Compromise between compactness of micelle and overlap integral toward Fِrster resonance energy transfer from an indoloquinoline derivative to fluorescein: A fluorometric study

Förster resonance energy transfer (FRET) from an indoloquinoline derivative, 2,8-Dichloro-5-methyl-5H-indolo[3,2-c]quinoline (DCMIQ) to fluorescein (FL) is studied in anionic micelles formed by surfactants of varying chain lengths by steady state fluorescence spectroscopy. The Förster distance is found to change in different media. However, the calculated FRET efficiency for the donor–acceptor pair does not follow the trend observed for the overlap integrals. The aggregation number and hence the micellization kinetics on the dynamic surface properties of the surfactants seem to be responsible for such heterogeneity. Compromise between compactness of the micelle and overlap integral toward FRET has been proposed with experimental evidence.