Synthesis of two persistent fluorinated tetrathiatriarylmethyl (TAM) radicals for biomedical EPR applications.

Tetrathiatriarylmethyl radicals are attractive spin probes extensively used in biomedical magnetic resonance applications. We report a straightforward synthesis of two original tetrathiatriarylmethyl radicals incorporating, respectively, 15 and 45 fluorine atoms, and thus possessing a high affinity to fluorous media. F15T-03 and F45T-03 exhibit a single sharp EPR spectrum and their EPR line broadening is highly sensitive to molecular oxygen. These spin probes are specially designed for assessment of tumor oxygenation using perfluorocarbon formulations.