Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024591 (malignant hyperthermia)
 2,353 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Novel polyoxometalates (POMs)-functionalized mesoporous hybrid silicas (SiW11/MHS) were synthesized for the first time by the co-condensation of tetraethoxysilane (TEOS) with Keggin-type monovacant SiW11 in the presence of block copolymer EO20PO70EO20 (P123). The as-obtained SiW11/MHS samples were characterized by FT-IR, UV/DRS, XRD, ICP-AES, and N2 adsorption-desorption measurements. It is shown that not only a hexagonal packing of channels with homogeneous pore diameter is obtained, but also Keggin units remain perfectly in the hybrid materials, and Si species insert into the vacancies of lacunary SiW11 during the synthesis to form SiW11Si2 structure, which condenses with the framework of mesoporous silica thus grafting POM molecules onto the pore wall of mesoporous silica by covalent linkage. This linkage results in a firmer immobilization of POMs on the mesoporous material. The water-leaching percent of POMs in the hybrid material is much less than those in the impregnated samples. Therefore, the synthesis strategy for the hybrid material is significant for acquiring supported POM catalysts of high efficiency and practicability.
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PMID:Direct synthesis of polyoxometalates-functionalized mesoporous hybrid silicas. 1745 Aug 78

Novel polyoxometalate (POM)-grafting mesoporous hybrid silicas, XW(11)/MHS (X=P, Si) and TBAPW(11)Si(2)/MHS, have been prepared respectively by co-condensation and post-synthesis routes based on the employment of Keggin-type monovacant XW(11) or a Si-substituted compound TBAPW(11)Si(2) as POM precursors. Upon characterization of the samples by FT-IR, XRD, ICP-AES, TEM and N(2) adsorption-desorption measurement, it was found that Keggin units were retained perfectly in ordered hexagonal mesopore channels with SBA-15 architecture and immobilized by covalent linkages on the mesopore wall. These materials, especially the co-condensed samples, exhibited stable and reversible photochromic properties under UV irradiation although no special organic component was supplied additionally as an electron donor. An investigation of the photochromism revealed that the photochromic response depended on the centre atom of the POM species (i.e., the redox potential of the POM), the content of the POM and the synthetic route of the sample, while the bleaching process was correlated not only to the redox potential but also to the pore size of the sample. The photochromic mechanism was also studied in detail by cyclic voltammetry, ESR, FT-IR and XPS techniques. It was found that the remaining P123 template acted as a reducing agent and was oxidized during the photochromic process accompanied by the reduction of the POM to heteropolyblue. Thus, a close contact between the POM and the remaining P123 chain in the sample is necessary. Low close-contact degree results in poor photochromic behavior of the post-synthesized sample and impregnated samples.
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PMID:Photochromic ordered mesoporous hybrid materials based on covalently grafted polyoxometalates. 2144 50

New tungstophosphate-functionalized ordered mesoporous silica was synthesized based on monovacant PW11 and block copolymer template. Upon characterizations of the as-obtained PW11/MHS samples by FT-IR, XRD, ICP-AES and N2 adsorption-desorption measurements, it was revealed that Keggin units were retained perfectly in hexagonally symmetrical mesopore channels and bound covalently onto the pore walls of mesoporous silica. The material exhibits stable and reversible photochromic property upon UV irradiation even though no a special organic component was supplied as electron donor. This may provide a new approach to construct photochromic materials of potential applications in high-density optical memories and other optical devices.
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PMID:Synthesis and photochromism of tungstophosphate-functionalized ordered mesoporous hybrid silica. 2144 92