Metal–Organic Frameworks

For the first time, the zeolite-imidazole (ZIF-67) framework, a new subfamily of metal-organic frameworks (MOFs), is synthesized on the graphene oxide (GO) platform. Co2+ (as a central atom) and 2-methylimidazole (as organic ligands) were assembled to fabricate ZIF-67/GO NPs for providing epoxy-based anti-corrosion coatings with both active (self-healing) and passive (barrier) performance. Also, the ZIF-67/GO NPs were modified by 3-Aminopropyl triethoxysilane (APS) to improve the particles compatibility with the epoxy matrix and control their solubility in saline media...

Novel control strategies for membrane biofouling with eco-friendly photocatalytic technology are critically needed in practical operation of membrane bioreactors (MBRs). In this study, a metal-organic frameworks (MOF) based photocatalytic membrane was firstly applied in an anammox MBR for a long-term biofouling control, where bacteria were inactivated and foulants were degraded simultaneously, with environmentally friendly and renewable visible light energy. By physicochemical characterization, the synthesized photocatalyst of CdS/MIL-101 showed superior visible-light photocatalytic ability, and the 1 wt% CdS/MIL-101 modified membrane C2 showed enhanced hydrophilicity and water permeability compared with the pristine membrane C0...

A Poly (3,4-ethylenedioxothiophene) (PEDOT)/UiO-66 composite was electrodeposited on an etched stainless-steel wire as head-space solid-phase microextraction (HS-SPME) coating. A robust, well controlled thickness, and uniform coating of metal organic framework composites can be realized by the electrodeposited strategy. The incorporated UiO-66 not only enhanced the uniformity and stability of the composite coating, but also effectively decreased the stacking phenomenon of PEDOT and improved its extraction efficiency, which was over 100 times higher than that of the PEDOT coating without UiO-66...

Herein, a luminescent water-stable terbium-based metal-organic framework (MOF) {[Tb(Cmdcp)(H2 O)3 ]2 (NO3 )2 ·5H2 O}n (1, H3 CmdcpBr = N-carboxymethyl-(3,5-dicarboxyl)pyridinium bromide) has been synthesized and used for the recyclable sensing of PO4 3- and Al3+ in tandem. MOF 1 acts as a fluorescent sensor for PO4 3- by the luminescence "turn-off" mechanism with high selectivity over other anions, such as F- , Cl- , Br- , I- , NO3 - , H2 PO4 - , HSO4 - , HCO3 - , HSO3 - , SO4 2- , CO3 2- and HPO4 2- ...

A sensitive molecularly imprinted fluorescent nanosensor based on zeolitic imidazolate frameworks-8 (ZIF-8) and upconversion nanoparticles (UCNPs) was developed for the determination of trace alpha-cypermethrin (α-CPM) for the first time. The sensor was synthesized by a layer-by-layer self-assembly strategy. UCNPs with a maximum emission wavelength of 544.5 nm under 980 nm excitation were firstly prepared as the luminous core. Then, ZIF-8 with the large specific surface and porosity was introduced, which not only improved the mass transfer and adsorption capacity of the sensor but also increased the fluorescence intensity of UCNPs as a protective layer...

In aquatic environments, the ecological risks posed by metals are greatly affected by water chemistry, thereby creating challenges for water quality management. Biotic ligand models (BLMs) have become the most widely used tools to interpret and predict water chemistry effects. Traditional BLM development methods require a large number of toxicity tests and organisms, and model predictions are limited to certain toxicity statistics (e.g., 48-h median effective concentration, 48-h EC50 ), to which the models were calibrated...

Metal halide perovskites (MHPs) have excellent optoelectronic and photovoltaic applications because of their cost-effectiveness, tunable emission, high photoluminescence quantum yields, and excellent charge carrier properties. However, the potential applications of the entire MHP family are facing a major challenge arising from its weak resistance to moisture, polar solvents, temperature, and light exposure. A viable strategy to enhance the stability of MHPs could lie in their incorporation into a porous template...

A new cobalt metal-organic framework ( 2D-Co-MOF ) based on well-defined layered double cores that are strongly connected by intermolecular bonds has been developed. Its 3D structure is held together by π-π stacking interactions between the labile pyridine ligands of the nanosheets. In aqueous solution, the axial pyridine ligands are exchanged by water molecules, producing a delamination of the material, where the individual double nanosheets preserve their structure. The original 3D layered structure can be restored by a solvothermal process with pyridine, so that the material shows a "memory effect" during the delamination-pillarization process...

In the present study, MIL-101(Fe) and amine-carbon quantum dots (CQDs) were combined via a post-synthetic modification (PSM) method; thus, a novel MIL-101(Fe)@amine-CQD hybrid fluorescent probe sensor for the detection of 6-mercaptopurine (6-MP) was synthesized. Amine-CQDs as a fluorescent material can convert the bonding interaction between MIL-101(Fe) and 6-MP into recognizable fluorescence signals, and MIL-101 (Fe) as an adsorbent can pre-concentrate 6-MP. Hereupon, this new sensor demonstrates high selectivity and sensitivity towards the detection of 6-MP...

Structural transitions of host systems in response to guest binding dominate many chemical processes. We report an unprecedented type of structural flexibility within a meta-rigid material, MFM-520, which exhibits a reversible periodic-to-aperiodic structural transition resulting from a drastic distortion of a [ZnO4 N] node controlled by the specific host-guest interactions. The aperiodic crystal structure of MFM-520 has no three-dimensional (3D) lattice periodicity but shows translational symmetry in higher-dimensional (3 + 2)D space...

Nanomaterial-based enzyme-mimetic catalysts (Enz-Cats) have received considerable attention because of their optimized and enhanced catalytic performances and selectivities in diverse physiological environments compared with natural enzymes. Recently, owing to their molecular/atomic-level catalytic centers, high porosity, large surface area, high loading capacity, and homogeneous structure, metal-organic frameworks (MOFs) have emerged as one of the most promising materials in engineering Enz-Cats. Here, the recent advances in the design of MOF-engineered Enz-Cats, including their preparation methods, composite constructions, structural characterizations, and biomedical applications, are highlighted and commented upon...

Metal-organic frameworks (MOFs), featuring porous crystalline structures with coordinated metal nodes and organic linkers, have recently stimulated increasing concerns in diverse applications. By virtue of their versatile and highly tunable compositions and structures, constructing hollow architectures will further endow MOFs with enhanced properties and designability, exceeding molecular scale. MOFs could be considered as promising building units to fabricate complicated hollow nanocomposites with faster mass transport, multiple active components, more exposed active sites, and better compatibility than bulk MOFs...

Tuning the electronic structure of single-atom active sites via engineering atomic configuration is an effective strategy to boost oxygen reduction reaction (ORR), but still remains challenging because of the lack of rational guidance and effective methods. Here, we demonstrate the correlation between atomic configuration induced electronic density of single-atom Co active sites and ORR performance by combining density functional theory (DFT) calculations and electrochemical analysis. Guided by DFT calculations, we designed and synthesized a MOFs-derived Co single-atom catalyst with the optimal Co 1 -N 3 PS active moiety incorporated in hollow carbon polyhedron (Co 1 -N 3 PS/HC)...

Electrochemical reduction of carbon dioxide is a clean and highly attractive strategy for the production of organic products. However, this is hindered severely by the high negative potential required to activate carbon dioxide. Here, we report the preparation of a copper-electrode onto which the porous metal-organic framework [Cu2 (L)] [H4 L = 4,4',4″,4'''-(1,4-phenylenebis(pyridine-4,2,6-triyl))tetrabenzoic acid] can be deposited by electro-synthesis templated by an ionic liquid. This decorated electrode shows a remarkable onset potential for reduction of carbon dioxide to formic acid at -1...

Co3 O4 has been extensively studied as an anode material for lithium-ion batteries (LIBs) because of its high theoretical capacity. However, during the charging-discharging processes, the issues of large volume change and low electric conductivity arise, which significantly limit the practical applications of Co3 O4 . To solve these issues, a Co3 O4 /CeO2 heterostructure derived from metal-organic frameworks (MOFs) was designed and synthesized through one-step microwave synthesis. Benefiting from the mesoporous structure and presence of hetero-components, Co3 O4 /CeO2 having the molar ratio of Co/Ce = 5:1 (denoted as 5Co3 O4 /CeO2 ) exhibits high reversible capacity and excellent cycling stability when used as an anode material for LIBs...

Metal-organic frameworks (MOFs)-derived catalysts exhibit highly-efficient hydrogen or oxygen evolution performance on water splitting. However, it is an urgent problem to construct bifunctional electrocatalysts for both hydrogen and oxygen evolution performance. Herein, we adopted Ag nanowires as templates to prepare one-dimensional Ag nanowire@ZIF-8@ZIF-67 precursors (1D AgNW@ZIF-8@ZIF-67). Through pyrolysis, AgNW@ZIF-8@ZIF-67 precursors transformed into nitrogen-doped carbon frameworks (NCF) embedded with zinc-cobalt (ZnCo) nanoparticles on the surface of Ag NWs (denoted as Ag@ZnCo/NCF nanohybrids)...

In recent years, a new type of micro-porous material, namely metal organic framework material, has received more and more attention from many basic and industrial fields because these materials possess unique advantages. In this work, through the powerful sonochemical preparation method, a three-dimensional cluster-based CdII -MOFs, {[Cd(abtz)2 (H2 O)2 ]·(ClO4 )2 ·H2 O}n (1, abtz = 1-(4-aminobenzyl)-1H-1,2,4-triazole) can be quickly synthesized in the facile ultrasonic method. Powder X-ray diffraction (PXRD) measurement confirms that these bulky samples 1 (synthesized on different ultrasonic powers and ultrasonic time conditions) were pure...

A "turn-on" fluorescent probe based on amino-functionalized metal-organic frameworks (MOF-5-NH2 ) is developed for the detection of Cu2+ , Pb2+ and pyrophosphate (P2 O7 4- , PPi). The fluorescence emission of fluorescent materials obtained by one-step synthesis is attributed to organic ligands. Cu2+ and Pb2+ coordinate with the amino group on the surface of the MOF-5-NH2 , which is ascribed to the host-guest electron transfer between analyte and probe, giving rise to the fluorescence quenching. After adding PPi, the intense affinity between Cu2+ and PPi remove Cu2+ from the MOF-5-NH2 , blocking of the electron transfer process, and the fluorescence can be recovered...

Perovskite-like ABX3 metal-organic frameworks (MOFs) have gathered great interest due to their intriguing chemical and physical properties, including their magnetism, ferroelectricity, and multiferroicity. Pressure is an effective thermal parameter in tuning related properties in MOFs due to the adjustable organic framework. Though spectrum experiments have been made on the structural evolution during decompression, there is a lack of electrical studies on the order-disorder ferroelectric transition in the metal-organic frameworks under pressure...

Anion recognition by neutral hosts that function in aqueous solution is an emerging area of interest in supramolecular chemistry. The design of neutral architectures for anion recognition still remains a challenge. Among neutral anion receptor systems, urea and its derivatives are considered as "privileged groups" in supramolecular anion recognition, since they have two proximate polarized N-H bonds exploitable for anion recognition. Despite promising advancements in urea-based structures, the strong hydrogen bond drives detrimental self-association...