spectrum we observe, the structure of extremely complicated molecules can be elucidated extremely quickly.
Most of the work of the SBD group involves NMR spectroscopy and the development of methods to improve its use. By using parahydrogen to generate molecules that show novel magnetic behaviour, we can enhance the strength of the detected NMR signal by many hundreds of times its normal level. We can therefore observe and identify molecules in concentrations that are far below those we normally require. In this way, true reaction intermediates that feature in many important industrial-scale processes can be identified and characterised.