The most advanced methodology for the pyroprocessing of spent nuclear fuel is the electrorefining of uranium metal in LiCl–KCl eutectic, in which uranium is solubilized as U(III). The production of U(III) in LiCl–KCl eutectic by the chlorination of uranium metal using BiCl3 has been performed for research purposes. In this work, this reaction was studied in-situ by visual observation, electronic absorption spectroscopy and electrochemistry at 450 °C. The most likely mechanism has been determined to involve the initial direct oxidation of uranium metal by Bi(III) to U(IV). The dissolved U(IV) then reacts with unreacted uranium metal to form U(III).

Electrostatic interactions as a strong driving force for neutral apolar host–guest complexation is revealed via a large-scale computational approach.

Herein we computationally explore the modulation of the release kinetics of an encapsulated guest molecule from the cucurbit[7]uril (CB7) cavity by ligands binding to the host portal. We uncovered a correlation between the ligand-binding affinity with CB7 and the guest residence time, allowing us to rapidly predict the release kinetics through straightforward energy minimization calculations. These high-throughput predictions in turn enable a Monte-Carlo Tree Search (MCTS) to de novo design a series of cap-shaped ligand molecules with large binding affinities and boosting guest residence times by up to 7 orders of magnitude. Notably, halogenated aromatic compounds emerge as top-ranking ligands. Detailed modeling suggests the presence of halogen-bonding between the ligands and the CB7 portal. Meanwhile, the binding of top-ranked ligands is supported by 1H NMR and 2D DOSY-NMR. Our findings open up possibilities in gating of molecular transport through a nanoscale cavity with potential applications in nanopore technology and controlled drug release.