Professor Warren is supported by a grant for exploratory research from the Experimental Physical Chemistry Program to develop the methods that will take advantage of a newly observed phenomenon in which irradiation of samples with circularly polarized light causes frequency shifts in the NMR spectral lines of a chiral molecule. Since each NMR nucleus, depending on its location relative to the chromophore, will experience a different sign and magnitude of frequency shift, this phenomenon has the potential of being able to distinguish among the protons located close to the chromophore in a congested spectrum. It is possible to eliminate all signals from achiral molecules in the majority, in order to observe minority chiral species by taking a difference spectrum for left vs. right circularly polarized light. Since many important molecules are optically active, this phenomenon could have very powerful applications. There are possibilities of incorporating this technique into multidimensional NMR spectroscopy of complex systems, with the laser on in one dimension. %%% This exploratory research project will make use of the just discovered effect on the nuclear magnetic resonance (NMR) signals of nuclei that are located close to the chromophore group of a molecule possessing handedness (optically active) upon irradiation with circularly polarized visible light using a laser. It is possible to eliminate entirely all signals in the NMR spectrum from all other non-optically active molecules in the sample. If successful, this technique could have a great impact on the NMR spectroscopy of samples containing biological molecules.
