- Synthesis of colloidal Janus nanoparticles by asymmetric capping of mesoporous silica with phenylsilsesquioxane
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Colloidal mesoporous silica nanoparticles asymmetrically capped with non-porous phenylsilsesquioxane have been prepared by adding phenyltriethoxysilane to an aqueous dispersion of mesostructured silica-surfactant composite nanoparticles. The integration of colloidal stability, mesoporosity and the Janus structure is quite promising for materials design applicable in various fields, including catalysis, biomedicine and coatings.
- Ujiie, Hiroto,Shimojima, Atsushi,Kuroda, Kazuyuki
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supporting information
p. 3211 - 3214
(2015/06/03)
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- Acid-catalyzed condensation reaction of phenylsilanetriol: Unexpected formation of cis,trans -1,3,5-trihydroxy-1,3,5-triphenylcyclotrisiloxane as the main product and its isolation
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cis,trans-1,3,5-Trihydroxy-1,3,5-triphenylcyclotrisiloxane was successfully isolated and fully characterized by spectroscopic methods and single-crystal X-ray diffraction. This compound was believed to be highly unstable and only exist as a transient species in low concentration during the condensation reaction of phenylsilanetriol or its precursors. The isolated pure cyclotrisiloxane is, however, surprisingly stable even in acidic solution and partially isomerizes to the cis,cis isomer.
- Yagihashi, Fujio,Igarashi, Masayasu,Nakajima, Yumiko,Ando, Wataru,Sato, Kazuhiko,Yumoto, Yoshiyuki,Matsui, Chinami,Shimada, Shigeru
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supporting information
p. 6278 - 6281
(2015/02/19)
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- The enzymatic cleavage of Si-O bonds: A kinetic analysis of the biocatalyzed hydrolysis of phenyltrimethoxysilane
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Previously we reported the ability of trypsin to mediate the cross-linking of alkoxysily-functionalized silicone polymers. Although enzymes and silicon-containing compounds are not necessarily incompatible species, the exact mechanism of how enzymes process silicon substrates is not fully understood. The focus of this current work was to examine the reaction kinetics associated with the processing of an alkoxysilane substrate by enzymes using 29Si NMR so as to gain a greater insight into the actual reaction mechanism, especially those involving more complex silicone systems. A series of time course 29Si NMR experiments using D2O revealed that the trypsin-mediated hydrolysis of a single alkoxy moiety in water is a pseudo-first order reaction. The relative effect of the enzyme was determined to be β = 3.549 while the relative effect of water was γ = 3.325. Prolonged contact with phenyltrimethoxysilane was not sufficiently deleterious to the enzyme and did not induce the complete and irreversible denaturation of trypsin. Computational evidence suggests that while in the active site of the enzyme, serine addition to silicon to forms a pentacoordinate species and is favoured over histidine addition.
- Frampton, Mark B.,Simionescu, Razvan,Dudding, Travis,Zelisko, Paul M.
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experimental part
p. 105 - 112
(2011/01/03)
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