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Synthesis And Optical Properties Of Multi-branched Chromophores With Oxadiazole

Posted on:2006-01-31Degree:MasterType:Thesis
Country:ChinaCandidate:G H LiuFull Text:PDF
GTID:2121360155467482Subject:Materials science
Abstract/Summary:PDF Full Text Request
Four new chromophores with carbazole as molecular "core"bearing either oxadiazole or triphenylamine unit as the periphery "branch"respectively have been firstly synthesised and characterized by the mass spectra and 1HNMR spectra in this paper. These molecules are: [1] trans-2,8-bis(4-vinyl triphenylamino)-N-ethyl carbazole (NT-G1); [2] trans-2,8-bis[(2-4'-ethoxyl phenyl-5-4'-styryl)-1,3,4-oxadiazole]-N-ethyl carbazole (NO-G1); (3)trans-3,7-bis-2-{{3,5-di-[5-(4-tert.butyl phenyl)-1,3,4-oxadiazole] -phenyl}-vinyl}-N-ethylcarbazole(BOVC); [3] trans-3,7-bis-2-{{3,5-di-[5-(4-ethoxylphenyl) -1,3,4-oxadiazole]-phenyl}-1,3,4-oxadiazole}-N-ethyl carbazole(EOOC). To comparatively investigate in photoluminescence properties and two-photon fluorescence of these four compounds in different solvents and concentrations, absorption spectra, fluorescence spectra on one-photon-/two-photon-excitation in either solution or in film were examined. The result have shown: (1) Chromophore NO-G1 possesses strong two-photon absorption (TPA) with the cross-section (δTPA) as high as 454 GM and two-photon emission cross-section (δTPF) being as 21 times as that of fluorescence reference. As compared with NT-G1, NO-G1 has more than 2-fold increase in the two-photon absorption (TPA) cross section, which is probably accounted for the resonance enhancement in the excited states due to its longer conjugation length, planar geometry and molecular pn-structure alike. (2) The photoluminescence intensity for mono-branched NT-G1 and NO-G1 are very high, in comparison with multi-branched BOVC and EOOC, because the "core"and "branch"in NT-G1 and NO-G1 are joined by para-orientation, while the "core"and "branch"in BOVC and EOOC are joined at meta-position. However, the fluorescence intensity for multi-branched BOVC and EOOC becomes much higher in PES film than in its own solution, since the free rotation of molecular single bonds is limited in the rigid medium.
Keywords/Search Tags:one-photon fluorescence, two-photon absorption, two-photon fluorescence, luminescence film
PDF Full Text Request
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