The Relationship between NMR Chemical Shifts of Thermally Polarized and Hyperpolarized Y Complexes and Their Solution Structures.

Recently developed dynamic nuclear polarization (DNP) technology offers the potential of increasing the NMR sensitivity of even rare nuclei for biological imaging applications. Hyperpolarized Y is an ideal candidate because of its narrow NMR linewidth, favorable spin quantum number (I=1/2 ), and long longitudinal relaxation times (T ). Strong NMR signals were detected in hyperpolarized Y samples of a variety of yttrium complexes. A dataset of Y NMR data composed of 23 complexes with polyaminocarboxylate ligands was obtained using hyperpolarized Y measurements or H, Y-HMQC spectroscopy. These data were used to derive an empirical equation that describes the correlation between the Y chemical shift and the chemical structure of the complexes. This empirical correlation serves as a guide for the design of Y sensors. Relativistic (DKH2) DFT calculations were found to predict the experimental Y chemical shifts to a rather good accuracy.