Three-Dimensional Polycatenation of a Uranium-Based Metal–Organic Cage: Structural Complexity and Radiation Detection

Abstract

The potential applications of metal–organic cages (MOCs) are mostly achieved through specific host–guest interactions within their cavities. Electronic applications would require an effective electron transport pathway, which has been extensively studied in hybrid organic–inorganic materials with extended structures. These properties have not been considered for MOCs because cage-to-cage interactions in these materials have rarely been examined and are challenging to functionalize. We report here a previously unobserved actinide-based MOC assembled from four hexagonal-bipyramidal-coordinated uranyl ions and six bidentate flexible ligands. Remarkably, each isolated cage is further interlocked with six adjacent ones through mechanical bonds, resulting in the first case of a 0D → 3D f-element polycatenated metal–organic cage, SCU-14. Long-range π–π stacking extending throughout the structure is built via polycatenation, providing a visible carrier transmission path. SCU-14 is also an extremely rare case of an intrinsically semiconductive MOC with a wide band gap of 2.61 eV. Combined with the high X-ray attenuation efficiency, SCU-14 can effectively convert X-ray photons to electrical current signals and presents a promising sensitivity of 54.93 μC Gy–1 cm–2.

Synthesis of luminescent thorium-based metal–organic frameworks with 1,2,4,5-tetrakis(4-carboxyphenyl)benzene

“…After a total dose of 20–100 kGy γ irradiation for 7 hours, the PXRD patterns of each crystal after irradiation showed that its frame structure still existed and did not collapse within the radiation intensity determined by the experiment. All these materials had radiation resistance comparable to that of SCU-14, 32 a uranium-based MOF which was irradiated continuously at a cumulative dose of 120 kGy with little change in photoelectric response.…”

Cationic Metal–Organic Framework-Based Mixed-Matrix Membranes for Fast Sensing and Removal of Cr2O72− Within Water

“…Metal–organic frameworks (MOFs), also known as the coordination polymer, are a promising class of porous materials constructed through the self-assembly of organic linkers and metal ions/clusters ( Cui et al, 2018 ; Esrafili et al, 2020 ; Hu et al, 2020 ; Cao et al, 2021 ; Lv et al, 2021 ; Wu et al, 2021 ). Due to the merits of large surface areas, tunable structures, and excellent stability, MOFs have been widely employed in various applications, such as gas storage and separation, sensing, catalysis, and biomedicine ( Wang et al, 2018 ; Zheng et al, 2018 ; Wu S. et al, 2020 ; Cheng et al, 2020 ; Hu E. et al, 2021 ; Hu M.-L. et al, 2021 ; Esrafili et al, 2021 ; Li et al, 2021 ; Zhou et al, 2021 ). Recently, several powder-form MOFs have been explored to remove and detect Cr 2 O 7 2− from aqueous water simultaneously ( Lin et al, 2017 ; Liu et al, 2019 ).…”

Viologen‐Based Uranyl Coordination Polymers: Anion‐Induced Structural Diversity and the Potential as a Fluorescent Probe

“…[6] U-IHEP-9 acts as a heterogeneous photocatalyst for CO 2 cycloaddition under the driving of visible light at room temperature. [7] Wang's group reported a uranyl MOC (metalorganic cage) based on a sulfur-containing bidentate carboxylic ligand, [8] which can effectively convert X-ray photons to electrical current signals and presents a promising sensitivity of 54.93 μC • Gy À 1 • cm À 2 .…”