This research project involves the development of experimental methods for detecting less receptive nuclei with special emphasis placed on 13C and 15N. The application of such methods to biologically important system and their theoretical consequences are stressed. The value of chemical shifts in structural correlations of liquid samples has been very well documented and these concepts are now being developed in the shielding tensor. The 3D aspects of shielding tensors becomes one of the significant aspects of this proposal. Solid state work on either powders or single crystals is required to obtain shielding tensors and their principal orientations in the molecular frame. Use of tensor data along with theory is advancing our understanding of the origins of chemical shielding and its use in shift structure correlations. The expansion from a isotropic shift to six tensor parameters in solids provides details unavailable in liquids. Thus, work will be directed towards the development of single crystal methods for biomolecules of a size not here-to-fore possible. Recent advances of a 2D magic angle turning (MAT) experiment now provides a method for obtaining solid power patterns for compounds with 2-3 dozen different carbons. Several new modifications have been developed to better address structural problems. These include two 3-D PHORMAT experiments. One is a separated local field and also a CS-CS-CS 3D PHORMAT spectrum. A new technique for importing greater evaluation resolution, TIGER, is reducing the time necessary for acquiring PHORMAT data on any complex molecules. A combination of these methods is providing shift tensor information on a variety of biomolecules important in biomedical applications. Use of Dynamic Nuclear Polarization (DNP) from unpaired electrons with 15N detection indicates that enhancement factors of about 2 orders of magnitude may be possible for a large number of compounds. As 15N shifts exhibit even greater dependence upon structural effects than 13C, this enhancement portends well for 15N chemical shifts of biomolecules. Thus, the extension to use both 14N and 13C offers a significant opportunity to expand our long term 13C program.
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