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1.
Chemistry ; 2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31633825

RESUMO

Scintillator is a unique class of luminescent materials with specific applications towards radiation detection. The emitters within state-of-the-art scintillators are mostly limited to bismuth, cerium, europium, thallium, lead, tungsten etc. Shared feature in these elements is relative high atomic number responsible for high radiation stopping power and radiation-induced luminescence. Searching for new scintillating materials is an essential target aiming at specific applications. In this Concept article, we will discuss our recent works on the topic of "uranyl-bearing scintillators". As a vergin territory in this field, uranyl-bearing scintillator shows intrinsic merits for designing new materials with X-ray detection capability, i.e. the large photoelectric cross-section, high X-ray attenuation efficiency, and high crystal density. In addition, we also present the challenge in the further development on the uranyl-bearing scintillators.

2.
Chem Commun (Camb) ; 55(78): 11715-11718, 2019 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-31509115

RESUMO

When exposed to UV (365 nm, 2 mW) radiation, the bulk crystals of a two-dimensional metal-organic framework [Hphen]2[(UO2)2(ox)3] (1,phen = 1,10-phenanthroline, ox = oxalate) are exfoliated into thin sheets (2 µm) and its photoluminescence can be quenched in an incredibly sensitive manner, setting 1 as a superior UV-detection material. When upgrading the UV source into a 300 W xenon light source, the crystals of 1 can be further exfoliated into monolayer nanosheets (0.92 nm).

3.
Angew Chem Int Ed Engl ; 58(45): 16110-16114, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31518048

RESUMO

The design and synthesis of uranium sorbent materials with high uptake efficiency, capacity and selectivity, as well as excellent hydrolytic stability and radiation resistance remains a challenge. Herein, a polyoxometalate (POM)-organic framework material (SCU-19) with a rare inclined polycatenation structure was designed, synthesized through a solvothermal method, and tested for uranium separation. Under dark conditions, SCU-19 can efficiently capture uranium through ligand complexation using its exposed oxo atoms and partial chemical reduction from UVI to UIV by the low-valent Mo atoms in the POM. An additional UVI photocatalytic reduction mechanism can occur under visible light irradiation, leading to a higher uranium removal without saturation and faster sorption kinetics. SCU-19 is the only uranium sorbent material with three distinct sorption mechanisms, as further demonstrated by X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure (XANES) analysis.

4.
Chemistry ; 25(54): 12567-12575, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31376188

RESUMO

Designability is an attractive feature for metal-organic frameworks (MOFs) and essential for reticular chemistry, and many ideas are significantly useful in the carboxylate system. Bi-, tri-, and tetra-topic phosphonate ligands are used to achieve framework structures. However, an efficient method for designing phosphonate MOFs is still on the way, especially for uranyl phosphonates, owing to the complicated coordination modes of the phosphonate group. Uranyl phosphonates prefer layer or pillar-layered structures as the topology extension for uranyl units occurs in the plane perpendicular to the linear uranium-oxo bonds and phosphonate ligands favor the formation of compact structures. Therefore, an approach that can construct three-dimensional (3D) uranyl phosphonate MOFs is desired. In this paper, a sterically hindered phosphonate ligand method (SHPL) is described and is successfully used to achieve 3D framework structures of uranyl phosphonates. Four MOF compounds ([AMIM]2 (UO2 )(TppmH4 )⋅H2 O (UPF-101), [BMMIM]2 (UO2 )3 (TppmH4 )2 ⋅H2 O (UPF-102), [Py14]2 (UO2 )3 (TppmH4 )2 ⋅3 H2 O (UPF-103), and [BMIM](UO2 )3 (TppmH3 )F2 ⋅2 H2 O (UPF-104); [AMIM]=1-allyl-3-methylimidazolium, [BMMIM]=1-butyl-2,3-dimethylimidazolium, [Py14]=N-butyl-N-methylpyrrolidinium, and [BMIM]=1-butyl-3-methylimidazolium) are obtained by ionothermal synthesis, with zero-dimensional nodes of uranyl phosphonates linked by steric tetra-topic ligands, namely tetrakis[4-(dihyroxyphosphoryl)phenyl]methane (TppmH8 ), to give 3D framework structures. Characterization by PXRD, UV/Vis, IR, Raman spectroscopy, and thermogravimetry (TG) were also performed.

5.
Proc Natl Acad Sci U S A ; 116(36): 17654-17658, 2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31427529

RESUMO

The chemistry of d-block metal-metal multiple bonds has been extensively investigated in the past 5 decades. However, the synthesis and characterization of species with f-block metal-metal multiple bonds are significantly more challenging and such species remain extremely rare. Here, we report the identification of a uranium-rhodium triple bond in a heterometallic cluster, which was synthesized under routine conditions. The uranium-rhodium triple-bond length of 2.31 Å in this cluster is only 3% longer than the sum of the covalent triple-bond radii of uranium and rhodium (2.24 Å). Computational studies reveal that the nature of this uranium-rhodium triple bond is 1 covalent bond with 2 rhodium-to-uranium dative bonds. This heterometallic cluster represents a species with f-block metal-metal triple bond structurally authenticated by X-ray diffraction. These studies not only demonstrate the authenticity of the uranium-metal triple bond, but also provide a possibility for the synthesis of other f-block metal-metal multiple bonds. We expect that this work may further our understanding of the bonding between uranium and transition metals, which may help to design new d-f heterometallic catalysts with uranium-metal bonds for small-molecule activation and to promote the utilization of abundant depleted uranium resources.

6.
Nat Commun ; 10(1): 3782, 2019 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-31439841

RESUMO

Three-dimensional bimetallic nanoframes with high spatial diffusivity and surface heterogeneity possess remarkable catalytic activities owing to their highly exposed active surfaces and tunable electronic structure. Here we report a general one-pot strategy to prepare ultrathin octahedral Au3Ag nanoframes, with the formation mechanism explicitly elucidated through well-monitored temporal nanostructure evolution. Rich crystalline defects lead to lowered atomic coordination and varied electronic states of the metal atoms as evidenced by extensive structural characterizations. When used for electrocatalytic methanol oxidation, the Au3Ag nanoframes demonstrate superior performance with a high specific activity of 3.38 mA cm-2, 3.9 times that of the commercial Pt/C. More intriguingly, the kinetics of methanol oxidation on the Au3Ag nanoframes is counter-intuitively promoted by carbon monoxide. The enhancement is ascribed to the altered reaction pathway and enhanced OH- co-adsorption on the defect-rich surfaces, which can be well understood from the d-band model and comprehensive density functional theory simulations.

7.
Dalton Trans ; 48(34): 12808-12811, 2019 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-31348473

RESUMO

A unique selective crystallization strategy based on an iodate-sulfate mixed-anion system has been developed for lanthanide separation. Periodic divergences in crystal formation energy enable simple Nd/Dy, La/Lu, Gd/Tb, La/Dy, and Nd/Lu separations through crystallization of the early lanthanides, giving rise to separation factors up to 123(5), 100(2), 2.4(2), 137(9), and 85(6), respectively.

8.
Ann Biomed Eng ; 2019 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-31290037

RESUMO

Melanoma is the deadliest type of skin cancer with its prevalence on the rise. Recently, the melanocyte stem cells in hair follicles have been identified as the possible origin of melanoma upon exposure to ultraviolet radiation (UVR) through skin. It is hypothesized that colourless vellus hair (predominant in childhood) can serve as an alternative pathway in transmitting these ultraviolet (UV) photons to the stem cells. To investigate this, we have used the CRAIC microspectrophotometer to investigate the optical properties of 'vellus-like' hairs and terminal hairs of different colours using UV-VIS-NIR light sources. It was found that the average attenuation coefficient of 'vellus-like' hair is significantly lower than that of terminal hair in the UVA (p < 0.0001) and UVB (p < 0.001) wavelength ranges. Next, the optical properties of hairs are applied to simulations for examining their influence on UV transmission into the skin. The results show that the presence of vellus hair would increase the solar UV transmission to the melanocyte stem cell layer significantly. The findings explain why children are particularly vulnerable to sun exposure and the positive correlation found between the incidence of melanoma in adults' bodies and the number of vellus hairs in these areas.

9.
Nat Commun ; 10(1): 2570, 2019 06 25.
Artigo em Inglês | MEDLINE | ID: mdl-31239437

RESUMO

Searching for actinide decorporation agents with advantages of high decorporation efficiency, minimal biological toxicity, and high oral efficiency is crucial for nuclear safety and the sustainable development of nuclear energy. Removing actinides deposited in bones after intake is one of the most significant challenges remaining in this field because of the instantaneous formation of highly stable actinide phosphate complexes upon contact with hydroxyapatite. Here we report a hydroxypyridinone-based ligand (5LIO-1-Cm-3,2-HOPO) exhibiting stronger affinity for U(VI) compared with the reported tetradentate hydroxypyridinone ligands. This is further revealed by the first principles calculation analysis on bonding between the ligand and uranium. Both in vitro uranium removal assay and in vivo decorporation experiments with mice show that 5LIO-1-Cm-3,2-HOPO can remove uranium from kidneys and bones with high efficiencies, while the decorporation efficiency is nearly independent of the treatment time. Moreover, this ligand shows a high oral decorporation efficiency, making it attractive for practical applications.


Assuntos
Osso e Ossos/química , Quelantes/administração & dosagem , Piridonas/administração & dosagem , Lesões por Radiação/terapia , Urânio/toxicidade , Adsorção , Animais , Osso e Ossos/metabolismo , Quelantes/química , Feminino , Humanos , Rim/química , Rim/metabolismo , Ligantes , Camundongos , Piridonas/química , Lesões por Radiação/induzido quimicamente , Lesões por Radiação/metabolismo , Urânio/química , Urânio/metabolismo
11.
ACS Appl Mater Interfaces ; 11(24): 21619-21626, 2019 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-31140771

RESUMO

The nano-MOF+ technique was employed by assembling nanoporous metal-organic framework (MOF) UiO-66 with nanoscale zero-valent iron (ZVI) particles to remove uranyl ions from aqueous solution under anoxic condition for the first time. The synthesized composite of Fe0@UiO-66-COOH exhibits a synergic effect between uranyl sorption by MOF host of UiO-66-COOH and chemical reduction by ZVI, reaching much elevated removal capacity and rate in comparison to those of the pristine UiO-66-COOH. The combined complexation and reduction mechanisms are further elucidated by the synchrotron radiation X-ray absorption near-edge structure analysis. This work highlights the bright future of the nano-MOF+ technique in the application of uranium removal, especially for the remediation of the uranium-contaminated subsurface environment.

12.
J Am Chem Soc ; 2019 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-31064178

RESUMO

Semiconductive metal-organic frameworks (MOFs) have attracted extraordinary research interest in recent years; however, electronic applications based on these emerging materials are still in their infancy. Herein, we show that a lanthanide-based semiconductive MOF (SCU-12) can effectively convert X-ray photons to electrical current signals under continuous hard X-ray radiation. The semiconductive MOF-based polycrystalline detection device presents a promising X-ray sensitivity with the value of 23.8 µC Gyair-1 cm-2 under 80 kVp X-ray exposure, competitive with the commercially available amorphous selenium ( α-Se) detector. The lowest detectable X-ray dose rate is 0.705 µGy s-1, representing the record value among all X-ray detectors fabricated by polycrystalline materials. This work discloses the first demonstration of hard radiation detection by semiconductive MOFs, providing a horizon that can guide the synthesis of a new generation of radiation detection materials by taking the advantages of structural designability and property tunability in the MOF system.

13.
Nat Commun ; 10(1): 1646, 2019 04 09.
Artigo em Inglês | MEDLINE | ID: mdl-30967551

RESUMO

The elimination of specific contaminants from competitors poses a significant challenge. Rather than relying on a single direct interaction, the cooperation of multiple functionalities is an emerging strategy for adsorbents design to achieve the required affinity. Here, we describe that the interaction with the target species can be altered by modifying the local environment of the direct contact site, as demonstrated by manipulating the affinity of pyridinium-based anion nanotraps toward pertechnetate. Systematic control of the substituent effect allows the resulting anion nanotraps to combine multiple features, overcoming the long-term challenge of TcO4- segregation under extreme conditions of super acidity and basicity, strong irradiation field, and high ionic strength. The top material exhibits the highest sorption capacity together with record-high extraction efficiencies after a single treatment from conditions relevant to the used nuclear fuel (Hanford tank wastes, 95%) and legacy nuclear wastes (Savannah River Sites, 80%) among materials reported thus far.

14.
Angew Chem Int Ed Engl ; 58(15): 4968-4972, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30761705

RESUMO

99 Tc contamination at legacy nuclear sites is a serious and unsolved environmental issue. The selective remediation of 99 TcO4 - in the presence of a large excess of NO3 - and SO4 2- from natural waste systems represents a significant scientific and technical challenge, since anions with a higher charge density are often preferentially sorbed by traditional anion-exchange materials. We present a solution to this challenge based on a stable cationic metal-organic framework, SCU-102 (Ni2 (tipm)3 (NO3 )4 ), which exhibits fast sorption kinetics, a large capacity (291 mg g-1 ), a high distribution coefficient, and, most importantly, a record-high TcO4 - uptake selectivity. This material can almost quantitatively remove TcO4 - in the presence of a large excess of NO3 - and SO4 2- . Decontamination experiments confirm that SCU-102 represents the optimal Tc scavenger with the highest reported clean-up efficiency, while first-principle simulations reveal that the origin of the selectivity is the recognition of TcO4 - by the hydrophobic pockets of the structure.

15.
Inorg Chem ; 58(4): 2807-2812, 2019 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-30701969

RESUMO

Traditional inorganic X-ray scintillators are designed based on several representative metal ions (e.g., Tl+, Pb2+, Bi3+) with highly emissive nature and high atomic number aiming at the outstanding radiation stopping power. The combination of these two features gives rise to a high energy conversion efficiency from X-ray to visible emission, which is a prerequisite for an ideal scintillator and is currently one of the major limits for the further development of this field. Inspired by our recent observation on the intrinsic scintillating phenomenon in the heaviest naturally occurring element uranium, we report here a family of inorganic scintillators through combination of uranyl ions with diverse oxoanion groups (i.e., borate, phosphate, molybdate, germanate, etc.). Na2UO2(MoO4)2·(H2O) (UMO) is selected as a prototype of a uranyl-bearing inorganic scintillator, to show its intrinsic advantages in the X-ray excited luminescence (XEL), strong X-ray attenuation coefficient (XAC), reduced afterglow, and decent radiation stability, as compared with one of the most important commercial inorganic scintillators CsI:Tl.

16.
Inorg Chem ; 58(5): 3349-3354, 2019 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-30735401

RESUMO

Uranium poses a threat for severe renal and bone damage in vivo. With the rapid development of nuclear industry, it is more urgent than ever to search for potential in vivo uranium chelators. In this work, 3-hydroxy-2-pyrrolidinone (HPD) is investigated as a new potential uranium decorporation ligand. The potentiometric titration measurements were carried out, and the stability constants were determined to be log ß110 = 10.5(7), log ß120 = 20.7(9), and log ß130 = 28.2(4). The species distribution diagram shows that nearly all uranyl is complexed by HPD at pH 7.4 under the defined condition. A single crystal of uranyl and HPD complexes, [(UO2)3O(H2O)3(C4H6NO2)3]·NO3·12H2O (uranyl-HPD), was obtained via an evaporation method. The overall structure of uranyl-HPD is a trimer that consists of three uranyl units and three HPD ligands. The uranyl unit is equatorially coordinated by three oxygen atoms from two HPD agents, one coordinated water molecule, and one µ3-O atom that is shared by three uranyl units. The results of the cytotoxicity assay indicate that the ligand is less toxic than the chelators used clinically (i.e., DTPA-ZnNa3 and 3-hydroxy-1,2-dimethyl-4(1 H)-pyridone (DFP)). The results of the uranium removal assay using the NRK-52E cell show that it could reduce as much as 58% of the uranium content at the cellular level. Furthermore, the in vivo uranium decorporation assays demonstrate that HPD can remove 52% of uranium deposited in the kidney but shows poor uranium removal efficacy in the bone.


Assuntos
Quelantes/farmacologia , Pirrolidinonas/farmacologia , Termodinâmica , Urânio/isolamento & purificação , Animais , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Quelantes/química , Ligantes , Estrutura Molecular , Pirrolidinonas/química , Ratos , Soluções , Urânio/química
17.
Nat Chem ; 11(3): 248-253, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30692660

RESUMO

Heterometallic clusters are important in catalysis and small-molecule activation because of the multimetallic synergistic effects from different metals. However, multimetallic species that contain uranium-metal bonds remain very scarce due to the difficulties in their synthesis. Here we present a straightforward strategy to construct a series of heterometallic clusters with multiple uranium-metal bonds. These complexes were created by facile reactions of a uranium precursor with Ni(COD)2 (COD, cyclooctadiene). The multimetallic clusters' cores are supported by a heptadentate N4P3 scaffold. Theoretical investigations indicate the formation of uranium-nickel bonds in a U2Ni2 and a U2Ni3 species, but also show that they exhibit a uranium-uranium interaction; thus, the electronic configuration of uranium in these species is U(III)-5f26d1. This study provides further understanding of the bonding between f-block elements and transition metals, which may allow the construction of d-f heterometallic clusters and the investigation of their potential applications.

18.
Dalton Trans ; 48(5): 1595-1598, 2019 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-30629050

RESUMO

Three (3,4)-connected uranyl-organic frameworks (UOFs) with pto and tbo topologies were synthesized. The UOF with a pto net possesses a 2-fold interpenetrating network and exhibits 2D interconnected channels. The UOF with a tbo net is constructed from two types of ultralarge nanocages. All these compounds can efficiently remove large cationic dye crystal violet (CV) through a cation exchange mechanism.

19.
Talanta ; 196: 515-522, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30683399

RESUMO

We report here the investigation of using a luminescent europium organic framework, [Eu2(MTBC)(OH)2(DMF)3(H2O)4]·2DMF·7H2O (denoted as compound 1), for detecting of both Cu2+ and UO22+ with high sensitivity. Based on the spectroscopy analysis, compound 1 could selectively respond to Cu2+ and UO22+ ions among other selected monovalent, divalent, trivalent metal cations based on a turn-off mechanism. The detection limit of compound 1 towards Cu2+ ion was as low as 17.2 µg/L, which is much lower than the maximum tolerable concentration of Cu2+ in drinking water (2 mg/L) defined by United States Environmental Protection Agency. On the other hand, the detection limit towards UO22+ ions is 309.2 µg/L, which could be used for detecting uranium in relative severely contaminated areas. The concentration-dependent luminescence intensity evolution process could be fully understood by the absorption kinetics and isotherm investigations. Furthermore, the quenching mechanism was elucidated by the UV-vis, excitation, luminescence, and lifetime studies. Compound 1, as the first MOF based luminescence probe for both Cu2+ and UO22+ ions, provides insight into developing MOF-based multifunctional sensors for both nonradioactive and radioactive elements.

20.
Environ Sci Technol ; 2018 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-30516368

RESUMO

Traditional analytical methods of thorium contamination suffer from several disadvantages such as time-consuming procedure and equipment-intensive nature, leading to substantial challenges in rapid and onsite monitoring of thorium concentration in complex natural water systems. We report here the first case of luminescent metal organic framework based probe (ThP-1) for highly sensitive and selective self-calibrated sensing of Th4+ contamination in natural fresh water media with a notably facilitated detection procedure. The detection limit of ThP-1 was determined to be 24.2 ppb, much lower than the thorium contamination standard of 246 ppb in drinking water defined by the World Health Organization. Importantly, the detection procedure based on the rarely reported self-calibration manner is greatly beneficial on improving the detection accuracy. The self-calibrated luminescence evolution process is of great anti-interference ability capable of detecting thorium contamination in a wide concentration range from 24.2 ppb to 300 ppm, which can not be achieved directly by the traditional methods. The Th4+-selective luminescence response originates from the selective uptake and efficient enrichment of Th4+ by the host framework of ThP-1 through inner-sphere coordination, which is further confirmed by batch experiments, X-ray absorption spectroscopic study, and DFT calculations.

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