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Issue 2, 2014
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Conjugated polyelectrolytes with guanidinium side groups. Synthesis, photophysics and pyrophosphate sensing

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Abstract

Two cationic poly(phenylene ethynylene) conjugated polyelectrolytes (CPEs) featuring guanidinium side groups were the subject of investigation. Two polymers were examined, one is an alternating co-polymer (P1) in which the guanidinium groups are on every other repeat unit and the second is a homopolymer with the guanidinium groups on every repeat unit. The photophysical properties of the CPEs were investigated in CH3OH and H2O solution by absorption, steady-state fluorescence and fluorescence lifetime spectroscopy. The results indicate that P1 and P2 are molecularly dissolved in CH3OH solution; however, in water the polymers aggregate as evidenced by a substantial reduction in the fluorescence yield. Addition of the non-ionic surfactant (Triton X-100) into the weakly fluorescent aqueous solution of P1 increased the fluorescence by forming a polymer/surfactant complex. The fluorescence of the polymer/surfactant complex in aqueous solution was effectively quenched by the addition of pyrophosphate (PPi) with Stern–Volmer quenching constants (Ksv) ∼ 1.7 × 105 M−1; the quenching occurs because PPi binds to the guanidinium groups and induces the aggregation of the polymer/surfactant complex. In addition, by using fluorescence correlation spectroscopy it was found that the diffusion time of the aggregated complex is increased 9-fold in comparison with the free CPE/surfactant complex. A sensor is developed utilizing the significant changes in fluorescence induced by the addition of PPi.

Graphical abstract: Conjugated polyelectrolytes with guanidinium side groups. Synthesis, photophysics and pyrophosphate sensing

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Publication details

The article was received on 19 Aug 2013, accepted on 29 Oct 2013 and first published on 04 Nov 2013


Article type: Paper
DOI: 10.1039/C3PP50288K
Citation: Photochem. Photobiol. Sci., 2014,13, 293-300
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    Conjugated polyelectrolytes with guanidinium side groups. Synthesis, photophysics and pyrophosphate sensing

    X. Zhu, J. Yang and K. S. Schanze, Photochem. Photobiol. Sci., 2014, 13, 293
    DOI: 10.1039/C3PP50288K

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