Cobalt metal organic framework as an efficient heterogeneous catalyst for the oxidation of alkanes and alkenes

Mesoporous metal-organic framework NH2-MIL-101(Cr) as an efficient photocatalyst for the epoxidation of styrene

Oxidation of styrene is a key reaction in the synthesis of pharmaceuticals and fine chemicals, and therefore oxidizing styrene with selective, efficient, and recyclable heterogeneous catalysts is significant from an environmental and economic standpoint. In this study, we report the transition Cr-based metal-organic framework [NH2-MIL-101(Cr)] as a heterogeneous photocatalyst, which efficiently promotes styrene epoxidation using H2O2 as a green oxidant, achieving high conversion efficiency (98%) and excellent selectivity (82%) under ambient conditions. Radical detection and quenching experiments reveal that the superoxide radical anion (O2˙-) acts as an active oxygen species, selectively promoting the oxidation of styrene to its oxidized form. This work provides insight into the development of a sustainable and cost-effective method for producing styrene oxide.

Potential Application Values of Two Multicoloured Coordination Compounds as Multicolor Luminescent Materials

Two Co(II)-based coordination compounds, namely {[Co(apc)2]·H2O}n (1) and [Co(apc)2(H2O)2] (2), have been successfully prepared via reaction of a multifunctional ligand 2-aminopyrimidine-5-carboxylic acid (Hapc) with Co(NO3)2·6H2O based on different reaction environments. Both compounds were studied via elemental analysis (EA), single crystal X-ray diffraction analysis (SC-XRD), thermogravimetric analysis (TG), powder X-ray diffraction (PXRD) and infrared spectroscopy (IR). Fluorescence spectroscopy was employed to analyze the fluorescence properties of the ligand and the two compounds. The results revealed that the two compounds exhibited green and blue fluorescence, surpassing the original ligand in terms of properties. Based on the distinct fluorescence colors of the two compounds, there is potential to create multicolored fluorescent materials by adjusting their material ratios. This prospect could further extend their applications in the field of fluorescent materials.

Fe/Co-MOF Nanocatalysts: Greener Chemistry Approach for the Removal of Toxic Metals and Catalytic Applications

This study describes the preparation of new bimetallic (Fe/Co)-organic framework (Bi-MOF) nanocatalysts with different percentages of iron/cobalt for their use and reuse in adsorption, antibacterial, antioxidant, and catalytic applications following the principles of green chemistry. The prepared catalysts were characterized using several techniques, including X-ray powder diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and scanning electron microscopy. These techniques proved the formation of MOFs, and the average crystallite sizes were 25.3-53.1, 27.6-67.2, 3.0-18.9, 3.0-12.9, and 3.0-23.6 nm for the Fe-MOF, Co-MOF, 10%Fe:90%Co-MOF, 50%Fe:50%Co-MOF, and 90%Fe:10%Co-MOF samples, respectively. The nanoscale (Fe/Co) Bi-MOF catalysts as efficient heterogeneous solid catalysts showed high catalytic activity with excellent yields and short reaction times in the catalytic reactions of quinoxaline and dibenzoxanthene compounds, in addition to their antioxidant and antibacterial activities. Furthermore, the nanoscale (Fe/Co) Bi-MOF catalysts efficiently removed toxic metal pollutants (Pb²⁺, Hg²⁺, Cd²⁺, and Cu²⁺) from aqueous solutions with high adsorption capacity.

Water-Driven Structural Transformation in Cobalt Trimesate Metal-Organic Frameworks

We report on the synthesis and the characterization of a novel cobalt trimesate metal-organic framework, designated as KCL-102. Powder X-ray diffraction pattern of KCL-102 is dominated by a reflection at 10.2° (d-spacing = 8.7 Å), while diffuse reflectance UV-Vis spectroscopy indicates that the divalent cobalt centers are in two different coordination geometries: tetrahedral and octahedral. Further, the material shows low stability in humid air, and it transforms into the well-known phase of hydrous cobalt trimesate, Co3(BTC)2·12H2O. We associated this transition with the conversion of the tetrahedral cobalt to octahedral cobalt.

Electrocatalytic performance of NiNH2BDC MOF based composites with rGO for methanol oxidation reaction

Present work comprehensively investigated the electrochemical response of Nickel-2 Aminoterephthalic acid Metal-Organic Framework (NiNH2BDC) and its reduced graphitic carbon (rGO) based hybrids for methanol (CH3OH) oxidation reaction (MOR) in an alkaline environment. In a thorough analysis of a solvothermally synthesized Metal-Organic Frameworks (MOFs) and its reduced graphitic carbon-based hybrids, functional groups detection was performed by FTIR, the morphological study by SEM, crystal structure analysis via XRD, and elemental analysis through XPS while electrochemical testing was accomplished by Chronoamperometry (CA), Cyclic Voltametric method (CV), Electrochemically Active Surface Area (EASA), Tafel slope (b), Electron Impedance Spectroscopy (EIS), Mass Activity, and roughness factor. Among all the fabricated composites, NiNH2BDC MOF/5 wt% rGO hybrid by possessing an auspicious current density (j) of 267.7 mA/cm2 at 0.699 V (vs Hg/HgO), a Tafel slope value of 60.8 mV dec-1, EASA value of 15.7 cm2, and by exhibiting resistance of 13.26 Ω in a 3 M CH3OH/1 M NaOH solution displays grander electrocatalytic activity as compared to state-of-the-art platinum-based electrocatalysts.

Microwave-Assisted Air Epoxidation of Mixed Biolefins over a Spherical Bimetal ZnCo-MOF Catalyst

Here, we report the synthesis of spherical bimetal ZnCo-MOF materials by a hydrothermal rotacrystallization method and their catalytic activity on the air epoxidation of mixed biolefins enhanced by microwaves. The structural and chemical properties of the ZnCo-MOF materials were fully characterized by XRD, IR, SEM, TG, XPS, and NH₃-TPD. The morphology of the material exhibited a three-dimensional spherical structure. From an NH₃-TPD test of the ZnCo-MOF catalyst, it could be concluded that the Zn_0.1Co₁-MOF-H-150 rpm material had the highest acidic content and the strongest acidity among the catalysts synthesized by different methods, which gave the best performance in the epoxidation of mixed biolefins. The air epoxidation reaction was carried out under atmospheric pressure and microwave conditions, in the absence of any initiator or coreducing agent. Moreover, the Zn_0.1Co₁-MOF catalyst could be recycled six times without reducing the catalytic activity significantly, which showed the stability of spherical catalyst material under microwaves.

Cobalt-Based Metal Organic Frameworks as Solids Catalysts for Oxidation Reactions

Metal organic frameworks (MOFs) are porous crystalline solids whose frameworks are constituted by metal ions/nodes with rigid organic linkers leading to the formation of materials having high surface area and pore volume. One of the unique features of MOFs is the presence of coordinatively unsaturated metal sites in their crystalline lattice that can act as Lewis acid sites promoting organic transformations, including aerobic oxidation reactions of various substrates such as hydrocarbons, alcohols, and sulfides. This review article summarizes the existing Co-based MOFs for oxidation reactions organized according to the nature of substrates like hydrocarbon, alcohol, olefin, and water. Both aerobic conditions and peroxide oxidants are discussed. Emphasis is placed on comparing the advantages of using MOFs as solid catalysts with respect to homogeneous salts in terms of product selectivity and long-term stability. The final section provides our view on future developments in this field.

Development of Nickel-BTC-MOF-Derived Nanocomposites with rGO Towards Electrocatalytic Oxidation of Methanol and Its Product Analysis

In this study, electrochemical oxidation of methanol to formic acid using the economical and highly active catalytic Nickel Benzene tricarboxylic acid metal organic framework (Ni-BTC-MOF) and reduced graphene oxide (rGO) nanocomposites modified glassy carbon electrode GCE in alkaline media, which was examined via cyclic voltammetry technique. Nickel based MOF and rGO nanocomposites were prepared by solvothermal approach, followed by morphological and structural characterization of prepared samples through X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and energy dispersive X-ray (EDX) analysis. The electrochemical testing of synthesized materials represents the effect of the sequential increase in rGO concentration on electrocatalytic activity. The Ni-BTC/4 wt % rGO composite with a pronounced current density of 200.22 mA/cm2 at 0.69 V versus Hg/HgO electrode at 50 mV/s was found to be a potential candidate for methanol oxidation in Direct Methanol Fuel Cell (DMFC) applications. Product analysis was carried out through Gas Chromatography (GC) and Nuclear Magnetic Resonance (NMR) spectroscopy, which confirmed the formation of formic acid during the oxidation process, with approximately 62% yield.

Metal complex catalysis in the chemistry of lower diamondoids

The review presents the first survey of published data on the use of compounds, complexes and nanoparticles of transition metals (Fe, Co, Ni, Mn, V, Mo, Cu, Pd, Pt, Rh, Ru, Os, Au, Re and Th) in the catalytic transformations of lower diamondoids — adamantane, diamantane and their derivatives. Catalytic halogenation, oxidation, alkylation and cross-coupling reactions are considered, and the formation pathways of C–N, C–S and C–Se bonds in the series of adamantanoids are discussed. Reaction conditions, appropriate catalytic systems and the structures of products are presented.

The bibliography includes 242 references.

Redox-Active Cobalt(II/III) Metal-Organic Framework for Selective Oxidation of Cyclohexene

We report herein a new cobalt(II/III) mixed-valence metal-organic framework formulated as [Co^IICo₂^III(μ₃-O)(bdc)₃(tpt)]·guest 1, where bdc = benzene-1,4-dicarboxylate and tpt = 2,4,6-tri(4-pyridinyl)-1,3,5-triazine, which can be used as a redox-active heterogeneous catalyst for selective oxidation of cyclohexene on the allylic position without destroying the adjacent double bond. Two oxidants were chosen to demonstrate this result. For using tert-butyl hydroperoxide, the conversion rate is 63% and only allylic oxidation products ( tert-butyl-2-cyclohexenyl-1-peroxide, 86%; 2-cyclohexen-1-one, 14%) are found, whereas if using O₂ as oxidant, a total conversion of 38% is achieved and also only the allylic oxidation products (cyclohexenyl hydroperoxide, 72%; 2-cyclohexen-1-one, 20%; and cyclohex-2-en-1-ol, 8%) are found. The absence of any adduct on the double bond may be due to the unique radical chain mechanism triggered by the mixed-valent [Co^IICo₂^III(μ₃-O)] centers.

Coordination frameworks containing compounds as catalysts

This article describes a collection of MOF containing compounds as catalysts in a diverse range of organic transformation reactions.

A novel copper(ii)–lanthanum(iii) metal organic framework as a selective catalyst for the aerobic oxidation of benzylic hydrocarbons and cycloalkenes

The synthesis and catalytic activity of a novel heteronuclear Cu^II and La^III metal organic framework (MOF) having pyridinedicarboxylic acid (CuLa-MOF) is reported.

Porous Cu–BTC silica monoliths as efficient heterogeneous catalysts for the selective oxidation of alkylbenzenes

Macro-/mesoporous silica supported Cu–BTC monoliths were in situ synthesized as efficient reusable heterogeneous catalysts for the selective oxidation from alkylbenzenes to ketones with moderate to excellent yields. The catalytic selectivity of such low-cost catalysts due to the sizes and shapes of the substrates.