UTSA-74: A MOF-74 Isomer with Two Accessible Binding Sites per Metal Center for Highly Selective Gas Separation

Applying MOF+ technique for in situ preparation of a hybrid material for hydrogenation reaction

We demonstrate herein the preparation of a hybrid material for catalytic purpose by our recently developed MOF⁺ method. Impressively, the results show that the resultant catalyst displays superior catalytic performances for hydrogenation on olefin and selective semihydrogenation on phenylacetylene.

Electrooxidation of Pd–Cu NP loaded porous carbon derived from a Cu-MOF

We have synthesized Pd–Cu NP loaded porous carbon through the direct carbonization of a porous Cu based MOF for efficient electrooxidation.

A MOF-derived method to construct well-arranged porous nanosheets for lithium ion batteries

In this work, we report a facile route to fabricate a ZnCo₂O₄ nanosheet derived from metal–organic frameworks.

Carbon dioxide capture and conversion by an acid-base resistant metal-organic framework

Considering the rapid increase of CO₂ emission, especially from power plants, there is a constant need for materials which can effectively eliminate post-combustion CO₂ (the main component: CO₂/N₂ = 15/85). Here, we show the design and synthesis of a Cu(II) metal-organic framework (FJI-H14) with a high density of active sites, which displays unusual acid and base stability and high volumetric uptake (171 cm³ cm⁻³) of CO₂ under ambient conditions (298 K, 1 atm), making it a potential adsorbing agent for post-combustion CO₂. Moreover, CO₂ from simulated post-combustion flue gas can be smoothly converted into corresponding cyclic carbonates by the FJI-H14 catalyst. Such high CO₂ adsorption capacity and moderate catalytic activity may result from the synergistic effect of multiple active sites.

Increasing CO₂ emissions pose serious environmental issues. Here, the authors report the synthesis of a robust metal-organic framework which displays high volumetric uptake of post-combustion CO₂ under ambient conditions and can catalyze CO₂ fixation into cyclic carbonates.

Highly Selective Separation of C2H2 from CO2 by a New Dichromate-Based Hybrid Ultramicroporous Material

A new hybrid ultramicroporous material, [Ni(1,4-di(pyridine-2-yl)benzene)₂(Cr₂O₇)]_n (DICRO-4-Ni-i), has been prepared and structurally characterized. Pure gas sorption isotherms and molecular modeling of sorbate-sorbent interactions imply strong selectivity for C₂H₂ over CO₂ (S_AC). Dynamic gas breakthrough coupled with temperature-programmed desorption experiments were conducted on DICRO-4-Ni-i and two other porous materials reported to exhibit high S_AC, TIFSIX-2-Cu-i and MIL-100(Fe), using a C₂H₂/CO₂/He (10:5:85) gas mixture. Whereas CO₂/C₂H₂ coadsorption by MIL-100(Fe) mitigated the purity of trapped C₂H₂, negligible coadsorption and high S_AC were observed for DICRO-4-Ni-i and TIFSIX-2-Cu-i.

Metal-Organic Frameworks for Heterogeneous Basic Catalysis

Great attention has been given to metal-organic frameworks (MOFs)-derived solid bases because of their attractive structure and catalytic performance in various organic reactions. The extraordinary skeleton structure of MOFs provides many possibilities for incorporation of diverse basic functionalities, which is unachievable for conventional solid bases. The past decade has witnessed remarkable advances in this vibrant research area; however, MOFs for heterogeneous basic catalysis have never been reviewed until now. Therefore, a review summarizing MOFs-derived base catalysts is highly expected. In this review, we present an overview of the recent progress in MOFs-derived solid bases covering preparation, characterization, and catalytic applications. In the preparation section, the solid bases are divided into two categories, namely, MOFs with intrinsic basicity and MOFs with modified basicity. The basicity can originate from either metal sites or organic ligands. Different approaches used for generation of basic sites are included, and each approach is described with representative examples. The fundamental principles for the design and fabrication of MOFs with basic functionalities are featured. In the characterization section, experimental techniques and theoretical calculations employed for characterization of basic MOFs are summarized. Some representive experimental techniques, such as temperature-programmed desorption of CO₂ (CO₂-TPD) and infrared (IR) spectra of different probing molecules, are covered. Following preparation and characterization, the catalytic applications of MOFs-derived solid bases are dealt with. These solid bases have potential to catalyze some well-known "base-catalyzed reactions" like Knoevenagel condensation, aldol condensation, and Michael addition. Meanwhile, in contrast to conventional solid bases, MOFs show some different catalytic properties due to their special structural and surface properties. Remarkably, characteristic features of MOFs-derived solid bases are described by comparing with conventional inorganic counterparts, keeping in mind the current opportunities and challenges in this field.

Why Porous Materials Have Selective Adsorptions: A Rational Aspect from Electrodynamics

Gas storage/separation is a typical application of porous materials such as metal organic frameworks (MOFs). The adsorption/separation behavior results from the host-guest and/or guest-guest interaction and equilibration (host, porous material; guest, adsorbates). Although the driving forces for gas adsorption have been investigated, a detailed picture of interactions between gas molecules and MOFs has not clearly emerged. Herein, a new cobalt microporous MOF [Co(tipb)(adc)](DMF)₃(H₂O)_1.5, which possesses a rare self-interpenetrated gra topology, has been prepared with both tipb and H₂adc ligands (tipb = 1,3,5-tris(p-imidazolylphenyl)benzene, adc = 9,10-anthracenedicarboxylate). This MOF shows high stability and exceptional selective adsorption of CO₂ over N₂, O₂, and CH₄. In particular, a theoretical assumption of a "regional dynamic electric field effect" is proposed to clarify the selective adsorption. Moreover, we suggest that the proposed effect may be one of the most important factors impacting gas separation and storage in porous materials.

A new layer-stacked porous framework showing sorption selectivity for CO2 and luminescence

Luminescent Zn-MOF based stacked layers were assembled, featuring multiple CO₂-binding sites and selective CO₂ adsorption over CH₄.

Gate-opening upon CO2 adsorption on a metal–organic framework that mimics a natural stimuli-response system

A dynamic d-champhorate-based protuberant-grid-type framework, undergoes gate opening and closing processes that were triggered by the stimuli of the adsorption or desorption of CO₂. It is able to specifically recognize CO₂ over than N₂ and H₂ and shows a high CO₂ uptake of 90 mg g⁻¹ under 35 bar at 298 K.

A crystalline zinc(ii) complex showing hollow hexagonal tubular morphology evolution, selective dye absorption and unique response to UV irradiation

A protonated mononuclear complex [Zn(Hbpvp)Cl₃] (1) is assembled by solvothermal reaction of Zn(NO₃)₂·6H₂O with 3,5-bis-(2-(pyridin-4-yl)vinyl)pyridine (bpvp) in DMF/H₂O with a few drops of concentrated HCl added.

Photoswitching adsorption selectivity in a diarylethene–azobenzene MOF

The first photoactive MOF composed of both azobenzene and diarylethene units is reported and used to modulate adsorption selectivity via light.

Non-interpenetrated Cu-based MOF constructed from a rediscovered tetrahedral ligand

A stable non-interpenetrated MOF, UOF-1 (UOF = University of Otago framework), was made by combining the rigid tetrahedral tetrakis(4-carboxyphenyl)adamantane (L) ligand and copper(ii) paddle-wheel SBU. This low-density open framework displayed excellent selectivity for CO₂ over N₂ at practical operating conditions.

Screening metal–organic frameworks for mixture separations in fixed-bed adsorbers using a combined selectivity/capacity metric

For screening purposes, mixture separations with MOFs are evaluated on the basis of a combined selectivity/capacity metric.

An in situ investigation of the water-induced phase transformation of UTSA-74 to MOF-74(Zn)

In water, UTSA-74 transforms through a dissolution–recrystallization process to its polymorph MOF-74(Zn).

UiO-66 and its Br-modified derivates for elemental mercury removal

Phenyl bromine-appended metal-organic frameworks (Br-MOFs) were synthesized and applied in elemental mercury (Hg⁰) removal from simulated flue gas, considering the stability of bromine on the materials at the same time. The techniques of PXRD, nitrogen adsorption, TGA and XPS were used to characterize the materials. Phenyl bromide on the MOFs was the main active site for Hg⁰ capture. The optimal Br-MOF showed high Hg⁰ removal efficiency of more than 99% for 48h at 200°C, whereas the efficiency of un-functionalized MOF and conventional bromine impregnated active carbon dropped to 59.8% and 91.2% within 5h, respectively. The crystalline integrity of the Br-MOF was maintained after Hg⁰ adsorption. Br-MOF exhibited enhanced Hg⁰ removal efficiency when SO₂ was introduced to the flue gas. However, exposure Br-MOF to flue gas with steam resulted in low Hg⁰ removal efficiency. Bromine leaching experiments proved that Br-MOFs have high bromine stability over the Hg⁰ adsorption process, avoiding the possible bromine pollution caused by the conventional bromine impregnated adsorbents. All of these results demonstrated the phenyl bromine-appended MOFs to be potential Hg⁰ adsorbent regarding its high Hg⁰ capture efficiency and low environmental risk.

MOF catalysis of FeII-to-FeIII reaction for an ultrafast and one-step generation of the Fe2O3@MOF composite and uranium(vi) reduction by iron(ii) under ambient conditions

Surface is for the first time attested to be one of outstanding merits of metal–organic frameworks (MOFs).

A highly stable amino-coordinated MOF for unprecedented block off N2 adsorption and extraordinary CO2/N2 separation

ZJU-198 for high CO₂/N₂ separation and low isosteric heat.