Inorganic Chemistry最新文献

The photosynthesis of hydrogen peroxide (H₂O₂), involving water oxidation and oxygen reduction, is crucial for optimizing light utilization. Here, a previously synthesized one-dimensional chain-like semiconductive uranyl coordination polymer (NDC-UCP) was used for the efficient overall photosynthetic reaction of H₂O₂ and its photocatalytic mechanism was systematically investigated. The excellent stability of NDC-UCP enables continuous H₂O₂ production for up to 96 h. Its unique hydrogen extraction capability enhances the photocatalytic performance, achieving a H₂O₂ production rate of 283.80 μmol g^-1 h^-1. Two mechanisms for H₂O₂ generation were revealed: efficient electron-hole separation in NDC-UCP facilitates a two-step one-electron oxygen reduction and direct water oxidation, while hydrogen abstraction of UO₂²⁺ generates hydroxyl (·OH) and hydroperoxyl radicals (HO₂^·), enhancing H₂O₂ photosynthesis. This study highlights the potential of uranyl coordination polymers in H₂O₂ production and their synergistic exciton dissociation and hydrogen abstraction functionalities in photocatalytic redox reactions.

With their rigid and preorganized skeleton, bispidine (3,7-diazabicyclo[3.3.1]nonane) chelators are very appealing for the preparation of metal complexes with high kinetic inertness. With the aim to develop new Tb(III)-based medical imaging probes, this study describes the synthesis and physicochemical properties of two novel terbium(III) complexes with octadentate bispidine-based ligands substituted with either pyridine-phosphonate (H₆L¹) or picolinate (H₄L²) subunits. Thermodynamic stability constants of the corresponding Tb(III) complexes have been determined by potentiometric, UV-visible absorption spectrophotometric and spectrofluorimetric methods. Despite their apparent similarity, these two octadentate ligands differ in their most stable conformation: chair-chair conformation for H₄L² and boat-chair conformation for H₆L¹, as confirmed by ¹H NMR studies and suggested by physicochemical investigations. This conformational change induces different protonation schemes for the two ligands. The kinetic inertness of the Tb complexes has been studied in various media and assessed by transmetalation and transchelation experiments. In particular, Tb(L²) displayed a remarkable kinetic inertness with no measurable dissociation over two months in mouse serum at 10^-5 M concentration. The complex was also very inert in the presence of a 50-fold excess of Zn(II) in H₂O at pH = 7.4 (7% of dissociation over two months). The complexes with ligand L¹ are significantly less inert, emphasizing the influence of the ligand conformation on the kinetic inertness of the Ln(III) complexes. Finally, the luminescence properties of the isolated complexes have also been investigated. A bright green luminescence was observed, especially for Tb(L²), which displays a high quantum yield value of 50% in H₂O (60% in D₂O; λ_exc = 263 nm). In addition, luminescence lifetimes of 1.9(2) and 1.7(2) ms have been measured for Tb(L¹) and Tb(L²), respectively, hence confirming the formation of nona-coordinated complexes with one inner-sphere water molecule. These data on a bispidine scaffold pave the way for developing bright, inert luminescent probes for bioimaging and for radiolabeling applications with Tb(III) radioisotopes.

The ring-opening copolymerization (ROCOP) of epoxides with CO₂ or anhydrides is a promising strategy to produce sustainable polycarbonates and polyesters. Currently, most catalysts are reliant on scarce and expensive cobalt as the active center, while more abundant aluminum and iron catalysts often suffer from lower activities. Here, two novel heterodinuclear catalysts, featuring abundant Al(III), Fe(III), and K(I) active centers, are synthesized, and their performance in the polymerization of four different monomer combinations is compared to that of their Co(III) analogue. The novel Al(III)K(I) catalyst exhibits outstanding activities in the cyclohexane oxide (CHO)/CO₂ ROCOP, and at 1 bar CO₂ pressure it is the fastest aluminum-based catalyst reported to date. The M(III) site electronics for all three catalysts, Al(III)K(I), Fe(III)K(I), and Co(III)K(I), are measured using IR and NMR spectroscopy, cyclic voltammetry, and single crystal X-ray diffraction. A correlation between M(III) electron density and catalytic activity is revealed and, based on the established structure-activity relationship, recommendations for the future catalyst design of abundant Al(III)- and Fe(III)-based catalysts are made. The catalytic performances of both Al(III)K(I) and Fe(III)K(I) are further contextualized against the relative elemental abundance and cost. On the balance of performance, abundance, and cost, the Al(III)K(I) complex is the better catalyst for the carbon dioxide/epoxide ROCOP, while Fe(III)K(I) is preferable for anhydride/epoxide ROCOP.

There has long been a pursuit for a metal-organic framework (MOF)-based adsorbent for various hydrocarbon separations. Herein, we utilized simple trimesic acid and 1,2,4-triazole, together with the heterometallic strategy to produce two quaternary MOFs with a kgm-type structure. The cooperative coordination allows the immobilization of metal clusters into the pore channels, creating an appropriate pore size and high density of open metal sites. The resulting material shows excellent C₂H₂/CO₂ separation performance with good stability.