Remarkable Photophysics and Amplified Quenching of Conjugated Polyelectrolyte Oligomers

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• 作者：Fude Feng ; Jie Yang ; Dongping Xie ; Tracy D. McCarley ; Kirk S. Schanze
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2013
• 出版时间：May 2, 2013
• 年：2013
• 卷：4
• 期：9
• 页码：1410-1414
• 全文大小：355K
• 年卷期：v.4,no.9(May 2, 2013)
• ISSN：1948-7185

文摘

We report the photophysics and fluorescence quenching of a series of monodisperse, anionic 蟺-conjugated oligomers that are molecularly dissolved in aqueous solution. These structurally well-defined oligomers feature oligo(phenylene ethynylene) backbones with two 鈭扖H₂COO鈥?/sup> 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鈥揤olmer (SV) fluorescence quenching studies using cationic charge- and energy-transfer quenchers reveal that all of the oligomers give rise to SV quenching constants (K_SV) in excess of 10⁶ M^鈥?, 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.

Keywords:

conjugated oligomer; fluorescence; amplified quenching; aggregation; fluorescence correlation spectroscopy