Publications by authors named "Kirill P Larionov"
Zr-monosubstituted polyoxometalates (Zr-POMs) of the Lindqvist (BuN)[{WOZr(μ-OH)}] (), Keggin (BuN)[{PWOZr(μ-OH)}] (), and Wells-Dawson (BuN)KH[{PWOZr}(μ-OH)] () structures catalyze oxidation of alcohols using aqueous hydrogen peroxide as an oxidant. With 1 equiv of HO and 1 mol % of Zr-POM, selectivity toward aldehydes and ketones varied from good to excellent, depending on the alcohol nature. Catalytic activity and attainable substrate conversions strongly depended on the Zr-POM structure and most often decreased in the order > ≫ .
View Article and Find Full Text PDFThe Zr-monosubstituted Keggin-type dimeric phosphotungstate (BuN)[{PWOZr(μ-OH)(HO)}] () efficiently catalyzes epoxidation of C═C bonds in various kinds of alkenes, including terminal ones, with aqueous HO as oxidant. Less sterically hindered double bonds are preferably epoxidized despite their lower nucleophilicity. Basic additives (BuNOH) in the amount of 1 equiv per dimer suppress HO unproductive decomposition, increase substrate conversion, improve yield of heterolytic oxidation products and oxidant utilization efficiency, and also affect regioselectivity of epoxidation, enhancing oxygen transfer to sterically hindered electron-rich C═C bonds.
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- The decomposition of hydrogen peroxide (HO) during catalytic oxidation processes, like alkene epoxidation, is not well-understood, complicating efforts to improve product selectivity and oxidant efficiency.
- Researchers studied a Zr-monosubstituted dimeric Lindqvist tungstate catalyst that showed high activity for HO degradation in acetonitrile, revealing a first-order reaction that is affected by HO concentration and has a lower activation energy compared to other catalysts.
- Spectroscopic studies confirmed the generation of reactive oxygen species, leading to the production of oxidation products, while optimizations achieved a 90% yield of ascaridole, supported by density functional theory calculations that detailed the decomposition mechanism.
Probes sensitive to mechanical stress are in demand for the analysis of pressure distribution in materials, and the design of pressure sensors based on metal-organic frameworks (MOFs) is highly promising due to their structural tunability. We report a new pressure-sensing material, which is based on the UiO-66 framework with trace amounts of a spin probe (0.03 wt%) encapsulated in cavities.
View Article and Find Full Text PDFThe catalytic performance of Zr-abtc and MIP-200 metal-organic frameworks consisting of 8-connected Zr clusters and tetratopic linkers was investigated in H O -based selective oxidations and compared with that of 12-coordinated UiO-66 and UiO-67. Zr-abtc demonstrated advantages in both substrate conversion and product selectivity for epoxidation of electron-deficient C=C bonds in α,β-unsaturated ketones. The significant predominance of 1,2-epoxide in carvone epoxidation, coupled with high sulfone selectivity in thioether oxidation, points to a nucleophilic oxidation mechanism over Zr-abtc.
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- Zr-based metal-organic frameworks (Zr-MOF) UiO-66 and UiO-67 show exceptional selectivity in catalyzing thioether oxidation, achieving 96-99% selectivity toward sulfones with around 50% sulfide conversion using just one equivalent of hydrogen peroxide.
- The reaction mechanism was explored through various multidisciplinary techniques, revealing a nucleophilic nature of the peroxo species involved, supported by multiple observations including nucleophilic parameters and competitive oxidation ratios.
- Additionally, the catalytic activity of Zr-MOFs extends to epoxidation reactions, highlighting a complex interplay between nucleophilic and electrophilic oxidizing species and underscoring the role of weak basic sites in enhancing their catalytic efficiency.