Water-soluble hyperbranched polyelectrolytes with high fluorescence quantum yield: Facile synthesis and selective chemosensor for Hg²⁺ and Cu²⁺ ions
2010
Bao, Biqing | Yuwen, Lihui | Zhan, Xiaowei | Wang, Lianhui
New water-soluble hyperbranched polyfluorenes bearing carboxylate side chains have been synthesized by the simple "A2 + B2 + C3" protocol based on Suzuki coupling polymerization. The linear polyfluorene analogue LPFA was also synthesized for comparative investigation. The optical properties of the neutral precursory polymers in CHCl₃ and final carboxylic-anionic conjugated polyelectrolytes in buffer solution were investigated. The obtained hyperbranched polyelectrolyte HPFA2 with lower content of branch unit (2%) showed excellent solubility and high fluorescence quantum yield (φF = 89%) in aqueous solution. Fluorescence quenching of HPFA2 by different metal ions was also investigated, the polyelectrolyte showed high selectivity for Hg²⁺ and Cu²⁺ ions relative to other various metal ions in buffer solution. The Stern-Volmer constant Ksv was determined to be 0.80 x 10⁶ M⁻¹ for Hg²⁺ and 3.11 x 10⁶ M⁻¹ for Cu²⁺, respectively, indicating the potential application of HPFA2 as a highly selective and sensitive chemosensor for Hg²⁺ and Cu²⁺ ions in aqueous solution.
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