title: Improved Spectral Coverage and Fluorescence Quenching in Donor-acceptor Systems Involving Indolo[3-2-b]carbazole and Boron-dipyrromethene or Diketopyrrolopyrrole.
abstract: A novel π-conjugated triad and a polymer incorporating indolo[3,2-b]-carbazole (ICZ) and 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) were synthesized via a Sonogashira coupling. Compared to the parent BODIPY the absorption and fluorescence spectrum were for both compounds broader and redshifted. The redshift of the fluorescence and the decrease of the fluorescence quantum yield and decay time upon increasing solvent polarity were attributed to the formation of a partial charge-transfer state. Upon excitation in the ICZ absorption band the ICZ fluorescence was quenched in both compounds mainly due to energy transfer to the BODIPY moiety. In a similar ICZ-π-DPP polymer (where DPP is diketopyrrolopyrrole), a smaller redshift of the absorption and fluorescence spectra compared to the parent DPP was observed. A less efficient quenching of the ICZ fluorescence in the ICZ-π-DPP polymer could be related to the unfavorable orientation of the transition dipoles of ICZ and DPP. The rate constant for energy transfer was for all compounds an order of magnitude smaller than predicted by Förster theory. While in a solid film of the triad a further redshift of the absorption maximum of nearly 100 nm was observed, no such shift was observed for the ICZ-π-BODIPY polymer.
authors: Molecular Imaging and Photonics, Chemistry Department, KULeuven, Leuven, Belgium.
authors: Adis
authors: A
authors: Khetubol
authors: Sven
authors: S
authors: Van Snick
authors: Melissa L
authors: ML
authors: Clark
authors: Eduard
authors: E
authors: Fron
authors: Eduardo
authors: E
authors: Coutiño-González
authors: Arvid
authors: A
authors: Cloet
authors: Koen
authors: K
authors: Kennes
authors: Yuliar
authors: Y
authors: Firdaus
authors: Maarten
authors: M
authors: Vlasselaer
authors: Volker
authors: V
authors: Leen
authors: Wim
authors: W
authors: Dehaen
authors: Mark
authors: M
authors: Van der Auweraer