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dc.contributor.authorFernandes, Mariana
dc.contributor.authorNobre, Sonia S.
dc.contributor.authorXu Qinghong,
dc.contributor.authorCarcel, Carole
dc.contributor.authorCachia, Jean Nicolas
dc.contributor.authorCattoen, Xavier
dc.contributor.authorSousa, Jose M.
dc.contributor.authorFerreira, Rute A. S.
dc.contributor.authorCarlos, Luis D.
dc.contributor.authorSantilli, Celso Valentim [UNESP]
dc.contributor.authorMan, Michel Wong Chi
dc.contributor.authorBermudez, Veronica de Zea
dc.identifier.citationJournal of Physical Chemistry B. Washington: Amer Chemical Soc, v. 115, n. 37, p. 10877-10891, 2011.
dc.description.abstractDiurea cross-linked bridged silsesquioxanes (BSs) C(10)C(11)C(10) derived from organosilane precursors, including decylene chains as side spacers and alkylene chains with variable length as central spacers (EtO)(3)Si- (CH(2))(10)-Y(CH(2))(n)-Y-(CH(2))(10)-Si(OEt)(3) (n = 7, 9-12; Y = urea group and Et = ethyl), have been synthesized through the combination of self-directed assembly and an acid-catalyzed sol gel route involving the addition of dimethylsulfoxide (DMSO) and a large excess of water. This new family of hybrids has enabled us to conclude that the length of the side spacers plays a unique role in the structuring of alkylene-based BSs, although their morphology remains unaffected. All the samples adopt a lamellar structure. While the alkylene chains are totally disordered in the case of the C(10)C(7)C(10) sample, a variable proportion of all-trans and gauche conformers exists in the materials with longer central spacers. The highest degree of structuring occurs for n = 9. The inclusion of decylene instead of propylene chains as side spacers leads to the formation of a stronger hydrogen-bonded urea-urea array as evidenced by two dimensional correlation Fourier transform infrared spectroscopic analysis. The emission spectra and emission quantum yields of the C(10)C(n)C(10) Cm materials are similar to those reported for diurea cross-linked alkylene-based BSs incorporating propylene chains as side spacers and prepared under different experimental conditions. The emission of the C(10)C(n)C(10) hybrids is ascribed to the overlap of two distinct components that occur within the urea cross-linkages and within the siliceous nanodomains. Time-resolved photoluminescence spectroscopy has provided evidence that the average distance between the siliceous domains and the urea cross-links is similar in the C(10)C(n)C(10) BSs and in oxyethylene-based hybrid analogues incorporating propylene chains as side spacers (diureasils), an indication that the longer side chains in the former materials adopt gauche conformations. It has also allowed us to demonstrate for the first time that the emission features of the urea-related component of the emission of alkylene-based BSs depend critically on the length of the side spacers.en
dc.description.sponsorshipFundação para a Ciência e a Tecnologia (FCT)
dc.description.sponsorshipCentre national de la recherche scientifique (CNRS)
dc.description.sponsorshipUniversity Montpellier
dc.description.sponsorshipLaboratório Nacional de Luz Síncrotron (LNLS)
dc.publisherAmer Chemical Soc
dc.relation.ispartofJournal of Physical Chemistry B
dc.sourceWeb of Science
dc.titleSelf-Structuring of Lamellar Bridged Silsesquioxanes with Long Side Spacersen
dcterms.rightsHolderAmer Chemical Soc
dc.contributor.institutionUMR 5253 CNRS UM2 ENSCM UM1
dc.contributor.institutionUniv Tras Os Montes & Alto Douro
dc.contributor.institutionUniv Aveiro
dc.contributor.institutionUniv Porto
dc.contributor.institutionUniversidade Estadual Paulista (UNESP)
dc.description.affiliationUMR 5253 CNRS UM2 ENSCM UM1, Inst Charles Gerhardt Montpellier, F-34296 Montpellier 5, France
dc.description.affiliationUniv Tras Os Montes & Alto Douro, Dept Chem, P-5001801 Vila Real, Portugal
dc.description.affiliationUniv Tras Os Montes & Alto Douro, CQ VR, P-5001801 Vila Real, Portugal
dc.description.affiliationUniv Aveiro, CICECO, Dept Phys, P-3810193 Aveiro, Portugal
dc.description.affiliationUniv Porto, Fac Engn, Dept Chem Engn, LEPAE, P-4200465 Oporto, Portugal
dc.description.affiliationUNESP, Inst Chem, BR-14800900 Araraquara, SP, Brazil
dc.description.affiliationUnespUNESP, Inst Chem, BR-14800900 Araraquara, SP, Brazil
dc.rights.accessRightsAcesso restrito
dc.description.sponsorshipIdFCT: 441.00 2009/2010
dc.description.sponsorshipIdFCT: SFRH/BD/38530/2007
unesp.campusUniversidade Estadual Paulista (UNESP), Instituto de Química, Araraquarapt
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