Photoinduced Bimolecular Electron Transfer from Cyano Anions in Ionic Liquids
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- 作者：Boning Wu ; Min Liang ; Mark Maroncelli ; Edward W. Castner Jr.
- 刊名：Journal of Physical Chemistry B
- 出版年：2015
- 出版时间：November 19, 2015
- 年：2015
- 卷：119
- 期：46
- 页码：14790-14799
- 全文大小：545K
- ISSN：1520-5207
文摘
Ionic liquids with electron-donating anions are used to investigate rates and mechanisms of photoinduced bimolecular electron transfer to the photoexcited acceptor 9,10-dicyanoanthracene (9,10-DCNA). The set of five cyano anion ILs studied comprises the 1-ethyl-3-methylimidazolium cation paired with each of these five anions: selenocyanate, thiocyanate, dicyanamide, tricyanomethanide, and tetracyanoborate. Measurements with these anions dilute in acetonitrile and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide show that the selenocyanate and tricyanomethanide anions are strong quenchers of the 9,10-DCNA fluorescence, thiocyanate is a moderately strong quencher, dicyanamide is a weak quencher, and no quenching is observed for tetracyanoborate. Quenching rates are obtained from both time-resolved fluorescence transients and time-integrated spectra. Application of a Smoluchowski diffusion-and-reaction model showed that the complex kinetics observed can be fit using only two adjustable parameters, D and V0, where D is the relative diffusion coefficient between donor and acceptor and V0 is the value of the electronic coupling at donor鈥揳cceptor contact.