¹³⁷Cs is extremely dangerous as it has a high fission yield of 6.09 % and a half-life of 30.17 years, and its salts are highly water-soluble. ¹³⁷Cs⁺ ions must also be effectively removed from nuclear waste in reprocessing plants, however, this task is difficult as the ¹³⁷Cs⁺ ion concentration is lower than other cations present.

Kyung Byung Yoon and co-workers, Sogang Unversity, Seoul, South Korea, have developed a porous vanadosilicate material that contains both V⁴⁺ and V⁵⁺ ions. This material is a better Cs⁺ remover than the current leader in the field, which is a protonated crystalline silicotitanate. The new vanadate material forms a hexadeca-coordinated complex with the Cs⁺ ions, which is the largest coordination number reported to date for any metal center. The complex also contains extremely strong Cs⁺−O bonds.

The researchers carried out a series of test experiments for the removal of Cs⁺ ions from groundwater, seawater, and highly basic nuclear waste and confirmed that their new material is superior to at least five other existing materials.

• A Novel Vanadosilicate with Hexadeca-Coordinated Cs+Ions as a Highly Effective Cs⁺ Remover,
  Shuvo Jit Datta, Won Kyung Moon, Do Young Choi, In Chul Hwang, Kyung Byung Yoon,
  Angew. Chem. Int. Ed. 2014, 53, 7203–7208.
  DOI: 10.1002/anie.201402778

The hexadeca-coordinated complex with the Cs+ ions is the largest coordination number reported to date for any metal center.
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