Chao Xu

The old polypyridyl ligand DPP acts as a turn-on sensor for PFOA over PFOS in water through excimer emission, providing a new design platform for selective PFAS sensing.

A novel macrocyclic ion receptor has been designed by anchoring twelve 2,6-bis-triazolyl-pyridine (PyTri) units onto a pillar[6]arene platform, which demonstrates outstanding Am/Eu selectivity under highly acidic conditions.

Mutual actinide separation is critical for nuclear waste remediation, superheavy-element production, and f-block-element-based radiopharmaceuticals, yet it remains a formidable challenge owing to the high chemical similarity of these elements and the harsh conditions typically encountered, such as high acidity and intense radioactivity. Here, we show that combining lipophilic TODGA with the histidine-decorated hydrophilic ligand Phen-2DIHis enables the efficient separation of Am(III), Cm(III), and Cf(III) under highly acidic conditions. This system provides substantially enhanced separation factors for both Am(III)/Cf(III) (383) and Cm(III)/Cf(III) (36.9) compared to benchmark methods while maintaining practical metal distributions by directing the targeted actinide ions into opposite phases. Spectroscopic titrations and slope analyses support predominant 1:1 metal–ligand complexation. Theoretical calculations further suggest that nitrate-involved outer-sphere hydrogen bonding from the histidine termini may contribute unexpectedly to the thermodynamic bias for separation processes. These results highlight weak interactions beyond the inner coordination sphere as a critical design handle for mutual actinide separation under strongly acidic conditions.

Neptunium (Np), a key actinide element in the nuclear fuel cycle, presents critical scientific challenges regarding its environmental migration behavior and efficient separation technologies, which are essential for nuclear waste safe disposal and resource recovery. This study systematically investigates the aqueous coordination chemistry of Np(V) with three representative small-molecule ligands, benzoic acid, phenol, and salicylic acid, that model the coordination environment of natural organic matter. Utilizing variable-temperature spectrophotometric titration coupled with density functional theory (DFT) calculations, we elucidated the composition, stability constants, and thermodynamic parameters of the formed complexes. The coordination processes were found to be endothermic and entropy-driven, with ligand affinity following the order: salicylic acid ≫ phenol > benzoic acid. Salicylic acid exhibited exceptional entropy gain and coordination stability due to the chelating effect of its ortho-carboxylate-phenolate groups. This work provides molecular-level insights into the coordination mechanisms between Np(V) and oxygen-containing functional groups. The obtained quantitative thermodynamic and structural data establish a molecular-level reference framework for understanding the intrinsic coordination behavior of Np(V) with representative oxygen-donor functional groups. These fundamental insights may inform future assessments of Np speciation in complex environmental media and provide a thermodynamic basis for the rational design of functional materials for Np separation.

Neptunium (Np) is a long-lived, highly radiotoxic transuranic element of critical concern in the nuclear fuel cycle and the final geological disposal of radioactive waste. Owing to the redox sensitivity of Np and its tendency to complex with natural organic matter, the environmental mobility of Np can be significantly affected by a wide variety of geochemical processes. In this study, we investigated the interactions among Np(V), humic acid (HA), and Fe(II) under anaerobic aqueous conditions. Techniques including solvent extraction, ultrafiltration, dynamic light scattering, and UV–vis–NIR absorption spectroscopy were employed to quantitatively characterize the impacts of HA and Fe(II) on the oxidation-state distribution and aqueous speciation of Np. The results demonstrate that HA can effectively complex Np(V) and subsequently reduce Np(V) to Np(IV) to a limited extent. The presence of Fe(II) significantly alters the reaction pathway, markedly promoting the reduction of Np(V) and the formation of colloidal species that enhance Np retention in the natural environment. This work provides the first mechanistic insight into Np redox transformation and speciation evolution in the Np-HA-Fe ternary system, highlighting the synergistic role of Fe(II) and HA in governing the environmental fate of Np. These findings offer critical scientific support for the accurate prediction of Np mobility in groundwater and the reliable long-term safety assessment of geological repositories.

Addressing the challenges of nuclear waste management and strategic resource recovery necessitates novel functional materials for the integrated and efficient capture of critical elements. This work reports a class of multifunctional eutectic mixtures (EMs) constructed from crown ether (hydrogen‐bond acceptor, HBA) and partially esterified organophosphorus acids (hydrogen‐bond donor, HBD). This design integrates the high selectivity of crown ether toward Sr(II) with the strong affinity of organophosphorus ligands for U(VI)/Pu(IV), achieving unprecedented single‐step extraction efficiencies exceeding 99.9% for U(VI), 99.8% for Pu(IV), and 99% for Sr(II) under extreme and nearly realistic conditions. This exceptional performance originates from the differentiated metal coordination of crown ether and phosphoric esters, coupled with a synergistic “coordination‐encapsulation” effect mediated by the formation of reverse micellar supramolecular structures. Our findings not only provide high‐performance materials for the simultaneous recovery of critical radionuclides but also demonstrate the great potential of EMs as a sustainable platform for addressing complex separation scenarios.

The growing need for high-purity lanthanides demands more selective separation strategies. Existing approaches mainly follow lock-and-key or induced-fit principles: the former uses fixed binding cavities for size-based recognition and the latter relies on adaptive, energy-favored architectures. Although impressive trends such as reversed, V-shaped, and S-shaped selectivity have been achieved, cation-specific selectivity remains rare. Here, we show that an asymmetric ligand design at the atomic level can be highly effective. Introducing sulfur into a phenanthroline-diimine scaffold produced an asymmetrical ligand with unexpected Nd selectivity among light lanthanides. Spectroscopic titrations confirmed this behavior: despite lowering overall binding affinity, sulfur incorporation enhanced Nd selectivity by two orders over La and Eu. This validates the asymmetric ligand design as a promising route to f-element discrimination.

A novel hydrophobic DES system, featuring a TOPO and dihydroxybenzene network, enables rapid in situ reduction and highly efficient extraction of Np( v ) via a synergistic “coordination-driven reduction” mechanism for advanced nuclear waste treatment.