Ring-opening of (di)benzofurans is a significant area of research in organic chemistry, offering versatile and direct synthetic strategies to access valuable functional phenol derivatives. Transition metal catalysis, particularly nickel-catalyzed reactions, has been extensively explored for the selective cleavage of the C–O bond in (di)benzofuran. Metal-free methods, such as acid catalysis and strong base-mediated process, have also emerged as important alternatives. Organometallic reagents, including Grignard and organolithium reagents, play a pivotal role in promoting efficient C–O bond activation. The field of (di)benzofuran ring opening holds great promise for the synthesis of complex molecules with diverse applications in pharmaceuticals, materials science, and fine chemical synthesis. Continued research efforts will pave the way for innovative strategies and broaden the utility of (di)benzofuran derivatives in various fields.

Density functional theory studies on the reduction of H₂O₂ on a nonheme iron center is shown to lead to dioxygen products efficiently through the formation of a μ-1,2-peroxo bridged diiron(III)dihydroxo complex from two iron(IV)-oxo(hydroxo) intermediates.

Abstract

Hydrogen peroxide is a versatile reductant that under the right conditions can react to form dioxygen in an electrochemical reaction. This reaction has a low carbon footprint and applications are being sought for batteries. In this work a computational study is presented on a recently reported nonheme iron(II) complex where we study mechanistic pathways leading to dioxygen formation from H₂O₂. The work shows that upon reduction of the iron(III)-hydroperoxo species it rapidly leads through heterolytic cleavage of the dioxygen bond to form iron(IV)-oxo(hydroxo). The dimerization reaction of two iron(IV)-oxo(hydroxo) complexes then leads to formation of the dioxygen bond rapidly with small barriers. Dissociation of the dimer expels dioxygen in an exothermic reaction. An alternative mechanism through the formation of a μ-1,2-peroxo-μ-1,1-hydroperoxodiiron(II) intermediate was also tested but found to be highly endergonic. These studies highlight the electrochemical feasibilities of nonheme iron(III)-hydroperoxo complexes.

This study provides a new two-dimensional C−N coupling catalyst for urea production by loading three Mo-atoms on graphdiyne.

Abstract

Synthesis of urea by electrochemical C−N coupling is a promising alternative to the conventional approaches. A metal-cluster catalyst generally possesses multi-atomic active sites and can achieve co-adsorption and activation of several species. As a two-dimensional porous material, graphdiyne (GDY) is predicated to be a good substrate for loading a metal cluster. In this study, tri-metallic Mo-embedded graphdiyne (Mo₃@GDY) stands out for efficient urea synthesis among several TM₃@GDY (TM=Mo, Fe, Co, Ni and Cu), based on density functional theory (DFT) computations. The co-adsorption of side-on N₂ and end-on CO on Mo₃@GDY is benefit to the formation of the urea precursor *NCON with a negative free energy change (−0.66 eV). The final hydrogenation step is the potential-determining step (PDS) with a medium onset potential (-0.71 V). This work extends the application of GDY and first provides a new approach for the electrochemical synthesis of urea by loading tri-metallic atoms on GDY.

Hydroxyapatite (HAP) contains abundant defect sites and easily releases hydroxyl groups to produce new vacancies under calcination at high temperature. The highly dispersed VO_x/HAP catalyst was prepared by an impregnation method using these defects as inducement. VO_x species with different structures were analysed by XRD, XPS, H₂-TPR, Raman and UV–vis spectroscopy. At low calcination temperatures (500 °C and 600 °C), the V species are mainly V₂O₅ crystals. At high calcination temperatures (above 700 °C), VO_x on the HAP surface fills these defect sites and strongly interacts with HAP to form Ca−O−V or P−O−V bands. These scattered defects improved the dispersion of V species. An emphasis is given to the study of the catalytic performances in ODH of cyclohexane over the VHAP catalysts. The highly dispersed VO_x/HAP catalyst showed a high selectivity of cyclohexene, and the selectivity reached 48.2 % when the conversion of was 13.1 % at 410 °C. These improved selectivity is directly related to the chemical environment of highly dispersed VO_x species. In addition, the acidity reduction caused by high temperature calcination leads to the decrease of the adsorption capacity of VHAP to cyclohexene, which promotes the desorption of cyclohexene on the catalyst surface, inhibits the deep oxidation of cyclohexene and improves the selectivity.

Abstract

Hydroxyapatite (HAP) contains abundant defect sites and easily releases hydroxyl groups to produce new vacancies under calcination at high temperature. The highly dispersed VO_x/HAP catalyst was prepared by an impregnation method using these defects as inducement. VO_x species with different structures were analysed by XRD, XPS, H₂-TPR, Raman and UV–vis spectroscopy. At low calcination temperatures (500 °C and 600 °C), the V species are mainly V₂O5 crystals. At high calcination temperatures (above 700 °C), VO_x on the HAP surface fills these defect sites and strongly interacts with HAP to form Ca−O−V or P−O−V bands. These scattered defects improved the dispersion of V species. These highly dispersed VO_x/HAP catalysts were used for oxidative dehydrogenation (ODH) of cyclohexane to cyclohexene. The highly dispersed VOx/HAP catalyst showed a high selectivity for cyclohexene, and the selectivity reached 48.2 % when the conversion of cyclohexane was 13.1 % at 410 °C.

A fullerol-based ruthenium complex was prepared, and the heterogeneous (fullerol)-Ru-based water oxidation catalysts (WOC) anchored on the surface of the nano-TiO₂ were developed. Mechanistic studies revealed the anchoring of Ru-based WOC to TiO₂ result in a decrease in the redox potentials of Ru^IV/III couples,a nd decrease the barrier of the crucial O−O bond-forming step, and thus the catalytic activity of the nano-catalysts was improved.

Abstract

Ruthenium polypyridine complexes are the most effective catalysts for the water oxidation reaction (WOR), but the catalytic activity still has a large room for improvement. Herein, a fullerol-based ruthenium complex was prepared by the covalent grafting of the polypyridyl ruthenium complex of water oxidation catalyst (WOC) with fullerol, and the (fullerol)-Ru-based WOCs anchored on the surface of nano-TiO₂ were prepared through a sensitization strategy. The synthesized heterogeneous nano-catalysts are fully characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), infrared spectroscopy (IR), Brunauer–Emmett–Teller (BET) specific surface area and pore size distribution, and diffusion reflection ultraviolet-visible spectrum (DRS). The chemical oxygen evolution experiments reveal that the WOR catalyzed by the catalyst is a first-order reaction with respect to Ce (NH₄)₂(NO₃)₆ (denoted as CAN) concentration when using CAN as the sacrificial oxidant under acidic conditions. The anchoring of Ru-based WOC to TiO₂ result in a decrease in the redox potentials of Ru^IV/III couples, which decrease the barrier of the crucial O−O bond-forming step, and the heterogeneous nano-catalyst exhibit a high catalytic activity with a turnover frequency of 13.4 s⁻¹ and more excellent stability with a 15-min-turn over number of 1054 for TiO₂-fullerol-based ruthenium complex WOC.