Mg1−xCoxLi2(3,5-pdcH)2(DMF)2 (x = 0, 0.285, 0.575, 1): a series of heterometallic coordination polymers doped with magnetic Co2+ ions

Presented is a series of Mg_1−xCo_xLi-HCPs with the turn-on effect of anti-ferromagnetic properties upon the doping of high-spin Co²⁺ ions at Mg²⁺ sites.

Sensing and capture of toxic and hazardous gases and vapors by metal–organic frameworks

This review summaries recent progress in the luminescent detection and adsorptive removal of harmful gases and vapors by metal–organic frameworks, as well as the principles and strategies guiding the design of these materials.

Degradation of chemical warfare agents over cotton fabric functionalized with UiO-66-NH2

Herein, cotton fabric was treated with an alkaline solution to increase the content of surface hydroxyl groups and then functionalized with UiO-66-NH₂, a nanoporous metal–organic framework. Instrumental analysis of the thus treated fabric revealed that its surface was covered with UiO-66-NH₂ crystals in a uniform manner. The ability of the functionalized fabric to degrade two chemical warfare agents (soman and sulfur mustard) was probed by testing its permeability to these two agents (swatch testing), and the excellent degradation performance was concluded to be well suited for a broad range of filtration and decontamination applications.

We develop a very efficient modification method of cotton fabric to be functionalized with a MOF via mercerization.

Green and rapid mechanosynthesis of high-porosity NU- and UiO-type metal–organic frameworks

Dodecanuclear zirconium precursor enables a rapid and efficient mechanochemical synthesis of advanced MOFs NU-901 and UiO-67 with surface areas of up to 2250 m² g⁻¹.

Binuclear Mn2+ complexes of a biphenyltetracarboxylic acid with variable N-donor ligands: syntheses, structures, and magnetic properties

A series of manganese(ii) coordination polymers show a variety of features due to the recognition and assembly processes of the N-donor ligands.

Highly stable mesoporous silica nanospheres embedded with FeCo/graphitic shell nanocrystals as magnetically recyclable multifunctional adsorbents for wastewater treatment

We report the first synthesis of highly stable and efficiently recyclable multifunctional adsorbents containing FeCo/GC nanoparticles with the strongest magnetic properties.

Acid- and base-stable porous mechanically interlocked 2D metal–organic polyrotaxane forin situorganochlorine insecticide encapsulation, sensing and removal

The encapsulation and removal of extremely toxic dieldrin by compound1.

Multifunctional luminescent Zn(ii)-based metal–organic framework for high proton-conductivity and detection of Cr3+ ions in the presence of mixed metal ions

A luminescent MOF with rectangular channels shows high proton conductivity up to 0.95 × 10⁻² S cm⁻¹ and selective Cr³⁺ sensing properties in presence of mixed metal ions.

Metal coordination and metal activation abilities of commonly unreactive chloromethanes toward metal–organic frameworks

The commonly inert chloromethanes, dichloromethane and trichloromethane, can exchange other solvents bonded at open coordination sites in metal–organic frameworks, providing a new route to activate the open coordination sites for subsequent use in applications.

Post-synthetic modification of zirconium metal–organic frameworks by catalyst-free aza-Michael additions

UiO-66-NH₂ reacts with acrylonitrile, acrylic acid, methyl acrylate and methyl vinyl ketone leading to post-synthetic modification of the MOF through C–N bond formation. The acrylonitrile-modified MOF undergoes further reaction to form a tetrazolate-modified MOF.

Exploring the syntheses, structures, topologies, luminescence sensing and magnetism of Zn(ii) and Mn(ii) coordination polymers based on a semirigid tricarboxylate ligand

Two Zn(ii)-CPs and two Mn(ii)-CPs were constructed from metal salts, H₃cpota and N-heterocyclic group ligands. Their structures, magnetic properties and luminescence sensing properties have been studied in detail.

Efficient extraction of inorganic selenium from water by a Zr metal–organic framework: investigation of volumetric uptake capacity and binding motifs

MOF-808 displays enhanced gravimetric and volumetric uptake capacities for selenium oxyanions and the binding motifs are crystallographically characterized.

Effect of surface acidity of cyano-bridged polynuclear metal complexes on the catalytic activity for the hydrolysis of organophosphates

Heterogeneous catalysis of cyano-bridged polynuclear metal complexes was examined for the hydrolysis of toxic organophosphates. The surface acidity of cyano-bridged polynuclear metal complexes strongly effects on the catalytic activity.

UiO-66-NH2 Metal-Organic Framework (MOF) Nucleation on TiO2, ZnO, and Al2O3 Atomic Layer Deposition-Treated Polymer Fibers: Role of Metal Oxide on MOF Growth and Catalytic Hydrolysis of Chemical Warfare Agent Simulants

Metal-organic frameworks (MOFs) chemically bound to polymeric microfibrous textiles show promising performance for many future applications. In particular, Zr-based UiO-66-family MOF-textiles have been shown to catalytically degrade highly toxic chemical warfare agents (CWAs), where favorable MOF/polymer bonding and adhesion are attained by placing a nanoscale metal-oxide layer on the polymer fiber preceding MOF growth. To date, however, the nucleation mechanism of Zr-based MOFs on different metal oxides and how product performance is affected are not well understood. Herein, we provide new insight into how different inorganic nucleation films (i.e., Al₂O₃, ZnO, or TiO₂) conformally coated on polypropylene (PP) nonwoven textiles via atomic layer deposition (ALD) influence the quality, overall surface area, and the fractional yield of UiO-66-NH₂ MOF crystals solvothermally grown on fiber substrates. Of the materials explored, we find that TiO₂ ALD layers lead to the most effective overall MOF/fiber adhesion, uniformity, and a rapid catalytic degradation rate for a CWA simulant, dimethyl p-nitrophenyl phosphate (DMNP) with t_1/2 = 15 min, 580-fold faster than the catalytic performance of untreated PP textiles. Interestingly, compared to ALD TiO₂ and Al₂O₃, ALD ZnO induces a larger MOF yield in solution and mass loading on PP fibrous mats. However, this larger MOF yield is ascribed to chemical instability of the ZnO layer under MOF formation condition, leading to Zn²⁺ ions that promote further homogeneous MOF growth. Insights presented here improve understanding of compatibility between active MOF materials and substrate surfaces, which we believe will help advanced MOF composite materials for a variety of useful functions.

Methane Adsorption in Zr-Based MOFs: Comparison and Critical Evaluation of Force Fields

The search for nanoporous materials that are highly performing for gas storage and separation is one of the contemporary challenges in material design. The computational tools to aid these experimental efforts are widely available, and adsorption isotherms are routinely computed for huge sets of (hypothetical) frameworks. Clearly the computational results depend on the interactions between the adsorbed species and the adsorbent, which are commonly described using force fields. In this paper, an extensive comparison and in-depth investigation of several force fields from literature is reported for the case of methane adsorption in the Zr-based Metal-Organic Frameworks UiO-66, UiO-67, DUT-52, NU-1000, and MOF-808. Significant quantitative differences in the computed uptake are observed when comparing different force fields, but most qualitative features are common which suggests some predictive power of the simulations when it comes to these properties. More insight into the host-guest interactions is obtained by benchmarking the force fields with an extensive number of ab initio computed single molecule interaction energies. This analysis at the molecular level reveals that especially ab initio derived force fields perform well in reproducing the ab initio interaction energies. Finally, the high sensitivity of uptake predictions on the underlying potential energy surface is explored.

Degradation of Paraoxon and the Chemical Warfare Agents VX, Tabun, and Soman by the Metal-Organic Frameworks UiO-66-NH2, MOF-808, NU-1000, and PCN-777

In recent years, Zr-based metal-organic frameworks (MOFs) have been developed that facilitate catalytic degradation of toxic organophosphate agents, such as chemical warfare agents (CWAs). Because of strict regulations, experiments using live agents are not possible for most laboratories and, as a result, simulants are used in the majority of cases. Reports that employ real CWAs are scarce and do not cover the whole spectrum of agents. We here present a comparative study in which UiO-66-NH₂, NU-1000, MOF-808, and PCN-777 are evaluated for their effectiveness in the degradation of paraoxon and the chemical warfare agents tabun, VX, and soman, in N-ethylmorpholine buffer (pH 10) as well as in pure water. All MOFs showed excellent ability to degrade the agents under basic conditions. It was further disclosed that tabun is degraded by different mechanisms depending on the conditions. The presence of an amine, either as part of the MOF structure (UiO-66-NH₂) or in the agent itself (VX, tabun), is the most important factor governing degradation rates in water. The results show that MOFs have great potential in future protective applications. Although the use of simulants provides valuable information for initial screening and selection of new MOFs, the use of live agents revealed additional mechanisms that should aid the future development of even better catalysts.

Extending the Use of Highly Porous and Functionalized MOFs to Th(IV) Capture

Thorium separation has recently become a hot topic because of the potential application of thorium as a future nuclear fuel, while metal-organic framework (MOF) materials have received much attention in the separation field due to their unique properties. Herein, a highly porous and stable MOF, UiO-66, and its carboxyl derivatives (UiO-66-COOH and UiO-66-(COOH)₂) were synthesized and explored for the first time for Th(IV) capture from a weak acidic solution. Although the introduction of carboxyl groups into UiO-66 leads to an obvious decrease in the surface area and pore volume, the adsorbability toward Th(IV) is greatly enhanced. At pH = 3.0, the saturated sorption capacity for Th(IV) into UiO-66-(COOH)₂ reached 350 mg/g, representing one of the largest values for Th(IV) capture by solid extraction. Moreover, the functionalized MOFs show fast sorption kinetics and desirable selectivity toward Th(IV) over a range of competing metal ions. A possible mechanism for the selective recognition of Th(IV) by these MOFs was explored on the basis of extended X-ray absorption fine structure and Fourier transform infrared analysis. It is concluded that UiO-66-COOH and UiO-66-(COOH)₂ sorb Th(IV) through the coordination of carboxyl anions in the pores of the MOFs, whereas in the case of UiO-66, both the precipitation and the exchange with the organic solvent contribute to the Th(IV) uptake. This study contributes to the assessment of the feasibility of MOFs applied in actinides separation and better understanding of actinides sorption behavior in this kind of hybrid porous solid materials.

Chemical Warfare Agents Detoxification Properties of Zirconium Metal-Organic Frameworks by Synergistic Incorporation of Nucleophilic and Basic Sites

The development of protective self-detoxifying materials is an important societal challenge to counteract risk of attacks employing highly toxic chemical warfare agents (CWAs). In this work, we have developed bifunctional zirconium metal-organic frameworks (MOFs) incorporating variable amounts of nucleophilic amino residues by means of formation of the mixed ligand [Zr₆O₄(OH)₄(bdc)_6(1-x)(bdc-NH₂)_6x] (UiO-66-xNH₂) and [Zr₆O₄(OH)₄(bpdc)_6(1-x)(bpdc-(NH₂)₂)_6x] (UiO-67-x(NH₂)₂) systems where bdc = benzene-1,4-dicarboxylate; bdc-NH₂= benzene-2-amino-1,4-dicarboxylate; bpdc = 4,4'-biphenyldicarboxylate; bpdc-(NH₂)₂ = 2,2'-diamino-4,4'-biphenyldicarboxylate and x = 0, 0.25, 0.5, 0.75, 1. In a second step, the UiO-66-xNH₂ and UiO-67-x(NH₂)₂ systems have been postsynthetically modified by introduction of highly basic lithium tert-butoxide (LiO^tBu) on the oxohydroxometallic clusters of the mixed ligand MOFs to yield UiO-66-xNH₂@LiO^tBu and UiO-67-x(NH₂)₂@LiO^tBu materials. The results show that the combination of pre and postsynthetic modifications on these MOF series gives rise to fine-tuning of the catalytic activity toward the hydrolytic degradation of both simulants and real CWAs in unbuffered aqueous solutions. Indeed, UiO-66-0.25NH₂@LiO^tBu is able to hydrolyze both CWAs simulants (diisopropylfluorophosphate (DIFP), 2-chloroethylethylsulfide (CEES), and real CWAs (soman (GD), sulfur mustard (HD)) quickly in aqueous solution. These results are related to a suitable combination of robustness, nucleophilicity, basicity, and accessibility to the porous framework.

A microporous cationic metal–organic framework for the efficient removal of dichromate and the selective adsorption of dyes from water

A microporous anionic metal–organic framework has been synthesized, which can be used as the effective adsorbent to methyl orange and Cr₂O₇²⁻ from aqueous solutions.

The mixed-ligand strategy to assemble a microporous anionic metal–organic framework: Ln3+ post-functionalization, sensors and selective adsorption of dyes

A microporous anionic metal–organic framework has been synthesized, which can be used as potential sensor to organic molecules and selective adsorbent to dyes.

Electrospun metal–organic framework polymer composites for the catalytic degradation of methyl paraoxon

Electrospun polymer fibers containing poly(methyl methacrylate) (PMMA), Ti(OH)₄, and UiO-66 convert a chemical warfare agent simulant to non-toxic product via catalytic hydrolysis.

A microporous MOF with open metal sites and Lewis basic sites for selective CO2 capture

A new robust indium–organic framework (InOF-15, In-BQDC) exhibits high IAST selective CO₂ sorption performance for CO₂/CH₄ and CO₂/N₂ mixtures at 273 K, which has been attributed to the coexistence of OMSs and LBSs for strong synergistic effect.

Porous crystalline materials: closing remarks

This paper is derived from my ‘closing remarks’ lecture at the 287th Faraday Discussions meeting on New Directions in Porous Crystalline Materials, Edinburgh, UK, 5–7 June, 2017. This meeting comprised sessions on the design of porous networks, and their capture, storage, separation, conducting properties, catalysts, resistance to chemicals and moisture, simulation, and electronic structures. This paper details the achievements and developments in the field, as reflected in invited speakers’ papers and discussions with the attendees during the meeting.