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With the development of crystalline porous materials toward methane storage, the stability issue of metal–organic framework (MOF) materials has caused great concern despite high working capacity. Considering the high stability of zirconium-based MOFs and effective functions of amide groups toward gas adsorption, herein, a series of UiO-66 type of Zr-MOFs, namely, Zr-fcu-H/F/CH3/OH, were successfully designed and synthesized by virtue of amide-functionalized dicarboxylate ligands bearing distinct side groups (i.e., −H, −F, −CH3, and −OH) and ZrCl4in the presence of trifluoroacetic acid as the modulator. Single-crystal X-ray diffraction and topology analyses reveal that these compounds are archetypal fcuMOFs encompassing octahedral and tetrahedral cages, respectively. The N2sorption isotherms and acid–base stability tests demonstrate that the materials possess not only relatively high surface areas, pore volumes, and appropriate pore sizes but also great hydrolytic stabilities ranging pH = 3–11. Furthermore, the volumetric methane storage working capacities of Zr-fcu-H, Zr-fcu-F, Zr-fcu-CH3, and Zr-fcu-OH at 298/273 K and 80 bar are 187/217, 175/193, 167/187, and 154/171 cm3(STP) cm–3, respectively, which indicate that the zirconium-based crystalline porous materials are capable of storing relatively high amounts of methane.

Due to their intrinsic structural features, the design and synthesis of a new type of zeolite-like metal–organic frameworks (ZMOFs) is highly desirable but challenging. Herein, solvothermal reactions between an angular dicarboxylate linker and rare-earth (RE) ions afforded two RE-MOFs, namely, Tb-ZMOF-2 and Tb-ZMOF-3, respectively. Structural analyses reveal that Tb-ZMOF-2 encompasses a novel [446482] cage, while Tb-ZMOF-3 contains nonanuclear (i.e., D6R) and hexanuclear (i.e., D4R) RE clusters simultaneously, subsequently resulting in two new zeolitic topologies. Thanks to its high surface area and pore volume, Tb-ZMOF-2 demonstrates considerably high gravimetric and volumetric methane storage working capacities.

Solvothermal reaction between Fe3O(CH3COO)6(H2O)3and terphenyl-3,3′’,5,5′’-tetracarboxylic acid (H4TPTC) afforded a scarce multinary MOF of Quin-Fe-TPTC (Quin and TPTC are abbreviated from quinary and terphenyl-3,3′’,5,5′’-tetracarboxylate, respectively), which exemplifies the first quinary MOF comprising one metal and one linker in contrast to the documented ones assembled from one metal and four linkers or two metals and three linkers. The variation of linker aspect ratio and the deformation of the trinuclear iron cluster may be responsible for creating such a compound. Quin-Fe-TPTC exhibits bihelical channels interconnected through (hemi) cage cavities replete with methyl groups, resulting in C2H6-selective adsorption from a binary C2H6and C2H4mixture and benefiting one-step C2H4purification. This was validated by not only IAST prediction but also by dynamic column breakthrough experiments.

Due to the industrial requirements for high production and high quality of ethylene, efficient purification of ethylene from acetylene and ethane is of prime importance but challenging. Dynamic metal–organic frameworks (MOFs) have demonstrated intriguing structural dynamics and diverse applications recently. Among them, although a few flexible ones have exhibited interesting ethylene purification capability, rigid ones were yet barely investigated for such purpose. In this regard, a cerium(III)-based MOF was solvothermally synthesized, which is rigid and assembled from rod molecular building blocks associated with coordinative N,N-dimethylformamide (DMF) molecules. After liberating different degrees of DMF ligands via heating under vacuum or acetone exchange, both partially desolvated compounds of Ce-MOF-1 and Ce-MOF-2 were concertedly isolated in a fashion of single-crystal to single-crystal transformation. Although both newly generated materials crystallize in the same space group, they exhibit dissimilar unit cell parameters and slightly distinct ultramicropore sizes and pore microenvironments, thanks to the discrepancy in the desolvation degree. Consequently, Ce-MOF-1 and Ce-MOF-2 individually demonstrate C2H2- and C2H6-selective adsorption behavior, resulting in the potential tandem separation of C2H4from C2H2and C2H6mixtures. The above results were successfully supported by not only single gas adsorption isotherms but also grand canonical Monte Carlo (GCMC) calculation studies and dynamic breakthrough experiments. The present work may pave the way for rigid MOFs aiming at advancing applications via solid-state structural dynamics.

Reticular chemistry and methane storage materials have been predominately focused on finite metal-cluster-based metal–organic frameworks (MOFs). In contrast, MOFs constructed from infinite rod secondary building units (SBUs), i.e., rod MOFs, are less developed, and the existing ones are typically built from simple one-way helical, zigzag, or (mixed)polyhedron SBUs. Herein, inspired by a recent unveiled structure of Zn6(H2O)3(BTP)4and by means of an amide-functionalized preliminary single tricarboxylate, a subsequent mixed tricarboxylate, and dicarboxylate linkers, an intricate three-way rod MOF and the next three isoreticular three-way rod MOFs have been successfully realized, namely, 3W-ROD-1 and 3W-ROD-2-X (X = −OH, −F, and −CH3), respectively. The structural analyses disclosed that the four compounds were constructed from unprecedented three-way invariant nonintersecting trigonal rod-packing SBUs cross-linked via the noncovalent-interaction-driven self-assembly of pseudo hexacarboxylates with the original tricarboxylate or different functional ditopic linkers, resulting in cage-like pore geometries accessible via ultramicroporous apertures concomitant with the complex topology transitivity, namely, 18 42 and 18 44. Sorption studies show that the apparent surface areas of these materials are among the most highly porous materials for rod MOFs. Due to the presence of favorable pocket sites created by X, ketone, and proximal amide groups as revealed by Monte Carlo molecular dynamics (MCMD) computational calculations, the MOFs exhibit impressive methane storage working capacities, outperforming the well-known rod Ni-MOF-74 and representing the highest values among rigid rod MOFs.

The efficient single-step purification of ethylene from ternary C2mixtures containing ethane and acetylene is challenging and demanding. Herein, we introduce a novel cerium-based metal–organic framework (MOF) of Ce-NTB-rtksynthesized via a ligand-conformer strategy. The Ce-NTB-rtkfeatures a rare tetranuclear cerium cluster and 2D kgdlayers pillared by a 3D rtlframework concomitant with an extraordinary (3,3,12)-c network. The compound encompasses microporous cavities replete with a nonpolar microenvironment. Gas sorption and breakthrough experiments demonstrate its superior affinity for C2H6and C2H2over C2H4, enabling effective single-step ethylene purification. Computational simulations reveal that preferential adsorptions are facilitated by different interaction strengths of C–H···O hydrogen bonds. The performance of Ce-NTB-rtkin separation selectivity and regeneration capacity makes it a promising candidate for sustainable and cost-effective ethylene purification, showcasing the potential of MOFs in advanced gas separation applications.

Design and synthesis of multinary metal–organic frameworks (MOFs) are of paramount importance but challenging. Nevertheless, pore space partitioning has provided a valuable avenue to isolate ternary MOFs bearing advanced gas storage and separation properties. Herein, a rare (3,3,8)-c Fe-BQDC-BTC-TPBTC MOF was constructed by means of solvothermal reaction between iron ions, a zigzag dicarboxylate H2BQDC ligand and another two C3-symmetry TPBTC and H3BTC linkers. In contrast to the frequently observed single hexagonal channel type, the acs net within Fe-BQDC-BTC-TPBTC possesses two types of hexagonal channels. One of them is capable of fitting two differently sized C3-symmetry ligands, engendering an unusual quaternary MOF with a new partially partitioned acs 2/3-plus net eventually. Fe-BQDC-BTC-TPBTC demonstrates a complex bimodal porous system concomitant with a potential separation property toward the MTO product of ethylene and propene mixtures as verified by single gas adsorption and transient column breakthrough experiments, respectively.

Inspired by the elegant construction of molecular spheres, solvothermal reactions between ZrCl4and a bent ditopic carboxylate-based linker afforded two framework-isometric zirconium-based MOFs possessing bonand reotopologies, respectively. Both MOFs demonstrate not only hierarchically mesoporous porosities but also excellent hydrolytic stabilities. Moreover, both phases exhibit relatively high gravimetric energy gas storage working capacities between 80 and 5 bar, i.e., 3.87 wt % H2at 77 K for bonphase and 0.26 g (CH4) g–1at 273 K for the reophase, respectively.

CeIV6-based metal–organic frameworks (MOFs) have gained increasing attention recently because of their diverse potential applications and similarity to prominent Zr-MOFs, e.g., the UiO-66 series. However, the reported CeIV6-based MOFs were all structurally determined by means of the powder X-ray diffraction technique, indicative of less practice and convenience. Herein, four single-crystalline CeIV6-based MOFs were successfully isolated and characterized by single-crystal X-ray diffraction, disclosing two series of topologically distinct isoreticular nets accompanied by nine-coordinated central CeIVions, i.e., 8-connected hexand 12-connected fcu, respectively, in contrast to the previously reported sole fcutopology based on the combination of linear dicarboxylate ligands and a CeIV6cluster associated with eight-coordinated central CeIVions according to the UiO-66 structural model. Moreover, all four single-crystalline compounds exhibit permanent microporous porosities and a certain amount of gas uptake toward CO2, CH4, and H2.

Rational design and construction of metal–organic frameworks (MOFs) with intricate structural complexity are of prime importance in reticular chemistry. We report our latest addition to the design toolbox in reticular chemistry, namely the concept of merged nets based on merging two edge-transitive nets into a minimal edge-transitive net for the rational construction of intricate mixed-linker MOFs. In essence, a valuable net for design enclosing two edges (not related by symmetry) is rationally generated by merging two edge-transitive nets, namely (3,6)-coordinated spnand 6-coordinated hxg. The resultant merged-net, a (3,6,12)-coordinated sphnet with net transitivity [32] enclosing three nodes and two distinct edges, offers potential for deliberate design of intricate mixed-linker MOFs. We report implementation of the merged-net approach for the construction of isoreticular rare-earth mixed-linker MOFs, sph-MOF-1 to -4, based on the assembly of 12-c hexanuclear carboxylate-based molecular building blocks (MBBs), displaying cuboctahedral building units, 3-c tritopic ligands, and 6-c hexatopic ligands. The resultant sph-MOFs represent the first examples of MOFs where the underlying net is merged from two 3-periodic edge-transitive nets, spnand hxg. Distinctively, the sph-MOF-3 represents the first example of a mixed-linker MOF to enclose both trigonal and hexagonal linkers. The merged-nets approach allows the logical practice of isoreticular chemistry by taking into account the mathematically correlated dimensions of the two ligands to afford the deliberate construction of a mixed-linker mesoporous MOF, sph-MOF-4. The merged-net equation and two key parameters, ratio constant and MBB constant, are disclosed. A merged-net strategy for the design of mixed-linker MOFs by strictly controlling the size ratio between edges is introduced.

An amide-containing adenine-mediated rod metal-organic framework was solvothermally constructed by means of mixed-linker approach, which exhibits both C2H2and C2H6selective adsorption, resulting in one-step ethylene purification from a ternary mixture of C2H2/C2H4/C2H6as proved by not only IAST prediction, but also column breakthrough experiments. [Display omitted]

How to accurately detect and efficiently sweep Cr(VI) from contaminated water has come into focus. Zirconium-based metal–organic frameworks (MOFs) play vital roles in water environmental chemistry due to excellent hydrolysis-resistant stability. However, as photochemical probes and photocatalysts, poor performances in detection sensitivity, selectivity, and photosensitiveness limit sole Zr-MOFs’ applications. So, it is urgent to quest valid strategies to break through the dilemmas. Embedding luminous dyes into MOFs has been considered one of the most feasible avenues. Herein, a dual-emissive RhB@Zr-MOF with orange-yellow fluorescence has been assembled by in situ-encapsulating rhodamine B (RhB) into a zirconium–biquinoline-based MOF. Actually, within RhB@Zr-MOF, the aggregation fluorescence quenching (ACQ) effect of RhB molecules was effectively avoided. Notably, RhB@Zr-MOF exhibits a rapid fluorescence quenching response toward Cr(VI) ions with high selectivity, sensitivity, and anti-interference abilities. More interestingly, unlike the most widely reported fluorescence resonance energy transfer (FRET) between MOFs and encapsulated guest modules, photoinduced electron transfer from RhB to Zr-MOF has been confirmed by modeling the ground state and excited states of RhB@Zr-MOF using density functional theory (DFT) and time-dependent DFT (TD-DFT). The effective electron transfer makes RhB@Zr-MOF more sensitive in probing Cr2O72–and CrO42–ions with ultralow detection limit (DL) values of 6.27 and 5.26 ppb, respectively. Prominently, the detection sensitivity based on DL values has been increased about 6 and 9 times, respectively, compared with pristine Zr-MOF. Moreover, rather negative CB and positive VB potentials make RhB@Zr-MOF have excellent photochemical scavenging ability toward Cr(VI) and MO.

The design and synthesis of a single metal–organic framework (MOF) material with simultaneously high gravimetric and volumetric methane storage working capacities are still a great challenge. The open metal site (OMS) in MOFs is generally regarded as an advantage to enhance host–guest affinity. However, it is detrimental to the methane storage working capacity to some extent due to the resulting high low-pressure uptake. Moreover, the reported methane storage MOFs are predominately focusing on edge-transitive or low-connected mixed-linker networks. In contrast, high-connected mixed-linker MOFs have been less investigated for methane storage. Herein, three isoreticular nine-connected trinuclear iron-based Fe-ncb-MOFs without OMSs have been judiciously designed and successfully constructed by means of the mixed-linker approach associated with the fixing amide-functionalized pyridyl-carboxylate ligand LP(4-(pyridin-4-ylcarbamoyl)benzoate) and three differing sized dicarboxylate ligands. High-pressure methane adsorption measurements show that, with the isoreticular extension from BDC (1,4-benzenedicarboxylate) to BPDC (4,4′-biphenyldicarboxylate) and ABDC (azobenzene-4,4′-dicarboxylate), three Fe-ncb-MOFs exhibit gradually increasing not only gravimetric but also volumetric storage capacities because of their balancing gravimetric surface area and volumetric surface area, hierarchical pore system, and modest CH4heats of adsorption. Among them, the Fe-ncb-ABDC demonstrates a rare combination of simultaneously high gravimetric and volumetric CH4storage working capacities of 0.302/0.37 g g–1and 196/240 cm3(STP) cm–3at 298/273 K and between 80 and 5 bar, respectively, which outperform the 8-c Fe-8T18-ABDC assembled from a shorter pyridyl-carboxylate ligand IN (isonicotinate) and ABDC, due to its limited pore volume, the presence of OMSs, and more confined pore spaces, and place Fe-ncb-ABDC among the best performing MOFs.

Chromium Cr(VI) is frequently used in many fields and has been intensively researched for detection and/or removal from contaminated water. However, the existing approaches are still of low efficiency, high cost, and cumbersome in operation. It is thus highly imperative to hunt for alternative avenues to get out of the predicament. In this work, two bcutopological and highly stable zirconium-metal–organic frameworks (Zr-MOFs) of 1and 2have been deliberately prepared, displaying channel-type interior spaces replete with free bipyridine/biquinoline matrices and Zr-O defect sites. Because of their unique intrinsic features of high porosity and photosensitivity, 1and 2were deployed as versatile platforms to sense, adsorb, and catalytically reduce Cr(VI) ions. Indeed, the Zr-MOF of 1performs excellently in fluorescence sensing and adsorption trapping of Cr(VI), with an ultralow detection limit of 0.0176 ppm and a fairly high saturated adsorption capacity of 145.77 mg/g, while 2is more powerful than 1in photochemical removal of Cr(VI), exhibiting a remarkable reduction efficiency of 98.05% just within 70 min and still up to 92.21% even after five consecutive photocatalytic cycles. Furthermore, possible photoluminescence, quenching, and reduction mechanisms were also tentatively proposed. This study may open up a new avenue for addressing some unresolved environmental issues, that is, the decontamination of highly toxic Cr(VI) from water.