Search results for "MCM"

Modelling electrocatalysis of hydroquinone oxidation by nicotinamide adenine dinucleaotide coenzyme encapsulated within SBA-15 and MCM-41 mesoporous …

2006

The electrochemical response of NADH associated to two mesoporous aluminosilicates, MCM-41 and SBA-15, is described upon attachment of such materials into polymer-film electrodes. The studied materials display a significant electrocatalytic activity towards the oxidation of 1,4-dihydrobenzoquinone, H2Q. Two models for describing the electrocatalytic process, based on the general theory of mediated electrocatalysis and the Lovric and Scholz formulation of the voltammetry of microparticles are discussed. Voltammetric and chronoamperometric data indicate that the electrocatalytic process involves the formation of a surface-confined NADH–H2Q adduct in the case of SBA-15, while a surface reactio…

Molecular mechanism of capillary condensation of acetonitrile vapor on MCM-41 with the aid of a time-correlation function analysis of IR spectroscopy

1998

Abstract The adsorption isotherm and IR spectra of acetonitrile adsorbed on MCM-41 (pore-width=3.2 nm) were measured at 303 K. The adsorption isotherm had a sharp jump at P / P 0 =0.3 without adsorption hysteresis. The CN stretching ν 2 -band of adsorbed acetonitrile had two-component α- and β-bands at 2263 and 2254 cm −1 , respectively, assigned to hydrogen-bonded molecules on surface hydroxyls of MCM-41 and physisorbed molecules in mesopores whose walls are coated with hydrogen-bonded molecules, respectively. The β-band was analyzed with a time correlation function, giving a reorientation time τ . The τ value of the adsorbed molecule before capillary condensation was smaller than that of …

Selective opening of nanoscopic capped mesoporous inorganic materials with nerve agent simulants; an application to design chromo-fluorogenic probes.

2011

A hybrid nanoscopic capped mesoporous material, that is selectively opened in the presence of nerve agent simulants, has been prepared and used as a probe for the chromo-fluorogenic detection of these chemicals. © 2011 The Royal Society of Chemistry.

Novel route in the synthesis of MCM-41 containing framework aluminum and its characterization

1999

Abstract Mesoporous molecular sieve MCM-41 with incorporated structural aluminum (Al-MCM-41) was prepared by hydrolysis of a solution of tetraethoxysilane and aluminum isopropoxide in the presence of ammonia as a catalyst. This method provides Al-MCM-41 of different Si/Al ratios from 13 to 297 corresponding to 0.3–7 mol% Al within an hour. X-ray diffraction and nitrogen adsorption measurements showed that the Al-MCM-41 prepared by this method had a highly ordered structure of pore arrays. Most Al atoms in these samples were incorporated tetrahedrally in the MCM-41 structure, which gave rise to cationic sites in the framework.

Epoxidation of dibenzocycloalkenes on Ti–Ge-MCM-41 and Ti-SBA-15 catalysts

2005

Abstract Epoxidation of a series of dibenzocycloalkenes: phenanthrene, 5H-dibenzo[ a , e ]cycloheptene, 5H-dibenzo[ a , c ] cycloheptene, 5,6-dihydrodibenzo[ a , e ]cyclo-octene, and dibenzo[ a , e ]cyclooctene with hydrogen peroxide was investigated on Ti- and Ge-modified Ti-incorporated-type mesoporous catalysts including MCM-41 and SBA-15 structures looking for the effect of the porous texture and Ge-promoting on both activity and selectivity to epoxide and H 2 O 2 efficiency. Ti–Ge-MCM-41 catalysts (Si/Ti = 43; Si/Ge = 85 and Si/Ti = 41; Si/Ge = 62) were prepared by a one-pot surfactant-assisted procedure based on the use of a cationic surfactant (CTAB, cetyltrimethylammonium bromide), …

Hydrogenation of Aromatics in Diesel Fuels on Pt/MCM-41 Catalysts

1997

Abstract The hydrogenation activity of Pt supported on two mesoporous MCM-41 samples differing in their chemical composition has been studied by following the kinetics of the hydrogenation of naphthalene at 225–275°C reaction temperature and 5.0 MPa total pressure and by comparing the kinetic parameters obtained with Pt supported on a mesoporous amorphous silica-alumina (MSA) and other conventional supports, such as commercial amorphous silica-alumina (ASA), zeolite USY, γ-alumina, and silica. The two mesoporous MCM-41 and MSA materials having very high surface areas allowed for a better dispersion of the Pt particles, and they showed a superior overall hydrogenation activity as compared to…

A new synthetic route to tribenzo[a,e,i][12]annulenes

2000

Abstract The tribenzo[a,e,i][12]annulene 10 and the corresponding twofold annulene 14 were prepared on synthetic routes which first led from suitably functionalised starting compounds (2, 11) to the 1,2-distyryl- and 1,2,3,4-tetrastyrylbenzene derivatives 9 and 13 with two and four formyl groups, respectively. The cyclisation to 10 and 14 was achieved by applying the McMurry reaction. The extended ring system of compound 14 represents a discotic mesogen. The generation of liquid crystals was obtained with eight hexyloxy chains on the periphery.

ChemInform Abstract: A New Synthetic Route to Tribenzo[a,e,i][12]annulenes.

2010

Abstract The tribenzo[a,e,i][12]annulene 10 and the corresponding twofold annulene 14 were prepared on synthetic routes which first led from suitably functionalised starting compounds (2, 11) to the 1,2-distyryl- and 1,2,3,4-tetrastyrylbenzene derivatives 9 and 13 with two and four formyl groups, respectively. The cyclisation to 10 and 14 was achieved by applying the McMurry reaction. The extended ring system of compound 14 represents a discotic mesogen. The generation of liquid crystals was obtained with eight hexyloxy chains on the periphery.

Microwave applications in the synthesis of nanostructured materials and in organic extractions

2009

Pt(II) complex @mesoporous silica: preparation, characterization and study of release

2016

Cisplatin analogs, having cytotoxic activity higher than that exerted by cisplatin, have recently triggered considerable interest by the community. The cis-[PtCl2(DMSO)HL]·2DMSO, where HL = 7-amino-2-(methylthio)[1,2,4]triazolo[1,5-a]pyrimidine-6-carboxylic acid, has shown a potent cytotoxic activity on HepG2 hepatocarcinoma cells, while under identical conditions, it did not affect normal immortalized human liver cells (Chang). In this work, the above complex has been incorporated into MCM41 mesoporous silica, pure and functionalized with amino group, which is considered one of the best host for a drug delivery system for carrying high dosages of a variety of drugs in their mesopores. Sinc…