Porous Anionic Uranyl–Organic Networks for Highly Efficient Cs+

4 days ago - Synopsis. Porous uranyl−organic networks are synthesized by a combination of a tetratopic carboxylate ligand and triangular [UO2(COO)3]...
1 downloads 10 Views 3MB Size
Download PDF
Article Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX

pubs.acs.org/IC

Porous Anionic Uranyl−Organic Networks for Highly Efficient Cs+ Adsorption and Investigation of the Mechanism Jing Ai,†,‡ Fang-Yuan Chen,§ Chao-Ying Gao,† Hong-Rui Tian,† Qing-Jiang Pan,*,§ and Zhong-Ming Sun*,† †

State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, Jilin 130022, People’s Republic of China ‡ University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China § Key Laboratory of Functional Inorganic Material Chemistry of Education Ministry, School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, People’s Republic of China S Supporting Information *

ABSTRACT: Exploitation of new materials for the removal of long-lived and highly radioactive actinides and their fission products produced in the nuclear fuel cycle is crucial for radionuclide management. Here, two rare porous anionic uranyl−organic frameworks (UOFs) have been successfully synthesized by a judicious combination of the tetratopic carboxylate ligand 1,3,6,8-tetrakis(p-benzoic acid)pyrene (H4TBAPy) and D3h-symmetrical triangular [UO2(COO)3]−. The resulting two compounds exhibit different architectures, albeit with similar coordination modes. Of interest is that they have excellent adsorption performance on Cs+ from aqueous solution. The high removal efficency would make them promising in applications of radioactive waste management. Notably, the framework of compound 2, [(CH3)2NH2]4[(UO2)4(TBAPy)3]·22DMF·37H2O is sufficiently robust to allow the accessibility of intriguing single crystals of a Cs+-adsorbed derivative, which helps to elucidate the adsorption mechanism. The structural, bonding, and spectroscopic properties of the above compounds are examined using relativistic density functional theory (DFT). It is found that the adsorption toward cesium on UOFs is energetically favored, which features largely ionic bonds and is dominated by electrostatic attraction.

■

with a large number of elements in the periodic table.11 Hexavalent uranium genereally has a linear dioxouranyl structure (UO22+) in most processings. Equatorial coordinations with four to six ligands form tetragonal, pentagonal, and hexagonal-bipyramidal geometries and commonly lead to onedimensional (1D) or 2D architectures.12,13 3D porous materials, however, remain scarce because they are prone to the formation of entangled dense networks. Therefore, it is greatly desirable to explore uranyl−organic hybrid materials with high dimensions and abundantly porous architectures.14,15 As a byproduct of the uranium fission process, 137Cs is the chief biohazard due to its relatively high radioactivity, toxicity, and solubility.16 Therefore, it is urgently necessary to reduce and remove these contaminants from liquid waste for water purification and environmental protection.17 So far, numerous approaches have been developed to treat nuclear wastewater, including adsorption, evaporation, microfiltration, and reverse osmosis. Adsorption is a prevalent and feasible method because

INTRODUCTION As world nuclear energy needs continuously increase, nuclear waste remediation especially for long-lived and highly radioactive actinides and their fission products produced in the nuclear fuel cycle has aroused widespread concern. In addition, serious nuclear accidents such as the catastrophe at the Chernobyl nuclear plant in northern Ukraine have led to the pollution of large areas of rivers and groundwater, and about five million people were exposed to radioactive contamination.1,2 Therefore, searching for new materials that can be used to deal with radioisotopes remains highly desirable in view of environmental protection and public safety. The synthesis of metal−organic frameworks (MOFs) containing actinides is a promising approach to immobilize radioisotopes. However, actinide-based MOFs have been reported less frequently, in contrast to abundant and diverse metal−organic frameworks based on transition metals and lanthanides, even for uranium MOFs (labeled as UOFs).3−10 As one of the most commonly investigated actinide elements, uranium exhibits a rich coordination chemistry due to intriguing electronic structures and fascinating bonding ability © XXXX American Chemical Society

Received: January 11, 2018

A

DOI: 10.1021/acs.inorgchem.8b00099 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry

Figure 1. (a) Ligand coordination environment in compounds 1 and 2. (b) Singlet network of compound 1 viewed along the a axis. (c) Singlet network of compound 1 viewed along the b axis. (d) 2-fold interpenetrating 2D network of compound 1 viewed along the c axis. (e) View of the 3D network of 2 along the b axis. (f) View of the 3D network of 2 along the c axis.

of its simplicity, high effectiveness, and eco-friendliness.18 A variety of adsorbents are currently used for Cs+ removal. For example, Yamauchi and co-workers have prepared nanostructured Prussian Blue particles, and their maximum Cs+ adsorption capacity is 131 mg g−1.19 The novel material KMS-2 was reported by the Kanatzidis group, which exhibits a prominent ability for Cs+ capture and removal.20 Uraniumcontaining porous materials as adsorbents for Cs+ adsorption have rarely been reported; Wang and co-workers used a polycatenated uranyl organic framework to adsorb Cs+, which was able to remove up to 94.51% of Cs+ cations from solutions.2a Since most previous work has mainly focused on obtaining new adsorbents and enhancing Cs+ adsorption capacity, the adsorption mechanisms remain unclear. It is not known how Cs+ cations interact with adsorption materials. The rigid tetracarboxylic acid ligand 1,3,6,8-tetrakis(pbenzoic acid)pyrene (H4TBAPy) was selected to construct porous UOFs in this work. The utilization of highly symmetrical carboxylic ligands with low steric hindrance facilitates fabrication of porous structures.21 Careful experimental control yielded two porous UOFs, [(CH3)2NH2]4[(UO2)4(TBAPy)3]·18DMF·17H2O (1) and [(CH3)2NH2]4[(UO2)4(TBAPy)3]·22DMF·37H2O (2). Both compounds possess open channels and show excellent adsorption performance for Cs+ cations from aqueous solution. Impressively, the 3D framework of 2 retains high chemical stability, albeit with large porosity. More interestingly, the robust framework allows the accessibility of single crystals of the Cs+-adsorbed derivative. Adsorption behaviors were addressed further. The adsorption mechanism was proposed by experimental characterizations and density functional theory (DFT) calculations.

■

(H4TBAPy), which was synthesized by a previously documented procedure.22 Measurements. X-ray powder diffraction (XRD) data were carried out with a MiniFlex 600 X-ray powder diffractometer with monochromated Cu Kα radiation (λ = 1.54178 Å) at 40 kV and 40 mA. Thermal gravimetric analysis (TGA) data were collected on a thermal analysis instrument (SDT 2960, TA Instruments, New Castle, DE, USA) in an air atmosphere with a heating rate of 10 °C/min up to 800 °C. Solid-state UV−visible absorption spectroscopy studies were performed with a Hitachi U-4100 spectrophotometer. The infrared (IR) spectra were recorded on a Nicolet 7600 FT-IR spectrometer within the 4000−500 cm−1 region. Inductively coupled plasma (ICP) analysis data were recorded using a PerkinElmer Optima 3300DV spectrometer. Energy disperse spectroscopy (EDS) data were obtained on a scanning electron microscope (Hitachi S-4800) using a Bruker AXS 4010 XFlash detector. Elemental analyses (C, H, and N) were conducted on a PerkinElmer 2400 elemental analyzer. Synthesis of [(CH3)2NH2]4[(UO2)4(TBAPy)3]·18DMF·17H2O (Compound 1). UO2(NO3)2·6H2O (0.05 M, 0.5 mL), H4TBAPy (17 mg, 0.01 mmol), DMF (1.0 mL), H2O (0.5 mL), and HNO3 (65%, 0.02 mL) were loaded into a 20 mL autoclave. The autoclave was sealed, heated to 160 °C in an oven for 3 days, and then cooled to room temperature naturally. Yellow plate crystals of compound 1 were produced. Yield: 14.5 mg (82.1% based on H4TBAPy). Anal. Calcd for compound 1: C, 47.34; H, 5.25; N, 6.26. Found: C, 47.25; H, 5.36; N, 6.12. Synthesis of [(CH3)2NH2]4[(UO2)4(TBAPy)3]·22DMF·37H2O (Compound 2). Zn(UO2)2(OAc)6·7H2O (50 mg, 0.05 mmol), H4TBAPy (17 mg, 0.025 mmol), DMF (1.0 mL), H2O (0.5 mL), and HNO3 (65%, 0.2 mL) were loaded into a 20 mL autoclave. The autoclave was sealed, heated to 160 °C in an oven for 3 days, and then cooled to room temperature naturally. Orange block crystals of compound 2 were produced. Yield: 7.9 mg (48.5% based on H4TBAPy). Anal. Calcd for compound 2: C, 44.38; H, 5.85; N, 6.54. Found: C, 44.26; H, 5.97; N, 6.61. Cs+ Adsorption Experiments. A typical adsorption experiment of the two compounds with CsCl is as follows. Synthesized single crystals of compounds 1 and 2 were placed in glass vials (5 mL), respectively, 3 mL of a 500 ppm aqueous solution of CsCl was added, and the vials were then covered. The solutions were allowed to stand without disturbance at room temperature for 12 h. Appropriate crystals were picked out and characterized by single-crystal X-ray diffraction for structural analysis and EDS for elemental analysis; the samples were washed with deionized water three times before EDS analysis.

METHODS

Caution! Standard procedures for handling radioactive material should be followed, although the uranyl compounds used in the laboratory contained depleted uranium. Materials. All reagents and solvents for the syntheses were purchased commercially and used without further purification, except for the organic ligand 1,3,6,8-tetrakis(p-benzoic acid)pyrene B

DOI: 10.1021/acs.inorgchem.8b00099 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry X-ray Crystal Structure Determination. Single-crystal X-ray diffraction (SXRD) data of compounds were collected on a Bruker diffractometer using Mo Kα radiation (λ = 0.71073 Å) at 273 K. Data reductions were performed using the SAINT processing program. The title compounds were solved with direct methods (SHELXTL, Olex2) and then refined using SHELXL-2014 and Olex2 software packages to convergence.23 Non-hydrogen atoms were refined on the basis of anisotropic displacement parameters in the final cycles. All hydrogen atoms were placed by geometrical considerations and were added to the structure factor calculation. The SQUEEZE subroutine of PLATON was used to remove the diffraction contribution from disordered guest molecules of compounds. A summary of the crystallographic data for the compounds is given in Table S1. Selected bond distances and angles are summarized in Tables S2 and S3. CCDC 1584564−1584566 contain crystallographic data for this paper. Computational Details. The PBE functional24 of the generalized gradient approximation (GGA) was applied in all calculations unless otherwise noted. First, optimizations were finished by the Priroda code,25,26 where a scalar all-electron relativistic approach and allelectron Gaussian basis sets were used.25 Frequency calculations confirmed the minimal nature of the optimized structure. Populationbased Mayer27 bond orders were calculated. QTAIM (quantum theory of atoms in molecules)28,29 was performed with the Gaussian09 and Multiwfn 3.3.3 packages, which is able to characterize metal−ligand bonding.30 Stuttgart relativistic large-core effective core potentials and corresponding basis sets were employed for uranium;31−33 LanL2DZ was used for cesium, 6-31G* for O, and 3-21G for C and H atoms. With the same approach, Mayer and Wiberg bond orders were also calculated. Electronic structures and spectroscopy in solution was examined with the ADF 2014 code.34−36 The solvent effects of water were considered with the conductor-like screening model, COSMO.37,38 Klamt radii were H 1.30 Å, C 2.00 Å, O 1.72 Å, Cs 1.57 Å, and U 1.70 Å.39−44 The ZORA scalar relativistic approach45−48 was employed, associated with Slater-type TZP basis sets. Time-dependent DFT (TD-DFT) was used to calculate electronic absorption spectra in water. To provide an insight into the interaction nature between UOFs and cesium, an energy decomposition49 was also taken into account for trans-1a-Cs and cis-1a-Cs.

N2 adsorption experiment for 1 was performed at 77 K, giving a sorption capability of up to 309 cm3 g−1 (Figure S10). Zinc uranyl acetate was used to replace uranyl nitrate as the uranium source in the synthetic reaction, yielding the noninterpenetrating 3D porous framework 2. It is interesting to note that the Zn2+ was not coordinated to the framework, but the slow release of uranyl ions from zinc uranyl acetate is of significance for the formation of 2.51 Compound 2 crystallizes in the orthorhombic space group Cmc21 and shows a rare noninterpenetrating 3D microporous framework; all of the uranium ions reside in a hexagonal-bipyramidal coordination environment, exactly the same as that in 1. Six oxygen atoms from three different carboxylic groups coordinate to one UO2+. The pyrene-based ligand employs four bidentate carboxylate groups linking uranyl atoms. The framework is built from typical [UO2(COO)3]− SBUs (secondary building units) and organic [TBAPy]4− linkers. As shown in Figure 1e,f, the two hexagonal bipyramids centered by U1 and U2 ions share organic ligands to form uranyl−organic layers, which are further linked by H4TBAPy moieties to form a rare uranyl-based 3D porous structure. By simplification of the[UO2(COO)3]− SBU as a 3-connecting node and the carboxylate ligand as a 4connecting node, a 3D 3,3,4,4−4 nodal net is generated with a point symbol of {82.104}{82.10}2{83}2{85.12}2 (Figure S8). The effective size of the windows is ca. 17 × 12 Å2 along the b axis. The solvent-accessible volume is determined by the PLATON program to be about 56.6% of the total crystal volume (11815.2 Å3 out of the 20876.0 Å3 unit cell volume). It exhibits a maximum uptake of 519 cm3 g−1 at 77 K from the N2 sorption isotherm (Figure S11). The IR spectra of two synthesized compounds as well as the H4TBAPy ligand are shown in Figure S12. It is shown that general patterns of IR spectra of 1 and 2 are similar. Therefore, only the IR spectroscopy of 1 was identified in detail. The bands at 1654, 1604, 1508, and 1418 cm−1 are attributed to the skeletal vibration of the aromatic ring. In comparison with the infrared spectrum of the H4TBAPy ligand, the carbonyl CO stretching vibration band at around 1690 cm−1 nearly disappears completely in the two compounds, indicatingthat the carboxylate groups are coordinated with the uranyl units. Furthermore, strong peaks centered around 915 and 855 cm−1 are attributed to the asymmetric and symmetric stretching modes of the UO bond.52 Kinetic Studies for Compounds of Cs+ Adsorption. The title compounds are structurally equipped with large channels and [(CH3)2NH2]+ cations, which inspired us to explore their adsorption behaviors. The adsorption performance of Cs+ was determined by ICP and EDS, and the kinetics of compounds 1 and 2 adsorbing Cs+ ions from CsCl solution have been investigated (Tables S5 and S6). The adsorption rate of the adsorbents at an initial concentration of 1 ppm is illustrated in Figure 2. The concentration of Cs+ ions for compound 2 steeply decreased and reached equilibrium within 20 min at room temperature, while that for 1 was extended to 30 min, which may be attributed to its structure interpenetration. It is worth noting that the Cs+ adsorptions for both compounds are much faster in comparison to most other adsorbents such as GaSbS, ETS-4, and AM-2, whose equilibrium time is more than 600 min.16,53 The experimental data fit well with a pseudo-second-order kinetic model, indicating that the adsorption for Cs+ onto the compounds is a chemical process,54 and this was also confirmed by DFT calculations, given below. Furthermore, the XRD patterns of

■

RESULTS AND DISCUSSION Structure Description. Single-crystal X-ray diffraction results reveal that compound 1 crystallizes in monoclinic space group C2/m and displays a 2-fold interpenetrating 2D layered structure. As shown in Figure 1a, both uranium cations are in a hexagonal-bipyramidal geometry with the uranyl (UO22+) oxygen atoms at the axial positions and six oxygen atoms in the equatorial plane from three different carboxylate groups. The U−Oyl bond lengths are 1.738(8) and 1.773(8) Å for U1 and 1.726(1) and 1.755(9) Å for U2. The distances in the equatorial plane range from 2.436(6) to 2.481(6) Å for U1 and from 2.448(6) to 2.472(6) Å for U2. All of the bond lengths show good agreement with those of uranyl materials reported previously.50 The single network of 1 possesses a large void space with large channel dimensions of approximately 17 × 19 Å2 along the a axis and 23 × 19 Å2 along the b axis (Figure 1b,c). The large aperture allows the two crystallographically equivalent networks to interpenetrate each other, leading to a 2-fold interpenetrated 2D network and further strengthening the stability of the whole skeleton (Figure 1d). Topological analyses show that 1 features a 3,4,4−3 nodal net with a point symbol of {4.82}4{42.84}2{86} (Figure S7). In spite of its interpenetrated structure, the pore volume of 1 is still impressive. The total effective pore volume of 1 with removal of solvent molecules is 62.2% (7162.4 Å3 out of the 11519.0 Å3 unit cell volume), as calculated by the PLATON program. An C

DOI: 10.1021/acs.inorgchem.8b00099 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry

From the perspective of overall configuration, 2-Cs resembles 2 (Figures S6 and S9). Competitive Ion Exchange Experiments. The separation of toxic radioactive contaminants from complex solutions is of vital significance for environmental protection. Hence, competitive reactions for Cs+ from solution in the presence of various metal cations were performed and monitored by ICP. Two sets of competitive ion exchange reactions with a 1:10:10:10 molar ratio of Cs+, Rb+, K+, and Na+ ions (A) and a 1:10:10:10 molar ratio of Cs+, Mg2+, Sr2+, and La3+ ions (B) were carried out (Tables S8−S11). For experiment A (Figure 4), as the ion radius increases, we can see a nice trend

Figure 2. (a) Kinetics of Cs+ adsorption of compound 1 plotted as the Cs+ ion concentration (ppm) vs the time t (min). (b) Pseudo-secondorder kinetic model of Cs+ adsorption on adsorbent 1. (c) Kinetics of Cs+ adsorption of compound 2 plotted as the Cs+ ion concentration (ppm) vs the time t (min). (d) Pseudo-second-order kinetic model of Cs+ adsorption on adsorbent 2.

the Cs+-exchanged materials matched experimental and simulated patterns. No significant differences were observed, indicating that the frameworks of title compounds were well retained (Figures S15 and S17). Cs+ Adsorption Study by Single Crystal. To the best of our knowledge, although a great number of Cs+ adsorption experiments for MOF-based materials have been investigated (Table S7), the crystallinity of most materials suffered serious damage after adsorbing Cs+. The resulting Cs-adsorbed derivative is not suitable for single-crystal XRD characterization, which hinders an in-depth understanding of the adsorption mechanism at the atomic level.55 Impressively, compound 2 possesses high chemical stability despite its large porosity. Its framework is sufficiently robust to allow the accessibility of intriguing single crystals of a Cs+-adsorbed derivative (denoted as 2-Cs). Single-crystal XRD analysis indicates that [(CH3)2NH2]+ cations in the channels are exchanged by Cs+. EDS results in Figure S18 further corroborate the successful ion exchange. As shown in Figure 3, each Cs+ cation of 2-Cs is complexed by four carboxylate oxygen atoms in a chelating coordination mode. Two adjacent [UO2(COO)3]− SBUs, for instance centered on U1 and U2, share Cs atoms to form a 1D chain, and then these 1D chains are further linked by a H4TBAPy ligand to construct a 3D extended architecture.

Figure 4. Selective adsorption of the test ions.

with Na, K, Rb, and Cs. However, when divalent and trivalent ions are used in experiment B (Figure S19), the selectivity of Cs+ decreased, indicating that the selective adsorption is subject to both size and charge. The distribution coefficients Kd are shown in Figure 4, and it can be seen that the Kd value of Cs+ is several times those of some other metal cations. It is worth noting that the selectivity toward Cs+ for compound 1 was weaker than that for 2, which may originate from its structure interpenetration with steric hindrance around the adsorption sites reducing its competitiveness (Figure S5). Our preliminary results suggest that the title compounds with suitable ion exchange groups can be potential alternate materials for Cs+ removal. Density Functional Theory Calculations. To further understand the experimental results, we applied relativistic DFT to calculate several molecular models in Figure 5 and Figure S20. Model compounds of experimental 2-Cs were addressed to rationalize the adsorption nature of UOFs. A slight difference is found for calculated geometry parameters and IR vibrational spectra of various molecular

Figure 3. (a) Ball and stick representation of compound 2. (b) Ball-and-stick representation of compound 2-Cs. (c) 1D chain structure of 2-Cs. D

DOI: 10.1021/acs.inorgchem.8b00099 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry

0.056 eV difference is found in their adsorption energies. The geometry parameters optimized by PBE0 are slightly shorter than those of PBE (Table S17), which are related to the functional nature. Electronic absorption spectra of 1a, trans-1a-Cs, and cis-1aCs were calculated by TD-DFT. As seen in Figure 6, the two

Figure 5. Optimized structures of model compounds. Figure 6. Simulated absorption spectra of model compound 1a and Cs-adsorbed trans-1a-Cs and cis-1a-Cs from TD-DFT calculations, in comparison with experimental spectra of 1 and 2 (top left).

models (Tables S13 and S14). Moreover, these results are in agreement with experimental values (Tables S2 and S3). For example, a 1.81 Å UOyl distance (mean value) was calculated, being slightly longer than the experimental value of 1.76 Å. The vibrational peaks of 1a at 815 and 900 cm−1 (Figure S21) are comparable to the experimental peaks at 855 and 915 cm−1 (Figure S12), respectively. Therefore, the designed models are reliable to describe real experimental compounds. As an alternative method of describing metal−ligand bonds,56−58 QTAIM59 was used to examine interactions between uranium/cesium and oxygen atoms. Large absolute values of electron density ρ(r) (au), the Laplacian of electron density ∇2ρ(r), and energy density H(r) at the bond critical points (BCPs) indicate a strong covalent bond for UOyl, which is consistent with large bond orders between 2.21 and 2.38 (Table S15). U−Oeq has small QTAIM data, suggesting a dative bond with large ionic charter. Differently, much smaller values were calculated for Cs−Oeq and Cs−Oyl bonds. This reveals a much greater extent of ionic character in Cs−O than in U−Oeq. Herein we used the energy decomposition approach60 to explore the nature of Cs adsorbed onto UOFs. The adsorption energies (ΔETBE) were calculated to be −5.67 and −5.77 eV for trans-1a-Cs and cis-1a-Cs, respectively (Table S16). One can note that the steric and orbital interaction energies are −4.90 and −0.77 eV for trans-1a-Cs, respectively. The steric term is composed of −5.96 eV electrostatic interaction and 1.06 eV Pauli repulsion. A similar case is found for cis-1a-Cs. In brief, the adsorption behavior of UOFs (i.e., Cs−O bonds) is dominated by electrostatic attraction and is slightly modified by the orbital interactions (14%). For comparison, the energydecomposed U−Oeq bond shows the same nature as Cs−O but possesses higher contribution from the orbital interactions (32%). To verify the accuracy of GGA-PBE results, hybrid PBE0 calculations were performed for trans-1a-Cs′ (Figure S20), which is a simplified analogue of trans-1a-Cs. Only a

broad bands (303 and 424 nm for 1 and 313 and 436 nm for 2) observed in experiments were well reproduced by the calculated results for 1a (333 and 451 nm). Analyses of excited states (Figure 7) attribute the absorptions to a π(pyrene) →

Figure 7. Electron transition diagrams from TD-DFT calculations for absorptions of 1a.

π*(pyrene-PhCOOH) transition (ILCT), where the highenergy absorption has only a slight π(pyrene) → U(5f) charge transfer (LMCT) character. Cesium analogues also yield a general pattern of two bands, but their high-energy absorptions have an increasing contribution of LMCT, as shown in Figure S23.

■

CONCLUSION In summary, the introduction of a rigid, highly symmetrical tetracarboxylic ligand into a uranyl organic system allowed the successful syntheses of two rare porous uranyl organic compounds under hydrothermal conditions. The experimenE

DOI: 10.1021/acs.inorgchem.8b00099 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry

Jiang, D. L. A 3D Covalent Organic Framework with Exceptionally High Iodine Capture Capability. Chem. - Eur. J. 2018, 24, 585−589. (3) (a) Kreno, L. E.; Leong, K.; Farha, O. K.; Allendorf, M.; Van Duyne, R. P.; Hupp, J. T. Metal−Organic Framework Materials as Chemical Sensors. Chem. Rev. 2012, 112, 1105−1125. (b) Cui, Y. J.; Xu, H.; Yue, Y. F.; Guo, Z. Y.; Yu, J. C.; Chen, Z. X.; Gao, J. K.; Yang, Y.; Qian, G. D.; Chen, B. L. A Luminescent Mixed-Lanthanide Metal− Organic Framework Thermometer. J. Am. Chem. Soc. 2012, 134, 3979−3982. (c) Bao, S.-S.; Li, N.-Z.; Taylor, J. M.; Shen, Y.; Kitagawa, H.; Zheng, L.-M. Co−Ca Phosphonate Showing Humidity-Sensitive Single Crystal to Single Crystal Structural Transformation and Tunable Proton Conduction Properties. Chem. Mater. 2015, 27, 8116−8125. (4) Rao, X. T.; Song, T.; Gao, J. K.; Cui, Y. J.; Yang, Y.; Wu, C. D.; Chen, B. L.; Qian, G. D. A Highly Sensitive Mixed Lanthanide Metal− Organic Framework Self-Calibrated Luminescent Thermometer. J. Am. Chem. Soc. 2013, 135, 15559−15564. (5) Farha, O. K.; Hupp, J. T. Rational Design, Synthesis, Purification, and Activation of Metal−Organic Framework Materials. Acc. Chem. Res. 2010, 43, 1166−1175. (6) Xu, Y.-L.; Gao, Q.; Zhao, M.; Zhang, H.-J.; Zhang, Y.-H.; Chang, Z. Impact of the flexibility of pillar linkers on the structure and CO2 adsorption property of “pillar-layered”MOFs. Chin. Chem. Lett. 2017, 28, 55−59. (7) (a) Cui, Y. J.; Zhu, F. L.; Chen, B. L.; Qian, G. D. Metal−organic frameworks for luminescence thermometry. Chem. Commun. 2015, 51, 7420−7431. (b) Zhang, S.-Y.; Zhang, X. P.; Li, H. M.; Niu, Z.; Shi, W.; Cheng, P. Dual-Functionalized Metal−Organic Frameworks Constructed from Hexatopic Ligand for Selective CO2 Adsorption. Inorg. Chem. 2015, 54, 2310−2314. (8) (a) Ding, J.-W.; Wang, R. A new green system of HPW@MOFs catalyzed desulfurization using O2 as oxidant. Chin. Chem. Lett. 2016, 27, 655−658. (b) Zhou, Z.; He, C.; Xiu, J. H.; Yang, L.; Duan, C. Y. Metal−Organic Polymers Containing Discrete Single-Walled Nanotube as a Heterogeneous Catalyst for the Cycloaddition of Carbon Dioxide to Epoxides. J. Am. Chem. Soc. 2015, 137, 15066−15069. (9) Shultz, A. M.; Farha, O. K.; Hupp, J. T.; Nguyen, S. T. A Catalytically Active, Permanently Microporous MOF with Metalloporphyrin Struts. J. Am. Chem. Soc. 2009, 131, 4204−4205. (10) (a) Wang, H. L.; Li, B.; Wu, H.; Hu, T.-L.; Yao, Z. Z.; Zhou, W.; Xiang, S. C.; Chen, B. L. Flexible Microporous Hydrogen-Bonded Organic Framework for Gas Sorption and Separation. J. Am. Chem. Soc. 2015, 137, 9963−9970. (b) Liu, W.; Dai, X.; Bai, Z. L.; Wang, Y. L.; Yang, Z. X.; Zhang, L. J.; Xu, L.; Chen, L. H.; Li, Y. X.; Gui, D. X.; Di, J.; Wang, J. X.; Zhou, R. H.; Chai, Z. F.; Wang, S. Highly Sensitive and Selective Uranium Detection in Natural WaterSystems Using a Luminescent Mesoporous Metal−Organic Framework Equipped with Abundant Lewis Basic Sites: A Combined Batch, X-ray Absorption Spectroscopy, and First Principles Simulation Investigation. Environ. Sci. Technol. 2017, 51, 3911−3921. (11) (a) Hu, K.-Q.; Jiang, X.; Wang, C.-Z.; Mei, L.; Xie, Z.-N.; Tao, W.-Q.; Zhang, X.-L.; Chai, Z.-F.; Shi, W.-Q. Solvent-Dependent Synthesis of Porous Anionic Uranyl−Organic Frameworks Featuring a Highly Symmetrical (3,4)-Connected ctn or bor Topology for Selective Dye Adsorption. Chem. - Eur. J. 2017, 23, 529−532. (b) Zheng, T.; Gao, Y.; Chen, L. H.; Liu, Z. Y.; Di, J.; Chai, Z. F.; Albrecht-Schmitt, T. E.; Wang, S. A. A new chiral uranyl phosphonate framework consisting of achiral building units generated from ionothermal reaction: structure and spectroscopy characterizations. Dalton Trans. 2015, 44, 18158−18166. (c) Zhu, L.-Z.; Wang, C.-Z.; Mei, L.; Wang, L.; Liu, Y. H.; Zhu, Z.-T.; Zhao, Y.-L.; Chai, Z.-F.; Shi, W.-Q. Two novel uranyl complexes of a semi-rigid aromatic tetracarboxylic acid supported by an organic base as an auxiliary ligand or a templating agent: an experimental and theoretical exploration. CrystEngComm 2015, 17, 3031−3040. (d) Sheng, D.; Zhu, L.; Xu, C.; Xiao, C.; Wang, Y.; Wang, Y.; Chen, L.; Di, J.; Chen, J.; Chai, Z.; Albrecht-Schmitt, T. E.; Wang, S. Efficient and Selective Uptake of TcO4− by a Cationic Metal− Organic Framework Material with Open Ag+ Sites. Environ. Sci. Technol. 2017, 51, 3471−3479. (e) Zhu, L.; Sheng, D.; Xu, C.; Dai, X.;

tally measured structures and IR and UV−visible spectra have been well reproduced by DFT calculations. Due to their porous structures and anionic frameworks, 1 and 2 are both capable of effectively absorbing Cs+ from low-concentration aqueous solution. This work has systematically elucidated the mechanism of Cs+ adsorption through a combination of experimental characterizations and density functional theory calculations and provided materials with promising properties for the disposal of mobile fission products during waste management and contamination remediation processes.

■

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.8b00099. Selected bond lengths and angles, powder X-ray diffraction patterns, IR spectra, computational details, optimized geometry parameters, and Cartesian coordinates of model complexes, orbital diagrams, and simulated IR and electronic absorption spectra (PDF) Accession Codes

CCDC 1584564−1584566 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing [email protected], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

■

AUTHOR INFORMATION

Corresponding Authors

*E-mail for Q.-J.P.: [email protected]. *E-mail for Z.-M.S.: [email protected]. ORCID

Qing-Jiang Pan: 0000-0003-2763-6976 Zhong-Ming Sun: 0000-0003-2894-6327 Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS We acknowledge the support of this work by the National Natural Science Foundation of China (Nos. 21722106, 21571171, and U1407101).

■

REFERENCES

(1) Cardis, E.; Howe, G.; Ron, E.; Bebeshko, V.; Bogdanova, T.; Bouville, A.; Carr, Z.; Chumak, V.; Davis, S.; Demidchik, Y.; Drozdovitch, V.; Gentner, N.; Gudzenko, N.; Hatch, M.; Ivanov, V.; Jacob, P.; Kapitonova, E.; Kenigsberg, Y.; Kesminiene, A.; Kopecky, K. J.; Kryuchkov, V.; Loos, A.; Pinchera, A.; Reiners, C.; Repacholi, M.; Shibata, Y.; Shore, R. E.; Thomas, G.; Tirmarche, M.; Yamashita, S.; Zvonova, I. Cancer consequences of the Chernobyl accident: 20 years on. J. Radiol. Prot. 2006, 26, 127−140. (2) (a) Wang, Y. L.; Liu, Z. Y.; Li, Y. X.; Bai, Z. L.; Liu, W.; Wang, Y. X.; Xu, X. M.; Xiao, C. L.; Sheng, D. P.; Di, J.; Su, J.; Chai, Z. F.; Albrecht-Schmitt, T. E.; Wang, S. A. Umbellate Distortions of the Uranyl Coordination Environment Result in a Stable and Porous Polycatenated Framework That Can Effectively Remove Cesium from Aqueous Solutions. J. Am. Chem. Soc. 2015, 137, 6144−6147. (b) Yoshida, N.; Kanda, J. Tracking the Fukushima Radionuclides. Science 2012, 336, 1115−1116. (c) Wang, C.; Wang, Y.; Ge, R.; Song, X. D.; Xing, X. Q.; Jiang, Q.; Lu, H.; Hao, C.; Guo, X. W.; Gao, Y. N.; F

DOI: 10.1021/acs.inorgchem.8b00099 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry Silver, M. A.; Li, J.; Li, P.; Wang, Y.; Wang, Y.; Chen, L.; Xiao, C.; Chen, J.; Zhou, R.; Zhang, C.; Farha, O. K.; Chai, Z.; Albrecht-Schmitt, T. E.; Wang, S. Identifying the Recognition Site for Selective Trapping of 99TcO4− in a Hydrolytically Stable and Radiation Resistant Cationic Metal−Organic Framework. J. Am. Chem. Soc. 2017, 139, 14873− 14876. (12) (a) Li, P.; Vermeulen, N. A.; Malliakas, C. D.; Gómez-Gualdrón, D. A.; Howarth, A. J.; Layla Mehdi, B.; Dohnalkova, A.; Browning, N. D.; O’Keeffe, M.; Farha, O. K. Bottom-up construction of a superstructure in a porous uranium-organic crystal. Science 2017, 356, 624−627. (b) Alsobrook, A. N.; Hauser, B. G.; Hupp, J. T.; Alekseev, E. V. Cubic and rhombohedral heterobimetallic networks constructed from uranium, transition metals, and phosphonoacetate: new methods for constructing porous materials. Chem. Commun. 2010, 46, 9167−9169. (13) (a) Mei, L.; Wu, Q.-Y.; Liu, C.-M.; Zhao, Y.-L.; Chai, Z.-F.; Shi, W.-Q. The first case of an actinide polyrotaxane incorporating cucurbituril: a unique ‘dragon-like’ twist induced by a specific coordination pattern of uranium. Chem. Commun. 2014, 50, 3612− 3615. (b) Zheng, T.; Gao, Y.; Gui, D. X.; Chen, L. H.; Sheng, D. P.; Di, J.; Chai, Z. F.; Albrecht-Schmitt, T. E.; Wang, S. A. Atypical temperature-dependence of symmetry transformation observed in a uranyl phosphonate. Dalton Trans. 2016, 45, 9031−9035. (c) Li, Y.; Yang, Z.; Wang, Y.; Bai, Z.; Zheng, T.; Dai, X.; Liu, S.; Gui, D.; Liu, W.; Chen, M.; Chen, L.; Di, J.; Zhu, L.; Zhou, R.; Chai, Z.; AlbrechtSchmitt, T. E.; Wang, S. A mesoporous cationic thorium-organic framework that rapidly traps anionic persistent organic pollutants. Nat. Commun. 2017, 8, 1354−1364. (14) (a) Thuéry, P. 2,2’-Bipyridine and 1,10-Phenanthroline as Coligands or Structure-Directing Agents in Uranyl−Organic Assemblies with Polycarboxylic Acids. Eur. J. Inorg. Chem. 2013, 2013, 4563− 4573. (b) Xie, J.; Wang, Y. X.; Liu, W.; Yin, X. M.; Chen, L. H.; Zou, Y. M.; Di, J.; Chai, Z. F.; Albrecht-Schmitt, T. E.; Liu, G. K.; Wang, S. A. Highly Sensitive Detection of Ionizing Radiations by a Photoluminescent Uranyl Organic Framework. Angew. Chem., Int. Ed. 2017, 56, 7500−7504. (15) (a) Hu, K.-Q.; Zhu, L.-Z.; Wang, C.-Z.; Mei, L.; Liu, Y.-H.; Gao, Z.-Q.; Chai, Z.-F.; Shi, W.-Q. Novel Uranyl Coordination Polymers Based on Quinoline-Containing Dicarboxylate by Altering Auxiliary Ligands: From 1D Chain to 3D Framework. Cryst. Cryst. Growth Des. 2016, 16, 4886−4896. (b) Li, P.; Vermeulen, N. A.; Gong, X. R.; Malliakas, C. D.; Stoddart, J. F.; Hupp, J. T.; Farha, O. K. Design and Synthesis of a Water-Stable Anionic Uranium-Based Metal−Organic Framework (MOF) with Ultra Large Pores. Angew. Chem., Int. Ed. 2016, 55, 10358−10362. (16) Datta, S. J.; Moon, W. K.; Choi, D. Y.; Hwang, I. C.; Yoon, K. B. A Novel Vanadosilicate with Hexadeca-Coordinated Cs+ Ions as a Highly Effective Cs+ Remover. Angew. Chem., Int. Ed. 2014, 53, 7203− 7208. (17) (a) Vincent, T.; Vincent, C.; Barré, Y.; Guari, Y.; Le Saout, G.; Guibal, E. Immobilization of metal hexacyanoferrates in chitin beads for cesium sorption: synthesis and characterization. J. Mater. Chem. A 2014, 2, 10007−10021. (b) Arnal, J. M.; Sancho, M.; García-Fayos, B. Treatment of 137Cs contaminated water by selective adsorption. Desalination 2013, 321, 22−27. (18) (a) Qi, X.-H.; Du, K.-Z.; Feng, M.-L.; Li, J.-R.; Du, C.-F.; Zhang, B.; Huang, X.-Y. A two-dimensionally microporous thiostannate with superior Cs+ and Sr2+ ion-exchange property. J. Mater. Chem. A 2015, 3, 5665−5673. (b) Al-Attar, L.; Dyer, A.; Paajanen, A.; Harjula, R. Purification of nuclear wastes by novel inorganic ion exchangers. J. Mater. Chem. 2003, 13, 2969−2974. (19) Torad, N. L.; Hu, M.; Imura, M.; Naito, M.; Yamauchi, Y. Large Cs adsorption capability of nanostructured Prussian Blue particles with high accessible surface areas. J. Mater. Chem. 2012, 22, 18261−18267. (20) Mertz, J. L.; Fard, Z. H.; Malliakas, C. D.; Manos, M. J.; Kanatzidis, M. G. Selective Removal of Cs+, Sr2+, and Ni2+ by K2xMgxSn3−xS6 (x = 0.5−1) (KMS-2). Relevant to Nuclear Waste Remediation. Chem. Mater. 2013, 25, 2116−2127.

(21) Liao, Z.-L.; Li, G.-D.; Wei, X.; Yu, Y.; Chen, J.-S. Construction of Three-Dimensional Uranyl−Organic Frameworks with Benzenetricarboxylate Ligands. Eur. J. Inorg. Chem. 2010, 2010, 3780−3788. (22) Stylianou, K. C.; Heck, R.; Chong, S. Y.; Bacsa, J.; Jones, J. T. A.; Khimyak, Y. Z.; Bradshaw, D.; Rosseinsky, M. J. A Guest-Responsive Fluorescent 3D Microporous Metal-Organic Framework Derived from a Long-Lifetime Pyrene Core. J. Am. Chem. Soc. 2010, 132, 4119− 4130. (23) (a) Sheldrick, G. M. SHELXT − Integrated space-group and crystal-structure determination. Acta Crystallogr., Sect. A: Found. Adv. 2015, 71, 3−8. (b) Dolomanov, O. V.; Bourhis, L. J.; Gildea, R. J.; Howard, J. A. K.; Puschmann, H. OLEX2: a complete structure solution, refinement and analysis program. J. Appl. Crystallogr. 2009, 42, 339−341. (24) Lu, T.; Chen, F. Multiwfn: A multifunctional wavefunction analyzer. J. Comput. Chem. 2012, 33, 580−592. (25) Laikov, D. N. A new class of atomic basis functions for accurate electronic structure calculations of molecules. Chem. Phys. Lett. 2005, 416, 116−120. (26) Laikov, D. N.; Ustynyuk, Y. A. PRIRODA-04: a quantumchemical program suite. New possibilities in the study of molecular systems with the application of parallel computing. Russ. Chem. Bull. 2005, 54, 820−826. (27) Mayer, I. Simple theorems, proof and derivations in quantum chemistry; Kluwer Academic/Plenum Publishers: New York, 2003. (28) Bader, R. F. W. Atoms in Molecules: A Quantum Theory; OUP: Oxford, U.K., 1990. (29) Matta, C. F., Boyd, R. J. In The Quantum Theory of Atoms in Molecules; Wiley-VCH: Weinheim, Germany, 2007. (30) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A., Jr.; Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, J. trvM.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R. P.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, O.; Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J. Gaussian 09, Revision D.01 ed.; Gaussian, Inc., Wallingford, CT,, 2009. (31) Bergner, A.; Dolg, M.; Kuchle, W.; Stoll, H.; Preuss, H. Ab initio energy-adjusted pseudopotentials for elements of groups 13−17. Mol. Phys. 1993, 80, 1431−1441. (32) Kaupp, M.; Schleyer, P. V.; Stoll, H.; Preuss, H. Pseudopotential approaches to Ca, Sr, and Ba hydrides. Why are some alkaline earth MX2 compounds bent? J. Chem. Phys. 1991, 94, 1360−1366. (33) Dolg, M.; Stoll, H.; Preuss, H.; Pitzer, R. M. Relativistic and correlation effects for element 105 (hahnium, Ha): a comparative study of M and MO (M= Nb, Ta, Ha) using energy-adjusted ab initio pseudopotentials. J. Phys. Chem. 1993, 97, 5852−5859. (34) te Velde, G.; Bickelhaupt, F. M.; Baerends, E. J.; Fonseca Guerra, C.; Van Gisbergen, S. J. A.; Snijders, J. G.; Ziegler, T. Chemistry with ADF. J. Comput. Chem. 2001, 22, 931−967. (35) Fonseca Guerra, C.; Snijders, J. G.; te Velde, G.; Baerends, E. J. Towards an order-N DFT method. Theor. Chem. Acc. 1998, 99, 391− 403. (36) Baerends, E. J.; Ziegler, T.; Autschbach, J.; Bashford, D.; Bérces, A.; Bickelhaupt, F. M.; Bo, C.; Boerrigter, P. M.; Cavallo, L.; Chong, D. P.; Deng, L.; Dickson, R. M.; Ellis, D. E.; van Faassen, M.; Fan, L.; Fischer, T. H.; Fonseca Guerra, C.; Franchini, M.; Ghysels, A.; Giammona, A.; van Gisbergen, S. J. A.; Götz, A. W.; Groeneveld, J. A.; Gritsenko, O. V.; Grüning, M.; Gusarov, S.; Harris, F. E.; van den Hoek, P.; Jacob, C. R.; Jacobsen, H.; Jensen, L.; Kaminski, J. W.; van Kesse, G.; Kootstra, F.; Kovalenko, A.; Krykunov, M. V.; van Lenthe, G

DOI: 10.1021/acs.inorgchem.8b00099 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry E.; McCormack, D. A.; Michalak, A.; Mitoraj, M.; Morton, S. M.; Neugebauer, J.; Nicu, V. P.; Noodleman, L.; Osinga, V. P.; Patchkovskii, S.; Pavanello, M.; Philipsen, P. H. T.; Post, D.; Pye, C. C.; Ravenek, W.; Rodríguez, J. I.; Ros, P.; Schipper, P. R. T.; van Schoot, H.; Schreckenbach, G.; Seldenthuis, J. S.; Seth, M.; Snijders, J. G.; Solà, M.; Swart, M.; Swerhone, D.; te Velde, G.; Vernooijs, P.; Versluis, L.; Visscher, L.; Visser, O.; Wang, F.; Wesolowski, T. A.; van Wezenbeek, E. M.; Wiesenekker, G.; Wolff, S. K.; Woo, T. K.; Yakovlev, A. L. ADF2014.06 ed.; SCM, Theoretical Chemistry, Vrije Universiteit, Amsterdam, The Netherlands, 2014. (37) Pye, C. C.; Ziegler, T. An implementation of the conductor-like screening model of solvation within the Amsterdam density functional package. Theor. Chem. Acc. 1999, 101, 396−408. (38) Klamt, A.; Schuurmann, G. COSMO: a new approach to dielectric screening in solvents with explicit expressions for the screening energy and its gradient. J. Chem. Soc., Perkin Trans. 2 1993, 799−805. (39) Klamt, A.; Jonas, V.; Burger, T.; Lohrenz, J. C. W. Refinement and Parametrization of COSMO-RS. J. Phys. Chem. A 1998, 102, 5074−5085. (40) Shamov, G. A.; Schreckenbach, G. Relativistic Density Functional Theory Study of Dioxoactinide(VI) and -(V) Complexation with Alaskaphyrin and Related Schiff-Base Macrocyclic Ligands. J. Phys. Chem. A 2006, 110, 9486−9499. (41) Pan, Q.-J.; Odoh, S. O.; Schreckenbach, G.; Arnold, P. L.; Love, J. B. Theoretical exploration of uranyl complexes of a designed polypyrrolic macrocycle: structure/property effects of hinge size on Pacman-shaped complexes. Dalton Trans. 2012, 41, 8878−8885. (42) Pan, Q.-J.; Schreckenbach, G.; Arnold, P. L.; Love, J. B. Theo retical predictions of cofacial bis(actinyl) complexes of a stretched Schiff-base calixpyrrole ligand. Chem. Commun. 2011, 47, 5720−5722. (43) Pan, Q. J.; Shamov, G. A.; Schreckenbach, G. Binuclear Uranium(VI) Complexes with a “Pacman” Expanded Porphyrin: Computational Evidence for Highly Unusual Bis-Actinyl Structures. Chem. - Eur. J. 2010, 16, 2282−2290. (44) Pan, Q. J.; Schreckenbach, G. Binuclear Hexa- and Pentavalent Uranium Complexes with a Polypyrrolic Ligand: A Density Functional Study of Water- and Hydronium-Induced Reactions. Inorg. Chem. 2010, 49, 6509−6517. (45) van Lenthe, E.; Ehlers, A.; Baerends, E. J. Geometry optimizations in the zero order regular approximation for relativistic effects. J. Chem. Phys. 1999, 110, 8943−8953. (46) van Lenthe, E.; Baerends, E. J.; Snijders, J. G. Relativistic total energy using regular approximations. J. Chem. Phys. 1994, 101, 9783− 9792. (47) van Lenthe, E.; Baerends, E. J.; Snijders, J. G. Relativistic regular two-component Hamiltonians. J. Chem. Phys. 1993, 99, 4597−4610. (48) van Lenthe, E.; Snijders, J.; Baerends, E. The zero-order regular approximation for relativistic effects: The effect of spin-orbit coupling in closed shell molecules. J. Chem. Phys. 1996, 105, 6505−6516. (49) Ziegler, T.; Rauk, A. On the calculation of bonding energies by the Hartree Fock Slater method. Theor. Chem. Acc. 1977, 46, 1−10. (50) Masci, B.; Thuéry, P. Pyrazinetetracarboxylic Acid as an Assembler Ligand in Uranyl−Organic Frameworks. Cryst. Growth Des. 2008, 8, 1689−1696. (51) Yang, W. T.; Wu, H.-Y.; Wang, R.-X.; Pan, Q.-J.; Sun, Z.-M.; Zhang, H. J. From 1D Chain to 3D Framework Uranyl Diphosphonates: Syntheses, Crystal Structures, and Selective Ion Exchange. Inorg. Chem. 2012, 51, 11458−11465. (52) Poojary, D. M.; Cabeza, A.; Aranda, M. A. G.; Bruque, S.; Clearfield, A. Structure Determination of a Complex Tubular Uranyl Phenylphosphonate, (UO2)3(HO3PC6H5)2(O3PC6H5)•H2O, from Conventional X-ray Powder Diffraction Data. Inorg. Chem. 1996, 35, 1468−1473. (53) (a) Pavel, C. C.; Popa, K. Investigations on the ion exchange process of Cs+ and Sr2+ cations by ETS materials. Chem. Eng. J. 2014, 245, 288−294. (b) Dö belin, N.; Armbruster, T. Microporous titanosilicate AM-2: Ion-exchange and thermal stability. Microporous Mesoporous Mater. 2007, 99, 279−287.

(54) Wu, Y.-N.; Zhou, M. M.; Zhang, B. R.; Wu, B. Z.; Li, J.; Qiao, J. L.; Guan, X. H.; Li, F. T. Amino acid assisted templating synthesis of hierarchical zeolitic imidazolate framework-8 for efficient arsenate removal. Nanoscale 2014, 6, 1105−1112. (55) (a) Aguila, B.; Banerjee, D.; Zimin, N.; Shin, Y.; Ma, S.; Thallapally, P. K. Selective removal of cesium and strontium using porous frameworks from high level nuclear waste. Chem. Commun. 2016, 52, 5940−5942. (b) Naeimi, S.; Faghihian, H. Performance of novel adsorbent prepared by magnetic metal-organic framework (MOF) modified by potassium nickel hexacyanoferrate for removal of Cs+ from aqueous solution. Sep. Purif. Technol. 2017, 175, 255−265. (c) Plabst, M.; McCusker, L. B.; Bein, T. Exceptional Ion-Exchange Selectivity in a Flexible Open Framework Lanthanum(III)tetrakisphosphonate. J. Am. Chem. Soc. 2009, 131, 18112−18118. (56) Dutkiewicz, M. S.; Farnaby, J. H.; Apostolidis, C.; Colineau, E.; Walter, O.; Magnani, N.; Gardiner, M. G.; Love, J. B.; Kaltsoyannis, N.; Caciuffo, R.; Arnold, P. L. Organometallic neptunium(III) complexes. Nat. Chem. 2016, 8, 797−802. (57) Kaltsoyannis, N. Covalency hinders AnO2(H2O)+ → AnO(OH)2+ isomerisation (An = Pa−Pu). Dalton Trans. 2016, 45, 3158− 3162. (58) Arnold, P. L.; Prescimone, A.; Farnaby, J. H.; Mansell, S. M.; Parsons, S.; Kaltsoyannis, N. Characterizing Pressure-Induced Uranium C-H Agostic Bonds. Angew. Chem., Int. Ed. 2015, 54, 6735−6739. (59) (a) Bader, R. F. W. A quantum theory of molecular structure and its applications. Chem. Rev. 1991, 91, 893−928. (b) Bader, R. F. W. A. Bond Path: A Universal Indicator of Bonded Interactions. J. Phys. Chem. A 1998, 102, 7314−7323. (60) (a) Ziegler, T.; Rauk, A. On the Calculation of Bonding Energies by the Hartree Fock Slater Method. Theor. Chem. Acc. 1977, 46, 1−10. (b) Bickelhaupt, F. M.; Baerends, E. J. Kohn-Sham Density Functional Theory: Predicting and Understanding Chemistry. Rev. Comput. Chem. 2007, 15, 1−86.

H

DOI: 10.1021/acs.inorgchem.8b00099 Inorg. Chem. XXXX, XXX, XXX−XXX