Hydroxide compounds of halogens

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K18981
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 34:Inorganic/coordination chemistry, analytical chemistry, and related fields
• Research Institution: Osaka University
• Principal Investigator: Kasamatsu Yoshitaka 大阪大学, 大学院理学研究科, 教授 (70435593)
• Project Period (FY): 2021-07-09 – 2024-03-31
• Keywords: アスタチン / ヨウ素 / 水酸化物 / 沈殿

Outline of Final Research Achievements

Hydroxide precipitation experiments were systematically performed using stable isotopes of Cl, Br, and I. To determine the yields, Mohr method was applied. Only for I, precipitation behavior was observed. Therefore, we investigated coprecipitation behavior of radioactive I-131 with samarium hydroxide. As a result, tens of percent of coprecipitation yields were obtained under some conditions, which reproduces the previous experimental data. These results maybe indicate the probability that I would form hydroxide precipitate. However, we found that iodine has extremely complicated chemical behavior.
We produced At-211 isotope by nuclear reaction using Bi target and performed coprecipitation experiments with samarium hydroxide. For the first time, we observed the coprecipitation behavior of At. The probability of hydroxide precipitation of At was suggested. In addition, discussion with the help of quantum chemical calculations considering relativistic effects was achieved.

Free Research Field

核・放射化学

Academic Significance and Societal Importance of the Research Achievements

水酸化ヨウ素の水酸化物沈殿の分離が確認できると、さらに重元素であるAtは、より陽イオンになりやすいことが予測できるため、より高収率での沈殿分離が期待できる。Atの水酸化物錯体の実験的観測を達成するだけでなく、固体試料としてAtの試料が得られると、その後にレーザーを用いたTOF質量分析の可能性が開け、初のAtの化学種同定の可能性も開ける。相対論効果の検証にも関係し、学術的に大きな意義がある研究といえる。さらに、アルファ核種を用いた癌の核医学治療において大きな治療効果が報告され、Atは癌治療の鍵となっている元素である。その性質の解明は、医療応用の面でも大きな意味を持つ。