Highly fluorinated metal complexes as dual F and PARACEST imaging agents

We reported a set of water-soluble transition metal complexes that can serve as both 19 F and PARACEST magnetic resonance imaging agents. The high number of equivalent fluorine atoms and the paramagnetic effect of metals offer these complexes high 19 F sensitivity as demonstrated by in vitro 19 F MRI experiments. The complexes contain carboxamide groups appended onto a cyclen macrocycle, which provide 1 H CEST peaks well differentiated from bulk water. The Co( ii ) agent displays two CEST peaks that can be utilized for ratiometric pH determination and the concept of combining 19 F MR and PARACEST as complementary imaging techniques was demonstrated with the Fe( ii ) complex. Highly fluorinated, water-soluble transition metal complexes serve as both 19 F and PARACEST magnetic resonance imaging agents.