Isotope Exchange-Based 18 F-Labeling Methods.

18 F-Labeling methods for the preparation of 18 F-labeled molecular probes can be classified into electrophilic fluorination, nucleophilic fluorination, metal-F coordination, and 18 F/ 19 F isotope exchange. Isotope exchange-based 18 F-labeling methods demonstrate mild conditions featuring water resistance and facile high-performance liquid chromatography-free purification in direct 18 F-labeling of substrates. This paper systematically reviews isotope exchange-based 18 F-labeling methods sorted by the adjacent atom bonding with F, i.e., carbon and noncarbon atoms (Si, B, P, S, Ga, Fe, etc.). The respective isotope exchange mechanism, radiolabeling condition, radiochemical yield, molar activity, and stability of the 18 F-product are mainly discussed for each isotope exchange-based 18 F-labeling method as well as the cutting-edge application of the corresponding 18 F-labeled molecular probes.