Pressure-Dependent Structural and Chemical Changes in a Metal

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Pressure-Dependent Structural and Chemical Changes in a MOF with One-Dimensional Pore Structure. Junhyuck Im, Donghoon Seoung, Gil Chan Hwang, Jong Won Jun, Sung Hwa Jhung, Chi-Chang Kao, Thomas Vogt, and Yongjae Lee Chem. Mater., Just Accepted Manuscript • DOI: 10.1021/acs.chemmater.6b01148 • Publication Date (Web): 14 Jul 2016 Downloaded from http://pubs.acs.org on July 19, 2016

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Chemistry of Materials

Junhyuck Im,† Donghoon Seoung,†,‡ Gil Chan Hwang,† Jong Won Jun,§ Sung Hwa Jhung,§ ChiChang Kao,‡ Thomas Vogt,∥ and Yongjae Lee*,† †

Department of Earth System Sciences, Yonsei University, Seoul 03722, Republic of Korea

‡

Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, CA 94025, United States

§

Department of Chemistry, Kyungpook National University, Daegu 41566, Republic of Korea

∥

NanoCenter, Department of Chemistry & Biochemistry, University of South Carolina, SC 29208, United States

ABSTRACT: Pressure-dependent structural and chemical changes of the metal-organic framework (MOF) compound MIL-47(V) have been investigated up to 3 GPa using different pore-penetrating liquids as pressure transmitting media (PTM). We find that at 0.3(1) GPa the terephthalic acid (TPA) template molecules located in the narrow channels of the as-synthesized MIL-47(V) are selectively replaced by methanol molecules from a methanol-ethanol-water mixture and from a methanol inclusion complex. Further pressure increase leads to a gradual narrowing of the channels up to 1.9(1) GPa, where a second irreversible insertion of methanol molecules leads to more methanol molecules being inserted into the pores. After pressure release methanol molecules remain within the pores and can be removed only after heating to 400 °C. In contrast, when MIL-47(V) is compressed in water, a reversible replacement of the TPA by H2O molecules takes place near 1 GPa. The observed structural and chemical changes observed in MIL-47(V) demonstrate unique high pressure chemistry depending on the size and type of molecules present in the liquid PTM. This allows post-synthetic non-thermal pressure-induced removal and insertion of organic molecules in MOFs forming novel and stable phases at ambient conditions.

The structural and chemical diversity of metal-organic frameworks (MOFs) promises novel and unique applications in gas storage, separation and catalysis.1-4 Two pressure-induced structural changes observed in many MOFs during gas sorption are gating and breathing. Gating describes the opening or closing of pores at specific pressures and depends on the strength of the intermolecular interactions in MOFs.5 Breathing occurs when dis- or replacements of guest molecules result in non-continuous expansion and contraction of the unit cell.6 Both effects have been initially observed at lower pressures but Chapman et al7 and Moggach et al8 expanded the pressure range into the industrially still relevant GPa region using fluids as pressure-transmitting media in Cu-BTC and ZIF8, respectively. McKellar & Moggach9 and Tan & Cheetham10 summarize and discuss the mechanical and structural properties of MOFs at these higher pressures. Many pressure-induced structural and/or chemical changes in MOFs mirror those previously observed in zeolites such as pressure-induced insertion of H2O and CO2 at ambient or elevated temperatures.11-14

MIL-47(V) is a MOF with one-dimensional channels (Figure 1). At low pressures using non pore-penetrating gas molecules as PTM, activated or guest-free MIL-47(V) shows gating behavior between a large and narrow pore structure near 178.1 MPa.15 The behavior at higher pressures with liquid pore-penetrating PTM is not well known. Here we explore structural and chemical changes in assynthesized MIL-47(V) by in-situ pressure-dependent high-resolution synchrotron X-ray powder diffraction (XRD) up to 3 GPa using water and a methanol-ethanolwater (MEW) mixture as PTM.16 We have uncovered in MIL-47(V), for the first time, a reversible pressureinduced exchange (PIE) of TPA by H2O molecules and an irreversible two-step exchange of TPA molecules by methanol from either a MEW mixture or methanol solution. Furthermore, we establish the viability of postsynthetically creating new materials with a MIL-47(V) framework via an irreversible PIE of TPA by methanol molecules which are thermally stable up to 400 oC at ambient pressure.

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ford Synchrotron Radiation Lightsource (SSRL) and the beamline 10C at the Pohang Accelerate Laboratory (PAL). At the NSRRC, monochromatic X-ray with a wavelength of 0.6199 Å was used and the XRD patterns of MIL-47(V) were collected using MAR-345 imaging plate detector. At the beamline 7-2 at the SSRL, the focused X-ray beam with 0.7749 Å in wavelength was used and the XRD patterns of MIL-47(V) were obtained using Pilatus 300K-w direct photon counting detector. At the beamline 10C at the PAL, monochromatic X-ray with a wavelength of 0.6199 Å was used from multipole-wiggler beamline and XRD patterns were collected using MAR-345 imaging plate detector. The wavelength of the incident beam and the detector calibration was carried out using LaB6 standard reference material (SRM 660b) at the all synchrotron facilities.

Figure 1. Structural model of as-synthesized MIL-47(V) showing (a) channels containing TPA molecules in the abplane and (b) framework connectivity via terephthalate ligand. (c) Disordered distribution of the TPA along the c-axis in as-synthesized MIL-47(V). Hydrogen atoms of organic ligands are omitted

Materials. The MIL-47(V) was synthesized hydrothermally under autogeneous pressure following a reported method using microwave irradiation.17 Vanadium (III) chloride (VCl3, Sigma Aldrich, 97%), terephthalic acid (TPA, C6H4-1,4-(CO2H)2; Sigma Aldrich, 98%) and deionized water were mixed in a molar ratio of 1V:0.5TPA:80H2O. The reaction mixtures were stirred for 5 min, loaded into a Teflon-lined autoclave, sealed and placed in a microwave oven (Mars-5, CEM) and finally heated for 2 h at 175 °C under autogeneous pressure. After the synthesis, the as-synthesized MIL-47(V) sample was recovered by cooling, centrifugation, water washing and drying. Synchrotron X-ray diffraction. In situ synchrotron X-ray powder diffraction experiments were performed at the beamline 01C2 at the National Synchrotron Radiation Research Center (NSRRC), the beamline 7-2 at the Stan-

High-pressure experiments. A modified MerrillBassett type diamond anvil cell (DAC) with two opposed diamonds supported by tungsten-carbide plates18 was used for high-pressure XRD measurements. The anvils used were brilliant-cut type-1A diamonds with a culet diameter of 700 μm. The DAC has a rectangular asymmetric slot on one side to provide an opening of ca. 40 degrees, through which diffraction data are measured. The powdered sample was loaded into a 400 μm diameter and less than 150 μm thick sample chamber obtained by electro-spark erosion in a pre-indented stainless steel foil gasket. A few ruby spheres of ~20 μm diameter were added as a pressure gauge. Subsequently, methanol-ethanolwater (labeled MEW) mixture solution (16 : 3 : 1 mixture of methanol : ethanol : water), pure water and pure methanol were added as hydrostatic pressure-transmitting medium (PTM). The pressure at the sample in the DAC was measured by detecting the shift of R1 emission line of included ruby spheres (precision: ± 0.05 GPa).19 The pressure was calculated using the equation below (1): P = A / B [ 1 + (Δλ / λ0)]B

(1)

where P is the pressure in megabars, λ is the wavelength of the ruby R line, A = 19.04 Mbar, B = 7.665.20 The sample was equilibrated for about 10 minutes in the DAC at each measured pressure. Changes in the unit cell lengths and volume were derived from a series of whole profile fitting procedure using the GSAS suite of programs.21, 22 Structure refinements. The selected structural models at several pressure phases of MIL-47(V) were established by Rietveld methods.23 The background curve was fitted with a Chebyshev polynomial with several coefficients, and the pseudo-Voigt profile function was used to fit the observed Bragg peaks. In order to reduce the number of parameters, isotropic displacement factors were fixed at 0.025 in MIL-47(V) in MEW mixture PTM. Geometrical soft-restraints on the V-O and O-O bond distances of the octahedra were applied: the distances between V-O were restrained to a target values of 1.980 ± 0.005 Å , and the O-O distances to 2.800 ± 0.005 Å for the V-octahedra. C-C bond distance of the organic ligand (terephthalate) was restrained to 1.392 ± 0.001 Å .24 In the final stages of the refinements, the weight of the soft-


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restrains was reduced, which did not lead to any significant changes in the interatomic distances, and the convergence was achieved by refining simultaneously all background and profile parameters, scale factor, lattice constants, 2θ zero, the atomic positional and occupancy factors.

ginally expands by ca. 1.6 %. The degree of orthorhombicity (ε), defined as 2(a-b)/(a+b), decreases from 0.365 in MIL-47(V)-AS to 0.013 in M-I at 0.3(1) GPa (Figure 3a and Table S5). This corresponds to an almost full opening of the channel.

The framework of the as-synthesized MIL-47(V) (labeled MIL-47(V)-AS) is made up from infinite chains of corner-sharing VIVO6 octahedra connected by terephthalate groups (Figure 1b).25 At ambient conditions this framework reveals a large channel with a cross-section of 17.6275(7) Å Χ 12.1827(4) Å along the [001] direction (Figure 1a). Along the channels, disordered TPA molecules are located with an occupancy ~0.45 (Figure 1c).25, 26 Chemical structures of all phases were derived from Rietveld refinements using the in situ high-pressure synchrotron XRD data (Figures 1, 3, S2, S3 and Tables S1, S2, S3, S4). The synchrotron X-ray powder diffraction patterns collected up to 2.3(1) GPa using a MEW mixture as PTM are shown in Figure 2a. The changes observed in the XRD pattern indicate four different phases: (i) a single phase of MIL-47(V)-AS at ambient conditions (black color), (ii) an expanded large-pore phase M-I appearing at ambient conditions after contact with the PTM (orange color) and stable up to 1.5(1) GPa (red color), (iii) a second distinct expanded phase (labeled M-II) between 1.9(1) GPa and 2.3(1) GPa (blue color), and a recovered phase with the same symmetry as M-I and M-II as well as a similar number of methanol molecules per unit cell as M-I after pressure release (M-I’, green color). At ambient conditions MIL-47(V)-AS has an orthorhombic unit cell with space group Pnam. After contact with the MEW mixture, the original MIL-47(V)-AS phase begins to transform into an expanded M-I phase with space group Imcm. The phase transition is complete at 0.3(1) GPa and a new set of peaks appear which are assigned to TPA expelled from the pores (TPA crystal cell parameter: a=7.8901, b=6.3267, c=3.7162, α=92.37, β=109.23, γ=96.11 in space group P1̅).24 The expanded M-I phase persists up to 1.5(1) GPa. At 1.9(1) revert back close to their positions observed at 0.3(1) GPa. The relative intensities of the other peaks, however, differ from those of the M-I phase. This indicates the presence of a new higher pressure phase M-II with space group Imcm. After pressure release at ambient conditions, a phase with similar methanol content to M-I but different locations of the methanol molecules is recovered (M-I’), while the peaks of the TPA crystal structure are still present (Figure 2a). Changes of the unit cell parameters of MIL-47(V) under pressure in the presence of an MEW mixture are shown in Figure 3a (Table S5). During the formation of the M-I phase upon contact with the MEW mixture, the a-axis contracts by ca. 12.5 % while the b-axis expands by ca. 22.6 %. The c-axis remains more or less constant. Upon applying pressure to 0.3(1) GPa and forming single phase M-I, the a-axis remains constant whereas the b-axis mar-

Figure 2. Pressure-dependent changes in synchrotron X-ray powder diffraction patterns of MIL-47(V) in (a) MEW mixture PTM and (b) water PTM. X-ray powder diffraction patterns emphasizing the absence of TPA phase in (c) MIL47(V)-AS immersed in water at ambient conditions and (d) AS recovered phase 1 day after pressure release. Simulated TPA peaks at ambient conditions are presented as bars at the bottom of (a)~(d). Also note the formation of ice VI peak at 1.8 GPa in the water PTM run.



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Figure 3. Pressure-dependent changes in the unit cell parameters (left y-axis), orthorhombicity (ε, right y-axis) defined by 2(ab)/(a+b) (right y-axis) of MIL-47(V) (a) in MEW mixture PTM and (b) in water PTM. Refined structural models are shown as insets where hydrogen atoms of organic ligands and guest molecules are omitted. The shortest inter-molecular distances and the distance between the guest molecules and VO6 are shown on the structure models. Estimated standard deviations are smaller than the size of symbols. Dot lines are guides to the eyes

Pressure above 0.3(1) GPa leads to a gradual increase and decrease of the a- and b-axes, respectively, resulting

in an increase of the orthorhombicity to 0.154 at 1.5(1) GPa. The changes in the orthorhombicity and the associated


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crystallographic changes correspond to a gradual flattening of the channels. Between 1.5(1) and 1.9(1) GPa, the flattened channels open again as indicated by the discontinuous decrease of the orthorhombicity to 0.029 at 1.9(1) GPa. This corresponds to ‘breathing’ as observed at lower gas pressures. Subsequently the orthorhombicity increases slightly to 0.049 at the highest measured pressure of 2.3(1) GPa. In the M-I’ recovered phase, the a- and b-axes do not revert back to those of the original MIL-47(V)-AS phase but remain ca. 9.6 % contracted and 19.2 % expanded, respectively, forming an open channel with orthorhombicity of 0.092 close to what was observed near 1.3 GPa in the M-I phase. The pressure-induced changes of the unit cell volumes up to 2.3(1) GPa (Figure S1) show an expansion of ~ 6.3 % after contact with the MEW mixture. Increasing the pressure to 0.3(1) GPa and completely transforming the material to the M-I phase results in an additional 1.3 % increase of the unit cell volume. The unit cell volume of M-I then contracts gradually up to 1.5(1) GPa. M-I has a bulk modulus (B0) of ca. 58(8) GPa. After forming the M-II phase at 1.9(1) GPa, the unit cell volume expands by ca. 0.5 %. The unit cell volume of the M-I’ recovered phase is found to be ca. 7.3 % larger than that of the original MIL-47(V)-AS phase. However, its methanol content and lattice parameters resemble that of the M-I phase, albeit with different locations for the oxygen and carbon atoms of the methanol molecules – we therefore refer to this phase as M-I’. When only water is used as PTM, the changes observed in the XRD patterns are different from those observed in the experiments using MEW and reveal only two different phases (Figure 2b): (i) a single MIL-47(V)-AS phase at ambient conditions (black color) which is observed up to 0.7(1) GPa, (ii) an expanded large-pore phase (labeled W) that starts to form at 0.7(1) GPa and coexists with the original AS up to 1.0(1) GPa (orange color), and then a single phase between 1.4(1) GPa and 2.9(1) GPa (red color). After pressure release we observe an AS phase (green color). The first two diffraction peaks (110) and (200) of MIL47(V)-AS undergo a gradual merging as pressure increases up to 1.0(1) GPa. The W phase at 1.0(1) GPa, similar to the large-pore phases observed when using MEW mixture as PTM, is indexed in an Imcm space group. However, unlike the anisotropic splitting observed in M-I and M-II, the peak positions and intensities of the W phase remain more or less constant when increasing pressure up to 2.9(1) GPa. After pressure release, the XRD pattern of the recovered phase is the same as the one of MIL-47(V)-AS, establishing the reversibility of this PIE. Pressure-induced changes of the unit cell parameters of MIL-47(V) using water as a PTM are shown in Figure 3b (Table S5). Up to 1.0(1) GPa, the a- and b-axes lengths of MIL-47(V)-AS show a gradual increase and decrease, respectively. As a result, the orthorhombicity increases from 0.365 at ambient conditions to 0.455 at 1.0(1) GPa, indicating a gradual flattening of the channels (Figure 3b and Table S5). The large-pore W phase formed at 1.0(1) GPa has a 14.6 % smaller a-axis length and a 28.4% larger b-axis, reducing the orthorhombicity to 0.041. During

this stage the channel shape is close to an ideal square. Further pressure increase results in a marginal increase and decrease of the a- and b-axes lengths, respectively, and the channels remain open up to a pressure of 2.9(1) GPa. After pressure release and exposure of the sample to ambient conditions, the recovered phase reverts back to the original MIL-47(V)-AS (Table S5). Again, the c-axis remains more or less constant throughout the entire pressure cycle. Overall, pressure-induced changes of the unit cell volume of MIL-47(V)-AS when using water as PTM reveals a one-step expansion by ca. 11.3 % at 1.0(1) GPa (Figure S1). The unit cell volume of the expanded largepore W phase then decreases gradually up to the final pressure of 2.9(1) GPa. The W phase has a bulk modulus (B0) of 48(5) GPa lower than the one found for M-I. The ambient pressure structure of MIL-47(V)-AS reveals a flattened channel with 2.618(8) TPA molecules per unit cell. The atomic coordinates of the TPA molecules were fixed based on the model by Barthelet et al.26 As the MIL-47(V)-AS converts fully into the M-I phase, i.e., upon contact with MEW mixture and under increasing pressure up to 0.3(1) GPa, the disordered TPA molecules are selectively replaced by methanol molecules. During this pressure-induced chemical exchange, the symmetry changes from Pnam to Imcm, and the rectangular flattened channels change to square-shaped ones as the orthorhombicity decreases and the unit cell volume expands (Figures 3a, S1 and Table S5). The methanol molecules are located at 2 distinctive sites with a total occupancy of ~12 methanol per unit cell (Table S1). As the pressure increases up to 1.5(1) GPa, the occupancy and distribution of the methanol molecules does not change as the channels flatten indicated by a gradual increase of the orthorhombicity (Figure 3a and Tables S1, S5). When M-I transforms to MII at 1.9(1) GPa, an additional 4 methanol molecules are inserted into the channels accompanied by a decrease in the orthorhombicity. Now, 16 methanol molecules per unit cell are located at 2 distinctive sites in the expanded channel. In the M-I’ recovered phase, ca. 11.3(2) methanol molecules per unit cell remain in the channel (Figure 3a and Table S1). These pressure-inserted methanol molecules can only be desorbed after heating to 400 °C (Figure S4). The alignment of the pressure-inserted methanol molecules with respect to the framework is depicted in Figure 3 (also in Figure S5). The O-C bond distance of methanol has been constrained to be 1.42 Å (Table S2).27 In both MI and M-II, the methanol molecules are ordered with either their carbon or oxygen atoms pointing towards the VO6 octahedra. The assignment of the carbon and oxygen atom sites, however, cannot be made unequivocally as the scattering contrast between these two atoms is too small. The inter-molecular distances between neighboring methanol molecules O-O (or O-C) and the distance between methanol molecules and the VO6 octahedra are in the range of 2.80(2) ~ 3.27(3) Å . In the M-I model with 12 methanol molecules per unit cell, the O-C bonds at two distinctive O-C sites are in the same ab-plane (Figure S5a). The increase of the methanol loading to 16 methanol in



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the M-II phase is achieved by shifting the O-C sites of one molecule along the c-axis with respect to the other one (Figure S5b). In the M-I’ recovered model, the distribution of the inserted methanol molecules remains similar to that in the high-pressure M-II phase, however, the occupancy of the methanol site is reduced to 11.3(2) methanol per unit cell (Figure S5c which is closer to what was observed in the M-I phase). In order to prove the selective chemical exchange of TPA with methanol from the MEW mixture PTM, further in situ XRD experiments have been performed using only methanol as PTM (Figure S6) as well as a flow-through solution at ambient pressure (Figure S7). We find that the general pressure-dependent changes of the unit cell volume and the XRD patterns when using MEW as PTM are well reproduced when using methanol as PTM. (Figure S6). We also find that the exchange of TPA with methanol occurs at ambient pressure by flowing methanol solution into the MIL-47(V)-AS powder for 20 minutes (Figure S7). Pressure-induced expansion and subsequent formation of M-II with 16 methanol molecules per unit cell, however, is not observed in the flow-through experiment. We propose that the hydrophobicity of the MIL-47(V) framework allows a selective replacement of TPA by methanol molecules from the MEW mixture or methanol solution. When water is used as PTM, pressures greater than 1 GPa are required to fully replace the TPA molecules. Although marginal replacement of TPA by water is seen from the appearance of the TPA peaks upon sealing the DAC in the presence of water, we posit that the sample is at low and very difficult to control pressures which cannot be detected by the ruby fluorescence method. We have tested the possibility of significant TPA replacement by water at ambient pressure, but the XRD patterns of MIL-47(V)-AS under water immersion show no peaks of the TPA phase to be present (Figure 2c). The occupancy of guest molecules in MIL-47(V)-AS increase slightly from 0.447(1) at ambient to 0.487(3) at 0.7(1) GPa (Table S3). Assuming that the TPA content is unchanged in the channel, the increased density observed would correspond to the insertion of ca. 2 H2O molecules. As the pressure increases, the channels flatten as indicated by the increase in the orthorhombicity from 0.365 at ambient to 0.455 at 1.0(1) GPa, where the full exchange of TPA by water molecules occurs and the W phase forms. The structural model of the W phase at 1.4(1) GPa shows that the TPA molecules are completely replaced by 40 water molecules per unit cell (Figure 3b, Table S3). This pressure-induced exchange of TPA with water is reversible, and the recovered phase shows that the channels contain ca. 2.61(1) TPA molecules per unit cell (Table S3). Although residual TPA peaks are observed just after pressure release in the XRD pattern (Figure 2b), TPA is the dominant guest molecules of the AS recovered phase as these TPA peaks disappear 24 hours after pressure release (Figure 2d). MIL-47(V)-AS is known to show a decomposition in two steps between 300 and 420 °C26 and our exsitu heating XRD data of the recovered phase confirm this

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two-step decomposition scheme (Figure S8). Furthermore, no stretching vibrations of water molecules are observed in the Raman spectra of the AS recovered phase (Figure S9). These measurements were performed 3 days after the recovery from the pressure cell.

We have demonstrated that pressure can be used to exchange TPA molecules in the as-synthesized MIL-47(V) by both methanol and water. The pressure-induced exchange (PIE) depends strongly on which molecules is present: PIE of water is reversible whereas PIE of methanol is irreversible and requires heat to desorb methanol at ambient pressure. The structural changes observed during these processes reveal changes in the channel sizes and shape indicating ‘breathing’ occurs even at GPa pressures. The observed structural and chemical changes under pressure show that is possible to remove and/or exchange organic molecules from within the cavities of MOFs28 at room temperature in a post-synthesis treatment. Irreversible PIE in MOFs could expand the use of the crystalline sponge method for molecules not stable significantly above room temperature [16]. ASSOCIATED CONTENT Supporting Information.

Figures S1-S9, showing pressure-dependent changes in the normalized volume, representative final Rietveld refinement fits, additional XRD patterns and structural models, and Raman spectrum; Tables S1-S5, showing refined atomic coordinates, refined selected bond distances and angles, and changes of the unit cell parameters, volumes and orthorhombicity. This materials is available free of charge via the Internet at http://pubs.acs.org. AUTHOR INFORMATION * [email protected] The authors declare no competing financial interest. ACKNOWLEDGMENT This work was supported by the Global Research Laboratory (NRF-2009-00408) and National Research Laboratory (NRF-2015R1A2A1A01007227) Programs of the Korean Ministry of Science, ICT and Planning (MSIP). Experiments using synchrotron were supported by Pohang Accelerator Laboratory in Korea through the abroad beam time program of Synchrotron Radiation Facility Project under the MSIP and have been performed under the approval of the NSLS, PF, SSRF, and NSRRC.

REFERENCES (1) Férey, G., Building Units Design and Scale Chemistry. J. Solid. State. Chem. 2000, 152, (1), 37-48.


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(2) O'Keeffe, M.; Eddaoudi, M.; Li, H.; Reineke, T.; Yaghi, O. M., Frameworks for Extended Solids: Geometrical Design Principles. J. Solid. State. Chem. 2000, 152, (1), 3-20. (3) Cheetham, A. K.; Rao, C. N. R.; Feller, R. K., Structural Diversity and Chemical Trends in Hybrid Inorganic-Organic Framework Materials. Chem. Commun. 2006, (46), 4780-4795. (4) Furukawa, H.; Cordova, K. E.; O’Keeffe, M.; Yaghi, O. M., The Chemistry and Applications of Metal-Organic Frameworks. Science 2013, 341, (6149), 1230444. (5) Kitaura, R.; Seki, K.; Akiyama, G.; Kitagawa, S., Porous Coordination-Polymer Crystals with Gated Channels Specific for Supercritical Gases. Angew. Chem. Int. Edit. 2003, 42, (4), 428-431. (6) Serre, C.; Millange, F.; Thouvenot, C.; Noguès, M.; Marsolier, G.; Louër, D.; Férey, G., Very Large Breathing Effect in the First Nanoporous Chromium(III)-Based Solids: MIL-53 or CrIII(OH)·{O2C−C6H4−CO2}·{HO2C−C6H4−CO2H}x·H2Oy. J. Am. Chem. Soc. 2002, 124, (45), 13519-13526. (7) Chapman, K. W.; Halder, G. J.; Chupas, P. J., GuestDependent High Pressure Phenomena in a Nanoporous Metal−Organic Framework Material. J. Am. Chem. Soc. 2008, 130, (32), 10524-10526. (8) Moggach, S. A.; Bennett, T. D.; Cheetham, A. K., The Effect of Pressure on ZIF-8: Increasing Pore Size with Pressure and the Formation of a High-Pressure Phase at 1.47 GPa. Angew. Chem. Int. Edit. 2009, 48, (38), 7087-7089. (9) McKellar, S. C.; Moggach, S. A., Structural Studies of MetalOrganic Frameworks under High Pressure. Acta Crystallogr. B 2015, 71, 587-607. (10) Tan, J. C.; Cheetham, A. K., Mechanical Properties of Hybrid Inorganic-Organic Framework Materials: Establishing Fundamental Structure-Property Relationships. Chem. Soc. Rev. 2011, 40, (2), 1059-1080. (11) Lee, Y.; Hriljac, J. A.; Vogt, T.; Parise, J. B.; Artioli, G., First Structural Investigation of a Super-Hydrated Zeolite. J. Am. Chem. Soc. 2001, 123, (50), 12732-12733. (12) Lee, Y.; Vogt, T.; Hriljac, J. A.; Parise, J. B.; Hanson, J. C.; Kim, S. J., Non-Framework Cation Migration and Irreversible Pressure-Induced Hydration in a Zeolite. Nature 2002, 420, (6915), 485-489. (13) Seoung, D.; Lee, Y.; Kao, C. C.; Vogt, T.; Lee, Y., SuperHydrated Zeolites: Pressure-Induced Hydration in Natrolites. Chem. Eur. J. 2013, 19, (33), 10876-10883. (14) Seoung, D.; Lee, Y.; Kao, C. C.; Vogt, T.; Lee, Y., Two-Step Pressure-Induced Superhydration in Small Pore Natrolite with Divalent Extra-Framework Cations. Chem. Mater. 2015, 27, (11), 3874-3880. (15) Yot, P. G.; Ma, Q.; Haines, J.; Yang, Q.; Ghoufi, A.; Devic, T.; Serre, C.; Dmitriev, V.; Férey, G.; Zhong, C.; Maurin, G., Large Breathing of the MOF MIL-47(V IV) under Mechanical Pressure: A Joint Experimental-Modelling Exploration. Chem. Sci. 2012, 3, (4), 1100-1104. (16) Klotz, S.; Chervin, J. C.; Munsch, P.; Le Marchand, G., Hydrostatic Limits of 11 Pressure Transmitting Media. J. Phys. D Appl. Phys. 2009, 42, (7), 075413. (17) Kang, I. J.; Khan, N. A.; Haque, E.; Jhung, S. H., Chemical and Thermal Stability of Isotypic Metal-Organic Frameworks: Effect of Metal Ions. Chem. Eur. J. 2011, 17, (23), 6437-6442. (18) Mao, H. O. K.; Hemley, R. J., Experimental Studies of Earth's Deep Interior: Accuracy and Versatility of DiamondAnvil Cells. Philos. Trans. A Math. Phys. Eng. Sci. 1996, 354, (1711), 1315-1332. (19) Bell, P. M.; Mao, H. K. Absolute pressure measurements and their comparison with the ruby fluorescence (R1) pressure scale to 1.5 Mbar; Carnegie Institution: Carnegie Institution of Washington Year Book, 1979; pp 665-669.

(20) Mao, H. K.; Xu, J.; Bell, P. M., Calbration of the Ruby Pressure Gauge to 800-kbar under Quasi-Hydrostatic Conditions. J. Geophys. Res.-Solid 1986, 91, (B5), 4673-4676. (21) Larson, A. C.; Dreele, R. B. V. GSAS-General Structure Analysis System; Los Alamos National Laboratory: 1986. (22) Toby, B. H., EXPGUI, a Graphical User Interface for GSAS. J. Appl. Crystallogr. 2001, 34, (2), 210-213. (23) Rietveld, H. M., A Profile Refinement Method for Nuclear and Magnetic Structures. J. Appl. Crystallogr. 1969, 2, 65-71. (24) Bailey, M.; Brown, C. J., The Crystal Structure of Terephthalic Acid. Acta Crystallogr. 1967, 22, (3), 387-391. (25) Trung, T. K.; Déroche, I.; Rivera, A.; Yang, Q.; Yot, P.; Ramsahye, N.; Vinot, S. D.; Devic, T.; Horcajada, P.; Serre, C.; Maurin, G.; Trens, P., Hydrocarbon Adsorption in the Isostructural Metal Organic Frameworks MIL-53(Cr) and MIL47(V). Micropor. Mesopor. Mat. 2011, 140, (1-3), 114-119. (26) Barthelet, K.; Marrot, J.; Riou, D.; Férey, G., A Breathing Hybrid Organic-Inorganic Solid with Very Large Pores and High Magnetic Characteristics. Angew. Chem. Int. Edit. 2002, 41, (2), 281-284. (27) Glockler, G., Carbon-Oxygen Bond Energies and Bond Dstances. J. Phys. Chem.-US 1958, 62, (9), 1049-1054. (28) Haque, E.; Khan, N. A.; Lee, J. E.; Jhung, S. H., Facile Prification of Prous Mtal Terephthalates with Ultrasonic Treatment in the Presence of Amides. Chem. Eur. J. 2009, 15, (43), 11730-11736.



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Pressure-Dependent Structural and Chemical Changes in a Metal

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