Recognising radioactive potential

Sorting out which radioactive isotope of an element can be used, for example, as a probe in medical diagnostics is one thing, but then being able to selectively extract that isotope is another problem altogether. The only radioactive rare earth element that is man-made - promethium - has an isotope (¹⁴⁷Pm) that is important as an X-ray source for bone mineral determination.

Researchers in China have for the first time found a way of selectively recognising and extracting ¹⁴⁷Pm from an acidic solution of Pm(iii) ions.

They have made a molecule with a cavity that is the perfect size to accommodate this isotope. This three-legged analogue of a macromolecule can accommodate a number of different sized lanthanide ions, but when it came to extracting them from solution, ¹⁴⁷Pm was by far the most popular.

Weisheng Liu from Lanzhou University explains the significance of his tripodal recognition molecule, ’this result provides new information for [the] design of excellent separation reagents of promethium and other rare earth elements’.

Katharine Sanderson