Gas diffusion and microstructural properties of ordered mesoporous silica fibers

Pore and surface diffusion of carbon dioxide (CO(2)) and ethylene (C(2)H(4)) in the nanopores of ordered mesoporous silica fibers about 200 microm in length was measured by the transient gravimetric method. The experimentally determined pore diffusivity data, coupled with the porosity, pore size, and fiber length, are used to obtain the actual length of the nanopores in silica fibers. These measurements reveal a structure of the ordered nanopores whirling helically around the fiber axis with a spiral diameter of about 15 microm and a pitch value of 1.6 microm. At room temperature the surface diffusion contributes about 10% to the total diffusional flux for these two gases in the nanopores of the ordered mesoporous silica fibers. The surface diffusion coefficients for the ordered mesoporous silica fibers are about 1 order of magnitude larger than the non-ordered mesoporous alumina or silica with similar pore size.     

Direct formation of thermally stabilized amorphous mesoporous Fe2O3/SiO2 nanocomposites by hydrolysis of aqueous iron III nitrate in sols of spherical silica particles

Nanocomposite materials containing 10% and 20% iron oxide/silica, Fe2O3/SiO2 (w/w), were prepared by direct hydrolysis of aqueous iron III nitrate solution in sols of freshly prepared spherical silica particles (St?ber particles) present in their mother liquors. This was followed by aging, drying, calcination up to 600 degrees C through two different ramp rates, and then isothermal calcinations at 600 degrees C for 3 h. The calcined and the uncalcined (dried at 120 degrees C) composites were characterized by thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffraction (XRD), N2 adsorption/desorption techniques, and scanning electron microscopy as required. XRD patterns of the calcined composites showed no line broadening at any d-spacing positions of iron oxide phases, thereby reflecting the amorphous nature of Fe2O3 in the composite. The calcined composites showed nitrogen adsorption isotherms characterizing type IV isotherms with high surface area. Moreover, surface area increased with the increasing of the iron oxide ratio and lowering of the calcination ramp rate. Results indicated that iron oxide particles were dispersed on the exterior of silica particles as isolated and/or aggregated nanoparticles. The formation of the title composite was discussed in terms of the hydrolysis and condensation mechanisms of the inorganic FeIII precursor in the silica sols. Thereby, fast nucleation and limited growth of hydrous iron oxide led to the formation of nanoparticles that spread interactively on the hydroxylated surface of spherical silica particles. Therefore, a nanostructured composite of amorphous nanoparticles of iron oxide (as a shell) spreading on the surface of silica particles (as a core) was formed. This morphology limited the aggregation of Fe2O3 nanoparticles, prevented silica particle coalescence at high temperatures, and enhanced thermal stability.     

Synthesis of some novel pyrazolo[1,5‐a]pyrimidine, 1,2,4‐triazolo[1,5‐a]pyrimidine,pyrido[2,3‐d]pyrimidine,pyrazolo[5,1‐c]‐1,2,4‐triazine and 1,2,4‐triazolo[5,1‐c]‐1,2,4‐triazine derivatives incorporating a thiazolo[3,2‐a]benzimidazole moiety

E‐3‐(N,N‐Dimethylamino)‐1‐(3‐methylthiazolo[3,2‐a]benzimidazol‐2‐yl)prop‐2‐en‐1‐one ( 2 ) was synthesized by the reaction of 1‐(3‐methylthiazolo[3,2‐a]benzimidazol‐2‐yl)ethanone ( 1 ) with dimethylformamide‐dimethylacetal. The reaction of 2 with 5‐amino‐3‐phenyl‐1H‐pyrazole ( 4a ) or 3‐amino‐1,2,4‐(1H)‐triazole ( 4b ) furnished pyrazolo[1,5‐a]pyrimidine and 1,2,4‐triazolo[1,5‐a]pyrimidine derivatives 6a and 6b , while the reaction of enaminone 2 with 6‐aminopyrimidine derivatives 7a,b afforded pyrido[2,3‐d]pyrimidine derivatives 9a,b , respectively. The diazonium salts 11a or 11b coupled with compound 2 to yield the pyrazolo[5,1‐c]‐1,2,4‐triazine and 1,2,4‐triazolo[5,1‐c]‐1,2,4‐triazine derivatives 13a and 13b . Some of the newly synthesized compounds exhibited a moderate effect against some bacterial and fungal species.     

Synthesis,spectral characterization and anticancer studies of three novel ruthenium(III) 2,2′‐bipyridine complexes

A series of three new ruthenium(III) bipyridine complexes, [RuCl₃(bipy)L] (L = C₆H₅CHO (Ru1), 4‐CH₃OC₆H₄CHO (Ru2) and 4‐NO₂C₆H₄CHO (Ru3); bipy = 2,2′‐bipyridine), have been synthesized and characterized using microanalysis, magnetic, spectroscopic (IR, UV–visible, electron spin resonance) and cyclic voltammetric techniques. All the ruthenium(III) complexes were found to be stable, paramagnetic and octahedrally coordinated. Electron spin resonance spectra showed an axial symmetry and indicated a tetragonal distortion for the octahedral complexes. All complexes were tested for their cytotoxicities against Ehrlich ascites carcinoma (EAC), superoxide dismutase‐like activities and cytoprotective effects of normal human red blood cells against photo‐irradiation. All the compounds were found to be cytotoxic with half maximal inhibitory concentration (IC₅₀) against EAC at concentrations of 70, 90 and 76 µg for Ru1, Ru2 and Ru3, respectively. Moreover, mean levels of DNA and RNA were significantly elevated in liver tissues of tumorized animals and significantly reduced after treatment of tumorized mice with the complexes. Copyright © 2015 John Wiley & Sons, Ltd.     

Reactions with Maleimides XI: 1 Dipolar Cycloaddition Reactions with Thiazolonylarylhydrazones: A New Route for the Synthesis of Several New Thiazolonylpyrazoles of Expected Biological Activities

Several new pyrrolopyrazoles were synthesised via the reaction of thiazolonylarylhydrazones with N-arylmaleimides followed by partial dehydrogenation using bromobenzene and complete aromatization using nitrobenzene. Structures were elucidated by elemental analyses and spectral data studies.     

Synthèse et propriétés photochimiques de modèles imides et amides contenant des structures norbornadiènes pentaméthylés

Four pentamethylated norbardiene (NBD) models containing imide, bis-imide and diamides were synthesized in the first step of this work with a good yield and characterized by IR, ¹HNMR and ¹³CNMR spectroscopies. These models were used for study, by UV-Visible spectrophotometry, of the photochemical isomerisation under solar radiations of NBD residues, which they contain to quadricyclane (QC). Acquired results show, for all these models, that more than 70 % of NBD are transformed into QC after only 30 minutes of solar radiations and following a first order rate.