Advances on the Determination of the Astatine Pourbaix Diagram: Predomination of AtO(OH)2− over At− in Basic Conditions

Sergentu, Dumitru‐Claudiu; Tezé, David; Sabatié-Gogová, Andrea; Alliot, Cyrille; Guo, Ning; Bassal, Fadel; Silva, Isidro Da; Deniaud, David; Maurice, Rémi; Champion, Julie; Galland, Nicolas; Montavon, Gilles

doi:10.1002/chem.201504403

Cited by 47 publications

(80 citation statements)

References 38 publications

(48 reference statements)

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“…In contrast, formation of astatine as pure At − in reducing media is considerably easier, since only one reduced species of the halogen is accessible . Therefore, it appears preferable to have access to alternative methods of astatination that involve the use of At − .…”

Section: Introductionmentioning

confidence: 96%

Unexpected Behavior of the Heaviest Halogen Astatine in the Nucleophilic Substitution of Aryliodonium Salts

Guérard

Lee

Baidoo

et al. 2016

Chemistry A European J

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Aryliodonium salts have become precursors of choice for the synthesis of 18F-labelled tracers for nuclear imaging. However little is known on the reactivity of these precursors with heavy halogenides, i.e. radioiodide and astatide at the radiotracer scale. Herein, we report the first comparative study of radiohalogenation of aryliodonium salts with [125I]-iodide and [211At]-astatide. Initial experiments on a model compound highlight a higher reactivity of astatide compared to iodide that could not be anticipated from the trends previously observed within the halogen series. Kinetic studies indicate a significant difference in activation energy (Ea = 23.5 and 17.1 kcal/mol with 125I− and 211At−, respectively). Quantum chemical calculations support the hypothesis of a monomeric iodonium-astatide intermediate whereas radio-iodination occurs in a dimeric environment. The good to excellent regioselectivity of halogenation and high yields achieved with diversely substituted aryliodonium salts indicates that this class of compounds is a promising alternative to the stannane chemistry currently used for radiohalogen labeling of tracers in nuclear medicine.

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Section: Introductionmentioning

confidence: 96%

Unexpected Behavior of the Heaviest Halogen Astatine in the Nucleophilic Substitution of Aryliodonium Salts

Guérard

Lee

Baidoo

et al. 2016

Chemistry A European J

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“…13 Most recent literature shows an interest in developing nucleophilic radioiodination approaches for these reasons, with for instance recent reports on the use of arylboron precursors. 14,15 …”

Section: Introductionmentioning

confidence: 99%

Bifunctional aryliodonium salts for highly efficient radioiodination and astatination of antibodies

Guérard

Navarro

Lee

et al. 2017

Bioorganic & Medicinal Chemistry

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In this report we describe the development of an alternative approach to arylstannane chemistry for radiolabeling antibodies with radioiodine or astatine based on aryliodonium salts precursors. Bifunctional aryliodonium salts were designed and tested for the synthesis of 125I and 211At labeled prosthetic groups for bioconjugation. The nature of the electron rich aryl group was varied and its impact on the regioselectivity of radiohalogenation was evaluated. Unexpectedly, whereas the 2-thienyl group provided the best regioselectivity towards the radioiodination of the aryl moiety of interest (98:2), it was less selective for astatination (87:13); the anisyl group providing the best regioselectivity of astatination (94:6). Under optimized conditions, both radioiodination and astatination could be performed very efficiently in mild conditions (radiochemical yields > 85%). The ionic nature of the precursors was exploited to develop an efficient purification approach: the HPLC step that is usually necessary in conventionnal approaches to optimize removal of organotin toxic precursors and side products was replaced by a filtration through a silica cartridge with a significantly reduced loss of radiolabeled product. The purified radioiodinated and astatinated prosthetic groups were then conjugated efficiently to an anti-CD138 monoclonal antibody (75–80% conjugation yield). By using this novel and simple radiohalogenation procedure, higher overall radiochemical yields of astatination were obtained in comparison with the use of an arylstannane precursor and procedures of the litterature for labeling the same antibody. Overall, due to their simplicity of use and high robustness, these new precursors should simplify the labeling of proteins of interest with iodine and astatine radioisotopes for imaging and therapeutic applications.

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“…Further research studies on the inorganic forms of astatine have been carried out more recently by Sergentu et al Detailed measurements on the adsorption and desorption of astatine on ion‐exchange resins and the comparison with iodine led to the proposal of the Pourbaix diagram shown in Figure .…”

Section: Investigations Of Chemical Propertiesmentioning

confidence: 99%

Astatine

Meyer

2018

Labelled Comp Radiopharmac

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This educational review describes and summarizes the historic discovery of element 85, the experiments leading to its physical and chemical characterization and comparison with its lighter homologue iodine. The half-lives of its longest living isotopes At and At with 8.3 and 7.22 hours respectively together with their alpha decay characteristics made these isotopes interesting for radiation biological research. However, the lack of stable isotopes of astatine presents a strong challenge for all characterizations. Nevertheless, the decay characteristics especially of At stimulated several research groups to develop labelling strategies for the preparation of astatinated radiopharmaceuticals for targeted alpha radiation therapy. Because of the distinct differences in the chemical behaviour of astatine, when compared with iodine, these approaches are quite challenging. Accordingly, quite different labelling strategies have been tested, namely nucleophilic and electrophilic substitution reactions as well as complex forming strategies. Classic and new developments for the preparation of these compounds are reviewed.

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Advances on the Determination of the Astatine Pourbaix Diagram: Predomination of AtO(OH)₂⁻ over At⁻ in Basic Conditions

Cited by 47 publications

References 38 publications

Unexpected Behavior of the Heaviest Halogen Astatine in the Nucleophilic Substitution of Aryliodonium Salts

Unexpected Behavior of the Heaviest Halogen Astatine in the Nucleophilic Substitution of Aryliodonium Salts

Bifunctional aryliodonium salts for highly efficient radioiodination and astatination of antibodies

Astatine

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