Mesoporous cubic

Morey, M., A. Davidson, H. Eckert, and G. Stucky, Pseudotetrahedral O3/2V = O Centers Immobilized on the Walls of Mesoporous, Cubic MCM-48 Support Preparation, Characterization and Reactivity toward Water as Investigated by V NMR and UV-Vis Spectroscopy s , Chem. Mater. (1996), 8(2), 486-92. 

A1 MAS-NMR spectra of mesoporous, cubic Na-Al-MCM-48 molecular sieve catalyst showed tetrahedrally-coordinated aluminium in both as-prepared and calcined samples.379... 

Y. Sakamoto, T.W. Kim, R. Ryoo, and O. Terasaki, Three-dimensional Structure of Large-Pore Mesoporous Cubic Ia3d Silica with Complementary Pores and its Carbon Replica by Electron Crystallography., Angew. Chem., Int. Ed., 2004, 43, 5231-5234. 

The majority of the hitherto reported non-siliceous mesoporous materials are hexagonally ordered or totally disordered. We recently reported a zirconium-based cubic mesostructure [15], which at that time could not be stabilized to result in a mesoporous material. Using the phosphate route developed previously for the stabilization of the hexagonal phase [13] we now also succeeded in Sorption isotherm of a phos- obtaining a mesoporous cubic... 

Similarly, monometallic Rh, Pd, and Au and bimetallic Pt-Rh and Pt-Pd nanowires were prepared in FSM-16 or HMM-1 by the photoreduction method [30,33,34]. The bimetallic wires gave lattice fringes in the HRTEM images, and the EDX analysis indicated the homogeneous composition of the two metals. These results show that the wires are alloys of Pt-Rh and Pt-Pd. Mesoporous silica films were also used as a template for the synthesis of uniform metal particles and wires in the channels [35,36]. Recently, highly ordered Pt nanodot arrays were synthesized in a mesoporous silica thin film with cubic symmetry by the photoreduction method [37]. The... 

Since the discovery by researchers at Mobil of a new family of crystalline mesoporous materials (1), a large effort has been expended on synthesis, characterization, and catalytic evalrration (2). MCM-41 is a one-dimerrsiorral, hexagonal structure. MCM-48 is a cubic structine with two, norrintersecting pore systems (3). MCM-50 is a layered stractme with silica sheets between the layers (4). Many scientists also looked into other mesoporous materials, of note the HMS (Hexagonal Molecular Sieve) family (5) and SBA-15 (acronym derived from Santa Barbara University) (6), bnt to date few materials have been both catalytically significant and inexpensive to synthesize. 

Figure 41.4 shows a typical XRD (X-Ray Diffraction) pattern of TUD-1, along with a TEM image (12). Similar to other mesoporous materials, TUD-1 has a broad peak at low 20. However, it has a broad background peak, commonly called an amorphous halo, and lacks any secondary peaks that are evident for example in the hexagonal MCM-41 and cubic MCM-48 structures. The TEM shows that the pores have no apparent periodicity. In this example the pore diameter is about 5 nm. 

Solid-state NMR spectroscopy was used for studying the formation of cubic mesoporous aluminophosphate thin films and powders. The analysis of the initial gel, the as-deposited materials and the thermally-treated materials elucidated the changes in the coordination of phosphorus and aluminium atoms and thus revealed how the framework formation and condensation proceeds. The consolidation process in thin films was different than the process in powders. Most probably this could be attributed to the effect of glass substrate. 

Figure 2.31P and 27AI MAS NMR spectra of F127- and FI 08-templated cubic large-pore mesoporous aluminophosphate thin films. 

Smarsly, B. Grosso, D. Brezesinski, T. Pinna, N. Boissiere, C. Antonietti, M. Sanchez, C. 2004. Highly crystalline cubic mesoporous Ti02 with 10-nm pore diameter made with a new block copolymer template. Chem. Mater. 16 2948-2952. 

Isoelectronic mesoporous Ti02 has been prepared by the same method but it is also not stable to template removal (224, 227). Hexagonal and cubic manganese oxide mesostructures (MOMS) have been prepared (228). Layered Mn(OH)2 is combined with CTAB and stirred at 75°C for 12 h. Depending on the CTAB concentration, either hexagonal MOMS-1 or cubic MOMS-2 is formed. The MOMS phases are apparently stable to calcination and exhibit semiconducting properties. 

In a preliminary study, cubic MCM-48 featuring a three-dimensional mesopore system was applied to generate heterogeneous organoneodymium-based isoprene... 

Recently, we and others demonstrated that appropriate germanide Zintl clusters in non-aqueous liquid-crystalline phases of cationic surfactants can assemble well-ordered mesostructured and mesoporous germanium-based semiconductors. These include mesostructured cubic gyroidal and hexagonal mesoporous Ge as well as ordered mesoporous binary intermetallic alloys and Ge-rich chalcogenide semiconductors. 

Figure 2 presents typical TEM images obtained from MSU-Ge-1 and the corresponding fast-Fourier transforms (FFT) taken along a thin area of the images. These images clearly indicate a high ordered mesoporous structure in body-centered cubic... 

The X-ray powder diffraction patterns of the parent materials showed the hexagonal structure characteristic for MCM-41 and SBA-15, and the cubic structure for MCM-48, respectively. All the patterns matched well with the reported patterns, confirming the successful synthesis of the mesoporous molecular sieves. The intensity of the reflection did not change essentially upon loading the carrier with the organometallic complexes, nor after a catalytic cycle, showing that the mesoporous structures were not affected by incorporation of the catalyst. 

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