pubs.acs.org/JACS Article Isoreticular Contraction of Metal−Organic Frameworks Induced by Cleavage of Covalent Bonds Yunhui Yang, Pilar Fernández-Seriñán, Inhar Imaz,* Felipe Gándara, Marcel Handke, Borja Ortín-Rubio, Judith Juanhuix, and Daniel Maspoch* Cite This: J. Am. Chem. Soc. 2023, 145, 17398−17405 Read Online ACCESS Metrics & More Article Recommendations * sı Supporting Information ABSTRACT: Isoreticular chemistry, in which the organic or inorganic moieties of reticular materials can be replaced without destroying their underlying nets, is a key concept for synthesizing new porous molecular materials and for tuning or functionalization of their pores. Here, we report that the rational cleavage of covalent bonds in a metal−organic framework (MOF) can trigger their isoreticular contraction, without the need for any additional organic linkers. We began by synthesizing two novel MOFs based on the MIL-142 family, (In)BCN-20B and (Sc)BCN-20C, which include cleavable as well as noncleavable organic linkers. Next, we selectively and quantitatively broke their cleavable linkers, demonstrating that various dynamic chemical and structural processes occur within these structures to drive the formation of isoreticular contracted MOFs. Thus, the contraction involves breaking of a covalent bond, subsequent breaking of a coordination bond, and finally, formation of a new coordination bond supported by structural behavior. Remarkably, given that the single-crystal character of the parent MOF is retained throughout the entire transformation, we were able to monitor the contraction by single-crystal X-ray diffraction. ■ INTRODUCTION Metal−organic frameworks (MOFs), a class of crystalline linker, in the presence of a solvent. This enables generation of new isoreticular MOFs: for example, ones in which inter- materials assembled by combining inorganic metal-based penetration can be controlled13,14 or that can exhibit nodes with organic linkers, exhibit long-range ordered nondefault topologies.15 In SALE, replacement is performed structures with permanent porosity.1,2 Given the nearly infinite chiefly by using external linkers whose length is equal to or possible permutations of their building blocks, MOFs are greater than that of the original linkers, thereby affording a highly versatile: they can be designed to have distinctive lattice of the same or greater size.16−18 Alternatively, a few features such as an exceptionally large surface area and studies have shown that the framework can also be contracted, adjustable pore sizes. by using shorter linkers, although this approach has not been The design and synthesis of MOFs have been expanded by widely explored.14,19,20 The contraction of lattices can also reticular chemistry, which provides high levels of chemical confer the resultant MOFs21 with unusual properties such as control. This is achieved mainly by either of two strategies: (i) negative and stepwise gas-adsorption, modulation of the radical spin stated in solid state, or stimuli responsiveness and predesign of a novel target net through judicious design of the selectivity, which can be utile for applications such as gas molecular building blocks or (ii) use of a known net as a storage and separation, catalysis, sensing, and controlled blueprint for a novel material, designed by applying the release.22−28 isoreticular principle.3−6 The primary aim of isoreticular Herein, we report a new approach to isoreticular contraction chemistry is to tune or functionalize the organic or inorganic of MOFs that is based on breaking of covalent bonds and does moieties without altering their underlying nets. Thus, it has not require addition of any external linkers (Figure 1). proven invaluable for modulating the properties of MOFs and Recently, we described clip-off chemistry, a new synthetic for optimizing their performance in myriad applications. Isoreticular MOFs can be synthesized by common direct synthesis7−9 or by postsynthetic modification (PSM). PSM- Received: May 25, 2023 based methodologies to synthesize isoreticular MOFs include Published: July 26, 2023 linker functionalization, transmetalation, sequential linker installation, and solvent-assisted linker exchange (SALE).10−12 Among these, SALE is based on substitution of a linker that bridges two metal ions/clusters, with an external © 2023 The Authors. Published by American Chemical Society https://doi.org/10.1021/jacs.3c05469 17398 J. Am. Chem. Soc. 2023, 145, 17398−17405 Journal of the American Chemical Society pubs.acs.org/JACS Article Figure 1. Schematic of the isoreticular contraction of (In)BCN-20B and (Sc)BCN-20C induced by cleavage of covalent bonds. Figure 2. (a) Crystal structure of (In)BCN-20B. (b) Schematic of the stepwise isoreticular contraction from (In)BCN-20B (left) to (In)BCN-20B′ (middle) to (In)BCN-20A (right). Corresponding SCXRD data, revealing the octahedral cages viewed along the crystallographic c and b axes, highlighting transformation of the CCA linker (orange) to the shorter BDC linker (violet), and contraction of the triangular face. (c) Crystal structure of (In)BCN-20A. strategy to make new molecules and materials based on the exhibiting contracted structures relative to their parent MOFs. selective, quantitative, and controlled cleavage of bonds in To this end, we have designed two new mixed-linker parent reticular materials.29 Here, we show that this concept can be MOFs that are isoreticular to the nht-(Fe)MIL-142 family:30,31 applied to control the stepwise synthesis of isoreticular MOFs (In)BCN-20B and (Sc)BCN-20C (BCN stands for Barcelona 17399 https://doi.org/10.1021/jacs.3c05469 J. Am. Chem. Soc. 2023, 145, 17398−17405 Journal of the American Chemical Society pubs.acs.org/JACS Article Material). This new isoreticular synthetic approach begins with the cleavage of an olefinic bond of one of the bridging linkers, which splits the linker into two monocoordinated ligands. This periodic and quantitative fracture in the MOF is followed by the decoordination of one of the monocoordinated ligands, using solvents. This ligand removal instantaneously induces both contraction of the lattice and a self-healing phenomenon, which involves the migration and coordination of the monocoordinated ligand remaining in the structure to the accessible metal ions. Interestingly, this stepwise isoreticular contraction of MOFs, which involves breaking of a covalent bond, subsequent breaking of a coordination bond, and finally, formation of a new coordination bond supported by dynamic structural behavior, can be followed by single-crystal X-ray diffraction (SCXRD), as these events occur in a single-crystal to single-crystal manner. ■ RESULTS AND DISCUSSION We began by synthesizing (In)BCN-20B. First, a dispersion of In(NO3)3·xH2O, 4,4′,4″-(1,3,5-triazine-2,4,6-triyl)tribenzoic acid (H3TATB) and 4-carboxycinnamic acid (H2CCA) in N,N-dimethylformamide (DMF) and HNO3 (3.5 M in DMF) was heated at 120 °C for 30 h. Next, the resulting hexagonal prismatic crystals were analyzed by SCXRD, which confirmed formation of a 3D framework isoreticular to nht-(Fe)MIL- 142B. (In)BCN-20B crystallizes in a trigonal lattice with an R3̅c (No. 167) space group, with unit cell parameters of a = b = 30.820 and c = 95.540 Å (Table S1). The 3D structure of (In)BCN-20B is formed by vertex-sharing distorted octahedral cages, with an underlying nht topology (Figure 2a). Each cage is formed by six trigonal prismatic In3O(−CO2)6 clusters located at vertices, which are connected by four tritopic TATB linkers and three ditopic CCA linkers. Note that these CCA linkers are symmetrically disordered about an inversion center, which results in similarity of spatial occupation between the dislocated aromatic rings of the CCA linker and those of a naphthalene molecule (Figures S1 and S2). The location of the two types of linkers within the cage defines one triangular face, whose edges are occupied by three CCA linkers (Figure 2b, left and Figure S3), and four triangular faces, each of which is occupied by one TATB linker. This means that each of the three remaining faces shares one of the edges occupied by a CCA linker with the first triangular face, whereas the other two edges are unoccupied. The overall framework of (In)BCN-20B shows a 2-fold interpenetrated structure, in which two catenane-like octahedral cages from two different nht nets interlocked via one of their pure TATB triangular faces (Figure S4). Further characterization of (In)BCN-20B confirmed its phase purity, as the experimental powder-XRD (PXRD) pattern matched the simulated one (Figure 3a). Furthermore, the 1H-NMR spectrum of the digested sample contained the Figure 3. (a) PXRD patterns of simulated (black) and experimental expected TATB/CCA ratio of 4:3 (Figure S6). (orange) (In)BCN-20B; simulated (gray) and experimental (cyan) Having synthesized (In)BCN-20B, we then cleaved all its (In)BCN-20B′; and simulated (light gray) and experimental (violet) alkene bonds and subsequently converted them into aldehyde/ (In)BCN-20A. (b) 1H-NMR spectra of (In)BCN-20B (orange), carboxylic acid groups via a solid−gas ozonolysis reac- (In)BCN-20B′ (cyan), and (In)BCN-20A (violet). The protons from olefinic bonds and terephthalate have been highlighted in orange and tion.29,32,33 First, 20 mg of single crystals of solvent-free violet, respectively. (c) Infrared spectra of (In)BCN-20B (orange), (In)BCN-20B were packed into a plastic tube. Next, dry ozone (In)BCN-20B′ (cyan), and (In)BCN-20A (violet). was flowed (∼15 g/Nm3) continuously through the sample for 35 min. Finally, the resultant crystals were analyzed by SCXRD, showing that ozonized (In)BCN-20B′ crystallized in that of (In)BCN-20B but with evident changes in its a trigonal lattice with an R3̅m (No. 166) space group, having connectivity through the CCA linkers. Indeed, SCXRD data unit cell parameters of a = b = 30.830 and c = 47.592 Å (Table confirmed the integrity of the inorganic In-oxo clusters and of S2). Overall, (In)BCN-20B′ exhibited a related 3D structure to the TATB linkers. However, at the positions initially occupied 17400 https://doi.org/10.1021/jacs.3c05469 J. Am. Chem. Soc. 2023, 145, 17398−17405 Journal of the American Chemical Society pubs.acs.org/JACS Article by the CCA linkers, the similarity in spatial occupation (Figure 2c). This new MOF crystallizes in the trigonal lattice between the dislocated aromatic rings of the CCA linker and with the space group R3̅m (No. 166) and lattice parameters of the naphthalene molecule was lost (Figure 2b, middle). This a = b = 28.783 and c = 47.708 Å (Table S3). (In)BCN-20A, observation clearly suggested that the CCA linkers no longer which is isostructural to nht-(Fe)MIL-142A,30 recovers the existed. initial 3D nht framework formed by vertex-sharing distorted To confirm the oxidative cleavage of CCA linkers into the octahedral cages. However, its cages are instead formed by six expected monocoordinated glyoxylate and single deprotonated In3O(−CO2)6 clusters connected by four tritopic TATB terephthalic acid (BDC) ligands (Figure 2b), we analyzed a linkers and three ditopic BDC linkers, the latter occupying digested (In)BCN-20B′ sample by 1H NMR and then the analogous position of the CCA linkers in (In)BCN-20B compared the resulting spectrum to that of the starting (Figure 2b, right). (In)BCN-20B (Figures 3b and S6, S8). The spectrum of the The phase transition from (In)BCN-20B′ to (In)BCN-20A digested (In)BCN-20B showed the characteristic peaks of the unambiguously unveiled a self-healing behavior, which we olefinic protons of CCA at δ = 7.64 and δ = 6.65 ppm. In envisaged occurs in three steps within the pores. First, DMF contrast, the spectrum of the digested (In)BCN-20B′ molecules enter the pores and replace the glyoxylate linkers. corroborated the disappearance of this olefinic signal. It also Here, the release of glyoxylate from the MOF was revealed the disappearance of the phenyl (δ = 7.94 and δ = experimentally confirmed by analyzing the DMF supernatant 7.81 ppm) and the carboxylic acid (δ = 13.06 ppm) protons of resulting from the incubation process by ESI-MS, from which the CCA but did show the characteristic signals for the the characteristic peak at m/z = 72.99 was detected (Figure terephthalic acid (BDC, δ = 8.04 ppm). Unfortunately, the S13). Second, the decoordination of glyoxylate causes the aldehyde proton of the glyoxylic acid was not detected, framework to act dynamically. In the third and final step, this presumably due to the fact that its boiling point (111 °C) is behavior leads to coordination of the free carboxylic acid group lower than the temperature (120 °C) at which the digestion of each BDC linker to the In3+ metal sites that were previously took place overnight. However, the presence of glyoxylic acid occupied by the glyoxylate. Accordingly, the BDC linker would was confirmed by electrospray ionization mass spectrometry have to migrate a distance of ∼2.4 Å. (ESI-MS) analysis in a negative ion mode using a (In)BCN- To further evaluate the degree of the aforementioned 20B′ sample digested under milder conditions (HF in DMSO flexibility, we compared the unit cell volumes of the three at room temperature). The ESI-MS spectrum showed a peak at MOFs: the initial (In)BCN-20B, the ozonated (In)BCN-20B′, m/z = 72.99, which matches the molecular mass of the and the self-healed (In)BCN-20A (Table S4). From (In)BCN- deprotonated glyoxylate [C2HO3]− (m/z = 73.03; Figure S9). 20B to (In)BCN-20B′, the unit cell volume only shrunk by These results clearly indicated that the olefinic bond of the 0.3%. However, from (In)BCN-20B′ to (In)BCN-20A, the cell ditopic CCA linkers had been quantitatively cleaved by volume decreased by 12.6%, an obvious volumetric contrac- ozonolysis and subsequently converted into two monocoordi- tion. We reasoned that the movements involving this dynamic nated ligands: a single deprotonated BDC and a glyoxylate. behavior could also be studied by comparing the structural Supporting this oxidative cleavage reaction, the FTIR spectrum changes in the octahedral cage units (Figures 2b and S14). In of the ozonated (In)BCN-20B′ exhibited a more intense C� the octahedral cage of the initial (In)BCN-20B, the length O stretch band at 1697 cm−1 relative to that in the spectrum of (note: all lengths were calculated starting from the carbon the non-ozonated (In)BCN-20B. Moreover, it showed atoms of the carboxylate groups of the linkers) of the edges of enhanced, broad absorbance at around 3300 cm−1, indicative the face constructed with CCA linkers is 8.0 Å, and the average of large perturbations caused by H-bonded hydroxyl groups of length of the remaining edges is 12.1 Å. As we had expected, the free carboxylic acid groups (Figures 3c and S10).34,35 Next, cleavage of the CCA linkers barely affected this octahedral cage we performed PXRD on a bulk sample of ozonated (In)BCN- unit: the length of the edges of the face occupied by the 20B′ to confirm its crystallinity and phase purity. The resulting cleaved CCA linkers only increased to 8.2 Å. We attributed this PXRD pattern matched the one calculated from the crystal slight increase to the steric hindrance effects of both the BDC structure (Figures 3a and S11), confirming that the cleavage of and the glyoxylate linkers. In (In)BCN-20A, this length alkene bonds via ozonolysis did not compromise the decreases significantly, down to 5.7 Å, because the BDC linker crystallinity throughout the bulk sample. Together these is much smaller than both the initial and the cleaved CCA results confirmed the quantitative cleavage of CCA linkers linkers. Contrariwise, this contraction barely affects the other and the consequent formation of a new structure with less edges involving the TATB linker, exhibiting an average length connectivity among its trimeric In3+ clusters. Indeed, analysis of 12.0 Å. of the topology of (In)BCN-20B′ using the ToposPro 5.3.3.5 Given that the structure of (In)BCN-20A differs markedly software,36 and considering TATB linkers as 3-connected from that of (In)BCN-20B or (In)BCN-20B′, we studied points of extension (3-c), and In3O(−CO2)6 clusters as nodes whether this transformation would occur throughout the bulk that have four coordination points (4-c), revealed formation of sample, using PXRD. Supporting a homogeneous trans- a 2-fold interpenetrated MOF with two independent under- formation, the PXRD pattern of (In)BCN-20A matched the lying trinodal (3,3,4)-c nets (topological code 3,3,4T22, one calculated from the corresponding structure determined by Figure S12). SCXRD (Figures 3a and S15). Comparing the PXRD patterns Having demonstrated that ditopic CCA linkers could be of (In)BCN-20A and (In)BCN-20B, we found that the cleaved into two monocoordinated ligands, we then explored diffraction peak of (In)BCN-20B at 2θ = 3.8° which the possibility of substituting these monocoordinated ligands corresponds to the (102̅) crystallographic plane being shifted with solvent molecules. First, crystals of (In)BCN-20B′ were to a higher angle (2θ = 5.1°) in the same plane of (In)BCN- incubated in DMF for 1 week at room temperature. Next, the 20A, thus confirming the compression of the framework. Phase resultant crystals were analyzed by SCXRD, which revealed homogeneity was also studied by FTIR and 1H NMR (Figures that a new 3D structure (In)BCN-20A had been formed S16 and S17). The FTIR spectrum revealed that the stretching 17401 https://doi.org/10.1021/jacs.3c05469 J. Am. Chem. Soc. 2023, 145, 17398−17405 Journal of the American Chemical Society pubs.acs.org/JACS Article Figure 4. (a) Crystal structure of (Sc)BCN-20C. (b) Schematic and corresponding SCXRD structures of the stepwise isoreticular contraction from (Sc)BCN-20C (top) to (Sc)BCN-20C′ (middle) to (Sc)BCN-20A (down). (c) Crystal structure of (Sc)BCN-20A. band of characteristic carbonyl groups (1697 cm−1) and the whose length is increased to 12.2 Å. The other edges of the broad absorbance at around 3300 cm−1 had been dramatically octahedra are slightly longer (12.3 Å) than those of (In)BCN- attenuated, identically to that of the initial (In)BCN-20B 20B. The phase purity of (Sc)BCN-20C was confirmed by (Figure 3c). The 1H NMR spectrum confirmed the expected PXRD, whose pattern matched the one simulated from TATB/BDC ratio of 4:3. SCXRD data (Figures S19 and S20), and by 1H NMR, the We would like to highlight that all our attempts to transform spectrum confirmed the expected BTB/Sti ratio of 4:3 (Figure (In)BCN-20B into (In)BCN-20A by direct linker exchange of S23). CCA by BDC were unsuccessful (see Section 2 of the Next, we performed a cleavage experiment on the Sti linkers Supporting Information). This suggests that covalent bond similar to the previous experiment on the CCA linkers (Figure cleavage of the CCA linker highly facilitates the internal 4b). Thus, ozone was flowed (∼15 g/Nm3) continuously restructuration of the framework, involving both flexible and through a crystalline sample of solvent-free (Sc)BCN-20C for self-healing behavior. 5 min. The quantitative cleavage of Sti linkers and conversion Seeking to investigate whether such behavior could occur in of the resultant fragments to the expected monocoordinated an isoreticular framework with greater distances between metal HBDC and 4-formylbenzoate (4-FBA) were corroborated by 1 clusters, we substituted the CCA linker with the 4,4′- H NMR, SCXRD, PXRD, and FTIR (Table S6, Figures S21, stilbenedicarboxylic acid (H2Sti) linker, which is longer S24, S25, and S29). Additionally, SCXRD data revealed that (Figure 4a). However, all our attempts at synthesizing the the structure of (Sc)BCN-20C’ is very similar to that of the isostructural MOF using In3+ were unsuccessful. Fortunately, initial (Sc)BCN-20C, with the corresponding octahedral cage we were able to synthesize its Sc3+ analogue using the (ditopic) units having similar dimensions. However, we observed one Sti linker and the (tritopic) 1,3,5-tris(4-carboxyphenyl)- significant difference: benzoate ligands�most likely, 4-FBA benzene (BTB) linker (Figure 4a). (Sc)BCN-20C crystallizes linkers with highly disordered aldehyde groups�bridging the in the monoclinic symmetry with a C2/c space group (No. 15) two interpenetrated nets and partially substituting the formate and lattice parameters of a = 60.279, b = 34.723, and c = ligands. This observation evidenced the mobility of these 37.136 Å (Table S5). As its analogues, it contains a 2-fold monocoordinated ligands inside the pores upon cleavage of the interpenetrated structure with two underlying nht nets (Figure ditopic linkers. S18). Note that the two nets are interconnected by formate Finally, endeavoring to remove the 4-FBA ligands and linkers that can be formed upon decomposition of DMF aided induce the dynamic and self-healing behavior for the formation by HNO3.31,37 These nets are built up from vertex-sharing of the isoreticular (Sc)-BCN-20A, we immersed (Sc)BCN- distorted octahedral cages, which are larger than those of 20C′ in DMF for a week. Interestingly, SCXRD of the resulting (In)BCN-20B or (In)BCN-20A. Their main difference lies in crystals confirmed the formation of this MOF (Table S7, the edges of the triangular face defined by three Sti linkers, Figures S18, S19, S22, and S26−S29), whose structure is 17402 https://doi.org/10.1021/jacs.3c05469 J. Am. Chem. Soc. 2023, 145, 17398−17405 Journal of the American Chemical Society pubs.acs.org/JACS Article isostructural to that of (In)BCN-20A (Figure 4b,c). (Sc)- BCN-20A crystallizes in a trigonal system with the space group ■ AUTHOR INFORMATION Corresponding Authors R3̅c (No. 167) and lattice parameters of a = b = 28.682 and c = Inhar Imaz − CSIC, and Barcelona Institute of Science and 95.606 Å. Accordingly, through this dynamic, self-healing Technology, Catalan Institute of Nanoscience and phenomenon, the cell volume had been dramatically com- Nanotechnology (ICN2), Bellaterra, Barcelona 08193, pressed by 30.7% (Table S8 and Figure S31). In this process, Spain; Departament de Química, Facultat de Ciències, all BDC linkers traveled a distance of ∼6.4 Å to coordinate to Universitat Autònoma de Barcelona, Bellaterra 08193, the Sc3+ metal sites, shrinking one of the triangular faces of the Spain; orcid.org/0000-0002-0278-1141; cages from 12.2 to 6.1 Å. Email: inhar.imaz@icn2.cat Daniel Maspoch − CSIC, and Barcelona Institute of Science ■ CONCLUSIONS In conclusion, we have shown that the cleavage of covalent and Technology, Catalan Institute of Nanoscience and Nanotechnology (ICN2), Bellaterra, Barcelona 08193, Spain; Departament de Química, Facultat de Ciències, bonds within bridging organic linkers in an MOF can trigger a Universitat Autònoma de Barcelona, Bellaterra 08193, series of chemical and structural dynamic processes that drive Spain; ICREA, Barcelona 08010, Spain; orcid.org/0000- the formation of an isoreticular contracted MOF. Remarkably, 0003-1325-9161; Email: daniel.maspoch@icn2.cat as the single-crystal character of the parent MOF is retained throughout the entire isoreticular transformation, we were able Authors to use SCXRD to obtain invaluable crystallographic snapshots Yunhui Yang − CSIC, and Barcelona Institute of Science and of the stepwise processes. Initially, applying our concept of Technology, Catalan Institute of Nanoscience and clip-off chemistry, we were able to cleave each bridging alkene- Nanotechnology (ICN2), Bellaterra, Barcelona 08193, containing organic linker into two monocoordinated ligands Spain; Departament de Química, Facultat de Ciències, via ozonolysis, thereby disconnecting two metal clusters. Universitat Autònoma de Barcelona, Bellaterra 08193, Spain Among these monocoordinated ligands, one is terminated Pilar Fernández-Seriñán − CSIC, and Barcelona Institute of with a carboxylic acid group, whereas the other ends in an Science and Technology, Catalan Institute of Nanoscience and aldehyde group. As this latter ligand is weaker, we were able to Nanotechnology (ICN2), Bellaterra, Barcelona 08193, decoordinate it from the metal center by simply treating the Spain; Departament de Química, Facultat de Ciències, MOF with DMF. This removal process conferred the structure Universitat Autònoma de Barcelona, Bellaterra 08193, with dynamic behavior that involved the migration and Spain; orcid.org/0000-0002-6456-7386 subsequent coordination of the other monocoordinated ligand Felipe Gándara − Consejo Superior de Investigaciones Científicas (CSIC), Materials Science Institute of Madrid with a free carboxylic acid group to the open metal site. In (ICMM), Madrid 28049, Spain; orcid.org/0000-0002- what we have called “self-healing behavior”, the metal clusters 1671-6260 that had been disconnected during cleavage of the linker bond Marcel Handke − CSIC, and Barcelona Institute of Science reconnected to form a new MOF isoreticular to the initial one, and Technology, Catalan Institute of Nanoscience and with a contracted structure. Thus, the complete transformation Nanotechnology (ICN2), Bellaterra, Barcelona 08193, involves breaking of covalent bonds, breaking and formation of Spain; Departament de Química, Facultat de Ciències, coordination bonds, and contraction of the crystal structure, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain with reductions in the cell volume of up to 30.7%, all occurring Borja Ortín-Rubio − CSIC, and Barcelona Institute of Science in a single-crystal to single-crystal manner. Overall, these and Technology, Catalan Institute of Nanoscience and stepwise isoreticular transformations exemplify the rich Nanotechnology (ICN2), Bellaterra, Barcelona 08193, chemistry that can be done inside MOF pores. They also Spain; Departament de Química, Facultat de Ciències, underscore the potential of clip-off chemistry (i.e., breaking of Universitat Autònoma de Barcelona, Bellaterra 08193, covalent bonds) to discover new phenomena in MOFs and to Spain; orcid.org/0000-0002-0533-3635 synthesize new MOFs or other materials. Judith Juanhuix − ALBA Synchrotron, Cerdanyola del Vallès, Barcelona 08290, Spain; orcid.org/0000-0003-3728- ■ * ASSOCIATED CONTENT sı Supporting Information 8215 Complete contact information is available at: https://pubs.acs.org/10.1021/jacs.3c05469 The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/jacs.3c05469. Notes Detailed syntheses, optical microscopy images, PXRD The authors declare no competing financial interest. diffractogram, FT-IR, ESI-MS, NMR, and crystallo- graphic details (PDF) ■ ACKNOWLEDGMENTS We thank Dr. Jorge Albalad for converting PXRD patterns and Accession Codes Dr. Dongsik Nam for useful discussions about crystallography. CCDC 2264121−2264126 contain the supplementary crys- This work has received funding from the European Union’s tallographic data for this paper. These data can be obtained Horizon 2020 research and innovation program under grant free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by agreement no. 101019003, Grants Ref. PID2021-124804NB- emailing data_request@ccdc.cam.ac.uk, or by contacting The I00 and PID2021-123287OB-I00 funded by MCIN/AEI/ Cambridge Crystallographic Data Centre, 12 Union Road, 10.13039/501100011033/ and by “ERDF A way of making Cambridge CB2 1EZ, UK; fax: +44 1223 336033. Europe”, and the Catalan AGAUR (project 2021 SGR 00458). 17403 https://doi.org/10.1021/jacs.3c05469 J. Am. Chem. Soc. 2023, 145, 17398−17405 Journal of the American Chemical Society pubs.acs.org/JACS Article This work was also funded by the CERCA program/ Positions of Metal Centers via Sequential Ligand Elimination and Generalitat de Catalunya. ICN2 is supported by the Severo Installation in MOFs. J. Am. Chem. Soc. 2018, 140, 10814−10819. Ochoa Centres of Excellence program, Grant CEX2021- (18) Yuan, S.; Qin, J.-S.; Su, J.; Li, B.; Li, J.; Chen, W.; Drake, H. F.; 001214-S, funded by MCIN/AEI/10.13039.501100011033. Zhang, P.; Yuan, D.; Zuo, J.; Zhou, H.-C. Sequential Transformation of Zirconium(IV)-MOFs into Heterobimetallic MOFs Bearing Y.Y. acknowledges the China Scholarship Council for scholar- Magnetic Anisotropic Cobalt(II) Centers. Angew. Chem., Int. Ed. ship support. 2018, 57, 12578−12583. ■ REFERENCES (1) Zhou, H.-C.; Long, J. R.; Yaghi, O. M. 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