Aggregation-Induced Amplified Quenching in Conjugated Polyelectrolytes with Interrupted Conjugation
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- 作者：Dongping Xie ; Anand Parthasarathy ; Kirk S. Schanze
- 刊名：Langmuir
- 出版年：2011
- 出版时间：October 4, 2011
- 年：2011
- 卷：27
- 期：19
- 页码：11732-11736
- 全文大小：804K
- 年卷期：v.27,no.19(October 4, 2011)
- ISSN：1520-5827
文摘
A pair of anionic conjugated polyelectrolytes that contain three-ring (phenylene ethynylene) units linked by a single 鈭扖H2鈥?or 鈭扥鈥?tether (P1 and P2, respectively) are studied. The linkers serve to interrupt the 蟺 conjugation along the polymer backbone. Fluorescence spectroscopy reveals that P2 forms a fluorescent aggregate in methanol and water; however, the fluorescence of P1 is much weaker in water, and P1 exhibits only weak aggregate fluorescence. Fluorescence quenching of the polymers was examined using methyl viologen (MV2+) as a cationic quencher. P1 shows only a weak amplified quenching effect, with a Stern鈥揤olmer quenching constant of KSV 鈮?6 脳 105 M鈥? in methanol. Interestingly, for P2 in methanol, the aggregate emission is strongly quenched with KSV 鈮?5 脳 106 M鈥?, which is comparable to the highest quenching efficiency observed for fully 蟺-conjugated polyelectrolytes. By contrast, the monomer emission is quenched much less efficiently, with KSV 鈮?2 脳 105 M鈥?. The results are explained by a model in which 鈭扥鈥?linked polymer P2 is able to fold into a helical conformation in solution, which facilitates the formation of extended 蟺-stacked aggregates allowing long-distance exciton transport.