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. 2024 Oct 8;146(41):28320–28328. doi: 10.1021/jacs.4c09173

Reversible Co(II)–Co(III) Transformation in a Family of Metal–Dipyrazolate Frameworks

Xiang-Jing Kong †,‡, Tao He †,‡,*, Andrey A Bezrukov ‡, Shaza Darwish ‡, Guang-Rui Si †, Yong-Zheng Zhang §, Wei Wu †, Yingjie Wang †, Xia Li ‡, Naveen Kumar ‡, Jian-Rong Li †,*, Michael J Zaworotko ‡,*
PMCID: PMC11487582  PMID: 39376039

Abstract

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Transformation between oxidation states is widespread in transition metal coordination chemistry and biochemistry, typically occurring in solution. However, air-induced oxidation in porous crystalline solids with retention of crystallinity is rare due to the dearth of materials with high structural stability that are inherently redox active. Herein, we report a new family of such materials, four isostructural cobalt–pyrazolate frameworks of face-centered cubic, fcu, topology, fcu-L-Co, that are sustained by Co8 molecular building blocks (MBBs) and dipyrazolate ligands, L. fcu-L-Co were observed to spontaneously transform from Co(II)8 to Co(III)8 MBBs in air with retention of crystallinity, marking the first such instance in metal–organic frameworks (MOFs). This transformation can also be achieved through water vapor sorption cycling, heating, or chemical oxidation. The reverse reactions were conducted by exposure of fcu-L-Co(III) to aqueous hydrazine. fcu-L-Co(II) exhibited high gravimetric water vapor uptakes of 0.55–0.68 g g–1 at 30% relative humidity (RH), while in fcu-L-Co(III) the inflection point shifted to lower RH and framework stability improved. Insight into the transformation between fcu-L-Co(II) and fcu-L-Co(III) was gained from single crystal X-ray diffraction and in situ spectroscopy. Overall, the crystal engineering approach we adopted has afforded a new family of MOFs that exhibit cobalt redox chemistry in a confined space coupled with high porosity.

Introduction

That transition metals can exist in multiple oxidation states, which is thanks to the existence of partially filled d orbitals, means that they can exhibit useful magnetic, optical, and redox properties.1,2 The ability to transform between different oxidation states through electron transfer enables coordination complexes to participate in various chemical reactions and life processes,3−5 as exemplified by the redox chemistry of the prototypal Werner complex [Co(NH3)6]2+, which can transform to [Co(NH3)6]3+ in air,6 and the conversion between Fe(II) and Fe(III) in hemoglobin and myoglobin, which enables oxygen transportation and supply in cells and tissues.7 Similarly, the oxidation state of cobalt is crucial for the biological activity of vitamin B12, where Co(III) is usually involved in enzymatic reactions and certain metabolic processes.8 Although the existence of multiple oxidation states in transition metals is so fundamental in chemistry and biochemistry, such redox chemistry in porous crystalline materials such as metal–organic frameworks9 (MOFs) and porous coordination networks (PCNs)10 remains understudied.

MOFs and PCNs have attracted growing interest for their promise in a diverse range of applications.11,12 Transition metals are extensively used in constructing MOFs due to their ability to form molecular building blocks (MBBs)13 with predictable coordination geometry and connectivity as well as the properties that they bring, including for catalysis.2,9,14,15 The oxidation state of a transition metal MBBs can profoundly impact structural features and gas adsorption performance.16,17 Redox activity has been demonstrated in MBB-based MOFs containing Cr2(COO)4 [Cr(II)/Cr(III)], M3(μ3-O)(COO)6 [M = Cr(II)/Cr(III), Fe(II)/Fe(III), and Co(II)/Co(III)], Mn4Cl(tetrazolate)8– [Mn(II)/Mn(III)], Ce6O4(OH)4(COO)12 [Ce(III)/Ce(IV)], and Ti8O8(OH)4(COO)12 [Ti(III)/Ti(IV)].15−23 Among these examples, the complete transformation of nodal oxidation states has rarely been established. Labile Fe(II)- and Cr(II)-MOFs were converted to PCN-426-M(III) analogs by air oxidation.16 Reversible cleavage and formation of O=O bonds were achieved on tetramanganese clusters in Mn3[(Mn4Cl)3BTT8]2 (BTT = 1,3,5-benzene-tristetrazolate), by Mn(II)/Mn(III) redox chemistry.17 The previous reports on Co(II)/Co(III) redox mainly include cases of mixed-valent Co(II)/Co(III) materials or examples with transient Co(III) species during catalysis.24−27 Complete Co(II)/Co(III) redox is even rare in MOFs. Dinca’s group studied the chemisorption of Cl2/Br2 in Co2Cl2BTDD, leading to Co2Cl2X2BTDD (X = Cl/Br).28 Sustained with rod building blocks, RBBs, Co2Cl2X2BTDD represents the first Co(III) MOF. To our knowledge, spontaneous and complete Co(II)/Co(III) redox chemistry of metal cluster MBB nodes has not yet been reported in MOFs with structural characterization of multiple redox states, a matter that we address herein.

Structural stability of MOFs and PCNs is a requirement for their potential utility in gas/vapor sorption and heterogeneous catalysis.29−32fcu topology has been targeted for design of stable MOFs thanks to the availability of high connectivity nodes such as 12-connected [Zr6O4(OH)4(COO)12], Zr6, and [Ni8(OH)4(H2O)2(az)12] (az = pyrazolate or triazolate), Ni8, and di-topic linker ligands such as dicarboxylates and diazolates (Figure 1).33−35 Zr6 MOFs are particularly well-studied,36 with MOF-801 and UiO-66 derivatives being stable enough to be of interest for water harvesting applications.37,38 Related azolate fcu MOFs remain understudied even though they can also offer excellent structural stability under environmental conditions.27,35,39,40 Herein, we report the synthesis and properties of a new family of fcu MOFs based upon the Co(II)8(OH)6(pz)122– (pz = pyrazolate) MBB and dipyrazolate linkers (Figure 1). The four isostructural MOFs reported herein, fcu-L-Co, [Co8(OH)6(L)6·2H3O·4H2O]n, exhibit spontaneous (air induced) and reversible transformation from Co(II) to Co(III), and fcu-L-Co(II) to fcu-L-Co(III).

Figure 1.

Figure 1

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Schematic representation of the crystal engineering approach used herein to access new fcu MOFs, fcu-L-Co, by combining Co8 MBBs and dipyrazolate linkers, highlighting the relationship with existing families of fcu MOFs based on 12-connected metal cluster nodes.

Results and Discussion

Design and Synthesis

Reports on the crystal engineering synthesis of kinetically stable pyrazolate fcu-MOFs have focused on those with Ni-based MBBs. Galli’s and Navarro’s groups employed dipyrazolate linkers to synthesize the [Ni8(OH)4(H2O)2(L)6]n ([Ni8(L)6], L = dipyrazolate) family.41,42 These fcu MOFs were studied in terms of gas adsorption and catalysis. Li’s group reported the crystal syntheses and structural properties of BUT-2, [Ni8(OH)4(H2O)2(L3)6]n, H2L3 = 4,4′-benzene-1,4-diylb-is(1H-pyrazole), and its derivatives.43fcu-MOF analogs based upon Co8 MBBs are limited to three reports, two involving triazolate linkers27,39 and one with dipyrazolate linkers.40 The Co8 MBB has also been reported in the ftw topology MOF [(NH4)2·[Co11(μ4–OH)6(CN)6(trz)12] (trz = 1,2,4-triazolate).44

We herein report the use of four dipyrazole linker ligands with hydrophilic central aromatic rings (pyridine, pyridazine, pyrazine, and pyrimidine), the recently reported 2,5-di(1H-pyrazol-4-yl)pyridine (1)45 and three new ligands, 3,6-di(1H-pyrazol-4-yl)pyridazine (2), 2,5-di(1H-pyrazol-4-yl)pyrazine (3), and 2,5-di(1H-pyrazol-4-yl)pyrimidine (4) (Figures 2d and S1–S4) to form isostructural fcu-MOFs. Solvothermal reactions between 1–4 and divalent cobalt salts yielded red/orange octahedral crystals of four new fcu-MOFs, fcu-1-Co(II), fcu-2-Co(II), fcu-3-Co(II), and fcu-4-Co(II) (Figure 2, see the MOFs Synthesis section in SI for full details). Single crystal X-ray diffraction (SCXRD) analysis revealed that these MOFs are isostructural and sustained by the same [Co8(μ4–OH)6(pz)12]2– (Co8) MBB.

Figure 2.

Figure 2

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Design and structure of fcu-L-Co. (a,d) Dipyrazolate linker ligands 1–4 and 12-connected [Co8(μ4–OH)6(pz)12]2– MBBs. (b) Structure of fcu-L-Co with (c) tetrahedron and (g) octahedron cages. Assembly between (e) linear linkers and icosahedral nodes resulted in (f) fcu networks.

Structure and Porosity Characterization

Unit cell and structure refinement parameters for the as-synthesized fcu-L-Co(II) MOFs are summarized in Table S1. Using fcu-3-Co(II) as an exemplar, it crystallized in the cubic crystal system with space group FmInline graphicm. The cobalt atom coordinates to three nitrogen atoms from three pyrazolate moieties and three μ4–OH entities in a distorted-octahedral coordination geometry. Eight cobalt atoms are connected by six μ4–OH entries to form a Co8(μ4–OH)6 core that can be simplified to a Co8 cube, which resembles the Ni8 cube found in [Ni8(OH)4(H2O)2(L)6]n and PCN-601.29,41,42,46 The Co8 cube is linked by 12 pyrazolate moieties from different 32– ligands to generate the anticipated fcu topology network (Figure 2a). Six H3O+/H2O entities are proximal to the μ4–OH moieties (O···O distance 3.894 Å) (Figure S5), two of which are assumed to be H3O+ cations to balance the overall negative charge of the MBBs (supported by the spectroscopy and thermal analysis results discussed below, and the pH around 7 of the solvothermal system) (Figure S6). The presence of H3O+ has also been observed in other compounds obtained from DMF.47,48 The 32– ligand has planar geometry (Figure 2a) to facilitate the fcu topology of fcu-3-Co(II) (Figure 2a,b,e, and f). Co–N bond distance of 2.0620(23) Å, Co–O bond distance of 2.2076(28) Å, and Co···Co distance of 3.0352(7) Å (Table S2) are consistent with the literature values for Co(II) ions.27,39,44 The formula of fcu-3-Co(II) is thus assigned as Co(II)8(OH)6(3)6(H3O+)2·4H2O. As is typical for fcu topology, two types of cages are present in fcu-3-Co(II): tetrahedral (sphere of diameter 8.8 Å, without taking van der Waals radii into account) (Figure 2c) and octahedral (17.6 Å diameter) (Figure 2g). These cages connect via hydrophilic windows (sphere of diameter 7.0 Å) enclosed by N-functionalized ligands (Figure S7). The solvent accessible void of fcu-3-Co(II) is 61.1% of its unit cell volume as determined by PLATON (Tables S1).49

Powder X-ray diffraction (PXRD) analysis was conducted to examine the crystallinity and phase purity of fcu-L-Co(II). The experimental PXRD patterns are consistent with those calculated from single crystal structure data (Figures S8–S11), indicating phase purity. To evaluate porosity, samples were characterized by N2 adsorption at 77 K after methanol exchange and evacuation at 80 °C. Saturated N2 uptakes of 525, 520, 538, and 567 cm3 g–1 (STP) were observed for the activated phases of fcu-1-Co(II), fcu-2-Co(II), fcu-3-Co(II), and fcu-4-Co(II) (Figure S12), respectively. The Brunauer–Emmett–Teller (BET) surface areas were determined to be 1656, 1642, 1693, and 1750 m2 g–1, respectively. Thermogravimetric analysis (TGA) revealed that fcu-1-Co(II) is stable up to 390 °C, fcu-2-Co(II) up to 350 °C, fcu-3-Co(II) up to 360 °C, and fcu-4-Co(II) up to 400 °C (Figure S13). These materials were also found to exhibit good chemical stability after various treatments (Figures S8–S11 and S14), laying the foundation for utility.

Structural Transformation

Prior to further study, we noted color differences among freshly made (fcu-L-Co(II), α phase, red), activated (fcu-L-Co(II), β phase, dark red), and long-term air exposed (fcu-L-Co(III), γ phase, purple) samples. All of these samples were characterized to explore the relevance between phases (Figures 3 and S15–S31). We take fcu-3-Co as an example (Figures 3a–b and S15). fcu-3-Co(III) was obtained by exposing MeOH-exchanged fcu-3-Co(II) to laboratory air for four months. The characteristic PXRD peaks of fcu-3-Co(III) had shifted to higher 2θ values relative to those of fcu-3-Co(II) (Figure S14), indicating shrinkage of the crystal structure. Transformation of fcu-3-Co(II) also occurred in the presence of aqueous H2O2/meta-chloroperoxybenzoic acid (m-CPBA). fcu-3-Co(II) was subsequently recovered by treating fcu-3-Co(III) with N2H4·H2O, as indicated by the red color of the resulting crystals and a PXRD pattern matching that of fcu-3-Co(II) (Figures S16 and S19). To further study this transformation process, in situ variable-temperature(VT)-PXRD experiments under ambient air, N2 flow, and vacuum were conducted (Figures 3d, S27, and S28). The PXRD peaks shifted to higher 2θ values with increasing temperature in all three cases. fcu-3-Co(III) was observed under a vacuum at 300 °C (Figure 3d). This phase was also observed under ambient air and N2 flow but at different temperatures (Table S3).

Figure 3.

Figure 3

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(a,b) Microscopic images and (c) PXRD patterns of different phases of fcu-3-Co collected under ambient conditions (as synthesized fcu-3-Co(II) (α phase), activated fcu-3-Co(II) (β phase), and oxidized fcu-3-Co(III) (γ phase)). (d) VT-PXRD patterns of the as-synthesized fcu-3-Co(II) (α phase) under a vacuum.

The above results indicate that oxidation from Co(II) to Co(III) has occurred in the presence of O2 (air) and oxidants or upon heating. This is consistent with the chemistry of Co(II) complexes, where oxidation can be triggered by O2 or H2O2.9,24,50 We propose the following reaction mechanism: (1) 8Co(II) + 6(μ4–OH) + 2H3O+ + 2O2 → 8Co(III) + 6(μ4-O) + 6H2O; (2) 8Co(II) + 6(μ4–OH) + 2H3O+ + 4H2O2 → 8Co(III) + 6(μ4-O) + 10H2O. Transformation from Co(II) to Co(III) was also achieved by heating under vacuum and N2 flow. Additional experiments were performed to gain further insight.

That crystals of fcu-3-Co(II)-β and fcu-3-Co(III) after treatments retained crystallinity allowed us to study them by SCXRD, which revealed that fcu-3-Co(II)-β retained space group FmInline graphicm (Table S1). The framework structure of fcu-3-Co(II)-β contracted relative to that of fcu-3-Co(II), with unit cell volume reduced from 16,262.2(2) to 15,560.6(9) Å attributable to shortening of Co–O and Co–N bond distances from 2.2076(28)/2.0620(23) Å to 2.1502(13)/1.9919(24) Å (Table S2 and S32). That partial oxidation of Co(II) to Co(III) has occurred is supported by in situ X-ray photoelectron spectroscopy (XPS) spectra (Figure 4b). The quality of fcu-3-Co(III) crystals had degraded after long-term air exposure, oxidants treatment, and heating, so only the unit cell parameters of fcu-3-Co(III) could be determined, giving a unit cell volume of 13,882.4(6) Å3. Nevertheless, SCXRD data were obtained after water vapor adsorption/desorption cycling measurements, which revealed a further unit cell volume reduction to 13,730.0(1) Å3, 15% less than that of fcu-3-Co(II)-α. The Co–O and Co–N bond distances further decreased to 1.9309(49) and 1.8537(44) Å, along with protrusion of the μ4-O2– moieties on the faces of the Co8 cube. In Co(II) compounds, typical Co–O/N bond lengths are expected to be around 2.1 Å, while bond lengths for Co(III) should be close to 1.9 Å, both in agreement with values of fcu-3-Co.28,51,52 Consequently, the volume of the Co8 cube contracted from 27.956 Å3 (fcu-3-Co(II)) to 16.856 Å3 (fcu-3-Co(III)), corresponding to a 40% shrinkage (Figure S32).

Figure 4.

Figure 4

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In situ spectroscopic study of Co(II) to Co(III) conversion in fcu-3-Co, experiments conducted on the MeOH exchanged and air dried fcu-3-Co(II) sample. (a) In situ IR spectra. In situ XPS: (b) Co 2p and (c) N 1s spectra. (d) TGA-MS curves.

This redox-induced phase transformation was also studied by in situ infrared (IR) spectroscopy (Figure 4a). The diagnostic stretching bands of μ4–OH centered at 3594 cm–1 weakened at 200 °C and shifted to 3587 cm–1 at 250 °C.53 Furthermore, the bending band at 1099 cm–1 showed a similar trend, indicating a transformation upon heating. In situ XPS spectra were collected on fcu-L-Co(II) to determine the oxidation state of cobalt ions at different temperatures (Figures 4b–c and S33–S36). In the cobalt spectra of fcu-3-Co(II), the peak at 777.6 eV that appeared at 100 °C was assigned to Co(III), which was not present in the room temperature (RT) sample (Figure 4b). Compared with the Co(II) signals of 780.4 and 779.4 eV as observed in the RT and heated samples, this peak is of lower energy and is consistent with reported values for Co(III).19,24 In addition to the peak at 531.2 eV, a peak of lower energy (528.8 eV) appeared in the oxygen spectra collected for heated samples (Figure S33b). In the nitrogen spectra, a new peak appeared at a lower energy of 397.6 eV as well (Figure 4c). These results support the proposed cobalt oxidation states conversion in the three forms of fcu-3-Co.

Thermogravimetric analysis–mass spectrometry (TGA-MS) analysis was also performed to probe the species released upon heating the fcu-3-Co(II) sample (Figures 4d and S37–S40). A signal for water was observed when fcu-3-Co(II) was heated at 63 °C, which was assigned to physisorbed water in pores. At 246 °C, both water and trace hydrogen were released (Figure 4d). Redox processes involving electron transfer within confined environments along with hydrogen evolution have been reported by Hashimoto’s and Hupp’s groups.54−56 Based on our experimental findings and literature reports, we propose a different transformation pathway under vacuum/inert conditions, in which water and hydrogen were generated as byproducts: 8Co(II) + 6(μ4–OH) + 2H3O+ → 8Co(III) + 6(μ4-O) + 2H2O + 4H2. When Co(II) converted to Co(III), one electron was transferred to the proton of μ4–OH or countercation H3O+ to yield hydrogen. Meanwhile, the μ4–OH moieties became μ4-O and H3O+ was converted to H2O, forming a neutral [Co(III)8(μ4-O)6(Pz)12] MBB in fcu-3-Co(III). These signals were also observed in the fcu-3-Co(II) sample without MeOH exchange, however, the spectra are more complicated due to the thermal decomposition of residual DMF (Figure S39). By contrast, there was no hydrogen release monitored for fcu-3-Co(III), with only a water signal observed at the same temperature (Figure S40).

We utilized superconducting quantum interference device (SQUID) magnetometry to quantify the content of Co(III) in fcu-L-Co(III) MOFs.28,57,58 Isothermal moment versus field (MvH) measurements were performed at 5 K, sweeping from −70 to 70 kOe and back, on both fcu-L-Co(II) and fcu-L-Co(III) samples (Figure S41). The results inferred low-spin 3d7 Co(II) ions (1.7–2.0 μB, S = 1/2) in fcu-L-Co(II), and predominantly high-spin 3d6 Co(III) (3.1–4.8 μB, S = 2) in fcu-L-Co(III) with some residual Co(II) sites. Specifically, 63%, 79%, 98%, and 92% of Co(II) ions were calculated to convert to Co(III) in fcu-1-Co(III), fcu-2-Co(III), fcu-3-Co(III), and fcu-4-Co(III), respectively. fcu-3-Co(III) and fcu-4-Co(III) had therefore undergone almost complete oxidation from Co(II) to Co(III), while partial oxidation was observed for fcu-1-Co(III) and fcu-2-Co(III). These results are consistent with the PXRD patterns of fcu-1-Co(III) and fcu-2-Co(III) that are characteristic of a Co(II)/Co(III) mixture (Figures S17–20). This behavior is different from that of Co2Cl2BTDD and Co2Cl2X2BTDD comprising Co-based RBBs.28,57 Coordinating with three nitrogen and three oxygen atoms in an octahedral geometry, the 3d7 electrons of MBB Co(II) adopt a low spin configuration: three pairs of electrons fill in three t2g orbits, and one unpaired electron in an eg orbit (Figure S32d).59 By contrast, Co(III) has one pair of electrons in a t2g orbital, and four unpaired electrons, indicative of high-spin 3d6 (Figure S32d). To the best of our knowledge, this study details the first time a spontaneous and reversible cluster MBB Co(II) to Co(III) transformation has been monitored by SCXRD in a MOF and also reports a rare example of a MOF that breathes through MBB transformation.

Water Vapor Sorption

The structure of fcu-L-Co(II) features large cages with hydrophilic windows, which motivated us to investigate its water vapor sorption properties. Isotherms were collected on activated samples at 298 K. All four variants exhibited S-shaped isotherms with steep uptake at <30% relative humidity (RH) (Figure 5a). The maximum water uptake for fcu-1-Co(II), fcu-2-Co(II), fcu-3-Co(II), and fcu-4-Co(II) was determined to be 0.64 g g–1, 0.63 g g–1, 0.74 g g–1, and 0.68 g g–1 at 95% RH, respectively. Among these materials, fcu-3-Co(II) exhibited the highest uptake of 0.68 g g–1 at 30% RH, which is second to Co2Cl2(BTDD) (0.83 g g–1) as reported by Dincă and coworkers.60 The uptake difference between adsorption at 30% RH and desorption at 5% RH is also high, calculated to be 0.44 g g–1 for fcu-1-Co(II), 0.44 g g–1 for fcu-2-Co(II), 0.60 g g–1 for fcu-3-Co(II), and 0.53 g g–1 for fcu-4-Co(II) (Table S4). SCXRD analysis on the water loaded structure of fcu-3-Co(II)-β revealed that the adsorbed water molecules are located around the Co8 MBBs and N-functionalized ligands, sustained by hydrogen bonds (Figure S42 and Table S5). There are 72 water molecules determined per formula, corresponding to an uptake of 0.67 g g–1 at 50% RH.

Figure 5.

Figure 5

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(a) Water vapor sorption isotherms of fcu-L-Co(II) at 298 K. (b) Comparison of water uptake under 30% RH at 298 K and the inflection point between fcu-L-Co(II) (green)/fcu-L-Co(III) (blue) and representative materials (black). (c) Water cycling test of fcu-3-Co(II) for 0%–60% RH humidity swing at 298 K. (d) Water isotherms collected before and after the cycling test of fcu-3-Co at 298 K.

Water vapor adsorption/desorption kinetics (0–30% and 0–60% RH) and cycling experiments (0–60% RH) were performed at 298 K (Figures 5c and S43–S49). Relative to the first cycle of fcu-1-Co(II), a 9% decrease of the working capacity (0.44 to 0.40 g g–1) was observed after 100 cycles (Figure S47). A 17% decrease from 0.45 to 0.37 g g–1 was seen for fcu-2-Co(III) (Figure S48). A decrease of 22% (0.68 to 0.53 g g–1) was recorded for fcu-3-Co after 40 cycles, with a 10% increase of the initial mass and a 12% decrease in maximum uptake, both of which remained almost unchanged in subsequent cycles (Figure 5c). fcu-4-Co behaved similarly to fcu-3-Co, with a capacity decrease of 23% after 40 cycles (0.64 to 0.48 g g–1) (Figure S49). Among these variants, the working capacity of fcu-3-Co after cycling (fcu-3-Co(III), 0.52 g g–1) was the highest (Figures 5c, S47–S49 and Table S4). The isotherms of fcu-L-Co(III) were also collected (Figures 5d,S50 and S51). Uptake of fcu-3-Co(III) after cycling was 0.50 g of g–1 at 60% RH, corresponding to a 26% decrease relative to that measured before cycling. This value is consistent with the total capacity decrease by 22% in cycling. In addition, the isotherms evolved to be reversible without initial hysteresis (Figure 5d). It should be noted that the density of fcu-3-Co(III) (0.878 g cm–3) is greater than that of fcu-3-Co(II) (0.744 g cm–3). The volumetric water capacities between 60% and 5% RH for the two phases are therefore comparable (0.50 g cm–3 for fcu-3-Co(II) and 0.46 g cm–3 for fcu-3-Co(III)). Meanwhile, the inflection point shifted to lower RH (from 25% to 20%) and framework stability improved in fcu-3-Co(III), which are both advantageous to water vapor sorption.

The quality of samples after cycling measurements (fcu-L-Co(III)) was first examined using PXRD. Crystallinity was retained while PXRD peaks shifted to higher 2θ relative to the fcu-L-Co(II) phases, indicating framework contraction. This aligns with the VT-PXRD data (Figures S8–S11 and 3). We also analyzed the single crystal structure of fcu-3-Co(III). After cycling, the unit cell volume of fcu-3-Co(III) decreased by 15% (Table S1). Such contraction accounts for the maximum water uptake decrease of 12% in the cycling experiments (Figure 5c). These results indicate that ambient adsorption/desorption cycles lead to controlled conversion of Co(II) to Co(III).

With respect to the initial mass increase during water vapor sorption cycling, as revealed by SCXRD, water molecules reside around the Co8 MBB of fcu-3-Co(III) and account for ∼10% of the mass of the framework. This value is consistent with the mass increase being the result of a pocket that strongly binds water molecules. fcu-3-Co(III) after cycling was reactivated at 100 °C and a second round of cycling was conducted to test 0–60% RH pressure swing at RT for 40 cycles. Thereafter, in situ activations at 100, 150, and 200 °C were performed successively, each followed by two cycles of pressure swing at RT (Figures S52 and S53). The results of these tests indicate that this phase had a water uptake of 0.58 g g–1 in the first cycle, decreasing to 0.56 g g–1 after 40 cycles along with an initial mass increase of 0.04 g g–1 (Figure S52). After activating the sample in situ at 150 °C, the initial mass came back to zero, while the uptake in the following adsorption was 0.55 g g–1 with a residual 0.02 g g–1 uptake after desorption, giving a working capacity of 0.53 g g–1 (Figures S52 and 53). Both capacity values agree with the final capacity (0.52 g g–1) in the first round of the cycling test. Overall, these results indicate that, whereas the phase after the first round of cycling exhibits almost constant water vapor sorption capacity, strongly adsorbed water molecules, which form multiple ···H··X (X = O or N) interactions with the surrounding ligands and MBBs (Figure S54) hinder complete desorption and require more energy for regeneration (Figures S52 and 53).

Conclusion

In summary, a family of four pyrazolate fcu topology MOFs have been constructed with a 12-connected Co8 MBB through a crystal engineering approach. The octahedrally coordinated Co(II) cations are redox active and can spontaneously transform in air to Co(III) in a single crystal to single crystal fashion. Further, this oxidation reaction can be initiated by heat or conventional oxidants. The effects of oxidation upon water vapor sorption properties were as follows: gravimetric uptake was reduced; volumetric uptake was similar; the inflection point shifted to lower RH (from 25% to 20%); cycling stability improved. Co(II) to Co(III) conversion therefore enhanced the water vapor harvesting performance. To our knowledge, this work represents the first demonstration of spontaneous cobalt cluster MBB redox chemistry in a MOF and, thanks to retention of crystallinity and in situ spectroscopy, insight into the reversible phase transformations was gained. These findings are instructive for designing and discovering reusable solid-state redox materials for efficient gas and vapor capture and catalysis.

Acknowledgments

J.R.L. acknowledges the National Natural Science Foundation of China (22225803 and 22038001). M.J.Z. acknowledges the financial support from the Science Foundation Ireland (16/IA/4624) and the European Research Council (ADG 885695). T.H. acknowledges the National Natural Science Foundation of China (22401168). We thank Dr. Lilia Croitor for analyzing the crystal data.

Supporting Information Available

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/jacs.4c09173.

  • Materials and instruments, details of ligands’ and MOFs’ synthesis, general characterizations (FT-IR, TGA, PXRD, etc.), and additional tables and figures; X-ray data for fcu-1-Co(II)-α; X-ray data for fcu-2-Co(II)-α; X-ray data for fcu-3-Co(II)-α; X-ray data for fcu-4-Co(II)-α; X-ray data for fcu-3-Co(II)-β; X-ray data for fcu-3-Co(III)-γ; X-ray data for fcu-3-Co(II)-β-H2O (PDF)

The authors declare no competing financial interest.

Supplementary Material

ja4c09173_si_001.pdf (13.1MB, pdf)

References

  1. Fenton D. E.Transition Metal Groups 9–11 Comprehensive Coordination Chemistry II, 2nd ed., McCleverty J. A.; Meyer T. J., Eds.; Elsevier Science, 2003. [Google Scholar]
  2. Li S.; Gao Y.; Li N.; Ge L.; Bu X.; Feng P. Transition metal-based bimetallic MOFs and MOF-derived catalysts for electrochemical oxygen evolution reaction. Energy Environ. Sci. 2021, 14 (4), 1897–1927. 10.1039/D0EE03697H. [DOI] [Google Scholar]
  3. Mandal A.; Kushwaha R.; Mandal A. A.; Bajpai S.; Yadav A. K.; Banerjee S. Transition Metal Complexes as Antimalarial Agents: A Review. ChemMedchem 2023, 18 (19), e202300326 10.1002/cmdc.202300326. [DOI] [PubMed] [Google Scholar]
  4. Marquez R. A.; Kalokowski E.; Espinosa M.; Bender J. T.; Son Y. J.; Kawashima K.; Chukwuneke C. E.; Smith L. A.; Celio H.; Dolocan A.; Zhan X.; Miller N.; Milliron D. J.; Resasco J.; Mullins C. B. Transition metal incorporation: Electrochemical, structure, and chemical composition effects on nickel oxyhydroxide oxygen-evolution electrocatalysts. Energy Environ. Sci. 2024, 17 (5), 2028–2045. 10.1039/D3EE03617K. [DOI] [Google Scholar]
  5. Li L.-J.; He Y.; Yang Y.; Guo J.; Lu Z.; Wang C.; Zhu S.; Zhu S.-F. Recent Advances in Mn, Fe, Co, and Ni-Catalyzed Organic Reactions. CCS Chem. 2024, 6 (3), 537–584. 10.31635/ccschem.023.202303412. [DOI] [Google Scholar]
  6. Cotton F. A.; Wilkinson G.; Murillo C. A.; Bochmann M.. Part 3 the Chemistry of The Transition Elements. In Advanced Inorganic Chemistry, 6thed.; Wiley-Interscience, 1999. [Google Scholar]
  7. Bilska-Wilkosz A.; Iciek M.; Gorny M.; Kowalczyk-Pachel D. The Role of Hemoproteins: Hemoglobin, Myoglobin and Neuroglobin in Endogenous Thiosulfate Production Processes. Int. J. Mol. Sci. 2017, 18 (6), 1315. 10.3390/ijms18061315. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Rizzo G.; Laganà A. S.. A review of vitamin B12, In Molecular Nutrition: Vitamins, Patel V. B., Ed.; Academic Press, 2020. [Google Scholar]
  9. Devic T.; Serre C. High valence 3p and transition metal based MOFs. Chem. Soc. Rev. 2014, 43 (16), 6097–6115. 10.1039/C4CS00081A. [DOI] [PubMed] [Google Scholar]
  10. O’Hearn D. J.; Bajpai A.; Zaworotko M. J. The “Chemistree” of Porous Coordination Networks: Taxonomic Classification of Porous Solids to Guide Crystal Engineering Studies. Small 2021, 17 (22), 2006351. 10.1002/smll.202006351. [DOI] [PubMed] [Google Scholar]
  11. Furukawa H.; Cordova K. E.; O’Keeffe M.; Yaghi O. M. The chemistry and applications of metal-organic frameworks. Science 2013, 341 (6149), 1230444. 10.1126/science.1230444. [DOI] [PubMed] [Google Scholar]
  12. Li H. Y.; Kong X. J.; Han S. D.; Pang J.; He T.; Wang G. M.; Bu X. H. Metalation of metal-organic frameworks: Fundamentals and applications. Chem. Soc. Rev. 2024, 53 (11), 5626–5676. 10.1039/D3CS00873H. [DOI] [PubMed] [Google Scholar]
  13. Guillerm V.; Kim D.; Eubank J. F.; Luebke R.; Liu X.; Adil K.; Lah M. S.; Eddaoudi M. A supermolecular building approach for the design and construction of metal-organic frameworks. Chem. Soc. Rev. 2014, 43 (16), 6141–6172. 10.1039/C4CS00135D. [DOI] [PubMed] [Google Scholar]
  14. D’Alessandro D. M. Exploiting redox activity in metal-organic frameworks: Concepts, trends and perspectives. Chem. Commun. 2016, 52 (58), 8957–8971. 10.1039/C6CC00805D. [DOI] [PubMed] [Google Scholar]
  15. Calbo J.; Golomb M. J.; Walsh A. Redox-active metal–organic frameworks for energy conversion and storage. J. Mater. Chem. A 2019, 7 (28), 16571–16597. 10.1039/C9TA04680A. [DOI] [Google Scholar]
  16. Liu T. F.; Zou L.; Feng D.; Chen Y. P.; Fordham S.; Wang X.; Liu Y.; Zhou H. C. Stepwise Synthesis of Robust Metal-Organic Frameworks via Postsynthetic Metathesis and Oxidation of Metal Nodes in a Single-Crystal to Single-Crystal Transformation. J. Am. Chem. Soc. 2014, 136 (22), 7813–7816. 10.1021/ja5023283. [DOI] [PubMed] [Google Scholar]
  17. He X.; Iliescu A.; Yang T.; Arguilla M. Q.; Chen T.; Kulik H. J.; Dinca M. Reversible O-O Bond Scission and O2 Evolution at MOF-Supported Tetramanganese Clusters. J. Am. Chem. Soc. 2023, 145 (30), 16872–16878. 10.1021/jacs.3c05374. [DOI] [PubMed] [Google Scholar]
  18. Leszczynski M. K.; Kornowicz A.; Prochowicz D.; Justyniak I.; Noworyta K.; Lewinski J. Straightforward Synthesis of Single-Crystalline and Redox-Active Cr(II)-carboxylate MOFs. Inorg. Chem. 2018, 57 (9), 4803–4806. 10.1021/acs.inorgchem.8b00395. [DOI] [PubMed] [Google Scholar]
  19. Zhang T.; Hu Y. Q.; Han T.; Zhai Y. Q.; Zheng Y. Z. Redox-Active Cobalt(II/III) Metal-Organic Framework for Selective Oxidation of Cyclohexene. ACS Appl. Mater. Interfaces 2018, 10 (18), 15786–15792. 10.1021/acsami.7b19323. [DOI] [PubMed] [Google Scholar]
  20. Smolders S.; Lomachenko K. A.; Bueken B.; Struyf A.; Bugaev A. L.; Atzori C.; Stock N.; Lamberti C.; Roeffaers M. B. J.; De Vos D. E. Unravelling the Redox-catalytic Behavior of Ce(4+) Metal-Organic Frameworks by X-ray Absorption Spectroscopy. ChemPhyschem. 2018, 19 (4), 373–378. 10.1002/cphc.201700967. [DOI] [PubMed] [Google Scholar]
  21. Dan-Hardi M.; Serre C.; Frot T.; Rozes L.; Maurin G.; Sanchez C.; Ferey G. A New Photoactive Crystalline Highly Porous Titanium(IV) Dicarboxylate. J. Am. Chem. Soc. 2009, 131 (31), 10857–10859. 10.1021/ja903726m. [DOI] [PubMed] [Google Scholar]
  22. Jaramillo D. E.; Jaffe A.; Snyder B. E. R.; Smith A.; Taw E.; Rohde R. C.; Dods M. N.; DeSnoo W.; Meihaus K. R.; Harris T. D.; Neaton J. B.; Long J. R. Metal-organic frameworks as O2-selective adsorbents for air separations. Chem. Sci. 2022, 13 (35), 10216–10237. 10.1039/D2SC03577D. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Murray L. J.; Dincă M.; Yano J.; Chavan S.; Bordiga S.; Brown C. M.; Long J. R. Highly-Selective and Reversible O2 Binding in Cr3(1,3,5-benzenetricarboxylate)2. J. Am. Chem. Soc. 2010, 132 (23), 7856–7857. 10.1021/ja1027925. [DOI] [PubMed] [Google Scholar]
  24. Liao P.-Q.; Chen H.; Zhou D.-D.; Liu S.-Y.; He C.-T.; Rui Z.; Ji H.; Zhang J.-P.; Chen X.-M. Monodentate hydroxide as a super strong yet reversible active site for CO2 capture from high-humidity flue gas. Energy Environ. Sci. 2015, 8 (3), 1011–1016. 10.1039/C4EE02717E. [DOI] [Google Scholar]
  25. Oktawiec J.; Jiang H. Z. H.; Vitillo J. G.; Reed D. A.; Darago L. E.; Trump B. A.; Bernales V.; Li H.; Colwell K. A.; Furukawa H.; et al. Negative cooperativity upon hydrogen bond-stabilized O2 adsorption in a redox-active metal–organic framework. Nat. Commun. 2020, 11 (1), 3087. 10.1038/s41467-020-16897-z. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Oktawiec J.; Jiang H. Z. H.; Turkiewicz A. B.; Long J. R. Influence of the primary and secondary coordination spheres on nitric oxide adsorption and reactivity in cobalt(II)-triazolate frameworks. Chem. Sci. 2021, 12 (43), 14590–14598. 10.1039/D1SC03994F. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Huang N. Y.; Shen J. Q.; Ye Z. M.; Zhang W. X.; Liao P. Q.; Chen X. M. An exceptionally stable octacobalt-cluster-based metal-organic framework for enhanced water oxidation catalysis. Chem. Sci. 2019, 10 (42), 9859–9864. 10.1039/C9SC03224J. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Tulchinsky Y.; Hendon C. H.; Lomachenko K. A.; Borfecchia E.; Melot B. C.; Hudson M. R.; Tarver J. D.; Korzynski M. D.; Stubbs A. W.; Kagan J. J.; Lamberti C.; Brown C. M.; Dinca M. Reversible Capture and Release of Cl2 and Br2 with a Redox-Active Metal-Organic Framework. J. Am. Chem. Soc. 2017, 139 (16), 5992–5997. 10.1021/jacs.7b02161. [DOI] [PubMed] [Google Scholar]
  29. He T.; Kong X.-J.; Li J.-R. Chemically Stable Metal-Organic Frameworks: Rational Construction and Application Expansion. Acc. Chem. Res. 2021, 54 (15), 3083–3094. 10.1021/acs.accounts.1c00280. [DOI] [PubMed] [Google Scholar]
  30. Burtch N. C.; Jasuja H.; Walton K. S. Water Stability and Adsorption in Metal-Organic Frameworks. Chem. Rev. 2014, 114 (20), 10575–10612. 10.1021/cr5002589. [DOI] [PubMed] [Google Scholar]
  31. Healy C.; Patil K. M.; Wilson B. H.; Hermanspahn L.; Harvey-Reid N. C.; Howard B. I.; Kleinjan C.; Kolien J.; Payet F.; Telfer S. G.; Kruger P. E.; Bennett T. D. The thermal stability of metal-organic frameworks. Coord. Chem. Rev. 2020, 419, 213388. 10.1016/j.ccr.2020.213388. [DOI] [Google Scholar]
  32. Howarth A. J.; Liu Y.; Li P.; Li Z.; Wang T. C.; Hupp J. T.; Farha O. K. Chemical, thermal and mechanical stabilities of metal–organic frameworks. Nat. Rev. Mater. 2016, 1 (3), 15018. 10.1038/natrevmats.2015.18. [DOI] [Google Scholar]
  33. Jiang H.; Alezi D.; Eddaoudi M. A reticular chemistry guide for the design of periodic solids. Nat. Rev. Mater. 2021, 6 (6), 466–487. 10.1038/s41578-021-00287-y. [DOI] [Google Scholar]
  34. Cavka J. H.; Jakobsen S.; Olsbye U.; Guillou N.; Lamberti C.; Bordiga S.; Lillerud K. P. A New Zirconium Inorganic Building Brick Forming Metal Organic Frameworks with Exceptional Stability. J. Am. Chem. Soc. 2008, 130 (42), 13850–13851. 10.1021/ja8057953. [DOI] [PubMed] [Google Scholar]
  35. Assen A. H.; Adil K.; Cordova K. E.; Belmabkhout Y. The chemistry of metal–organic frameworks with face-centered cubic topology. Coord. Chem. Rev. 2022, 468, 214644. 10.1016/j.ccr.2022.214644. [DOI] [Google Scholar]
  36. Bai Y.; Dou Y.; Xie L.-H.; Rutledge W.; Li J.-R.; Zhou H.-C. Zr-based metal-organic frameworks: Design, synthesis, structure, and applications. Chem. Soc. Rev. 2016, 45 (8), 2327–2367. 10.1039/C5CS00837A. [DOI] [PubMed] [Google Scholar]
  37. Furukawa H.; Gandara F.; Zhang Y. B.; Jiang J.; Queen W. L.; Hudson M. R.; Yaghi O. M. Water Adsorption in Porous Metal-Organic Frameworks and Related Materials. J. Am. Chem. Soc. 2014, 136 (11), 4369–4381. 10.1021/ja500330a. [DOI] [PubMed] [Google Scholar]
  38. Cmarik G. E.; Kim M.; Cohen S. M.; Walton K. S. Tuning the Adsorption Properties of UiO-66 via Ligand Functionalization. Langmuir 2012, 28 (44), 15606–15613. 10.1021/la3035352. [DOI] [PubMed] [Google Scholar]
  39. Holmberg R. J.; Kay M.; Korobkov I.; Kadantsev E.; Boyd P. G.; Aharen T.; Desgreniers S.; Woo T. K.; Murugesu M. An unprecedented Co(II) cuboctahedron as the secondary building unit in a Co-based metal-organic framework. Chem. Commun. 2014, 50 (40), 5333–5335. 10.1039/C3CC46396F. [DOI] [PubMed] [Google Scholar]
  40. Ma F.-X.; Lyu L.-Y.; Chen J.; Huang T.; Zhang T.; Cao R. Two highly stable isoreticular M8-pyrazolate (M = Co, Ni) metal–organic frameworks for CO2 conversion. Chem. Commun. 2024, 60 (10), 1293–1296. 10.1039/D3CC05270B. [DOI] [PubMed] [Google Scholar]
  41. Masciocchi N.; Galli S.; Colombo V.; Maspero A.; Palmisano G.; Seyyedi B.; Lamberti C.; Bordiga S. Cubic Octanuclear Ni(II) Clusters in Highly Porous Polypyrazolyl-based Materials. J. Am. Chem. Soc. 2010, 132 (23), 7902–7904. 10.1021/ja102862j. [DOI] [PubMed] [Google Scholar]
  42. Padial N. M.; Quartapelle Procopio E.; Montoro C.; Lopez E.; Oltra J. E.; Colombo V.; Maspero A.; Masciocchi N.; Galli S.; Senkovska I.; Kaskel S.; Barea E.; Navarro J. A. Highly hydrophobic isoreticular porous metal-organic frameworks for the capture of harmful volatile organic compounds. Angew. Chem., Int. Ed. 2013, 52 (32), 8290–8294. 10.1002/anie.201303484. [DOI] [PubMed] [Google Scholar]
  43. Zhang Y.-Z.; He T.; Kong X.-J.; Bian Z.-X.; Wu X.-Q.; Li J.-R. Single-Crystal Synthesis and Structures of Highly Stable Ni8-Pyrazolate-Based Metal–Organic Frameworks. ACS Mater. Lett. 2019, 1 (1), 20–24. 10.1021/acsmaterialslett.9b00021. [DOI] [Google Scholar]
  44. Ding B.; Zhang S.; Liu Z.-Y.; Yang E.-C.; Zhao X.-J. A spin-frustrated (4, 12)-connected metal-organic framework with unusual {Co8(μ4-OH)6}10+ cubes. Inorg. Chem. Commun. 2017, 83, 27–30. 10.1016/j.inoche.2017.05.022. [DOI] [Google Scholar]
  45. He T.; Kong X. J.; Bian Z. X.; Zhang Y. Z.; Si G. R.; Xie L. H.; Wu X. Q.; Huang H.; Chang Z.; Bu X. H.; Zaworotko M. J.; Nie Z. R.; Li J. R. Trace removal of benzene vapour using double-walled metal-dipyrazolate frameworks. Nat. Mater. 2022, 21 (6), 689–695. 10.1038/s41563-022-01237-x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  46. Wang K.; Lv X. L.; Feng D.; Li J.; Chen S.; Sun J.; Song L.; Xie Y.; Li J. R.; Zhou H. C. Pyrazolate-Based Porphyrinic Metal-Organic Framework with Extraordinary Base-Resistance. J. Am. Chem. Soc. 2016, 138 (3), 914–919. 10.1021/jacs.5b10881. [DOI] [PubMed] [Google Scholar]
  47. Park S. S.; Hendon C. H.; Fielding A. J.; Walsh A.; O’Keeffe M.; Dincă M. The Organic Secondary Building Unit: Strong Intermolecular pi Interactions Define Topology in MIT-25, a Mesoporous MOF with Proton-Replete Channels. J. Am. Chem. Soc. 2017, 139 (10), 3619–3622. 10.1021/jacs.6b13176. [DOI] [PubMed] [Google Scholar]
  48. Sapchenko S. A.; Demakov P. A.; Samsonenko D. G.; Dybtsev D. N.; Schroder M.; Fedin V. P. A Cryptand Metal-Organic Framework as a Platform for the Selective Uptake and Detection of Group I Metal Cations. Chem.-Eur. J. 2017, 23 (10), 2286–2289. 10.1002/chem.201605895. [DOI] [PubMed] [Google Scholar]
  49. Spek A. L. Single-crystal structure validation with the programPLATON. J. Appl. Crystallogr. 2003, 36 (1), 7–13. 10.1107/S0021889802022112. [DOI] [Google Scholar]
  50. Ji X.; Buzzeo M. C.; Banks C. E.; Compton R. G. Electrochemical Response of Cobalt(II) in the Presence of Ammonia. Electroanalysis 2006, 18 (1), 44–52. 10.1002/elan.200503361. [DOI] [Google Scholar]
  51. Barnet M. T.; Craven B. M.; Freeman H. C.; Kime N. E.; Ibers J. A. The Co–N bond lengths in CoIIand CoIIIhexammines. Chem. Commun. 1966, 307–308. 10.1039/C19660000307. [DOI] [Google Scholar]
  52. Ribeiro M. A.; Lanznaster M.; Silva M. M.; Resende J. A.; Pinheiro M. V.; Krambrock K.; Stumpf H. O.; Pinheiro C. B. Cobalt lawsone complexes: Searching for new valence tautomers. Dalton Trans. 2013, 42 (15), 5462–5470. 10.1039/c3dt32968b. [DOI] [PubMed] [Google Scholar]
  53. Lo S. H.; Feng L.; Tan K.; Huang Z.; Yuan S.; Wang K. Y.; Li B. H.; Liu W. L.; Day G. S.; Tao S.; Yang C. C.; Luo T. T.; Lin C. H.; Wang S. L.; Billinge S. J. L.; Lu K. L.; Chabal Y. J.; Zou X.; Zhou H. C. Rapid desolvation-triggered domino lattice rearrangement in a metal-organic framework. Nat. Chem. 2020, 12 (1), 90–97. 10.1038/s41557-019-0364-0. [DOI] [PubMed] [Google Scholar]
  54. Sato O.; Iyoda T.; Fujishima A.; Hashimoto K. Photoinduced Magnetization of a Cobalt-Iron Cyanide. Science 1996, 272 (5262), 704–705. 10.1126/science.272.5262.704. [DOI] [PubMed] [Google Scholar]
  55. Aguila D.; Prado Y.; Koumousi E. S.; Mathoniere C.; Clerac R. Switchable Fe/Co Prussian blue networks and molecular analogues. Chem. Soc. Rev. 2016, 45 (1), 203–224. 10.1039/C5CS00321K. [DOI] [PubMed] [Google Scholar]
  56. Yang Y.; Zhang X.; Kanchanakungwankul S.; Lu Z.; Noh H.; Syed Z. H.; Farha O. K.; Truhlar D. G.; Hupp J. T. Unexpected ″Spontaneous″ Evolution of Catalytic, MOF-Supported Single Cu(II) Cations to Catalytic, MOF-Supported Cu(0) Nanoparticles. J. Am. Chem. Soc. 2020, 142 (50), 21169–21177. 10.1021/jacs.0c10367. [DOI] [PubMed] [Google Scholar]
  57. Azbell T. J.; Milner P. J. Cobalt(III) Halide Metal-Organic Frameworks Drive Catalytic Halogen Exchange. J. Am. Chem. Soc. 2024, 146 (16), 11164–11172. 10.1021/jacs.3c13872. [DOI] [PMC free article] [PubMed] [Google Scholar]
  58. Zhang X.; Zhong H.; Zhang Q.; Zhang Q.; Wu C.; Yu J.; Ma Y.; An H.; Wang H.; Zou Y.; et al. High-spin Co3+ in cobalt oxyhydroxide for efficient water oxidation. Nat. Commun. 2024, 15 (1), 1383. 10.1038/s41467-024-45702-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  59. Crabtree R. H.The Organometallic Chemistry of the Transition Metals; John Wiley & Sons, 2014. [Google Scholar]
  60. Rieth A. J.; Yang S.; Wang E. N.; Dincă M. Record Atmospheric Fresh Water Capture and Heat Transfer with a Material Operating at the Water Uptake Reversibility Limit. ACS Cent. Sci. 2017, 3 (6), 668–672. 10.1021/acscentsci.7b00186. [DOI] [PMC free article] [PubMed] [Google Scholar]

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