Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States.
Langmuir. 2011 Mar 1;27(5):1565-8. doi: 10.1021/la104586t. Epub 2010 Dec 28.
A poly(phenylene ethynylene) conjugated polymer (PPE-NMe(3)(+)-COO(-)) containing tetraalkylammonium groups and carboxylate groups has been synthesized by Sonogashira coupling. Due to the presence of the strong cationic and weak anionic pendant units, the polymer undergoes a pH-induced transition from cationic polyelectrolyte to polyampholyte due to deprotonation of the carboxylic acid units in basic solution. Studies of the pH dependence of the polymers' optical properties reveal changes in absorption oscillator strength and fluorescence quantum efficiency that are triggered by the transition from cationic polyelectrolyte to polyampholyte nature. Stern-Volmer fluorescence quenching of PPE-NMe(3)(+)-COO(-) with a negatively charged quencher 1,4,5,8-naphthalenediimide-N,N-bis(methylsulfonate) (NDS) shows that the polymer fluorescence quenching is amplified at low pH where the polymer is a polycation, whereas the quenching efficiency is considerably less at high pH.
一种含有季铵盐基团和羧酸根的聚（亚苯基乙炔）共轭聚合物（PPE-NMe(3)(+)-COO(-)）通过 Sonogashira 偶联合成。由于存在强阳离子和弱阴离子侧基单元，聚合物在碱性溶液中由于羧酸单元的去质子化而经历从阳离子聚电解质到两性聚电解质的 pH 诱导转变。对聚合物光学性质的 pH 依赖性研究表明，吸收振子强度和荧光量子效率的变化是由从阳离子聚电解质到两性聚电解质性质的转变触发的。带负电荷的猝灭剂 1,4,5,8-萘二酰亚胺-N,N-双（甲基磺酸盐）（NDS）对 PPE-NMe(3)(+)-COO(-)的 Stern-Volmer 荧光猝灭表明，在聚合物为聚阳离子的低 pH 下，聚合物荧光猝灭被放大，而在高 pH 下，猝灭效率则显著降低。
