Phosphotungstic acid (PTA) immobilized onto imidazole functionalized fumed silica and was used as an efficient catalyst for epoxidation of a variety olefins using aqueous H2O2 oxidant. Negligible leaching PTA under the reaction conditions employed indicates strong interaction between imidazole. The catalysts could be separated reused after catalytic cycle. Evidence heterogenization on has been inferred from different spectroscopic techniques like IR, UV−vis, NMR. Importantly, nature binding...

Abstract Textile effluents contain triazine-substituted reactive dyes that cause health problems such as cancer, birth defects, and hormone damage. An electrochemical process was employed effectively to degrade azo dye with the aim of reducing production carcinogenic chemicals during biodegradation. C.I. Reactive Red 2 (RR2), a model pollutant contains dichloro triazine ring, subjected electrocoagulation using aluminium (Al) electrodes. A maximum 97% colour 72% chemical oxygen demand (COD)...

Copper(II) azide complexes of three tridentate ligands namely 2,6-(3,5-dimethylpyrazol-1-ylmethyl)pyridine (L), 2,6-(pyrazol-1-ylmethyl)pyridine (L'), and dipropylenetriamine (dpt) yield kinds with different azide-binding modes. The ligand L forms two end-on-end (μ-1,3) diazido-bridged binuclear complexes, [CuL(μ-N3)]2(ClO4)2 (1) [CuL(μ-N3)(ClO4)]2·2CH3CN (2), L' a perchlorato-bridged quasi-one-dimensional chain complex, [CuL'(N3)(ClO4)]n (3) monodentate coordination. ligation gives end-on...

The Schiff base (H2fsal-ohyba) derived from 3-formylsalicylic acid and o-hydroxybenzylamine has been covalently bonded to chloromethylated polystyrene cross-linked with 5% divinylbenzene (abbreviated as PS-H2fsal-ohyba, I). Treatment of [VO(acac)2] PS-H2fsal-ohyba in dimethylformamide (DMF) gave the oxovanadium(IV) complex PS-[VO(fsal-ohyba)·DMF] (1). Complex 1 can be oxidized into dioxovanadium(V) species, PS-K[VO2(fsal-ohyba)] (2) on aerial oxidation presence KOH or oxoperoxo...

The coordination geometry of zeolite-encapsulated copper(II)−histidine (CuHis) complexes, prepared by ion exchange the complexes from aqueous solutions into zeolite NaY, was determined a combination UV−vis−NIR diffuse reflectance spectroscopy (DRS), X-band EPR, electron-spin−echo envelope modulation (ESEEM), and high field (W-band) pulsed ENDOR techniques. EPR detected two distinct A B, which are different prevailing Cu(II) bis-His complex in solution (pH 7.3 with His:Cu(II) ratio 5:1)....

A nanocrystalline TiO2 was successfully synthesized using simple aqueous peroxo route and subsequently the surface characterization of carried out X-ray diffraction Scanning electron microscopy. The decomposed remazol brown dye solution under UV light irradiation with without ozone. effects pH, dose time for decomposition were also evaluated. maximum efficiency 96.6 % achieved minimal 45 min by UV/TiO2/O3 treatment. present study clearly indicates that nanoparticle is a promising material...

W-band (95 GHz) pulsed EPR and electron-nuclear double resonance (ENDOR) spectroscopic techniques were used to determine the hyperfine couplings of different protons Cu(II)-histidine complexes in frozen solutions. The results then obtain coordination mode tridentate histidine molecule serve as a reference for complexation other, more complex systems. Cu(II) with L-histidine DL-histidine-alpha-d,beta-d2 prepared H2O D2O, orientation-selective 1H 2H ENDOR spectra these recorded at 4.5 K. These...

Xanthine oxidase is a molybdenum-containing enzyme that catalyzes the hydroxylation of xanthine and wide variety other aromatic heterocycles. In course reaction with substrates such as 2-hydroxy-6-methylpurine (HMP), gives rise to Mo(V) EPR signal, denoted "very rapid", arises from an authentic catalytic intermediate. The two alternative mechanisms proposed for this differ critically in whether distance between Mo C8 purine nucleus intermediate short enough admit direct bonding interaction....

Continuous synthesis at ambient conditions: Dimethyl carbonate (DMC) is an important methylating and carbonylating agent. Transesterification of cyclic carbonates using methanol for the DMC environmentally benign. CaO–ZnO catalysts, prepared by a wet impregnation method, are effective catalysts transesterification ethylene in batch continuous reactors. Yields ca. 84 % can be achieved conditions. Detailed facts importance to specialist readers published as "Supporting Information". Such...

W-band (95 GHz) pulsed EPR and electron−nuclear double resonance spectroscopic techniques were used to investigate the manganese S1 binding site of protein concanavalin A in a frozen solution single crystal. 1H ENDOR spectra collected by using Davies sequence, whereas Mims was applied record 2H spectra. Different transitions selected performing measurements at different magnetic fields within spectrum. This selection, combined with large thermal polarization achieved ∼3.4 T low temperatures,...

Electron spin resonance, pulsed electron nuclear double resonance (ENDOR) spectroscopy at W- and X-band frequencies, hyperfine sublevel correlation (HYSCORE) have been employed to determine the location of V(IV) ions in H4PVMo11O40 heteropolyacid catalysts. In these materials heteropolyanions well-known structure Keggin molecule. Interactions unpaired electrons paramagnetic vanadyl (VO(2+)) with all relevant nuclei 1H, 31P, 51V) could be resolved. The complete analysis coupling tensor for...

Pulsed electron nuclear double-resonance (ENDOR) spectroscopy at W- and X-band frequencies has been employed to characterize the structure of NO adsorption sites involving sodium cations in zeolite NaA. The principal values hyperfine quadrupole coupling tensors as well orientation their axes system with respect g tensor coordinate frame Na+−NO complex could be determined by orientation-selective ENDOR spectroscopy. Such experiments benefit especially from high spectral resolution W-band...