The parent project for this FIRCA application uses electron and nuclear magnetic resonance methods to study the structure and effectiveness of inorganic complexes as paramagnetic contrast agents for clinical MRI use. This proposed collaboration will study a new class of oxygen- sensitive probes, with the ultimate goal of using these char species for Dynamic Nuclear Polarization (DNP) imaging, EPR and DNP oximetry applications. The overall goal is to increase the effectiveness of these potentially new contrast agents in MRI clinical applications (imaging and oximetry.) The working hypothesis is that by studying the whole class of char suspensions (most of which have previously been synthesized) under a variety of experimental conditions (high field, low field, variable temperature) they will ultimately be able to more fully understand (and possibly be able to optimize) the electron-nuclear polarization transfer process in multiple-phase systems.