Jiang Hui, Zhao Xiaoyong, Schanze Kirk S
Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200, USA.
Langmuir. 2006 Jun 20;22(13):5541-3. doi: 10.1021/la060429p.
The fluorescence of conjugated polyelectrolytes (CPEs) is quenched with very high efficiency by small molecule quenchers. This effect has been referred to as amplified quenching. In the present communication, we demonstrate that aggregation of a poly(phenylene ethynylene)-type CPE (PPE-CO2-) induced by Ca2+ has a pronounced effect on the amplified quenching of the polymer by the dication methyl viologen (MV2+). In particular, absorption and fluorescence spectroscopy of PPE-CO2- in methanol solution indicate that addition of a low concentration of Ca2+ induces aggregation of the polymer chains. The range of MV2+ concentrations within which linear Stern-Volmer quenching behavior is observed systematically decreases with increasing Ca2+ concentration to a point where superlinear quenching is observed immediately upon addition of MV2+. This finding is unequivocal evidence that the superlinear Stern-Volmer quenching behavior typically observed in CPE-quencher systems arises due to quencher-induced aggregation of the CPE chains.
共轭聚电解质（CPEs）的荧光会被小分子猝灭剂高效猝灭。这种效应被称为放大猝灭。在本论文中，我们证明了Ca2+诱导的聚（亚苯基乙炔）型CPE（PPE-CO2-）的聚集对聚合物被双阳离子甲基紫精（MV2+）的放大猝灭有显著影响。特别是，PPE-CO2-在甲醇溶液中的吸收光谱和荧光光谱表明，加入低浓度的Ca2+会诱导聚合物链的聚集。随着Ca2+浓度的增加，观察到线性斯特恩-沃尔默猝灭行为的MV2+浓度范围系统地减小，直至加入MV2+后立即观察到超线性猝灭。这一发现明确证明了在CPE-猝灭剂系统中通常观察到的超线性斯特恩-沃尔默猝灭行为是由于猝灭剂诱导的CPE链聚集所致。
