Characterization of new Pt(IV)–thiazole complexes: Analytical,spectral, molecular modeling and molecular docking studies and applications in two opposing pathways

New thiazole derivatives were synthesized and fully characterized, then coordinated with PtCl₄ salt. Also, the newly synthesized Pt(IV) complexes were investigated analytically (elemental and thermogravimetric analyses), spectrally (infrared, UV–visible, mass, ¹H NMR, ¹³C NMR, X‐ray diffraction) as well as theoretically (kinetics, modeling and docking). The data extracted led to the establishment of the best chemical and structural forms. Octahedral geometry was the only formula proposed for all complexes, which is favorable for d⁶ systems. The molecular ion peaks from mass spectral analysis coincide with all analytical data, confirming the molecular formula proposed. X‐ray diffraction (XRD) and scanning electron microscopy (SEM) allowed discrimination of features between crystalline particles and other amorphous morphology. By applying Gaussian09 as well as HyperChem 8.2 programs, the best structural forms were obtained, as well as computed significant parameters. Computed parameters such as softness, hardness, surface area and reactivity led us towards application in two opposing pathways: tumor inhibition and oxidation activation. The catalytic oxidation for CO was conducted over PtO₂, which was yielded from calcination of the most reactive complex. The success of catalytic role for synthesized PtO₂ was due to its particulate size and surface morphology, which were estimated from XRD patterns and SEM images, respectively. The antitumor activity was tested versus HCT‐116 and HepG‐2 cell lines. Mild toxicity was recorded for two of the derivatives and their corresponding complexes. This degree of toxicity is more favorable in most cases, due to exclusion of serious side effects, which is coherently attached with known antitumor drugs.     

New functionalized polyesters to achieve controlled architectures

Following our continued interest in the production of bioerodible and biodegradable functional polymers for biomedical applications, we synthesized and characterized new unsaturated polyesters. The presence of functional groups in the polymer backbone provided sites for chemical modification, and through a variation in the structure, the physical properties, such as the hydrophilicity and solubility, could be affected. With 1,1-di-n-butyl-stanna-2,7-dioxacyclo-4-heptene as the initiator in the ring-opening polymerization of polyesters, a new set of functionalized polyesters was created. The polymerization of ϵ-caprolactone resulted in poly(ϵ-caprolactone) with a double bond incorporated into the structure. The polymers were obtained in a controlled manner with low molecular dispersities. The double bond was previously incorporated into L -lactide polymers, and the two reactions were compared in this study. The conversion of ϵ-caprolactone, with a degree of polymerization of 50, was completed within 140 min, whereas for L -lactide, only a 45% conversion took place in the same period of time. The dispersities were somewhat higher with ϵ-caprolactone because of the higher reaction rate and, therefore, lower selectivity. The incorporated CC double bond in the polyesters provided a variety of opportunities for further modifications. In this case, the double bond of the L -lactide macromonomers was oxidized into epoxides. Epoxidation was carried out with m-chloroperoxybenzoic acid as a chemical reagent. The conversion of the double bonds into epoxides was completed, and the obtained yields were good (>95%). As a result of the mild reaction conditions, the epoxidation of the double bond was carried out quantitatively without any side reactions. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 444–452, 2004     

Mechanistic Insights into the Reversible Formation of Iodosylarene–Iron Porphyrin Complexes in the Reactions of Oxoiron(IV) Porphyrin π‐Cation Radicals and Iodoarenes: Equilibrium,Epoxidizing Intermediate,and Oxygen Exchange

We have shown previously that iodosylbenzene–iron(III ) porphyrin intermediates ( 2 ) are generated in the reactions of oxoiron(IV ) porphyrin π‐cation radicals ( 1 ) and iodobenzene (PhI), that 1 and 2 are at equilibrium in the presence of PhI, and that the epoxidation of olefins by 2 affords high yields of epoxide products. In the present work, we report detailed mechanistic studies on the nature of the equilibrium between 1 and 2 in the presence of iodoarenes (ArI), the determination of reactive species responsible for olefin epoxidation when two intermediates (i.e., 1 and 2 ) are present in a reaction solution, and the fast oxygen exchange between 1 and H₂¹⁸O in the presence of ArI. In the first part, we have provided strong evidence that 1 and 2 are indeed at equilibrium and that the equilibrium is controlled by factors such as the electronic nature of iron porphyrins, the electron richness of ArI, and the concentration of ArI. Secondly, we have demonstrated that 1 is the sole active oxidant in olefin epoxidation when 1 and 2 are present concurrently in a reaction solution. Finally, we have shown that the presence of ArI in a reaction solution containing 1 and H₂¹⁸O facilitates the oxygen exchange between the oxo group of 1 and H₂¹⁸O and that the oxygen exchange is markedly influenced by factors such as ArI incubation time, the amounts of ArI and H₂¹⁸O used, and the electronic nature of ArI. The latter results are rationalized by the formation of an undetectable amount of 2 from the reaction of 1 and ArI through equilibrium that leads to a fast oxygen exchange between 2 and H₂¹⁸O.     

Effect of the incomplete accommodation of the heterogeneous recombination energy on heat fluxes to a quartz surface

Taking both the heterogeneous catalytic processes, including the surface formation of particles with excited internal degrees of freedom, and the processes of multicomponent diffusion and heat transfer in the MESOX apparatus fully into account makes it possible to obtain a recombination coefficient and an accommodation coefficient of the oxygen-atoms-on-quartz recombination energy which are in good agreement with the experimental data. The heterogeneous catalysis model constructed can be used effectively for predicting the heat fluxes to the surface of reentry vehicles on their entry into the Earth’s atmosphere.     

Catalytic Activity of Nickel Alloys in Anodic Oxidation of the Hypophosphite Ion as a Function of Their Composition

The rate of anodic oxidation of the hypophosphite ion on alloys Ni-P, Ni-B, and Ni-Mo-P is studied as a function of their composition and structure. The organic compounds that are customarily used to stabilize electrolytes of electroless nickel plating are shown to come useful when controlling composition of the Ni-P coatings at the expense of their different influence on the rates of partial processes of deposition of the alloy components. The formation of catalytic activity of such coatings is affected mostly by a structural factor. With alloys Ni-P, Ni-B, and Ni-Mo-P, whose composition was varied by altering the concentration of the source of the alloying component, dependence of catalytic activity of the surface on the composition is defined mainly by an electronic factor.__________Translated from Elektrokhimiya, Vol. 41, No. 8, 2005, pp. 972–980.Original Russian Text Copyright © 2005 by Sotskaya, Dolgikh, Ryabinina.     

Tuning size and catalytic activity of nano-clusters of cobalt oxide

Cobalt oxides were prepared by three different methods: (1) by reacting cobalt nitrate with oxalic acid, (2) co-precipitating cobalt nitrate with sodium carbonate, and (3) using sodium dodecyl sulphate as organic surfactant. All three samples were characterized before and after calcination by solvent extraction and the resulting products examined by IR spectroscopy. In the case of method 3, the removal of surfactant was followed by TGA studies. Products from all three methods were identified by XRD. Peaks in low angle XRD indicate the porous nature of the oxides. The morphology of the pores was studied by transmission electron microscopy. Some irregular pore structures were obtained for samples from methods 1 and 2, with an average size of 4–6 nm. Only the product from method 3 using SDS as template showed ordered structure and optimum size, and Brunauer-Emmet-Teller surface areas of the as-prepared, as well as the treated samples, exhibited H3 type hysteresis. The samples from the three methods were used as catalysts in the oxidation reaction of cyclohexane under mild conditions and the catalytic efficiency of the cobalt oxide was comparable with mesoporous cobalt oxides.     

纳米复合固体超强酸SO_4~(2-)/ZrO_2-Fe_2O_3的制备及其催化合成硝基苯的研究

采用纳米化学技术制备了新型的纳米复合固体超强酸催化剂SO42-/ZrO2-Fe2O3,并用XRD、TEM进行了表征.结果表明:所研制的SO42-/ZrO2-Fe2O3催化剂为晶态纳米粒子,平均粒径为30 nm,分散性较好;当活化温度为580℃,反应温度为75℃,n(硝酸)/n(苯)=2,m(苯)/m(催化剂)=20,催化反应时间5 h时,硝基苯收率可达89.6%.     

介孔材料在烯烃环氧化中的催化应用

本文综述了介孔材料在烯烃环氧化反应中的应用,包括材料的制备方法、催化性能以及活性中心的表征。通过硅钛原子的合理匹配可以达到四配位钛的高度分散,从而提高催化活性。硅烷化处理增加材料表面的疏水性,能够大幅度提高活性和选择性。通过多种谱学和分子模拟等手段可表征骨架钛及其配位情况。     

不同沉淀剂制备的Ag／TS－1催化丙烯直接气相氧化合成环氧丙烷

 在423K、常压固定床石英反应器中，以丙烯直接气相氧化为探针反应，考察了催化剂制备方法、沉淀剂的种类和浓度对制备的Ag／TS－1催化剂催化性能的影响，采用TEM，XRD和UV－Vis等表征手段对Ag／TS－1催化剂进行了分析．结果表明，沉积－沉淀法是最佳的催化剂制备方法，但浸渍法也可制得具有环氧丙烷选择性的催化剂．K2CO3是一种良好的沉淀剂．以K2CO3为沉淀剂，硅钛比为64的TS－1为载体制备的Ag／TS－1催化剂上的丙烯转化率为1．72％，环氧丙烷选择性为98．2％．少量单质银的存在有利于环氧丙烷的生成，除银粒子的分散状态外，银粒子与载体TS－1间的相互作用对提高催化剂的选择性具有决定性作用．