Abstract
The effects of metal salts (NaCl, CaCl2·2H2O, EuCl3·6H2O and Eu(OAc)3) on the steady state and time resolved fluorescence behaviour of poly(para phenylene vinylene) oligomers containing benzo-15-crown-5 ether units (CE-OPV) have been investigated. The presence of EuCl3 causes a significant (8–9 fold) increase in the fluorescence emission intensity of the OPV segments, as compared to pure CE-OPV, in 99:1 methanol/chloroform solution and a small (∼9 nm) red shift in the emission maximum. The presence of Na+ or Ca2+ results in less marked increases in fluorescence intensity compared to Eu3+. In the presence of Eu3+ and Na+, the fluorescence intensity increases approximately linearly with metal ion concentration up to a metal ion/CE-OPV molar ratio of ∼10. The emission enhancement is not related to a simple 1:1 (CE-OPV:metal ion) complex formation process. In contrast, in acetonitrile, CE-OPV shows complex fluorescence quenching behaviour as a function of EuCl3 concentration. This solvent dependence suggests that the emission changes with metal concentration are related to the formation of charge-transferred complexes. The marked changes in fluorescence quantum yield of the PPV backbone due to complexation with metal ions makes CE-OPV a sensitive fluorescent probe for metal ions, or may be exploited for improving the quantum yield of PPV-based devices.
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Ramachandran, G., Simon, G., Cheng, Y. et al. The Dependence of Benzo-15-Crown-5 Ether-Containing Oligo Paraphenylene Vinylene (CE-OPV) Emission Upon Complexation with Metal Ions in Solution. Journal of Fluorescence 13, 427–436 (2003). https://doi.org/10.1023/A:1026169023668
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DOI: https://doi.org/10.1023/A:1026169023668