Since the discovery of the first all-boron fullerenes B₄₀^-/0, metal-doped borospherenes have received extensive attention. So far, in spite of theoretical efforts on metalloborospherenes, the feasibility of actinide analogues remains minimally explored. Here we report a series of actinide borospherenes AnB_n (An = U, Th; n = 36, 38, and 40) using DFT-PBE0 calculations. All the AnB_n complexes are found to possess endohedral structures (An@B_n) as the global minima. In particular, U@B₃₆ (C_2h, ³A_g) and Th@B₃₈ (D_2h, ¹A_g) exhibit nearly ideal endohedral borospherene structures. The C_2h U@B₃₆ and D_2h Th@B₃₈ complexes are predicted to be highly robust both thermodynamically and dynamically. In addition to the actinide size match to the cage, the covalent character of the metal-cage bonding in U@B₃₆ and Th@B₃₈ affords further stabilization. Bonding analysis indicates that U@B₃₆ and Th@B₃₈ can be qualified as 32-electron systems, and Th@B₃₈ exhibits 3D aromaticity with σ plus π double delocalization bonding. The results demonstrate that doping with appropriate actinide atoms is promising to stabilize diverse borospherenes, and may provide routes for borospherene modification and functionalization.

Although metal-organic frameworks (MOFs) have been reported as important porous materials for the potential utility in metal ion separation, coordinating the functionality, structure, and component of MOFs remains a great challenge. Herein, a series of anionic rare earth MOFs (RE-MOFs) were synthesized via a solvothermal template reaction and for the first time explored for uranium(VI) capture from an acidic medium. The unusually high extraction capacity of UO₂²⁺ (e.g., 538 mg U per g of Y-MOF) was achieved through ion-exchange with the concomitant release of Me₂NH₂⁺, during which the uranium(VI) extraction in the series of isostructural RE-MOFs was found to be highly sensitive to the ionic radii of the metal nodes. That is, the uranium(VI) adsorption capacities continuously increased as the ionic radii decreased. In-depth mechanism insight was obtained from molecular dynamics simulations, suggesting that both the accessible pore volume of the MOFs and hydrogen-bonding interactions contribute to the strong periodic tendency of uranium(VI) extraction.

Efficient anion recognition is of great significance for radioactive ⁹⁹TcO₄^- decontamination, but it remains a challenge for traditional sorbents. Herein, we put forward a tactic using soft crystalline cationic material with anion-adaptive dynamics for ⁹⁹TcO₄^- sequestration. A cucurbit[8]uril-based supramolecular metal-organic material is produced through a multi-component assembly strategy and used as a sorbent for effective trapping of TcO₄^-. Excellent separation of TcO₄^-/ReO₄^- is demonstrated by fast removal kinetics, good sorption capacity and high distribution coefficient. Remarkably, the most superior selectivity among metal-organic materials reported so far, together with good hydrolytic stability, indicates potential for efficient TcO₄^- removal. The structure incorporating ReO₄^- reveals that the supramolecular framework undergoes adaptive reconstruction facilitating the effective accommodation of TcO₄^-/ReO₄^-. The results highlight opportunities for development of soft anion-adaptive sorbents for highly selective anion decontamination.