Highly selective and “green” alcohol oxidations in water using aqueous 10% H2O2 and iron-benzenetricarboxylate metal–organic gel

Hierarchical porous metal–organic gels and derived materials: from fundamentals to potential applications

This review summarizes recent progress in the development and applications of metal–organic gels (MOGs) and their hybrids and derivatives dividing them into subclasses and discussing their synthesis, design and structure–property relationship.

Magneli-type tungsten oxide nanorods as catalysts for the selective oxidation of organic sulfides

Selective oxidation of thioethers is an important reaction to obtain sulfoxides as synthetic intermediates for applications in the chemical industry, medicinal chemistry and biology or the destruction of warfare agents. The reduced Magneli-type tungsten oxide WO_3-x possesses a unique oxidase-like activity which facilitates the oxidation of thioethers to the corresponding sulfoxides. More than 90% of the model system methylphenylsulfide could be converted to the sulfoxide with a selectivity of 98% at room temperature within 30 minutes, whereas oxidation to the corresponding sulfone was on a time scale of days. The concentration of the catalyst had a significant impact on the reaction rate. Reasonable catalytic effects were also observed for the selective oxidation of various organic sulfides with different substituents. The WO_3-x nanocatalysts could be recycled at least 5 times without decrease in activity. We propose a metal oxide-catalyzed route based on the clean oxidant hydrogen peroxide. Compared to other molecular or enzyme catalysts the WO_3-x system is a more robust redox-nanocatalyst, which is not susceptible to decomposition or denaturation under standard conditions. The unique oxidase-like activity of WO_3-x can be used for a wide range of applications in synthetic, environmental or medicinal chemistry.

Hydrogen Peroxide as a Green Oxidant for the Selective Catalytic Oxidation of Benzylic and Heterocyclic Alcohols in Different Media: An Overview

Among a plethora of known and established oxidant in organic chemistry, hydrogen peroxide stands in a special position. It is commercially and inexpensively available, highly effective, selective, and more importantly it is compatible with current environmental concerns, dictated by principles of green chemistry. Several chemicals or their intermediates that are important in our daily life such as pharmaceuticals, flavors, fragrances, etc. are products of oxidation of alcohols. In this review, we introduce hydrogen peroxide as an effective, selective, green and privileged oxidant for the catalyzed oxidation of primary and secondary benzylic and heterocyclic alcohols to corresponding carbonyl compounds in different media such as aqueous media, under solvent-free conditions, various organic solvent, and dual-phase system.

In Situ Synthesis of Gold Nanoparticles/Metal-Organic Gels Hybrids with Excellent Peroxidase-Like Activity for Sensitive Chemiluminescence Detection of Organophosphorus Pesticides

Until now, despite much progress in the study of metal-organic gels (MOGs), the modification of transition-metal containing MOGs with noble metal nanoparticles (NPs) is far from fully developed. Herein, iron-based MOGs nanosheet hybrids with gold NPs (AuNPs) immobilization were first synthesized by a facile in situ grown strategy at ambient conditions. It is found that the as-prepared AuNPs/MOGs (Fe) hybrids exhibited enhanced mimicking peroxidase-like activity, making them endowed with outstanding performance in chemiluminescence (CL) field in the presence of H₂O₂. The remarkable CL enhancement by AuNPs/MOGs (Fe) hybrids was attributed to the modification of AuNPs on MOGs (Fe) nanosheets, which could synergistically accelerate the CL reaction by speeding up the generation of OH^•, O₂^•-, and ¹O₂. Accordingly, a sensitive CL detection of organophosphorus pesticides was successfully achieved by the AuNPs/MOGs (Fe) hybrids CL enhancing system in the range of 5-800 nM with a detection limit of 1 nM. We envision that this highly active and novel enzyme mimetic catalyst can be applicable to other extended AuNPs/MOGs (Fe) hybrid-based CL systems for sensitive detection of various analytes.

Novel Iron(III)-Based Metal-Organic Gels with Superior Catalytic Performance toward Luminol Chemiluminescence

Novel metal-organic gels (MOGs) consisting of iron (Fe³⁺) as the central ion and 1,10-phenanthroline-2,9-dicarboxylic acid (PDA) as the ligand were synthesized by a mild facile strategy. The Fe(III)-containing metal-organic xerogels (Fe-MOXs), obtained after removing the solvents in MOGs, were found to exhibit outstanding performance in the catalysis of luminol chemiluminescence (CL) for the first time even in the absence of extra oxidants such as hydrogen peroxide. The possible CL mechanism was discussed according to the electro/optical measurements, including electron paramagnetic resonance (EPR), UV-vis absorption, and CL spectra, as well as the effects of radical scavengers on Fe-MOXs-catalyzed luminol CL system, suggesting that the CL emission of luminol might originate from the intrinsic oxidase-like catalytic activity of Fe-MOXs on the decomposition of dissolved oxygen. Additionally, the potential practical application of the resulting luminol-Fe-MOXs system was evaluated by the quantitative analysis of dopamine. Good linearity over the range from 0.05 to 0.6 μM was obtained with the limit of detection (LOD, 3σ) of 20.4 nM and acceptable recoveries ranging from 98.6 to 105.4% in human urine. These results may open up the promising application of novel metal-organic gels as highly effective catalysts in the field of chemiluminescence.

Chemoselective hydrogen peroxide oxidation of primary alcohols to aldehydes by a water-soluble and reusable iron(iii) catalyst in pure water at room temperature

A novel, water-soluble and reusable FeCl₃ catalyst showed high catalytic activity and chemoselectivity in the H₂O₂-oxidation of primary alcohols into aldehydes.

Alcohol oxidation with H2O2 catalyzed by a cheap and promptly available imine based iron complex

A cheap and easily available catalyst for alcohol oxidation with unexpected selectivity features.

Application of metal organic frameworks M(bdc)(ted)0.5 (M = Co, Zn, Ni, Cu) in the oxidation of benzyl alcohol

The selective oxidation of benzyl alcohol to benzaldehyde is an important process in heterogeneous catalysis and green organic chemistry.

Catalytic oxidation of water and alcohols by a robust iron(iii) complex bearing a cross-bridged cyclam ligand

An iron(iii) complex functions as a molecular catalyst for both oxidation of water and alcohols using sodium periodate as an oxidant.

Adsorption of Azo-Dye Orange II from Aqueous Solutions Using a Metal-Organic Framework Material: Iron- Benzenetricarboxylate

A Metal-Organic Framework (MOF), iron-benzenetricarboxylate (Fe(BTC)), has been studied for the adsorptive removal of azo-dye Orange II from aqueous solutions, where the effect of various parameters was tested and isotherm and kinetic models were suggested. The adsorption capacities of Fe(BTC) were much higher than those of an activated carbon. The experimental data can be best described by the Langmuir isotherm model (R² > 0.997) and revealed the ability of Fe(BTC) to adsorb 435 mg of Orange II per gram of adsorbent at the optimal conditions. The kinetics of Orange II adsorption followed a pseudo-second-order kinetic model, indicating the coexistence of physisorption and chemisorption, with intra-particle diffusion being the rate controlling step. The thermodynamic study revealed that the adsorption of Orange II was feasible, spontaneous and exothermic process (−25.53 kJ·mol⁻¹). The high recovery of the dye showed that Fe(BTC) can be employed as an effective and reusable adsorbent for the removal of Orange II from aqueous solutions and showed the economic interest of this adsorbent material for environmental purposes.

Chemoselective, iron(II)-catalyzed oxidation of a variety of secondary alcohols over primary alcohols utilizing H2O2 as the oxidant

A mild, iron-based catalyst system is presented that selectively oxidizes secondary alcohols to the corresponding hydroxy ketones in the presence of primary alcohols within 15 minutes at room temperature, utilizing H2O2 as the oxidant.