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Using Cyclic Voltammetry, UV-Vis-NIR, and EPR Spectroelectrochemistry to Analyze Organic Compounds
Published on: October 18, 2018
Conjugated polymers that respond to oxidation with increased emission
Eric L Dane1, Sarah B King, Timothy M Swager
1Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
Journal of the American Chemical Society
|May 18, 2010
Summary
Thioether-containing polymers exhibit a fluorescence turn-on response to oxidants, with oxidized forms showing enhanced quantum yields and photostability. This suggests potential for advanced oxidant sensing and emissive materials.
Area of Science:
- Materials Science
- Polymer Chemistry
- Organic Electronics
Background:
- Poly(para-phenylene-ethynylene) (PPE) copolymers are known for their fluorescence properties.
- Oxidation of thioether groups in polymers can alter their electronic and optical characteristics.
- Understanding the impact of oxidation on fluorescence quantum yield and lifetime is crucial for material design.
Purpose of the Study:
- To investigate the fluorescence turn-on response of thioether-containing PPE copolymers upon oxidation.
- To elucidate the mechanisms behind the observed increase in fluorescence quantum yield and lifetime.
- To explore the potential applications of these oxidized polymers in sensing and optoelectronics.
Main Methods:
- Synthesis of thioether-containing PPE copolymers.
- Controlled oxidation of thioether substituents to sulfoxides and sulfones.
- Spectroscopic analysis (absorption, emission) to evaluate changes in optical properties.
- Measurement of fluorescence quantum yield and lifetime.
Main Results:
- Selective oxidation of thioether groups to sulfoxides and sulfones induced a strong fluorescence turn-on response.
- Oxidation led to increased fluorescence quantum yield (Phi(F)) and fluorescence lifetime (tau(F)), attributed to enhanced spatial overlap of frontier molecular orbitals and reduced non-radiative decay.
- Contrary to expectations, sulfoxides did not consistently quench fluorescence; spectral changes indicated donor-acceptor interactions in some oxidized copolymers.
- Oxidized polymers demonstrated high fluorescence quantum yields in the solid state and improved photostability.
- A turn-on fluorescence response to hydrogen peroxide was observed in organic solvents with an oxidation catalyst.
Conclusions:
- Thioether-containing PPE copolymers offer a promising platform for developing fluorescent sensors for oxidants.
- The oxidation process enhances fluorescence efficiency and photostability, making these materials suitable for applications requiring robust optical performance.
- Tunable emission across the visible spectrum and efficient light emission are key advantages for potential applications in advanced materials.
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