Journal of Fluorescence

, Volume 22, Issue 4, pp 1165–1176 | Cite as

Spectral Properties of Y-Shaped Donor-Acceptor Push-Pull Imidazole-based Fluorophores: Comparison between Solution and Polymer Matrices

  • Martin Danko
  • Filip Bureš
  • Jiří Kulhánek
  • Pavol Hrdlovič
ORIGINAL PAPER

Abstract

The spectral properties of a novel type of Y-shaped fluorophores consisting of an imidazole ring end-capped with two electron-donating N,N-dimethylaminophenyl groups at positions C4 and C5 and one electron-withdrawing cyano group on the imidazole moiety at position C2 were examined. The π-linker separating the 4,5-bis[4-(N,N-dimethylamino)phenyl]-1H-imidazole donor moiety and the cyano group comprises 1,4-phenylene (1), (E)-phenylethenyl (2), (E)-phenylbuta-1,3-dienyl (3), biphenyl (4), (E)-phenylethenylphenyl (5) and phenylethynylphenyl (6) conjugated paths. The absorption and fluorescence spectra were obtained in toluene, dichloromethane, acetonitrile and methanol and in polymer matrices such as polystyrene (PS), poly(methyl methacrylate) (PMMA) and poly(vinylchloride) (PVC). The most intense absorption bands of fluorophores 16 were observed within the range of 283 to 330 nm. Less intense but longer-wavelength absorption bands designated as charge-transfer bands were observed at approximately 380–430 nm depending on the medium. The fluorophores exhibited strong fluorescence in the visible region with a Stokes shift of approximately 4300–5800 cm−1 in non-polar toluene and polystyrene, whereas very low intensity of fluorescence was observed with a Stokes shift in the 6500–7800 cm−1 region in polar methanol and acetonitrile. The large Stokes shift indicates a large difference in the spatial arrangement of the chromophore in the absorbing and emitting states. A relatively intense fluorescence (quantum yields of 0.12–0.69) was observed only for derivative 1 in all media except methanol. The fluorophores doped in matrices yielded more intense fluorescence compared with the fluorescence in liquid media. The use of solid polymer matrices lowers the probability of forming non-emissive excited states. The fluorescence lifetimes were short (1–4 ns) for all of the fluorophores in solvents and in polymer matrices.

Keywords

Fluorescence Push-pull System π-linker Imidazole Polymer matrices 

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Copyright information

© Springer Science+Business Media, LLC 2012

Authors and Affiliations

  • Martin Danko
    • 1
  • Filip Bureš
    • 2
  • Jiří Kulhánek
    • 2
  • Pavol Hrdlovič
    • 3
  1. 1.Polymer Institute, Center of Excellence GLYCOMED, Department of Synthesis and Characterization of Polymers, Slovak Academy of SciencesBratislavaSlovakia
  2. 2.Institute of Organic Chemistry and Technology, Faculty of Chemical Technology, University of PardubicePardubiceCzech Republic
  3. 3.Polymer Institute, Slovak Academy of SciencesBratislavaSlovakia

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