Showing papers in "Inorganic Chemistry in 2019"

A ZnII-Based Metal-Organic Framework with a Rare tcj Topology as a Turn-On Fluorescent Sensor for Acetylacetone.

Abstract: A ZnII-based metal-organic framework (MOF) with a rare tcj topology has been solvothermally synthesized and displays relatively good thermal and chemical stabilities. Interestingly, the MOF can sensitively and selectively sense acetylacetone (acac) via a fluorescence enhancement effect with a detection limit of 0.10 ppm and good reusability, which demonstrates the first example of a MOF-based turn-on fluorescent sensor for acac.

Hydrolysis of 2D Transition-Metal Carbides (MXenes)in Colloidal Solutions

Abstract: Although oxidation was deemed as the main factor responsible for the instability of MXenes in aqueous colloids, here we put forward and test a hypothesis about the central role of water as the prim...

{Zn6} Cluster Based Metal-Organic Framework with Enhanced Room-Temperature Phosphorescence and Optoelectronic Performances.

Abstract: Molecule-based solid-state materials with long lifetimes could enable longer migration distances for excitons, which are beneficial for vast applications in optoelectronic field. Herein, we report a hexanuclear zinc cluster based MOF exhibits highly enhanced phosphorescence about 2 orders of magnitude in comparison with the pristine phosphor ligand. The combination of both experimental and computational results suggest that the {Zn6} cluster is very important for adjusting molecular conformations, packing arrangement, and photophysical properties of the organic phosphor ligands within the MOF matrix. Optoelectronic measurements reveal that the MOF-modified electrode is catalytically active to hydrogen evolution under light irradiation in neutral solution. Thus, our study provide an effective way to achieve low-cost metal-based phosphorescence MOF, expanding its further optoelectronic applications.

Tetraphenylethylene-Decorated Metal-Organic Frameworks as Energy-Transfer Platform for the Detection of Nitro-Antibiotics and White-Light Emission.

Abstract: The highly porous luminescent metal–organic frameworks (MOFs) can act as fluorescent probes for the detection of nitro compounds and can also serve as containers and energy transfer platforms to co...

Highly Dense Packing of Chromophoric Linkers Achievable in a Pyrene-Based Metal–Organic Framework for Photoelectric Response

Abstract: Highly dense packing of chromophoric linkers is achieved in a novel pyrene-based metal-organic framework (MOF), [Zn(TBAPy)1/2(H2O)2], induced by an ionic liquid. This MOF displays a quick response to visible-light irradiation (photocurrent density of up to 4.492 μA cm-2) and is capable of repetitive on-off photocurrent switching with a large on-off ratio (37.55).

Cobalt(II)-Based 3D Coordination Polymer with Unusual 4,4,4-Connected Topology as a Dual-Responsive Fluorescent Chemosensor for Acetylacetone and Cr2O72.

Abstract: A cobalt(II) coordination polymer with an unusual 4,4,4-connected network was hydrothermally synthesized and observed with high thermal, solvent, and pH stabilities. This polymer can serve as the first dual-responsive fluorescent chemosensor for the selective detection of acetylacetone and Cr2O72- ion (pH 3.0) in aqueous systems.

Water-Stable Metal-Organic Frameworks with Selective Sensing on Fe3+ and Nitroaromatic Explosives, and Stimuli-Responsive Luminescence on Lanthanide Encapsulation.

Abstract: Three water-stable luminescent MOFs [Zn4(bptc)2(NMP)3(DMF)(H2O)2]n (1-a), [Cd4(bptc)2(NMP)3(DMF)2(H2O)1]n (1-b), and {[Zn2(bptc)(DMA)(H2O)2]·(DMA)2·H2O}n (2), possessing similar chemical components (M2:L1:Sol3) and topology structures, were synthesized by solvents control. Their excellent sensing on iron(III) cation and nitroaromatic explosives (NACs) with great selectivity, sensitivity and a high Ksv (4.54 × 104 for 1-b on PNP) were observed by quenching effects. Furthermore, Zn-MOFs exhibit interesting stimuli-responsive luminescence enhancement after the encapsulation of a series of IIIB cations stimulated different luminescent emitting and intensity enhancement through host–guest processes of the pores in MOFs, especially for two distinct responses of Zn-MOF on a Tb3+ cation.

HPW-Anchored UiO-66 Metal-Organic Framework: A Promising Photocatalyst Effective toward Tetracycline Hydrochloride Degradation and H2 Evolution via Z-Scheme Charge Dynamics.

Abstract: The abolition of environmental pollutants and production of hydrogen (H2) from water using a heterogeneous photocatalyst is a demanding science of the current scenario to solve the increasing environmental pollution and worldwide energy catastrophe in modern life. To validate this purpose, the design of low-cost and durable semiconductor-based photocatalysts with great light absorption capacity becomes the most challenging issue for researchers. Regarding this, herein the phosphotungstic acid (HPW)-anchored Zr6O4(OH)4(BDC)6 (UiO-66) metal-organic framework (MOF), i.e., HPW@UiO-66, has been prepared by a hydrothermal method and is efficient, stable, and capable of harvesting solar energy toward the degradation of tetracycline hydrochloride (TCH) and H2 production in the presence of a sacrificial donor. The ionic interaction between HPW and UiO-66 plays a key role toward the photostability and charge-transfer mechanism of the composite and is well characterized with X-ray diffraction, UV diffuse-reflectance spectroscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy. A total of 30 wt % HPW@UiO-66 shows a maximum degradation of about 87.24% of a 20 ppm TCH solution in 60 min of solar-light irradiation and about 353.89 μmol/h of H2 production. The conduction- and valence-band potentials are well characterized with Mott-Schottky measurement and a delay charge recombination process through electrochemical impedance spectroscopy. The proposed mediator-free Z-scheme-oriented electron-hole migration route is well supported by photoluminescence, and the scavenger test well explains the better charge-carrier separation and high catalytic performance of the prepared composite. This research will bestow an advantageous blueprint to fabricate novel and challenging photocatalysts toward the photocatalytic treatment of environmental pollutants and H2 evolution.

Cyan-Green Phosphor (Lu2M)(Al4Si)O12:Ce3+ for High-Quality LED Lamp: Tunable Photoluminescence Properties and Enhanced Thermal Stability

Abstract: High-quality white light-emitting diodes (w-LEDs) are mainly determined by conversion phosphors and the enhancement of cyan component that dominates the high color rendering index. New phosphors (Lu2M)(Al4Si)O12:Ce3+ (M = Mg, Ca, Sr and Ba), showing a cyan-green emission, have been achieved via the co-substitution of Lu3+-Al3+ by M2+-Si4+ pair in Lu3Al5O12:Ce3+ to compensate for the lack of cyan region and avoid using multiple phosphors. The excitation bands of (Lu2M)(Al4Si)O12:Ce3+ (M = Mg, Ca, Sr and Ba) show a red-shift from 434 to 445 nm which is attributed to the larger centroid shift and crystal field splitting. The enhanced structural rigidity associated with the accommodation of larger M2+ leads to a decreasing Stokes shift and the corresponding blue-shift (533 → 511 nm) in emission spectra, along with an improvement in thermal stability (keeping ∼93% at 150 °C). The cyan-green phosphor Lu2BaAl4SiO12:Ce3+ enables to fabricate a superhigh color rendering w-LED ( Ra = 96.6), verifying its superiority and application prospect in high-quality solid-state lightings.

NH2-MIL-53(Al) Metal-Organic Framework as the Smart Platform for Simultaneous High-Performance Detection and Removal of Hg2.

Abstract: The worsening pollution due to mercury species makes it inevitable to explore prospective versatile materials, which not only can detect mercury ions (Hg2+) with high sensitivity but also possesses efficient capture and removal ability. In this study, a series of classic organic ligand-based luminescence MOFs materials with high oxidation state central metals (Al3+, Zr4+, Cr3+, Fe3+, and Ti4+) were synthesized and were screened to achieve simultaneously Hg2+ detection and removal through the strong coordination of amino groups or nitrogen centers with Hg2+ and the intrinsic fluorescence intensity of MOFs regulated by the ligand-to-metal charge transfer (LMCT) effect. Among these checked materials, NH2-MIL-53(Al) exhibited the excellent ability for Hg2+ detection with wide response interval (1-17.3 μM), low detection limit (0.15 μM), good selectivity, wide pH adaptation (4.0-10.0), and strong anti-interference ability. Meanwhile, the resultant NH2-MIL-53(Al) possessed an efficient removal capability toward Hg2+, accompanied by a fast uptake kinetics (within 60 min) and large loading capacity (153.85 mg g-1). Furthermore, NH2-MIL-53(Al) also displayed satisfactory stability before and after Hg2+ treatment because of the formation of strong coordination bonds between high oxidation state aluminum (Al3+) and organic carboxylate ligands. Notably, the prepared NH2-MIL-53(Al) had no significant loss of adsorption performance even after being reused four times. All of these superior properties render the smart NH2-MIL-53(Al) nanohexahedron a great potential for simultaneous Hg2+ detection and removal from water.

Zr-Based Metal-Organic Frameworks with Intrinsic Peroxidase-Like Activity for Ultradeep Oxidative Desulfurization: Mechanism of H2O2 Decomposition.

Abstract: The restriction of sulfur content in fuels has become increasingly stringent as a result of the growing environmental concerns. Although several MOF-derived materials like POM@MOF composites have shown the ability to catalyze oxidative desulfurization (ODS), their catalytic activities inevitably obstructed by the encapsulated catalytic sites like POM due to the blockage of cavities. Therefore, MOFs with intrinsic and accessible catalytic sites are highly desirable for their applications in ultradeep ODS. Herein, four representative Zr-based MOFs (Zr-MOFs), namely, UiO-66, UiO-67, NU-1000, and MOF-808, were assessed for catalytic ODS. These MOFs were confirmed that they have peroxidase-like activity and can catalyze ODS with H2O2 as oxidant. Among them, MOF-808 showed the highest catalytic activity and it can fully desulfurize dibenzothiophene (DBT) in a model gasoline with a S concentration of 1000 ppm under 40 °C within 5 min. An extremely low apparent Arrhenius activation energy (22.0 KJ·mol-1) and an extraordinarily high TOF value (42.7 h-1) were obtained, ranking MOF-808 among the best catalysts for the catalytic DBT oxidation. Further studies confirmed that the excellent catalytic activity is mainly responsible for the high concentration of the accessible Zr-OH(H2O) catalytic sites decorated in MOF-808. The superoxide radicals (•O2-) and hydroxyl radicals (•OH) were identified and were proved to involve in the DBT oxidation. Besides, the effects of Bronsted and lewis acidity to the catalytic efficiency were also discussed. Based on the experimental results, a plausible mechanism concerning on Zr-OH(H2O) groups promoting the H2O2 decomposion in to both •O2- and •OH was first proposed. Moreover, MOF-808 can be facilely reused for at least eight runs without significant loss of its catalytic activity. By the integration of facile synthesis, high catalytic efficiency, and good stability, MOF-808 thus represents a new benchmark catalyst for catalytic oxidative desulfurization.

Microwave-Assisted Rapid Synthesis of Well-Shaped MOF-74 (Ni) for CO2 Efficient Capture.

Abstract: In the present work, a series of MOF-74 (Ni) materials with narrow micropore channels and abundant unsaturated metal sites was respectively prepared via hydrothermal (HT), condensation reflux (CE), and microwave-assisted (MW) methods. The physicochemical properties of synthesized materials were characterized by powder X-ray diffraction, N2-sorption, field-emission scanning electron microscopy, Fourier-transform infrared (FTIR), thermogravimetric (TG)/TG-FTIR, X-ray photoelectron spectroscopy, UV-vis-near infrared, NH3/CO2-temperature programmed desorption, and in situ diffuse reflectance infrared Fourier transform spectroscopy. Their CO2/N2 adsorption performances were evaluated by isotherm adsorption and dynamic adsorption experiments. We found that the MW is a rapid and facile protocol for the synthesis of MOF-74 (Ni) materials with highly efficient CO2 capture capacity. The well-shaped MW-140 adsorbent with superior CO2 adsorption capacity of 5.22 mmol/g at 25 °C can be obtained within 60 min by the MW process, almost 6 times higher than that of the commercial activated carbon (0.89 mmol/g). Results of dynamic adsorption experiments showed that the MW-140 material possesses the highest CO2 adsorption capacity of 3.37 mmol/g under humid conditions (RH = 90%). Importantly, MW-140 has excellent adsorption stability and recyclability, superior CO2 capture selectivity (CO2/N2 = 31), and appropriate isosteric heat in CO2 adsorption (21-38 kJ/mol), making it a promising and potential material for industrial CO2 capture. Characterization results demonstrated that the high capture capability of MOF-74 (Ni) materials can be attributed to the synergistic effect of abundant narrow micropore channels and rich five-coordinated Ni2+ open metal sites which are beneficial for the trapping of CO2 molecules.

Portable Colorimetric Detection of Mercury(II) Based on a Non-Noble Metal Nanozyme with Tunable Activity

Abstract: The nanozyme-based strategy is currently one of the frontiers in the detection of toxic heavy metal ions. However, the utilization of noble metal free nanozymes to construct an economically and environmentally sustainable methodology remains largely unknown. Here, chitosan-functionalized molybdenum(IV) selenide nanosheets (CS-MoSe2 NS), greenly synthesized by an ionic liquid-assisted grinding method, were exploited for the colorimetric sensing of mercury ions (Hg2+). The sensing principle was based on the activating effect of Hg2+ on CS-MoSe2 NS nanozyme activities, triggered by the in situ reduction of chitosan-captured Hg2+ ions on a MoSe2 NS surface. Using 3,3',5,5'-tetramethylbenzidine (TMB) as a colorimetric indicator, the concentrations of activator-like Hg2+ ions could be quantitatively and selectively monitored, reaching a limit of detection of 3.5 nM with the ultraviolet-visible spectrophotometer. In addition, the integration system of CS-MoSe2 NS with a smartphone achieved a portable detection limit as low as 8.4 nM Hg2+ within 15 min and showed high specificity and anti-interfering ability over other ions and great practicability in real water and serum samples. The eco-friendly properties of such sensing system were also confirmed. This work emphasizes the rational portable assembly of biocompatible nanozymes like CS-MoSe2 NS for the field detection of Hg2+ in food, biological, and environmental samples.

Cobalt(II) Coordination Polymers Assembled from Unexplored Pyridine-Carboxylic Acids: Structural Diversity and Catalytic Oxidation of Alcohols.

Abstract: New coordination polymers of cobalt(II), namely, [Co(μ4-cpna)(H2O)2]n (1), [Co(μ3-cpna)(phen)(H2O)]n·nH2O (2), [Co3(μ4-dppa)2(H2O)6]n·2nH2O (3), and [Co3(μ5-dppa)2(μ-4,4′-bipy)(H2O)2]n·4nH2O (4), h...

Environmentally Friendly, Co-catalyst-Free Chemical Fixation of CO2 at Mild Conditions Using Dual-Walled Nitrogen-Rich Three-Dimensional Porous Metal–Organic Frameworks

Abstract: Highly porous, polyhedral metal–organic frameworks (MOFs) of Co(II)/Ni(II), {[M6(TATAB)4(DABCO)3(H2O)3]·12DMF·9H2O}n (where M = Co(II) (1)/Ni(II) (2), H3TATAB = 4,4′,4″-s-triazine-1,3,5-triyl-tri-p...

Isostructural Tb3+/Eu3+ Co-Doped Metal-Organic Framework Based on Pyridine-Containing Dicarboxylate Ligands for Ratiometric Luminescence Temperature Sensing.

Abstract: In this work, we prepared two types of isostructural Ln3+-based metal-organic frameworks (LnMOFs) under solvothermal conditions, where two structurally similar pyridine-containing dicarboxylate ligands, 6-(4-carboxyphenyl)nicotinic acid and [2,2'-bipyridine]-5,5'-dicarboxylic acid, were used as the organic linkers. The as-synthesized LnMOF compounds were characterized using single-crystal X-ray diffraction (XRD), powder XRD, and thermogravimetric analysis. With the lanthanide co-doping approach, two mixed LnMOFs, Tb0.95Eu0.05cpna and Tb0.95Eu0.05bpydc, were obtained and evaluated for application as potential ratiometric luminescence thermometers. The temperature-dependent luminescence of the two materials was investigated, and their emission intensities, luminescence lifetimes, and thermometric parameters were compared. They exhibit an excellent S-shaped response for temperatures in the range of 25-300 K, with favorable relative sensitivity and temperature uncertainty. Moreover, their color changes from green at 25 K to red at 300 K, so that they are also suitable as colorimetric luminescent probes.

A Pillar-Layered Zn-LMOF with Uncoordinated Carboxylic Acid Sites: High Performance for Luminescence Sensing Fe3+ and TNP

Abstract: By using the mixed-linker strategy, a new pillar-layered luminescence Zn-LMOF (JLU-MOF71) ([Zn2Na2(TPHC)(4,4-Bipy)(DMF)]·8H2O) (TPHC = [1,1′:2′,1″-terphenyl]-3,3″,4,4′,4″,5′-hexacarboxylic acid, 4,...

An Exceptionally Stable Tb III -Based Metal-Organic Framework for Selectively and Sensitively Detecting Antibiotics in Aqueous Solution.

Abstract: An exceptionally stable metal-organic framework based on one-dimensional (1D) TbIII chains with significant green emission under excitation energy, {[Tb(TATMA)(H2O)·2H2O} n (namely, 1), has been fabricated successfully under hydrothermal conditions. By virtue of the spectral overlap between the absorbance spectra of nitrofurans (NFAs) and the excitation spectrum of MOF 1, the resultant sample exhibits outstandingly sensitive and selective luminescence detectability for NFT ( Ksv = 3.35 × 104 M-1) and NFZ ( Ksv = 3.00 × 104 M-1) by quenching phenomenon. More importantly, it can detect NFAs in water from bovine serum samples. The portable MOF film can be easily prepared and used with excellent stability and recursitivity.

Structural Evolution and Compositional Modulation of ZIF-8-Derived Hybrids Comprised of Metallic Ni Nanoparticles and Silica as Interlayer.

Abstract: Great efforts on metal-organic framework (MOF) derived nanostructures have been devoted to modulating the compositional and structural complexities to enhance performance in various applications. However, a facile method that can simultaneously manipulate the structures of the MOF-derived material and the chemical component remains a considerable challenge. Here we report a facile strategy to use the polyhedral ZIF-8 as a precursor for synthesizing ZIF-8-derived hybrids with different components and morphologies. The synthesis involves the preparation of ZIF-8 MOF templates and sequential covering of the ZIF-8 with a interlayer of silica and then polydopamine-Ni2+ (PDA-Ni2+) and carbonizing at different high temperatures under a nitrogen atmosphere, finally leading to ZIF-8-derived hybrids with different components and structures. In the whole process, the preliminary ZIF-8 precursor play a crucial role in the morphology and structure of the final carbonized products, which can be considered as templates for silica coating and precursors of N-doped carbon layer and Zn species. We also found that the SiO2 interlayer coating is a crucial procedure for the formation of yolk-shell structured ZIF-8@SiO2@PDA-Ni2+ composites. Owing to the uniformly distributed Ni NPs and unique structures of the composites, the as-prepared Ni-based composites show high performance in the catalysis of 4-nitrophenol as well as enrichment of histidine-rich proteins. In addition, this proposed strategy for the controllable design and synthesis of ZIF-8-derived nanocomposites paves a new way in developing superior active materials in energy storage conversion etc.

Hydrolytically Stable Nanotubular Cationic Metal–Organic Framework for Rapid and Efficient Removal of Toxic Oxo-Anions and Dyes from Water

Abstract: Cationic framework materials capable of removing anionic pollutants from wastewater are highly desirable but relatively rarely reported. Herein, a cationic MOF (SCNU-Z1-Cl) possessing tubular channels with diameter of 1.5 nm based on Ni(II) and a nitrogen-containing ligand has been synthesized and applied to capture hazardous anionic contaminants from water. The SCNU-Z1-Cl exhibits high BET surface area of 1636 m2/g, and shows high hydrolytically stability in pH range from 4 to 10. Owing to the large tubular channels and the uncoordinated anions in the framework, the aqueous-phase anion-exchange applications of SCNU-Z1-Cl were explored with environmentally toxic oxo-anions including CrO42-, Cr2O72-, MnO4-, and ReO4-, and organic dyes. The adsorption of oxoanions exhibits high uptake kinetics and the adsorption capacities of CrO42-, Cr2O72-, MnO4-, and ReO4- are 126, 241, 292, and 318 mg/g, respectively, which were some of the highest values in the field of MOF/COF. In additional, the selectively is high when other concurrent anions are exist. The anionic dyes with different sizes including methyl orange, acid orange A, congo red, as well as methyl blue can be adsorbed by SCNU-Z1-Cl in few minutes to about 1 h. The adsorption capacities for them are 285, 180, 585, and 262 mg/g, respectively. In contrast, the adsorption kinetics for catinionic dyes with different sizes is obviously lower and exhibit a size-selectively adsorption that only cationic dye with suitable size (rhodamine B) can be adsorbed by SCNU-Z1-Cl. Consequently, SCNU-Z1-Cl can sepearate organic dyes in three different modes: size-dependent, charge-dependent, and kinetics-dependent selective adsorption. The excellent adsorption and separation properties of SCNU-Z1-Cl is attribute to the cationic framework, large tubular channel, as well as the high positive Zeta potential.

Luminescent Ruthenium(II) Polypyridine Complexes for a Wide Variety of Biomolecular and Cellular Applications

Abstract: Ruthenium(II) polypyridine complexes are one of the most extensively studied and developed systems in the family of luminescent transition-metal complexes. Notably, there has been a large amount of interest in the biological applications of these luminescent ruthenium(II) complexes because of their rich photophysical and photochemical properties. In this Viewpoint, we explore past and recent works on the possible biological and cellular applications of these promising complexes, with a focus on their use as bioimaging reagents, biomolecular probes, and phototherapeutic agents.

One-Pot-Architectured Au-Nanodot-Promoted MoS2/ZnIn2S4: A Novel p–n Heterojunction Photocatalyst for Enhanced Hydrogen Production and Phenol Degradation

Abstract: Developing effective and simple one-pot synthetic strategies regarding the formation of heterojunction photocatalytic semiconductors remains an intense challenge in research pursuits. Further scheming of the p-n heterojunction has sustained renewed interest in catalysis, photocatalysis, energy storage, and conversion because they easily accelerate the bulk charge separation efficiency. Thus we have successfully designed a Au-MoS2/ZnIn2S4 heterojunction photocatalyst for the first time by adopting a simple one-pot hydrothermal technique, followed by a deposition-precipitation method. By adjusting the mole ratio of Mo with that of Zn and In precursors, we have fabricated a MoS2/ZnIn2S4 p-n heterojunction photocatalyst, and the established p-n heterojunction between MoS2 and ZnIn2S4 is demonstrated by various physicochemical and morphological characterizations. An interfacial junction is created between MoS2 and ZnIn2S4 at the depletion region via an in situ formation mechanism, leading to the enhancement of the charge separation through the p-n heterojunction and thus improving the photocatalytic activity. Moreover, the photocatalytic activity is projected to further improve by the incorporation of Au nanodots on the surface of MoS2/ZnIn2S4 photocatalysts. The increase in activity is due to the generation and participation of a large number of direct-electron-transfer-induced hot electrons in the photochemical reaction. From the experimental results, Au-MoS2/ZnIn2S4 heterojunction photocatalysts with only 1% MoS2 and 1% Au loading content displayed a 561.25 μmol/h H2 evolution rate and 84% degradation of phenol, which are nearly 15 and 6 times higher than those neat ZnIn2S4. In addition Au-MoS2/ZnIn2S4 photocatalysts exhibit a photocurrent density of ∼2.56 mAcm-2, which is nearly 2.4 times higher than that of the MoS2/ZnIn2S4 heterojunction photocatalyst. This exertion represents the synergetic enhancement of photocatalytic activity through the p-n heterojunction as well as the hot-electron participation by the metal nanocatalyst, which is an inspiration for developing efficient photocatalysts.

An Asymmetric Supercapacitor Based on a Non-Calcined 3D Pillared Cobalt(II) Metal-Organic Framework with Long Cyclic Stability.

Abstract: In this work, a new 3D metal-organic framework (MOF) {[Co3(μ4-tpa)3(μ-dapz)(DMF)2]·2DMF}n (Co(II)-TMU-63; H2tpa = terephthalic acid, dapz = pyrazine-2,5-diamine, DMF = dimethylformamide) containing low-cost and readily available ligands was generated, fully characterized, and used as an electrode material in supercapacitors without the need for a calcination process. Thus, the synthesis of this material represents an economical and cost-effective method in the energy field. The crystal structure of Co(II)-TMU-63 is assembled from two types of organic building blocks (μ4-tpa2- and μ-dapz ligands), which arrange the cobalt nodes into a complex layer-pillared net with an unreported 4,4,4,6T14 topology. The presence of open sites in this MOF is promising for studying electrochemical activity and other types of applications. In fact, Co(II)-TMU-63 as a novel electrode material when comparing with pristine MOFs shows great cycling stability, large capacity, and high energy density and so acts as an excellent supercapacitor (384 F g-1 at 6 A g-1). In addition, there was a stable cycling performance (90% capacitance) following 6000 cycles at 12 A g-1 current density. Also, the Co(II)-TMU-63//activated carbon (AC) asymmetric supercapacitor acted in a broad potential window of 1.7 V (0-1.7 V), exhibiting a high performance with 4.42 kW kg-1 power density (PD) and 24.13 Whkg-1 energy density (ED). These results show that the pristine MOFs have great potential toward improving different high-performance electrochemical energy storage devices, without requiring the pyrolysis or calcination stages. Hence, such materials are very promising for future advancement of the energy field.

Thiol-Functionalized Pores via Post-Synthesis Modification in a Metal-Organic Framework with Selective Removal of Hg(II) in Water.

Abstract: Owing to the rapid increase of Hg(II) ions in water resources, the design and development of new adsorbents for Hg(II) removal are becoming a significant challenge in environmental protection. Herein, a thiol-functionalized metal-organic framework (SH-MiL-68(In)) was successfully prepared through a post-synthesis modification procedure, and the framework intactness and porosity were well maintained after this process. SH-MiL-68(In) exhibited selective adsorption performance for Hg(II) ions in water. Meanwhile, SH-MiL-68(In) also shows a high adsorption capacity (450 mg g-1), large adsorption rate (rate constant k2 = 1.25 g mg-1 min-1), and good recycling of adsorption capacity toward Hg(II) ions. The excellent adsorption performance resulted from the strong binding interactions between -SH soft basic groups and Hg(II) soft acidic ions.

Fabrication of a Luminescence-Silent System Based on a Post-Synthetic Modification Cd-MOFs: A Highly Selective and Sensitive Turn-on Luminescent Probe for Ascorbic Acid Detection.

Abstract: A unique three-dimensional luminescent metal-organic framework (Cd-MOFs), [Cd(tpbpc)2]·2H2O·DMF (Htpbpc = 4'-[4,2';6',4″]-terpyridin-4'-yl-biphenyl-4-carboxylic acid; DMF = dimethylformamide), was synthesized and structurally characterized; it exhibits excellent luminescent property and structural stability in aqueous solutions. Interestingly, an unparalleled luminescence-silent system CrO42-@Cd-MOFs was successfully fabricated by postsynthetic modification of metal-organic frameworks. This luminescence-silent system represents a highly selective and sensitive turn-on luminescent responding to ascorbic acid. First, this advanced fluorescent sensor displays excellent performance for CrO42- ions with a quenching of fluorescence intensity originating from fluorescence resonance energy transfer (FRET) mechanism. What's more, the fluorescent intensity of CrO42-@Cd-MOFs system can be recovered (turn-on) for sensing ascorbic acid because of the elimination of FRET process. Such a novel fabrication strategy should offer the guidance to develop various MOFs-implicated luminescence-silent systems as "turn-on" sensors for detection of specific chemicals.

Dual-Emissive Metal-Organic Framework as a Fluorescent "Switch" for Ratiometric Sensing of Hypochlorite and Ascorbic Acid.

Abstract: The detection of hypochlorite (ClO-) content in tap water is extremely important because excess amounts of hypochlorite can convert into highly toxic species and inadequate amounts of hypochlorite cannot fully kill bacteria and viruses. Although several metal-organic frameworks (MOFs) have been successfully employed as fluorescent sensors for hypochlorite detection, all these sensors are based on single emission that responds to the dose of hypochlorite. Ratiometric sensors are highly desirable, which can improve the sensitivity, accuracy, and reliability via self-calibration. Herein, a nanoscale dual-emission multivariate 5-5-Eu/BPyDC@MOF-253-NH2 was synthesized by sequential mixed-ligand self-assembly and postsynthesis method. Among the two emission bands of 5-5-Eu/BPyDC@MOF-253-NH2, the strong blue emitting derived from ligands is sensitive to hypochlorite, while the red emitting derived from Eu(III) almost keeps invariable. Therefore, 5-5-Eu/BPyDC@MOF-253-NH2 was exploited as a fluorescent ratiometric nanosensor for "on-off" sensing of hypochlorite. Notably, the proposed sensing system showed an excellent performance including fast response (within 15 s), relative high specificity, wide linear range (0.1-30 μM), and low detection limit (0.094 μM). Besides, the suppressed blue emitting was recovered after the addition of ascorbic acid (AA) that consumes ClO- via the redox reaction. Therefore, 5-5-Eu/BPyDC@MOF-253-NH2 was further employed as a fluorescent ratiometric nanosensor for the "on-off-on" sensing of AA. This work represents the first MOF-based fluorescent "switch" for the ratiometric sensing of hypochlorite and the second for ratiometric sensing of AA.

Dual-Functionalized Mixed Keggin- and Lindqvist-Type Cu24-Based POM@MOF for Visible-Light-Driven H2 and O2 Evolution.

Abstract: The development of logical visible-light-driven heterogeneous photosystems for water splitting is a subject of new research. As the first example of a noble-metal-free photocatalyst for both H2 and...

Tuning the Solid-State White Light Emission of Postsynthetic Lanthanide-Encapsulated Double-Layer MOFs for Three-Color Luminescent Thermometry Applications.

Abstract: Postsynthetic modification represents an efficient strategy for the fabrication of tunable metal–organic frameworks (MOFs) and derived high-performance functional materials. Herein, we report the synthesis of a mixed-linker zinc(II)-based double-layered MOF (dlMOF) with dual-emissive luminescence, which was further applied as a host matrix to fabricate highly tunable Ln@dlMOF materials (Ln = Eu, Tb, Eu/Tb). The emission characteristics of these materials can be readily modulated over a wide spectrum, including white light emission, by simply tuning the Eu3+/Tb3+ molar ratio in EuTb@dlMOF. Furthermore, by virtue of the difference in thermal sensitivity between triple-emissive sources, the Eu3+/Tb3+-codoped thermometer EuTb@dlMOF exhibits real-time successive chromogenic switches from red (room temperature) to white (intermediate temperature) to blue/green (cryogenic temperature) emission in a wide temperature region. The versatile performance and the facile assembly from easily available linkers suggest th...

Ni–Ti Layered Double Hydroxide@Graphitic Carbon Nitride Nanosheet: A Novel Nanocomposite with High and Ultrafast Sonophotocatalytic Performance for Degradation of Antibiotics

Abstract: Pollution of water resources by antibiotics is a growing environmental concern. In this work, nanocomposites of g-C3N4@Ni–Ti layered double hydroxides (g-C3N4@Ni–Ti LDH NCs) with high surface areas...

Cr2O3 Nanoparticle-Reduced Graphene Oxide Hybrid: A Highly Active Electrocatalyst for N2 Reduction at Ambient Conditions.

Abstract: Electrochemical reduction is an eco-friendly alternative for energy-saving artificial N2 fixation. The development of this process requires efficient N2 reduction reaction (NRR) electrocatalysts to overcome the challenge with N2 activation. We show that a Cr2O3 nanoparticle-reduced graphene oxide hybrid (Cr2O3-rGO) is as an outstanding catalyst for electrochemical N2-to-NH3 conversion under ambient conditions. In 0.1 M HCl, Cr2O3-rGO achieves a high NH3 yield of 33.3 μg h–1 mg–1cat. at −0.7 V vs RHE and a high Faradaic efficiency of 7.33% at −0.6 V vs RHE, with excellent selectivity for NH3 synthesis and stability. Density functional theory calculations were executed to gain further insight into the mechanisms.