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A radiochemistry laboratory presents potential radiological hazards due to the handling of multiple radionuclides with various half-lives and modes of radiation emission. To minimize these hazards, appropriate safety management and radiation protection strategies should be in place. The radiochemistry laboratory at Soochow University is one such workplace that handles therapeutic radionuclides, fission products, and actinides in liquid, solid, and gas forms. This work highlights the significance of using safety precautions and radiation protection strategies before conducting experiments in such laboratories. The practical knowledge gained from a case of radioactive contamination is discussed to provide valuable experience for safely conducting radiochemistry experiments. [ABSTRACT FROM AUTHOR]

We present the first example of an 99 TcO 4 - anion entrapped within the cavity of a silver cluster, revealing an unprecedented photoinduced charge transfer phenomenon. [Ag 24 (C≡C t Bu) 20 ( 99 TcO 4 )]·(BF 4 ) 3 (denoted as 99 TcO 4 - @Ag 24 ) was successfully synthesized and structurally characterized. Single-crystal X-ray diffraction and Raman spectroscopy reveal that the tetrahedral structure of the 99 TcO 4 - anion sustains significant symmetry breaking with weakened Tc-O bond strength under confinement within the Ag 24 (C≡C t Bu) 20 4+ cluster. Notably, 99 TcO 4 - @Ag 24 exhibits a broadband electronic absorption spectrum in the visible region, which was absent for the other 99 TcO 4 - -containing compounds. Density functional theory calculations elucidate that host-guest electrostatic interactions result in an electron polarization effect between the 99 TcO 4 - anion core and the Ag 24 cationic shell. The emergence of an absorption band in 99 TcO 4 - @Ag 24 is rationalized by intermolecular charge transfer from the Ag 24 electronic states to the lowest unoccupied molecular orbitals of 99 TcO 4 - instead of the intramolecular electron transition observed in other 99 TcO 4 - -containing compounds.

Synthesizing large metal-organic framework (MOF) single crystals has garnered significant research interest, although it is hindered by the fast nucleation kinetics that gives rise to numerous small nuclei. Given the different chemical origins inherent in various types of MOFs, the development of a general approach to enhancing their crystal sizes presents a formidable challenge. Here, we propose a simple isotopic substitution strategy to promote size growth in MOFs by inhibiting nucleation, resulting in a substantial increase in the crystal volume ranging from 1.7- to 165-fold. Impressively, the crystals prepared under optimized conditions by normal approaches can be further enlarged by the isotope effect, yielding the largest MOF single crystal (2.9 cm × 0.48 cm × 0.23 cm) among the one-pot synthesis method. Detailed in situ characterizations reveal that the isotope effect can retard crystallization kinetics, establish a higher nucleation energy barrier, and consequently generate fewer nuclei that eventually grow larger. Compared with the smaller crystals, the isotope effect-enlarged crystal shows 33% improvement in the X-ray dose rate detection limit. This work enriches the understanding of the isotope effect on regulating the crystallization process and provides inspiration for exploring potential applications of large MOF single crystals.

Defects in metal-organic frameworks (MOFs) can significantly change their local microstructures, thus notably leading to an alteration-induced performance in sorption or catalysis. However, achieving de novo defect engineering in MOFs under ambient conditions without the scarification of their crystallinity remains a challenge. Herein, we successfully synthesize defective ZIF-7 through 60 Co gamma ray radiation under ambient conditions. The obtained ZIF-7 is defect-rich but also has excellent crystallinity, enhanced BET surface area, and hierarchical pore structure. Moreover, the amount and structure of these defects within ZIF-7 were determined from the two-dimensional (2D) 13 C- 1 H frequency-switched Lee-Goldburg heteronuclear correlation (FSLG-HETCOR) spectra, continuous rotation electron diffraction (cRED), and high-resolution transmission electron microscopy (HRTEM). Interestingly, the defects in ZIF-7 all strongly bind to CO 2 , leading to a remarkable enhancement of the CO 2 sorption capability compared with that synthesized by the solvothermal method.

225 Ac is considered as one of the most promising radioisotopes for alpha-therapy because its emitted high-energy α-particles can efficiently damage tumor cells. However, it also represents a significant threat to healthy tissues owing to extremely high radiotoxicity if targeted therapy fails. This calls for a pressing requirement of monitoring the biodistribution of 225 Ac in vivo during the treatment of tumors. However, the lack of imageable photons or positrons from therapeutic doses of 225 Ac makes this task currently quite challenging. We report here a nanoscale luminescent europium-organic framework (EuMOF) that allows for fast, simple, and efficient labeling of 225 Ac in its crystal structure with sufficient 225 Ac-retention stability based on similar coordination behaviors between Ac 3+ and Eu 3+ . After labeling, the short distance between 225 Ac and Eu 3+ in the structure leads to exceedingly efficient energy transduction from 225 Ac-emitted α-particles to surrounding Eu 3+ ions, which emits red luminescence through a scintillation process and produces sufficient photons for clearcut imaging. The in vivo intensity distribution of radioluminescence signal originating from the 225 Ac-labeled EuMOF is consistent with the dose of 225 Ac dispersed among the various organs determined by the radioanalytical measurement ex vivo , certifying the feasibility of in vivo directly monitoring 225 Ac using optical imaging for the first time. In addition, 225 Ac-labeled EuMOF displays notable efficiency in treating the tumor. These results provide a general design principle for fabricating 225 Ac-labeled radiopharmaceuticals with imaging photons and propose a simple way to in vivo track radionuclides with no imaging photons, including but not limited to 225 Ac.

Radon (Rn), a ubiquitous radioactive noble gas, is the main source of natural radiation to human and one of the major culprits for lung cancer. Reducing ambient Rn concentration by porous materials is considered as the most feasible and energy-saving option to lower this risk, but the in-depth Rn removal under ambient conditions remains an unresolved challenge, mainly due to the weak van der Waals (vdW) interaction between inert Rn and adsorbents and the extremely low partial pressure (<1.8 × 10 -14 bar, <10 6 Bq/m 3 ) of Rn in air. Adsorbents having either favorable adsorption thermodynamics or feasible diffusion kinetics perform poorly in in-depth Rn removal. Herein, we report the discovery of a metal-organic framework (ZIF-7-Im) for efficient Rn capture guided by computational screening and modeling. The size-matched pores in ZIF-7-Im abide by the thermodynamically favorable principle and the exquisitely engineered quasi-open apertures allow for feasible kinetics with little sacrifice of sorption thermodynamics. The as-prepared material can reduce the Rn concentration from hazardous levels to that below the detection limit of the Rn detector under ambient conditions, with an improvement of at least two orders of amplitude on the removal depth compared to the currently best-performing and only commercialized material activated charcoal.

Lanthanide/actinide separation is a worldwide challenge for atomic energy and nuclear waste treatment. Separation of americium (Am), a critical actinide element in the nuclear fuel cycle, from lanthanides (Ln) is highly desirable for minimizing the long-term radiotoxicity of nuclear waste, yet it is extremely challenging given the chemical similarity between trivalent Am(III) and Ln(III). Selective oxidation of Am(III) to a higher oxidation state (OS) could facilitate this separation, but so far, it is far from satisfactory for practical application as a result of the unstable nature of Am in a high OS. Herein, we find a novel strategy to generate stable pentavalent Am (Am(V)) through coordination of Am(III) with a diglycolamide ligand and oxidation with Bi(V) species in the presence of an organic solvent. This strategy leads to efficient stabilization of Am(V) and an extraordinarily high separation factor (>10 4 ) of Am from Ln through one single contact in solvent extraction, thereby opening a new avenue to study the high-OS chemistry of Am and fulfill the crucial task of Ln/Am separation in the nuclear fuel cycle. The synergistic coordination and oxidation process is found to occur in the organic solvent, and the mechanism has been well elucidated by quantum-theoretical modeling.

The material for managing and monitoring waste made from the waste itself is an excellent example of cyclic utilization, which could reduce issues and be more sustainable. A three-dimensional porous uranyl phosphonate MOF ( UPF-105 ) was synthesized via a hydrothermal method. UPF-105 is stable in aqueous solution with pH in the range of 1-11 and maintains crystallinity below 215 °C. The uncoordinated phosphonate groups in the channels act as functional anchors to selectively capture uranyl ions, with a maximum uranium adsorption capacity of 170.23 mg g -1 . The fluorescence of UPF-105 makes it a good candidate for a uranyl ion sensor in uranium-contaminated solutions with concentrations in the range of 5-90 ppm.

Exciton behaviors including exciton formation and dissociation dynamics play an essential role in the optoelectronic performance of semiconductive materials but remain unexplored in semiconductive metal-organic frameworks (MOFs). Herein, we reveal that the exciton behaviors in semiconductive MOFs can be regulated by framework-guest interactions, a feature often not achievable in traditional inorganic or organic semiconductors. Incorporation of the electron-deficient molecule within the pores of a terbium-based semiconductive MOF (Tb 2 L 2 ·4H 2 O·6DMF, L = TATAB 3- , 4,4',4″- s -triazine-1,3,5-triyltri- p -aminobenzoate, DMF = N , N -dimethylformamide) results in efficient energy transfer from the MOF skeleton to molecular acceptors, with a yield of up to 77.4%. This interaction facilitates distinctive exciton type conversion, giving rise to modified conductivity and photoelectric performance. We further fabricated a MOF-based X-ray detection device to demonstrate how the new architecture bolsters the optoelectronic efficiency, which outperforms the properties of parent semiconductive MOFs, with more than 60 times and 40 times enhancement of the photocurrent on-off ratio and detection sensitivity, respectively. With judiciously optimized exciton behaviors, the detection device exhibits a high sensitivity of 51.9 μC Gy air -1 cm -2 and records a charge carrier mobility-lifetime product of 1.12 × 10 -3 cm 2 V -1 among MOF-based X-ray detectors, which are competitive with values for commercially available detectors. These findings demonstrate a rational synthetic approach to designing exciton arrangements to improve the optoelectronic efficiency of semiconductive MOFs.

Applying physical pressure in the uranyl-sulfate system has resulted in the formation of the first purely inorganic uranyl oxo-salt phase with a considerable uranyl bend: Na 4 [(UO 2 )(SO 4 ) 3 ]. In addition to a strong bend of the typically almost linear O═U═O, the typically equatorial plane is broken up by two out-of-plane oxygen positions. Computational investigations show the origin of the bending to lie in the applied physical pressure and not in the electronic influence or steric hindrance. The increase in pressure onto the system has been shown to increase uranyl bending. Furthermore, the phase formation is compared with a reference phase of a similar structure without uranyl bending, and a transition pressure of 2.5 GPa is predicted, which is well in agreement with the experimental results.

99 Tc is one of the most abundant radiotoxic isotopes in used nuclear fuel with a high fission yield and a long half-life. Effective removal of pertechnetate (TcO 4 - ) from an aqueous solution is important for nuclear waste separation and remediation. Herein, we report a series of facilely obtained benzene-linked guanidiniums that could precipitate TcO 4 - and its nonradioactive surrogate ReO 4 - from a high-concentration acidic solution through self-assembly crystallization. The resulting perrhenate and pertechnetate solids exhibit exceptionally low aqueous solubility. The benzene-linked guanidiniums hold one of the highest TcO 4 - removal capacities (1279 mg g -1 ) among previously reported materials and possess a removal percentage of 59% for ReO 4 - in the presence of Cl - over 50 times. The crystallization mechanism was clearly illustrated by the single-crystal structures and density functional theory calculations, indicating that TcO 4 - is captured through a charge-assisted hydrogen bonding interaction and stabilized by π-π stacking layers. In addition, the removal process is easily recycled and no toxic organic reagents are introduced. This work provides a green approach to preliminarily separate TcO 4 - from high-level nuclear wastes.