Dr. Wissam Iali

My research project brings together skills in inorganic chemistry, catalysis, organic synthesis, physical chemistry and biochemistry to improve dramatically the sensitivity of NMR spectroscopy.

Novel catalytic approach to improve dramatically the sensitivity of NMR spectroscopy:

Nuclear magnetic resonance spectroscopy (NMR) is one of the most powerful method to analyse and discover molecules. However, the low sensitivity of this technique acts to limit its applicability, while adding substantially to cost. This problem arises from the very low value of the nuclear polarisation from which the NMR signal directly derives. Recently, the sensitivity of NMR has been improved by the concept of molecular hyperpolarisation that consists in artificially and transiently increasing the nuclear spin polarisation from the thermal equilibrium. This is performed by polarisation transfer from a purely singlet state nuclear spin order systems (parahydrogen = pH2). SABRE (Signal Amplification By Reversible Exchange) is promising hyperpolarisation technique via pH2 because it is based on a novel form of catalysis which employs the readily available pH2 as source of magnetism to enhance a very wide array of molecules without changing their chemical identity. SABRE effectively uses suitable catalyst to reversibly bind both pH2 and the substrate in order to assemble a reaction intermediate in which polarisation is able to transfer, at low magnetic fields (a few gauss for proton hyperpolarisation), from pH2 into the substrate (DOI: 10.1126/sciadv.aao6250). With this hyperpolarisation step, the nuclear polarisation levels can be enhanced by a factor of 104-105 above thermal equilibrium levels, resulting in the same gain for the NMR signals. The hyperpolarisation provides ultrasensitive NMR that enables the observation of reaction intermediates in catalytic cycles and provides new insight into mechanisms. The recent advent of hyperpolarisation methods has enabled scientists to dream of forgotten applications such as molecular imaging or real-time monitoring of metabolites.