F-Labeling Chemistry in Aqueous Media.

F-Labeled molecular tracers and subsequent positron emission tomography are indispensable molecular imaging tools in medical diagnosis and research. The preparation of F-labeled molecular tracers involves critical steps such as the F-labeling reaction, work-up, and F-product purification, which are governed by F-labeling chemistry. Since direct incorporation of F in aqueous media exhibits many advantages in practice, this Review summarizes the existing F-labeling methods in aqueous media, which are sorted by atoms forming chemical covalent bonds with F. The Review is focused on the respective reaction mechanism, the water effect and the applications of these methods for the development of F-radiopharmaceuticals. The research progress on aqueous nucleophilic labeling methods using [ F]F as the F source has been mainly discussed.