Polyoxometalates as ligands to synthesize, isolate and characterize compounds of rare isotopes on the microgram scale

The synthesis and study of radioactive compounds are both inherently limited by their toxicity, cost and isotope scarcity. Traditional methods using small inorganic or organic complexes typically require milligrams of sample-per attempt-which for some isotopes is equivalent to the world's annual supply. Here we demonstrate that polyoxometalates (POMs) enable the facile formation, crystallization, handling and detailed characterization of metal-ligand complexes from microgram quantities owing to their high molecular weight and controllable solubility properties. Three curium-POM complexes were prepared, using just 1-10 mu g per synthesis of the rare isotope (248)cm(3)(+), and characterized by single-crystal X-ray diffraction, showing an eight-coordinated Cm 3 + centre. Moreover, spectrophotometric, fluorescence, NMR and Raman analyses of several f-block element-POM complexes, including (243)AM(3+) and Cm-248(3+), showed otherwise unnoticeable differences between their solution versus solid-state chemistry, and actinide versus lanthanide behaviour. This POM-driven strategy represents a viable path to isolate even rarer complexes, notably with actinium or transcalifornium elements.

Automated summary

This study demonstrates the successful synthesis and study of metal-ligand complexes from microgram quantities using polyoxometalates (POMs), overcoming the limitations of toxicity, cost, and isotope scarcity. The research also reveals subtle differences between solution and solid-state chemistry, as well as actinide and lanthanide behavior.