• JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
 
  Bookmark and Share
 
 
Doctoral Thesis
DOI
https://doi.org/10.11606/T.75.2010.tde-24032011-093724
Document
Author
Full name
Emanuelle Reis Simas
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2010
Supervisor
Committee
Gehlen, Marcelo Henrique (President)
Goncalves, Debora
Atvars, Teresa Dib Zambon
Correa, Rodrigo José
Misoguti, Lino
Title in Portuguese
Fotoquímica de polímeros conjugados contendo centros de transferência de carga e migração de energia
Keywords in Portuguese
Anisotropia
Exciton
Fluorescência
Polifluoreno
Abstract in Portuguese
Neste trabalho foram estudados os processos de migração e transferência de energia em derivados de polifluoreno, de estrutura totalmente conjugada e de conjugação confinada. A dinâmica de estado excitado dos derivados PF-BNI, PFOPPV e PFPPV foi estudada em solução diluída de diferentes solventes através de espectroscopia eletrônica de alta resolução temporal. O derivado PF-BNI, contendo N-(2-benzotiazol)-1,8-naftalimida (BNI) como terminador da cadeia de poli(9,9'dioctilfluoreno), foi sintetizado pela rota de Yamamoto. O material apresenta alto rendimento quântico de fluorescência e suas propriedades de emissão são moduladas pela polaridade do solvente. As medidas de fluorescência resolvida no tempo mostraram a migração do exciton singlete ao longo da cadeia polimérica e a formação de um estado excitado de transferência de carga intracadeia (ICCT). Os derivados PFOPPV e PFPPV são copolímeros de fluoreno contendo unidades fluoreno-vinileno-fenileno no segmento cromofórico. No PFOPPV o segmento cromofórico é confinado entre segmentos alifáticos (-(CH2)8-) flexíveis, no PFPPV a cadeia principal é totalmente conjugada. A dinâmica de estado excitado dos derivados, PFOPPV e PFPPV, é caracterizada pela presença de segmentos cromofóricos contendo isômeros cis e trans. No PFOPPV, a sua estrutura segmentada permite a transferência de energia entre os segmentos cromofóricos, via interações dipolo-dipolo. A transferência acarreta a depolarização da emissão de fluorescência. No caso do PFPPV a migração de energia ocorre em menos de 20 ps e o decaimento de fluorescência decorre da emissão de segmentos contendo isômeros cis e trans, já na condição estacionária.
Title in English
Photochemistry of conjugated polymers containing charge transfer sites and energy migration
Keywords in English
Anisotropy
Exciton
Fluorescence
Polyfluorene
Abstract in English
This work reports the study of energy transfer and migration processes in fully conjugated and segmented polyfluorene derivatives. The excited-state dynamics of the derivatives, PF-BNI, PFOPPV and PFPPV was studied in diluted solution of different solvents by means of ultrafast time-resolved spectroscopy. Poly(9,9'-dioctylfluorene) end-capped with N-(2-benzothiazole)-1,8-naphthalimide, named PF-BNI, was prepared via Yamamoto-coupling reaction. This derivative is a highly fluorescence material with emission modulated by solvent polarity. Time-resolved fluorescence measurements showed the singlet exciton migration through the polymer backbone and the formation of an intrachain charge transfer excited-state (ICCT). PFOPPV and PFPPV are both fluorene copolymers containing fluorene-vinylene-phenylene moieties in the backbone. Whereas the PFPPV backbone is fully conjugated, the chromophore segment in PFOPPV backbone is confined between aliphatic (-(CH2)8-) flexible segments. The excited-state dynamics of both copolymers is characterized by the presence of conjugated moieties containing cis and trans isomers. The segmented structure of PFOPPV allows the resonant energy transfer between the chromophores, which is provided by dipole-dipole interactions. The energy transfer process leads to the depolarization of PFOPPV fluorescence emission. For PFPPV the energy migration occurs in less than 20 ps and the fluorescence decay is ascribed to the emission of chromophore segments containing cis and trans, already in a photostationary condition.
 
WARNING - Viewing this document is conditioned on your acceptance of the following terms of use:
This document is only for private use for research and teaching activities. Reproduction for commercial use is forbidden. This rights cover the whole data about this document as well as its contents. Any uses or copies of this document in whole or in part must include the author's name.
Publishing Date
2011-05-05
 
WARNING: Learn what derived works are clicking here.
All rights of the thesis/dissertation are from the authors
CeTI-SC/STI
Digital Library of Theses and Dissertations of USP. Copyright © 2001-2024. All rights reserved.