[18F]-Group 13 fluoride derivatives as radiotracers for positron emission tomography

Abstract

The field of ¹⁸F chemistry is rapidly expanding because of the use of this radionuclide in radiotracers for positron emission tomography (PET). Until recently, most [¹⁸F]-radiotracers were generated by the direct attachment of ¹⁸F to a carbon in the organic backbone of the radiotracer. The past decade has witnessed the emergence of a new strategy based on the formation of an ¹⁸F-group 13 element bond. This approach, which is rooted in the field of fluoride anion complexation/coordination chemistry, has led to the development of a remarkable family of boron, aluminium and gallium [¹⁸F]-fluoride anion complexing agents which can be conjugated with peptides and small molecules to generate disease specific PET radiotracers. This review is dedicated to the chemistry of these group 13 [¹⁸F]-fluorides anion complexing agents and their use in PET. Some of the key fluoride-binding motifs covered in this review include the trifluoroborate unit bound to neutral or cationic electron deficient backbones, the BF₂ unit of BODIPY dyes, and AlF or GaF₃ units coordinated to multidentate Lewis basic ligands. In addition to describing how these moieties can be converted into their [¹⁸F]-analogs, this review also dicusses their incorporation into bioconjugates for application in PET.