Studying radioactive materials is difficult for scientists because of the potential health risks. Some radioisotopes cost $10,000 per microgram (or $10 billion per gram). Some radioactive isotopes cannot be produced in sufficient quantities, making it difficult to study them in detail with current techniques. Scientists have recently developed a new approach to harvest detailed chemical information about radioactive and/or enriched stable isotopes. The new approach is highly efficient, requiring 1,000 times less material than previous state-of-the-art methods. It provides this performance without sacrificing data quality.
A paper describing this approach has been published in the journal Inorganic Chemistry.
The new method uses polyoxometalate ligands (POMs, i.e., molecular metal oxide cages), a class of molecules so far largely overlooked for radiochemical applications. The inherent properties of POMs allow the POMs to easily form compounds that form chemical bonds with targeted radioisotopes, then crystallize these compounds, and then study them with a variety of spectroscopic techniques while using several micrograms of material. mg or more for earlier methods.
In their demonstration, Lawrence Livermore National Laboratory and Oregon State University scientists synthesized three new curium compounds and determined their detailed structures by single crystal X-ray diffraction (SCXRD), as well as electronic, magnetic and vibrational properties via Raman. fluorescence, and nuclear magnetic resonance spectroscopy. The researchers also obtained equivalent compounds with americium. Environmentally, curium isotopes are not only radioactively toxic, but also rare and expensive to produce. Consequently, only about 10 curium-ligand compounds have been isolated and characterized using SCXRD since the element’s discovery in 1944.
With the newly proposed method, scientists will be able to study the chemical properties of rare and radioactive elements like never before. New research is critical to studying the chemistry of actinides. These are the elements at the bottom of the periodic table like actinium, americium and curium. Most actinides can only be produced on a minute scale in specialized facilities such as the Department of Energy’s high-flux isotope reactor. Scientists know relatively little about the chemistry of these elements. Learning more about them could benefit fields ranging from cancer medicine to nuclear energy to the synthesis of new elements.
The new POM-based method will enable the expansion of actinide chemistry while complying with current cost and low-availability constraints for research isotopes. Scientists can use this technique to provide new insights into the chemistry of some of the rarest and most toxic elements on Earth that could not be studied using previous methods.
More information:
Christopher A. Cola et al., Divalent trivalent lanthanide and actinide complexation by polyoxometalates via solution-phase NMR, Inorganic Chemistry (2022) DOI: 10.1021/acs.inorgchem.2c04014