[en] The tissue distribution of several organic astatine compounds was studied in rats in comparison with inorganic astatine. It can be concluded that astatinated compounds, like their iodine analogues, are easily dehalogenated. (author)

[en] In the cationic state astatine forms a stable complex with diethylenetriaminepentaacetic acid. Thanks to this complex, astatine can be bound to monoclonal antibodies of the RYa₁ type. The most favorable conditions for preparing astatine-labeled antibodies are established. The chromatographic analysis and electromigration experiments showed that astatine is firmly linked to a biomolecule in vitro and it did not escape from labeled monoclonal antibodies even under treatment with such highly effective astatine-complexing agent as thiourea. The immune activity of astatine-labeled antibodies did not change even after 20 h

[en] The organoastatine compounds obtained were identified by gas-liquid chromatography on a specially designed gas radiochromatograph with detection of eluted compounds both by their radioactivity and by thermal conductivity. Gas-liquid chromatography is the most efficient method for separation and identification of volatile organoastatine compounds

[en] The rates of electromigration of two astatine cations in aqueous solutions without supporting electrolyte have been studied. These cations were prepared in acid solutions using Cr(VI) and Na₂S₂O₈ for the oxidation of astatine. The oxidation state of one of them was 1+ but the second one may be a compound of 3+ oxidation state: AtO⁺ or H₂AtO₂⁺. (author)

[en] Determined are the values of carbon-astatine chemical bond breaking energy in benzolastatine, n- and izo-propylastatide, proceeding from temperature dependence of the constant of the thermal decomposition rate of these compounds. A plant is made to study the pyrolysis kinetics of weightless quantities of the substance. Conditions and results of investigation of pyrolysis kinetics are presented. Breaking energy of the carbon-astatine chemical bond in benzolastatine is 44.9+-5.1 kcal/mol, in n-propylastatide-38.6+-2.6 kcal/mol, and in izo-propylastatide-36.3+-2.3 kcal/mol. Obtained values of breaking energy of the carbon-astatine chemical bond appeared to be similar to extrapolar ones

[en] Full text of publication follows. Astatine 211 is considered to be one of the most promising candidates for targeted alpha therapy (TAT) (Refs 1, 2) and it is the subject of a wide research program in Nantes (France). A carrier molecule should transport At"2"1"1 to the cancer cells where alpha-particles emitted by the radionuclide would destroy the target. However binding astatine to cancer selective carrier molecules remains a difficult task. It is recognized that many of the basic chemical studies with astatine (At) have unfortunately been set aside, which currently hinders the development of radiotherapeutic agents (Ref 3). At"2"1"1 is produced in cyclotrons and all investigations were consequently derived from radiochemical studies at ultra-trace concentrations (typically smaller than 10"-"1"0 mol.L"-"1). Therefore no spectroscopic tools can be used to assess At chemistry at the molecular level. These two points clearly limit the investigations of its chemistry, and consequently the development of efficient labelling protocols. Based on these considerations, a research program has started to explore the fundamental properties of At using a multi-disciplinary approach combining radiochemistry, analytical chemistry and molecular modelling abilities. The object of this contribution is to present the main advances obtained during the past 8 years as regards especially to the particular metallic character of astatine. Our methodology enabled to define a Pourbaix diagram (Eh/pH diagram) for At in non-complexing acidic aqueous medium. In addition to At"- species, the experiments and quantum calculations highlighted the existence of two stable At"+ and AtO"+ cationic forms of astatine (Refs 4, 5). This truly contrasts with others halogens. Recent results on the chemical reactivity of AtO"+ demonstrate the potentiality to form both coordination and covalent bonds with organic and inorganic ligands (Refs 6, 8). The peculiarity of the AtO"+ behaviour in water solvent will be also discussed. References: 1) D. S. Wilbur, Current Radiopharmaceuticals, 2008, 3, 144-176; 2) G. Vaidyanathan et al., Current Radiopharmaceuticals, 2008, 1, 177-196; 3) D. S. Wilbur, Nature chemistry, 2013, 5, 246; 4) J. Champion et al., The Journal of Physical Chemistry A, 2010, 114, 576-582; 5) A. Sabatie-Gogova et al. Analytical Chimica acta, 2012, 721, 182; 6) J. Champion et al. Inorganica Chimica Acta, 2009, 362, 2654-2661; 7) J. Champion et al. Physical Chemistry Chemical Physics, 2011, 13, 14984-14992; 8) J. Champion et al. The Journal of Physical Chemistry A, 2013, 117, 1983-1990. (authors)

[en] The α-emitting radionuclide ²¹¹At possesses many of the desired nuclear, chemical and radiobiological properties which make it eminently suitable for cancer therapy. The syntheses of high activity ²¹¹At and high specific activity tumour-directed astatinated substrates, 6-[²¹¹At]-astato-MNDP and 4-[²¹¹At]-astato-MTB, have been outlined. The respective investigation of these compounds has been discussed within their context as possible high-LET endo-radiotherapeutic agents for thyroid, onco-phosphatase positive and melanotic neoplasms. (orig.)

No abstract available

[en] The products of oxidation of astatine were analyzed by various reagents with the aid of electrophoresis on paper. The chromatography of valency forms of astatine on paper was studied in several eluating systems. Conditions were found for oxidizing astatine to five and seven valency states. Astatine was oxidized by 2M KOCl-1M KOH; 20% solution of chloramine B-C₆H₅SO₂NaNCl; XeF₂ in neutral and alkali solutions, 3x10^-4 M and 3x10^-2 M KIO₄; 0.1 M KMnO₄ in alkali solution. The electrophoresis of astatine compounds was conducted at 1000-1200 V in neutral or weakly alkali electrolytes: 0.1 M Na₂SO₄ or dimethylformamide-3M NH₄OH taken in a volumetric ratio of mixture components of 1-to-2. The distribution of statine on paper after electrophoresis or the chromatography was determined by scintillation counters. A comparison was made between the behaviour of astatine and perastatine with iodate and periodate in electrophoresis on paper and paper chromatography. It was shown that perastatine is stable in alkali and neutral media, but in addition of an acid to solutions of perastatine reduces the latter to astatine

[en] Investigation on the chemical behaviour of astatine in the last decade are surveyed. The survey covers the physical and chemical properties of astatine, synthesis and identification of organic astatine compounds, their physicochemical properties. A special chapter is devoted to biomedical applications, including inorganic ²¹¹At species, ²¹¹At-labelled proteins and drugs. An extensive bibliography of the related literature is given. (N.T.) 129 refs.; 12 figs.; 14 tabs