Probing the Alkyl Ligands on Silylated Mesoporous MCM-41 Using Hyperpolarized129Xe NMR Spectroscopy

2005 ◽  
Vol 109 (2) ◽  
pp. 681-684 ◽  
Author(s):  
Shing-Jong Huang ◽  
Chin-Hui Huang ◽  
Wen-Hua Chen ◽  
Xianping Sun ◽  
Xizhi Zeng ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Mcm 41

scholarly journals Hoveyda–Grubbs type metathesis catalyst immobilized on mesoporous molecular sieves MCM-41 and SBA-15

2011 ◽  
Vol 7 ◽  
pp. 22-28 ◽  
Author(s):  
Hynek Balcar ◽  
Tushar Shinde ◽  
Naděžda Žilková ◽  
Zdeněk Bastl
Keyword(s):  
Nmr Spectroscopy ◽  
Molecular Sieves ◽  
Direct Interaction ◽  
Mesoporous Molecular Sieves ◽  
Support Surface ◽  
Wall Surface ◽  
Ring Closing Metathesis ◽  
Immobilized Catalysts ◽  
Metathesis Catalyst ◽  
Mcm 41

A commercially available Hoveyda–Grubbs type catalyst (RC303 Zhannan Pharma) was immobilized on mesoporous molecular sieves MCM-41 and on SBA-15 by direct interaction with the sieve wall surface. The immobilized catalysts exhibited high activity and nearly 100% selectivity in several types of alkene metathesis reactions. Ru leaching was found to depend on the substrate and solvent used (the lowest leaching was found for ring-closing metathesis of 1,7-octadiene in cyclohexane – 0.04% of catalyst Ru content). Results of XPS, UV–vis and NMR spectroscopy showed that at least 76% of the Ru content was bound to the support surface non-covalently and could be removed from the catalyst by washing with THF.

Probing the mobility of ibuprofen confined in MCM-41 materials using MAS-PFG NMR and hyperpolarised-129Xe NMR spectroscopy

2013 ◽  
Vol 15 (43) ◽  
pp. 18805 ◽  
Author(s):  
Flavien Guenneau ◽  
Kuldeep Panesar ◽  
Andrei Nossov ◽  
Marie-Anne Springuel-Huet ◽  
Thierry Azaïs ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
129Xe Nmr ◽  
Pfg Nmr ◽  
Mcm 41

scholarly journals Distribution of Gallium Nanocrystals in Ga/MCM-41 Mesocomposites by Continuous-Flow Hyperpolarized129Xe NMR Spectroscopy

2005 ◽  
Vol 77 (10) ◽  
pp. 3379-3382 ◽  
Author(s):  
Weiping Zhang ◽  
Christopher I. Ratcliffe ◽  
Igor L. Moudrakovski ◽  
Chung-Yuan Mou ◽  
John A. Ripmeester
Keyword(s):  
Nmr Spectroscopy ◽  
Continuous Flow ◽  
Mcm 41

Deuterium NMR Spectroscopy of Solvents Adsorbed onto the Surface of Mesoporous Silica

1996 ◽  
Vol 425 ◽  
Author(s):  
George S. Attard ◽  
Mark Edgar ◽  
James W. Emsley ◽  
Christine G. Göltner
Keyword(s):  
Nmr Spectroscopy ◽  
Orientational Order ◽  
Domain Size ◽  
Mesoporous Silicas ◽  
Deuterium Nmr ◽  
Nmr Spectrum ◽  
Domain Boundaries ◽  
Uniform Diameter ◽  
Degree Of Order ◽  
Mcm 41

AbstractA series of simple deuterium NMR experiments are used to investigate the surfaces of differently structured silicas by studying the sorption of deuteriated solvents. Two mesoporous silicas (MCM-41 and H1-silica), which display hexagonally arranged channels of uniform diameter are studied, as well as amorphous column silica. The deuterium NMR lineshape strongly depends on the anisotropic environment of the adsorbed deuteriated species (D2O, benzene-d6, pyridine-d5). This allows differentiation between probe molecules adsorbed to the internal surface (anisotropic) and to the external surface (isotropic, non-ordered surface of particles). Solvents adsorbed within the channels of the silica nanostructure retain a degree of orientational order while moving on the surface, thus producing a Pake pattern. In contrast, solvents adsorbed on the outside of the ordered channels and on domain boundaries retain no orientational order while moving on the surface, therefore giving rise to a singlet in the deuterium NMR spectrum. This phenomenon allows to judge and compare the qualities of hexagonal ceramic nanostructures. The results show that H1-silica exhibits a significantly higher degree of order, due to a larger domain size, than MCM-41.

Studies of adsorption of 2,2′-bipyridyl on the surface of highly regulated silica matrix of the MCM-41 type by means of 15N NMR spectroscopy

2010 ◽  
Vol 80 (10) ◽  
pp. 2027-2031 ◽  
Author(s):  
S. B. Lesnichin ◽  
N. Kamdem ◽  
D. Mauder ◽  
G. S. Denisov ◽  
I. G. Shenderovich
Keyword(s):  
Nmr Spectroscopy ◽  
Silica Matrix ◽  
15N Nmr ◽  
15N Nmr Spectroscopy ◽  
Mcm 41

Using Trimethylphosphine as a Probe Molecule to Study the Acid Sites in Al−MCM-41 Materials by Solid-State NMR Spectroscopy

2003 ◽  
Vol 107 (11) ◽  
pp. 2435-2442 ◽  
Author(s):  
Qing Luo ◽  
Feng Deng ◽  
Zhongyong Yuan ◽  
Jun Yang ◽  
Mingjin Zhang ◽  
...  
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Solid State Nmr ◽  
Acid Sites ◽  
Probe Molecule ◽  
Solid State Nmr Spectroscopy ◽  
Mcm 41

Copper tellurolate clusters in trimethylsilylated MCM-41 — Preparation and condensation

2006 ◽  
Vol 84 (2) ◽  
pp. 196-204 ◽  
Author(s):  
Collin M Kowalchuk ◽  
Harald Rösner ◽  
Dieter Fenske ◽  
Yining Huang ◽  
John F Corrigan
Keyword(s):  
Nmr Spectroscopy ◽  
Sorption Isotherms ◽  
Nitrogen Adsorption ◽  
Mas Nmr ◽  
Condensation Process ◽  
X Ray ◽  
Edx Analysis ◽  
Transmission Electron ◽  
Cp Mas Nmr ◽  
Mcm 41

The copper tellurolate cluster [(Cu6(TePh)6(PEtPh2)5] (1) has been loaded into the pores of a trimethylsilylated MCM-41 (TMS–MCM-41) framework. Solutions of 1 in tetrahydrofuran lead to good impregnation weight % (~10 wt%, 1). The resulting material was analysed by powder X-ray diffraction (PXRD), nitrogen sorption isotherms, thermogravimetric analysis (TGA), energy dispersive X-ray (EDX) analysis, 31P CP MAS NMR spectroscopy, and transmission electron microscopy (TEM). It was observed that the loading process proceeds with the intact cluster 1 being present within the hexagonal architecture. The intact nature of 1 makes it an ideal candidate for condensation by photochemical or thermal means. Both of these condensation treatments increase the Cu:Te ratio of 1 to approach that observed in binary semiconductor Cu2Te. The condensation process was analysed by GC–MS spectrometry and characterization of the condensed, isolated composites was performed by TGA, EDX analysis, 31P CP MAS NMR spectroscopy, nitrogen adsorption, and TEM measurements. Thermal condensation results in the formation of Cu2Te particles, whereas photochemical condensation yields larger copper-tellurolate nanoclusters.Key words: copper, tellurium, cluster, MCM-41, trimethylsilylated, photolysis, thermolysis, Cu2Te, composite, mesoporous material.

The design and catalytic performance of molybdenum active sites on an MCM-41 framework for the aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran

2019 ◽  
Vol 9 (3) ◽  
pp. 811-821 ◽  
Author(s):  
Zhao-Meng Wang ◽  
Li-Juan Liu ◽  
Bo Xiang ◽  
Yue Wang ◽  
Ya-Jing Lyu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Aerobic Oxidation ◽  
Catalytic Performance ◽  
Mcm 41

The catalytic activity decreases as –(SiO)3Mo(OH)(O) > –(SiO)2Mo(O)2 > –(O)4–MoO.

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