Proton-Transfer Mediated Quenching of Pyrene/Indole Charge-Transfer States in Isooctane Solutions
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- 作者：Marcela S. Altamirano ; Marí ; a del Valle Bohorquez ; Carlos M. Previtali ; Carlos A. Chesta
- 刊名：Journal of Physical Chemistry A
- 出版年：2008
- 出版时间：January 31, 2008
- 年：2008
- 卷：112
- 期：4
- 页码：589 - 593
- 全文大小：86K
- 年卷期：v.112,no.4(January 31, 2008)
- ISSN：1520-5215
文摘
The fluorescence quenching of pyrene (Py) by a series of N-methyl and N-H substituted indoles was studiedin isooctane at 298 K. The fluorescence quenching rate constants were evaluated by mean of steady-state andtime-resolved measurements. In all cases, the quenching process involves a charge-transfer (CT) mechanism.The Io/I and 
o/ Stern-Volmer plots obtained for the N-H indoles show a very unusual upward deviationwith increasing concentration of the quenchers. This behavior is attributed to the self-quenching of the CTintermediates by the free indoles in solution. The efficiency of quenching of the polyaromatic by the N-Hindoles increases abruptly in the presence of small amount of added pyridine (or propanol). A detailed analysisof the experimental data obtained in the presence of pyridine provides unambiguous evidence that the self-quenching process involves proton transfer from the CT states to indoles.
o/ Stern-Volmer plots obtained for the N-H indoles show a very unusual upward deviationwith increasing concentration of the quenchers. This behavior is attributed to the self-quenching of the CTintermediates by the free indoles in solution. The efficiency of quenching of the polyaromatic by the N-Hindoles increases abruptly in the presence of small amount of added pyridine (or propanol). A detailed analysisof the experimental data obtained in the presence of pyridine provides unambiguous evidence that the self-quenching process involves proton transfer from the CT states to indoles.