Intramolecular Condensation Reactions of α,ω-Bis(triethoxysilyl)alkanes. Formation of Cyclic Disilsesquioxanes

Loy, Douglas A.; Carpenter, Joseph P.; Myers, Sharon A.; Assink, Roger A.; Small, James H.; Greaves, John; Shea, Kenneth J.

doi:10.1021/ja961409k

Cited by 36 publications

(51 citation statements)

References 15 publications

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“…Reasons for this deficiency include hydrolytic Si±C bond cleavage, [7] competitive intramolecular cyclization, [20,21] and insolubility of the silsesquioxane precursor, as well as instability of the PMO framework due to excessive flexibility of the bridging organic group. Even though several elaborate organosilane precursors have been synthesized that show interesting properties ranging from heavy metal chelation [22±27] to catalysis, [28] many of these cannot self-assemble on their own.…”

Section: Introductionmentioning

confidence: 99%

Hybrid Periodic Mesoporous Organosilicas

Whitnall

Asefa

Ozin

2005

Adv Funct Materials

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In this study we report the synthesis of a new class of materials called hybrid periodic mesoporous organosilicas (HPMOs). By coupling a silsesquioxane precursor through at least two chemical linkages to the mesopore walls of a pre‐existing periodic mesoporous silica (PMS) or periodic mesoporous organosilica (PMO). Many of the problems of a conventional PMO material can be avoided while ensuring efficient use of the bridging organic functional groups of the silsesquioxane. We demonstrate this concept for PMS by anchoring various silsesquioxanes, such as ethene and ethane silsesquioxanes, to the mesopore walls of the PMS. The addition of anchored silsesquioxane monolayers and multilayers to the mesopore walls also allows for the strict control of the diameter of the mesopore as well as the mesopore wall thickness in the final HPMO material. Additionally it is shown that having the silsesquioxane located solely on the surface of the mesopores in HPMOs gives increased chemical accessibility of the organic bridge‐bonded moiety when compared with their PMO counterparts containing the bridge‐bonded organic both on the surface and within the pore walls.

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Section: Introductionmentioning

confidence: 99%

Hybrid Periodic Mesoporous Organosilicas

Whitnall

Asefa

Ozin

2005

Adv Funct Materials

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“…13 C NMR shows small peaks at δ = 24.0–25.8 ppm which could be assigned for alkyl chain (length ≥ 3) attached with Si (such as Si–CH 2 CH 2 CH 2 –Si, Si–CH 2 CH 2 CH 2 CH 2 –Si) according to the Ref. . However, none peaks can be observed at δ = ~8 and ~4 ppm for Si–CH 2 CH 2 –Si and Si–CH(CH 3 )–Si obtained from hydrosilylation of Si–H and vinyl groups.…”

Section: Resultsmentioning

confidence: 92%

Synthesis and Characterization of Ethylene‐Bridged Copolycarbosilazane as Precursors for Silicon Carbonitride Ceramics

Hou

et al. 2013

J. Am. Ceram. Soc.

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An ethylene‐bridged copolycarbosilazane precursor of copolysilylethylenediamine (co‐PSDA) is synthesized by polycondensation of ethylenediamine with the mixture of vinylmethyldichlorosilane and methyldichlorosilane in the presence of triethylamine as acid absorbing agent. Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR, 1H NMR and 13C NMR) spectral analysis of the as‐synthesized co‐PSDA suggests a structure of ethylene‐bridged polycarbosilazane having –Si–N–C–C–N– as backbone chain with –CH=CH2, –H and –CH3 attached to Si as side groups. Co‐PSDA can be cross‐linked at 80°C using 2, 2‐azobisisobutyronitrile as initiator through the polyaddition of the vinyl group and dehydrogenation/deamination of Si–H and N–H. Then the cross‐linked co‐PSDA precursor is pyrolyzed at 1000°C in argon, giving out amorphous silicon carbon nitride (SiCN) ceramics with a high ceramic yield of 76 wt%. The obtained SiCN ceramics consist of nitrogen‐rich silicon sites of SiN4 as predominant component and some SiCN3 sites, which should arise from the breaking of N–C bonds below 600°C and the formation of active N–Si bonds.

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“…A special feature of bridged silsesquioxanes is the tendency of some precursors to cyclic condensations (Loy et al 1996). The flexible alkylene-bridging group provides opportunity for intramolecular reactions (Shea and Loy 2001).…”

Section: Solgel Chemistry Of Bridged Silsesquioxanesmentioning

confidence: 99%

Hybrid Materials for Molecular Sieves

Elshof

2016

Handbook of Sol-Gel Science and Technology

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Intramolecular Condensation Reactions of α,ω-Bis(triethoxysilyl)alkanes. Formation of Cyclic Disilsesquioxanes

Cited by 36 publications

References 15 publications

Hybrid Periodic Mesoporous Organosilicas

Hybrid Periodic Mesoporous Organosilicas

Synthesis and Characterization of Ethylene‐Bridged Copolycarbosilazane as Precursors for Silicon Carbonitride Ceramics

Hybrid Materials for Molecular Sieves

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