Feng Fude, Yang Jie, Xie Dongping, McCarley Tracy D, Schanze Kirk S
†Department of Chemistry and Center for Macromolecular Science and Engineering, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200, United States.
‡Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803-1804, United States.
J Phys Chem Lett. 2013 May 2;4(9):1410-4. doi: 10.1021/jz400421g. Epub 2013 Apr 12.
We report the photophysics and fluorescence quenching of a series of monodisperse, anionic π-conjugated oligomers that are molecularly dissolved in aqueous solution. These structurally well-defined oligomers feature oligo(phenylene ethynylene) backbones with two -CH2COO(-) units on each repeat unit, with overall lengths of 5, 7, and 9 repeats. The ionic oligomers display a structured fluorescence band with high quantum efficiency in water, in contrast to the low fluorescence quantum efficiency and pronounced aggregation displayed by structurally similar oligomeric and polymeric (phenylene ethynylene) conjugated polyelectrolytes studied previously. Stern-Volmer (SV) fluorescence quenching studies using cationic charge- and energy-transfer quenchers reveal that all of the oligomers give rise to SV quenching constants (KSV) in excess of 10(6) M(-1), with values increasing with oligomer length, consistent with the amplified quenching effect. The amplified quenching effect is proposed to occur due to the formation of comparatively small oligomer aggregates.
我们报道了一系列分子溶解于水溶液中的单分散阴离子型π共轭低聚物的光物理性质和荧光猝灭情况。这些结构明确的低聚物具有聚（亚苯基乙炔）主链，每个重复单元带有两个-CH2COO(-)单元，总长度分别为5、7和9个重复单元。与之前研究的结构相似的低聚和聚合（亚苯基乙炔）共轭聚电解质表现出的低荧光量子效率和明显聚集现象不同，离子型低聚物在水中呈现出具有高量子效率的结构化荧光带。使用阳离子电荷和能量转移猝灭剂进行的斯特恩-沃尔默（SV）荧光猝灭研究表明，所有低聚物产生的SV猝灭常数（KSV）超过10(6) M(-1)，其值随低聚物长度增加，这与放大的猝灭效应一致。放大的猝灭效应被认为是由于形成了相对较小的低聚物聚集体而发生的。
