Chromium silsesquioxane based synthesis and characterization of a microporous Cr–Si–O material

Maxim, Nicolae; Abbenhuis, Hcl Erik; Stobbelaar, PJ Pieter; Mojet, BL Barbara Louise; Santen, RA Rutger van

doi:10.1039/a903684i

Cited by 36 publications

(15 citation statements)

References 19 publications

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“…While the formation of micropores by the calcination of POSS molecules has been previously reported [32][33][34][35][36][37][38][39][40][41][42][43][44], an increase in the BET surface area by the calcination of silica-supported POSS was not recognized from the results shown in Table 4, probably because of a low loading level of POSS.…”

Section: Characterization Of the Oxide Catalysts Prepared Using Ti-posscontrasting

confidence: 45%

“…In addition to their activities as homogeneous catalysts, their application to heterogeneous catalysis using metal-containing POSS as precursors has been examined [10,13,15,[24][25][26][27][28][29][30][31]. The preparation of microporous silicas containing well-dispersed metal oxide species by the controlled calcination of metal-containing POSS has been reported [32][33][34][35][36][37][38][39][40][41][42].…”

Section: Introductionmentioning

confidence: 99%

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Ti-bridged silsesquioxanes as precursors of silica-supported titanium oxide catalysts for the epoxidation of cyclooctene

Sakugawa

Wada

Inoue

2010

Journal of Catalysis

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ABSTRACT:Silica-supported titanium oxide catalysts were prepared by the controlled calcination of Ti-bridged polyhedral oligomeric silsesquioxanes (POSS) bearing four Si-O-Ti bonds, Ti[(c-C 5 H 9 ) 7 Si 7 O 11 (OSiMe 2 R)] 2 (1a; R = vinyl, 1b; R = methyl) and Ti[(c-C 5 H 9 ) 8 Si 8 O 13 )] 2 (2), supported on various silicas, and these catalysts showed excellent activities for the epoxidation of cyclooctene by t BuOOH as an oxidant to selectively give cyclooctene oxide in high yields. On the other hand, catalysts prepared using a corner-capped-type Ti-containing POSS, CpTi[(c-C 5 H 9 ) 7 Si 7 O 12 ] (3, Cp = cyclopentadienyl), or tetraisopropoxytitanium (4) showed lower activities. The 2 catalysts prepared from Ti-bridged POSS can be easily separated from the reaction mixture and reused without a significant loss of activity. These catalysts were also applicable for the epoxidation of limonene. A spectroscopic study revealed that calcination of Ti-bridged POSS supported on silica gave isolated tetrahedral Ti(IV) species, which would be responsible for the high activity, while calcination of silicasupported 3 or 4 gave aggregated surface titanium oxide species.

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Section: Characterization Of the Oxide Catalysts Prepared Using Ti-posscontrasting

confidence: 45%

Section: Introductionmentioning

confidence: 99%

Ti-bridged silsesquioxanes as precursors of silica-supported titanium oxide catalysts for the epoxidation of cyclooctene

Sakugawa

Wada

Inoue

2010

Journal of Catalysis

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“…17 In optics, they have a fruitful area of applicability as liquid crystals. 18 They have also been proposed as possible NLO species due to their high transparency, 19 as models for oxosurfaces in micro- 20 and mesoporous silica, 21 and as metal surface and cluster additives for silicon, 22 iron, 23 and gold. 24 The cage-like molecular structure of POSS makes them potentially useful substances for separating mixtures of gases as has been observed in siloxanes 25 and silicon-based capillary membranes.…”

Section: Introductionmentioning

confidence: 99%

Insertion Mechanism of N₂and O₂into T_n(n= 8, 10, 12)-Silsesquioxane Framework

Tejerina

Gordon

2002

J. Phys. Chem. B

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The process of insertion of molecular oxygen and nitrogen into polyhedral oligomeric silsesquioxanes (POSS) has been investigated theoretically. Using ab initio methods, the N2interaction with the POSS has been described with restricted Hartree−Fock (RHF) with a triple-ζ basis set, while systems involving O2 require restricted open shell (ROHF) wave functions, to account for their open-shell ground states. This insertion process is described in terms of the energetic change that the system X2::POSS undergoes when the gas molecule passes from the exterior to the interior of the cage through the largest of its faces. The formation of the cluster occurs through a transition structure that has been characterized for each system. The barrier is a function of the dimension of the face of the POSS and, hence, of the cage dimensions. The results of the calculation are consistent with experimental observations that the O2 molecules pass through a given membrane more easily than N2. Disciplines Chemistry CommentsReprinted (adapted) with permission from

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“…[(PhSiO 1.5 ) 10 X-ray Structure Determination: Single-crystal X-ray diffraction experiments for compounds 1 and 2 were carried out with a Bruker APEX II diffractometer. The structures of 1 and 2 were solved by the direct method and refined by the full-matrix least-squares technique for non-hydrogen atoms in the anisotropic approximation.…”

mentioning

confidence: 99%

Binuclear Cage‐Like Copper(II) Silsesquioxane (“Cooling Tower”) – Its High Catalytic Activity in the Oxidation of Benzene and Alcohols

et al. 2013

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Chromium silsesquioxane based synthesis and characterization of a microporous Cr–Si–O material

Cited by 36 publications

References 19 publications

Ti-bridged silsesquioxanes as precursors of silica-supported titanium oxide catalysts for the epoxidation of cyclooctene

Ti-bridged silsesquioxanes as precursors of silica-supported titanium oxide catalysts for the epoxidation of cyclooctene

Insertion Mechanism of N₂and O₂into T_n(n= 8, 10, 12)-Silsesquioxane Framework

Binuclear Cage‐Like Copper(II) Silsesquioxane (“Cooling Tower”) – Its High Catalytic Activity in the Oxidation of Benzene and Alcohols

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Chromium silsesquioxane based synthesis and characterization of a microporous Cr–Si–O material

Cited by 36 publications

References 19 publications

Ti-bridged silsesquioxanes as precursors of silica-supported titanium oxide catalysts for the epoxidation of cyclooctene

Ti-bridged silsesquioxanes as precursors of silica-supported titanium oxide catalysts for the epoxidation of cyclooctene

Insertion Mechanism of N2and O2into Tn(n= 8, 10, 12)-Silsesquioxane Framework

Binuclear Cage‐Like Copper(II) Silsesquioxane (“Cooling Tower”) – Its High Catalytic Activity in the Oxidation of Benzene and Alcohols

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Insertion Mechanism of N₂and O₂into T_n(n= 8, 10, 12)-Silsesquioxane Framework