Gallium Fluoride Complexes with Acyclic Bispicolinic Ligands as Potential New Fluorine‐18 Labelled Imaging Agents

Investigating the Mechanism of Aluminum Fluoride Chelation

Aluminum fluoride (AlF) complexes have been used over the past decade to incorporate [18F]fluoride into large biomolecules in a highly selective fashion by using relatively facile conditions. However, despite their widespread usage, there are a large number of variations in the reaction conditions, without a definitive discussion provided on the mechanism to understand how these changes would alter the end result. Herein, we report a detailed mechanistic investigation of the reaction, using a mixture of theoretical studies, fluorine-19 and fluorine-18 chemistry, and the consequences it has on the efficient clinical translation of AlF-containing imaging agents.

An Unusual Pair: Facile Formation and In Vivo Validation of Robust Sc-18 F Ternary Complexes for Molecular Imaging

Fluorine-18 remains the most widely clinically utilized radionuclide globally for positron emission tomography (PET). The emergence of therapeutic isotopes for the management of disease has produced a pronounced interest in matched, theranostic isotope pairs that can be employed in tandem for the diagnosis and stratification of patients for subsequent radiotherapy. ¹⁸ F, however, does not have a suitable therapeutic isotopologue. Here, we demonstrate that the formation of [¹⁸ F][Sc-F] ternary complexes is feasible under mild, aqueous conditions, producing chemically robust radiopharmaceuticals in high radiochemical yield and specific activity. A corresponding in vivo study with a cancer-targeting [¹⁸ F][Sc-F] tracer indicates excellent in vivo stability and produces exquisite PET image quality, rendering the ¹⁸ F/⁴⁷ Sc isotope pair an unusual, yet chemically matched theranostic pair with excellent potential for clinical translation.