AI Article Synopsis
- The study investigates how a series of N-methyl and N-H substituted indoles quench the fluorescence of pyrene in isooctane at room temperature.
- The quenching mechanism is primarily through charge-transfer (CT), with N-H indoles causing unusual upward deviations in fluorescence plots due to self-quenching by free indoles.
- Adding small amounts of pyridine or propanol significantly enhances the quenching efficiency, indicating that proton transfer plays a role in the self-quenching process.
Article Abstract
The fluorescence quenching of pyrene (Py) by a series of N-methyl and N-H substituted indoles was studied in isooctane at 298 K. The fluorescence quenching rate constants were evaluated by mean of steady-state and time-resolved measurements. In all cases, the quenching process involves a charge-transfer (CT) mechanism. The I(o)/I and tau(o)/tau Stern-Volmer plots obtained for the N-H indoles show a very unusual upward deviation with increasing concentration of the quenchers. This behavior is attributed to the self-quenching of the CT intermediates by the free indoles in solution. The efficiency of quenching of the polyaromatic by the N-H indoles increases abruptly in the presence of small amount of added pyridine (or propanol). A detailed analysis of 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.
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| http://dx.doi.org/10.1021/jp076294t | DOI Listing |
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