Design and synthesis of fluorinated dendrimers for sensitive (19)F MRI.

To achieve high sensitivity for (19)F MRI, a class of novel dendritic molecules with multiple pseudosymmetrical fluorines was designed and efficiently synthesized. Through iterative bromination and Williamson ether synthesis under mild conditions, a fluorinated dendrimer with 540 pseudosymmetrical fluorines was conveniently prepared without performing the group protection in a convergent way. The dendrimer is characterized by a strong (19)F NMR peak and short relaxation times. Eventually, an appreciably enhanced (19)F MRI at an extremely low concentration (18.5 μM) was achieved, which demonstrated the potential utility of such dendritic molecules in highly sensitive (19)F MRI.