‘NOAH’ technique could speed up process of elucidating chemical structures.
Nuclear magnetic resonance (NMR) spectroscopy is a core method for determining the structure of chemicals. Different types of two-dimensional NMR can identify distinct types of bonding connectivity in molecules, according to the energies at which certain nuclei — often hydrogen — absorb and re-emit radio-frequency radiation. But using multiple techniques can be time-consuming.
Ēriks Kupče at Coventry-based Bruker UK and Tim Claridge at the University of Oxford, UK, have developed a method that can perform up to five types of 2D NMR technique in one go. This method uses one initial preparation period for the hydrogen atoms, then sequentially identifies different elements linked to these atoms using a series of techniques that knock down specific parts of the initial hydrogen signal one at a time. For example, by looking for hydrogens bound to nitrogen first, most of the initial hydrogen signal can be preserved for use in the next analysis technique.
The authors use their method, dubbed NMR by ordered acquisition using hydrogen detection (NOAH), to outline 285 possible means of combining techniques into ‘super-sequences’.