Advances in the Chemistry of Astatine and Implications for the Development of Radiopharmaceuticals

Abstract

This article reports the very first experimental characterization of halogen bonds mediated by astatine, quantum chemistry calculations making up for the impossibility of using spectroscopic tools.

Complexation of Astatine(III) with Ketones: Roles of NO3–Counterion and Exploration of Possible Binding Modes

“…Astatine holds a unique position on the periodic table, situated near the bottom of the halogen series, only lighter than tennessine (Ts, Z = 117), while also being a member of the metalloids; which combined results in a rich, varied chemistry. − This is exemplified by the fact that six different oxidation states At – , At 0 , At + , At 3+ , At 5+ , and At 7+ have been reported, but a comprehensive understanding of the speciation and chemical properties of the different oxidation states has yet to be obtained . The situation is further complicated by the heavy element nature of At ( Z = 85), which results in a larger atomic radius (0.45 Å) and requires relativistic effects to be considered when examining its electronic structure .…”

211At and 125I‐Labeling of (Hetero)Aryliodonium Ylides: Astatine Wins Again

“…A better understanding of the chemical behavior of astatine allows the development of more rational approaches to design new radiolabeling reactions and ultimately benefits to the progress in 211 At-labelled radiopharmaceuticals. [8] Based on the observation that the astatide species (At À ) can be stable in a much broader pH/Eh domain than the At + species required for electrophilic reactions, [9] we recently initiated the investigation of nucleophilic 211 At-labeling approaches of aryl compounds with the intension to propose more robust radiolabeling procedures in the perspective of future clinical trials. The interest in the use of nucleophilic astatine is also found in most recent reports such as the 211 At-labeling of the promising neopentyl glycol scaffold.…”

Pourbaix Diagram of Astatine Revisited: Experimental Investigations

“…7,8 However, TAT requires 211 At to be attached to a biological vector, and knowledge of astatine speciation in solution is essential for the development of radiolabeling approaches. 9,10 The reported investigations of the chemical forms of astatine remain based on limited technical approaches. Some knowledge of astatine species was acquired according to (i) their behaviors in coprecipitation experiments, electromobility measurements, thin-layer chromatography measurements, and competition experiments in a biphasic system and (ii) comparisons with iodine chemistry.…”

“…11,12 These sketchy analyses are insufficient for determining the exact nature of the species involved in many reactions, with occasional inconsistencies in the literature. 10,13 A more detailed analysis of the data, however, allows the tracing back of important information such as the charge, 14,15 the stoichiometry of the species, 16,17 and quantitative data describing the formation of the species. 18−20 Molecular modeling has also proven to be of great help because it can provide extra information at the molecular level and quantitative data that can be compared with experimental values.…”