SYNTHESIS AND PHYSICOCHEMICAL STUDY OF THE CERIUM AND CEFAZOLIN METAL COMPLEX

В данной работе коллективом авторов путём взаимодействия водных растворов хлорида трёхвалентного церия и натриевой соли цефазолина получено и выделено в твердом виде металлокомплексное соединение. Его элементный состав установлен с помощью метода рентгеноспектрального электронно-зондового анализа, описаны термические характеристики данного соединения, температура его разложения, состав и способ координации внутренней сферы данного металлокомплекса был уточнен методами термогравиметрии, и дифференциальной сканирующей калориметрии и методом ИК-спектроскопии. На основании полученных данных установлено, что внутренняя сфера металллокомплекса содержит в своем составе три молекулы цефазолина и три молекулы внутрисферной воды. Состав внутренней сферы отвечает брутто-формуле [CeCzl(HO) ]. На основании данных ИК- спектроскопии сделаны выводы о координации цефазолина к центральному иону через амидную и карбоксильную группы. In this work, a team of authors obtained and isolated in solid form a metal complex compound by the interaction of aqueous solutions of trivalent cerium chloride and sodium salt of cefazolin. Its elemental composition was determined using the X-ray spectral electron probe analysis. The thermal characteristics of this compound, the temperature of its decomposition, the composition and the method of coordination of the inner sphere of this metal complex were clarified by the methods of thermogravimetry, differential scanning calorimetry and IR spectroscopy. Based on the data obtained, the inner sphere of the metal complex contains three molecules of cefazolin and three molecules of inner-sphere water. The composition of the inner sphere corresponds to the formula [CeCzl(HO) ]. Taking into account IR spectroscopy data, the authors concluded that the most likely way of coordination of cefazolin to the central ion is through the amide and carboxyl groups.

Green Synthesis of Nanostructure CeO2 Using Tea Extract: Characterization and Adsorption of Dye from Aqueous Phase

Nanostructure CeO2 powders were synthesized using tea waste extract as gel precursor. The as-prepared samples were characterized by thermogravimetric analyzer (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Based on the TGA/DTG analysis, the intermediates of cerium chloride hydrates (CeCl3.4H2O and CeCl3.H2O) and cerium anhydrous (CeCl3) were produced, and the formation temperature of CeO2 was estimated to be 773 K. The cubic fluorite structure of CeO2 was detected to be the predominant species and was completely formed at the calcination temperature of 773K–1073 K with a crystal size between 8.8 and 11.4 nm based on the XRD measurement. Moreover, the main chemical state of ceria on the surface of the synthesized samples was confirmed to be tetravalent ceria by XPS. All samples show a strong Raman signal at a well-defined chemical shift of 463 cm−1 and a significant symmetry feature was observed, suggesting that the tetravalent ceria is the dominant species throughout the bulk sample. All the synthesized CeO2 calcined at different temperatures showed higher adsorption efficiency for Congo red (CR) compared with commercial CeO2. The adsorption efficiency maintained a steady state of more than 95% when the concentration of CR and adsorption temperature were varied in this study. The kinetic analysis showed that the second-order model was the appropriate model to interpret the adsorption behavior of synthesized CeO2. The calculated adsorption capacity derived from the second-order model is in good agreement with the experimental data. The isotherm analysis revealed that the Freundlich and D-R models fit well for the synthesized CeO2 and represent physisorption with a multilayer mechanism. The thermodynamic parameters, including the changes in Gibb’s free energy, enthalpy, and entropy, suggested that the adsorption of CR on the synthesized CeO2 sample was a spontaneous and endothermic process.

Highly Diastereoselective Reactions of Isoxazolidine-4,5-diols with Grignard Reagents: A New Approach to anti,syn-γ-Amino-α,β-diols

An investigation of the reaction of 3,4-trans-isoxazolidine-4,5-diols with Grignard reagents is described for the first time. Their resemblance to five-membered cyclic hemiacetals allows them to react as α-hydroxy-β-(hydroxyamino)aldehydes in a highly stereoselective manner, providing anti,syn-γ-(hydroxyamino)-α,β-diols in moderate yields and with good to excellent syn-diastereoselectivities, which can be improved by the addition of anhydrous cerium chloride. The obtained (hydroxyamino­)diols serve as suitable precursors of anti,syn-γ-amino-α,β-diols that represent valuable scaffolds for the synthesis of various biologically active compounds.

Influence of Benzotriazole and Cerium Chloride on Anticorrosion Performance of Cu-0.25Se-0.25Te Alloy in 3.5 wt% NaCl Solution

The effect of the addition of benzotriazole (BTA) or cerium chloride separately and in combination on the anticorrosion performance of Cu-Se-Te alloy in 3.5 wt% NaCl solution has been investigated. The results show that the addition of either BTA or cerium chloride significantly reduces the corrosion rate of Cu-0.25Se-0.25Te, but BTA exhibits a better inhibition effect. Meanwhile, scanning electron microscope analysis displays that the separate addition of BTA or cerium chloride makes the depth of corrosion pit of the sample decrease and the corroded surface smooth. With the combination of BTA and cerium chloride rising, the surface of the sample becomes much flatter and no obvious corrosion pit is found. Energy dispersive spectrum and x-ray photoelectron spectroscopy analyses suggest that when BTA and cerium chloride are added together, CeO2, Ce(OH)3, or complex formed by Ce and BTA might deposit on the surface of copper alloy, which induces the passivation film on the surface of the alloy to become denser and enhances the binding strength of the interface between the surface film and the matrix, thus improving the corrosion inhibition performance of the complex system.