A CoII complex for 19F MRI-based detection of reactive oxygen species

A fluorinated, cobalt(ii)-based ¹⁹F MRI imaging agent switches from a paramagnetic high spin Co^II state to a diamagnetic low spin Co^III state following oxidation by H₂O₂ and other reactive oxygen species, resulting in a turn-on response via both ¹⁹F NMR and MRI.