A novel liquid crystalline dendrimer with peripheral mesogenic units was successfully prepared. Azo-reaction and Williamson synthesis were employed in the preparation of the mesogenic unit 4-[4-(6-hydroxyhexyloxy)-phe...A novel liquid crystalline dendrimer with peripheral mesogenic units was successfully prepared. Azo-reaction and Williamson synthesis were employed in the preparation of the mesogenic unit 4-[4-(6-hydroxyhexyloxy)-phenylazo]nitrobenzene (M-NO2). A terminal Si—Cl functional carbosilane dendrimer based on pentaerythritol was used as dendritic scaffold and subsequently functionalized with the aforementioned groups. Investigation of the liq-uid crystalline properties of the mesogen-functionalized dendrimer PCSi-1G-NO2 by polarizing optical microscopy, DSC, and X-ray diffraction showed that it exhibits smectic E (SE) phase, different from the corresponding mesog-enic unit, which shows nematic phase. Furthermore, the temperatures of both the melting point and the clearing point of the mesogen-functionalized dendrimer decrease, and the temperature region of the SE phase is wider than that of the nematic phase.展开更多
A series of c arbosilane dendrimers with acetyl end-group were synthesized. Their structures were characterized by 1H NMR, IR, and MS, respectively. Then dendrimers were coordinated with lanthanide ions （Eu3＋ and Tb...A series of c arbosilane dendrimers with acetyl end-group were synthesized. Their structures were characterized by 1H NMR, IR, and MS, respectively. Then dendrimers were coordinated with lanthanide ions （Eu3＋ and Tb3＋, respectively）. The luminescence spectra of the complexes show narrow-width emissions in visible light region. 2009 Sheng Yu Feng. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
Carbosilane dendrimers with 4-bromo-N,N-dimethylaniline as end groups were synthesized from methyltfichlorosilane, aUyl chloride, magnesium and 4-bromo-N,N-dimethylaniline. All compounds were characterized by ^1H NMR,...Carbosilane dendrimers with 4-bromo-N,N-dimethylaniline as end groups were synthesized from methyltfichlorosilane, aUyl chloride, magnesium and 4-bromo-N,N-dimethylaniline. All compounds were characterized by ^1H NMR, IR, MS.展开更多
Carbosilane dendrimers with p-bromophenyl core were synthesized by alternating Grignard and hydrosilylation reaction. And the α-naphthalenyl was connected to the core by the Suzuki coupling reaction. A new carbosilan...Carbosilane dendrimers with p-bromophenyl core were synthesized by alternating Grignard and hydrosilylation reaction. And the α-naphthalenyl was connected to the core by the Suzuki coupling reaction. A new carbosilane dendrimer with big π-conjugated structure [4-（naphthalen-l-yl）phenyl core] was given. It shows Suzuki coupling reaction is an effective and powerful core-functionalization method and the satisfactory result can be obtained through prolonging the reaction time with the increase of the generation of dendrimer.展开更多
Novel carbosilane liquid crystalline dendrimers based on 1,6-hexanediol were prepared. Using the precursors Gn-C1 （n = 1-3） with Si-C1 bonds on the periphery as dendritic scaffolds and 4-[4-（6-hydroxyhexyloxy）phen...Novel carbosilane liquid crystalline dendrimers based on 1,6-hexanediol were prepared. Using the precursors Gn-C1 （n = 1-3） with Si-C1 bonds on the periphery as dendritic scaffolds and 4-[4-（6-hydroxyhexyloxy）phenylazo]- nitrobenzene as mesogenic group, a series of carbosilane liquid crystalline dendrimers from the first to the third generation were synthesized. These carbosilane liquid crystalline dendrimers showed smectic phase.展开更多
Peroxide-cured high-temperature vulcanized （HTV） silicone rubber was prepared by using allyl-capped carbosilane dendrimers, in which the core molecule is Si（CHaCH=CH2）4, as the cross-linker. It showed that this ki...Peroxide-cured high-temperature vulcanized （HTV） silicone rubber was prepared by using allyl-capped carbosilane dendrimers, in which the core molecule is Si（CHaCH=CH2）4, as the cross-linker. It showed that this kind of allyl-capped carbosilane dendrimer improved the mechanical properties of silicone rubber.展开更多
Novel pentaerythritol-based carbosilane dendrimers centered at carbon have been synthesised. Starting from tetraallyl ether based upon pentaerythritol as the core molecule, a succession of alternate Pt-catalyzed hydro...Novel pentaerythritol-based carbosilane dendrimers centered at carbon have been synthesised. Starting from tetraallyl ether based upon pentaerythritol as the core molecule, a succession of alternate Pt-catalyzed hydrosilyla-tion of allyl groups with HSiCl3 and allylations of SiCl groups thus introduced with CH2=CHCH2MgBr in THF provided a divergent synthesis of three generations of carbosilane dendrimers in which the Si atoms are linked by CH2CH2CH2 groups. The reaction conditions for hydrosilylation must be well controlled. After purification by chromatography on silica gel pure products for each generation were obtained. The IR, 1H and 13C NMR spectra and elemental analysis data are consistent with the proposed structures. The molecular weights of the resulting car-bosilne dendrimers have been determined by vapor pressure osmometry.展开更多
A new β-cyclodextrin modified hyperbranched carbosilane stationary phase for gas chromatography was synthesized by substituting the -OH groups of β-cyclodextrin with hyperbranched carbosilane and was coated on the i...A new β-cyclodextrin modified hyperbranched carbosilane stationary phase for gas chromatography was synthesized by substituting the -OH groups of β-cyclodextrin with hyperbranched carbosilane and was coated on the inner wall of fused silica capillary column for gas chromatography. The chromatographic behaviors of the stationary phase were studied. The initial testing results showed that it possessed good separation abilities for several kinds of mixtures, such as benzenes, acrylates, ketones and alkylchlorides.展开更多
The preparation of carbosilane dendrimers with cores of myo-inositol and the outmost periphery groups of allyl groups has been reported. By using alternate hydrosilylation and alkenylation reactions, the dendrimer ha...The preparation of carbosilane dendrimers with cores of myo-inositol and the outmost periphery groups of allyl groups has been reported. By using alternate hydrosilylation and alkenylation reactions, the dendrimer have been carried up to the third generation with 48 allyl groups on the periphery.展开更多
A series of novel pentaerythritol-based carbosilane dendrimers have been synthesized. Using pentaerythritol-based tetraallyl ether as core molecule, the dendrimers have been prepared up to the third generation with 10...A series of novel pentaerythritol-based carbosilane dendrimers have been synthesized. Using pentaerythritol-based tetraallyl ether as core molecule, the dendrimers have been prepared up to the third generation with 108 allyl groups on the periphery by alternate allylation-hydro- silylation approach.展开更多
Liquid crystalline of a new carbosilane dendrimer of the second generation(D2) containing thirty-six 4-nitroazobenzene groups in its periphery was characterized by means of polarizing optical micrograph, DSC and WAXD....Liquid crystalline of a new carbosilane dendrimer of the second generation(D2) containing thirty-six 4-nitroazobenzene groups in its periphery was characterized by means of polarizing optical micrograph, DSC and WAXD. Mesogenic compound M5 exhibits threaded, schlieren and inversion lines texture of the nematic phase on the cooling from isotropic phase to solidified temperature. Dendrimer D2 shows the focal conic fan-shaped texture of the smectic A phase on the heating course from 69 to 187 ℃ and on the cooling course from 183 to 64 ℃. After cooling, the smectic E(S E) phase with a texture of the focal conic fan-shape with stripes and concentric arcs appears from smectic A(S A) phase. Phase behavior of dendrimer D2 in liquid crystalline state was K69S A187I182S A57S E47K. The isotropic-smectic A transition enthalpy, smectic A-smectic E transition enthalpy and isotropic-smectic A transition entropy were 1.8, 4.5 and 4.0 J/(K·mol), respectively, and were in agreement with or close to those of small molecular liquid crystal.展开更多
基金the National Natural Science Foundation of China (Nos.29874020 and 59573029).
文摘A novel liquid crystalline dendrimer with peripheral mesogenic units was successfully prepared. Azo-reaction and Williamson synthesis were employed in the preparation of the mesogenic unit 4-[4-(6-hydroxyhexyloxy)-phenylazo]nitrobenzene (M-NO2). A terminal Si—Cl functional carbosilane dendrimer based on pentaerythritol was used as dendritic scaffold and subsequently functionalized with the aforementioned groups. Investigation of the liq-uid crystalline properties of the mesogen-functionalized dendrimer PCSi-1G-NO2 by polarizing optical microscopy, DSC, and X-ray diffraction showed that it exhibits smectic E (SE) phase, different from the corresponding mesog-enic unit, which shows nematic phase. Furthermore, the temperatures of both the melting point and the clearing point of the mesogen-functionalized dendrimer decrease, and the temperature region of the SE phase is wider than that of the nematic phase.
基金supported by the National Natural Science Foundation of China(Nos.20574043,20874057)the Key Natural Science Foundation of Shandong Province of China(No.Z2007B02)
文摘A series of c arbosilane dendrimers with acetyl end-group were synthesized. Their structures were characterized by 1H NMR, IR, and MS, respectively. Then dendrimers were coordinated with lanthanide ions （Eu3＋ and Tb3＋, respectively）. The luminescence spectra of the complexes show narrow-width emissions in visible light region. 2009 Sheng Yu Feng. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
基金supported by the National Natural Science Foundation of China(No.20574043)the Natural Science Foundation of Shandong Province of China(No.Y2003B01).
文摘Carbosilane dendrimers with 4-bromo-N,N-dimethylaniline as end groups were synthesized from methyltfichlorosilane, aUyl chloride, magnesium and 4-bromo-N,N-dimethylaniline. All compounds were characterized by ^1H NMR, IR, MS.
文摘Carbosilane dendrimers with p-bromophenyl core were synthesized by alternating Grignard and hydrosilylation reaction. And the α-naphthalenyl was connected to the core by the Suzuki coupling reaction. A new carbosilane dendrimer with big π-conjugated structure [4-（naphthalen-l-yl）phenyl core] was given. It shows Suzuki coupling reaction is an effective and powerful core-functionalization method and the satisfactory result can be obtained through prolonging the reaction time with the increase of the generation of dendrimer.
基金Project supported by the National Natural Science Foundation of China （No. 20134020） and the Science Research Fund of the Ministry of Education of China （No. 104005）.
文摘Novel carbosilane liquid crystalline dendrimers based on 1,6-hexanediol were prepared. Using the precursors Gn-C1 （n = 1-3） with Si-C1 bonds on the periphery as dendritic scaffolds and 4-[4-（6-hydroxyhexyloxy）phenylazo]- nitrobenzene as mesogenic group, a series of carbosilane liquid crystalline dendrimers from the first to the third generation were synthesized. These carbosilane liquid crystalline dendrimers showed smectic phase.
文摘Peroxide-cured high-temperature vulcanized （HTV） silicone rubber was prepared by using allyl-capped carbosilane dendrimers, in which the core molecule is Si（CHaCH=CH2）4, as the cross-linker. It showed that this kind of allyl-capped carbosilane dendrimer improved the mechanical properties of silicone rubber.
基金Project supported by the National Natural Science Foundation of China (Nos. 29874020,59573029).
文摘Novel pentaerythritol-based carbosilane dendrimers centered at carbon have been synthesised. Starting from tetraallyl ether based upon pentaerythritol as the core molecule, a succession of alternate Pt-catalyzed hydrosilyla-tion of allyl groups with HSiCl3 and allylations of SiCl groups thus introduced with CH2=CHCH2MgBr in THF provided a divergent synthesis of three generations of carbosilane dendrimers in which the Si atoms are linked by CH2CH2CH2 groups. The reaction conditions for hydrosilylation must be well controlled. After purification by chromatography on silica gel pure products for each generation were obtained. The IR, 1H and 13C NMR spectra and elemental analysis data are consistent with the proposed structures. The molecular weights of the resulting car-bosilne dendrimers have been determined by vapor pressure osmometry.
基金support from the National Natural Science Foundation of China(No.20874057)the Key Natural Science Foundation of Shandong Province of China(No.ZR201 IBZOOl)
文摘A new β-cyclodextrin modified hyperbranched carbosilane stationary phase for gas chromatography was synthesized by substituting the -OH groups of β-cyclodextrin with hyperbranched carbosilane and was coated on the inner wall of fused silica capillary column for gas chromatography. The chromatographic behaviors of the stationary phase were studied. The initial testing results showed that it possessed good separation abilities for several kinds of mixtures, such as benzenes, acrylates, ketones and alkylchlorides.
基金We are grateful to the National Natural Science Foundation of China for financial support(No.29874020).
文摘The preparation of carbosilane dendrimers with cores of myo-inositol and the outmost periphery groups of allyl groups has been reported. By using alternate hydrosilylation and alkenylation reactions, the dendrimer have been carried up to the third generation with 48 allyl groups on the periphery.
基金This work was supported by the National Natural Science Foundation of China(No.29874020,59573029).
文摘A series of novel pentaerythritol-based carbosilane dendrimers have been synthesized. Using pentaerythritol-based tetraallyl ether as core molecule, the dendrimers have been prepared up to the third generation with 108 allyl groups on the periphery by alternate allylation-hydro- silylation approach.
文摘Liquid crystalline of a new carbosilane dendrimer of the second generation(D2) containing thirty-six 4-nitroazobenzene groups in its periphery was characterized by means of polarizing optical micrograph, DSC and WAXD. Mesogenic compound M5 exhibits threaded, schlieren and inversion lines texture of the nematic phase on the cooling from isotropic phase to solidified temperature. Dendrimer D2 shows the focal conic fan-shaped texture of the smectic A phase on the heating course from 69 to 187 ℃ and on the cooling course from 183 to 64 ℃. After cooling, the smectic E(S E) phase with a texture of the focal conic fan-shape with stripes and concentric arcs appears from smectic A(S A) phase. Phase behavior of dendrimer D2 in liquid crystalline state was K69S A187I182S A57S E47K. The isotropic-smectic A transition enthalpy, smectic A-smectic E transition enthalpy and isotropic-smectic A transition entropy were 1.8, 4.5 and 4.0 J/(K·mol), respectively, and were in agreement with or close to those of small molecular liquid crystal.
