PHOTOPHYSICAL STUDIES OF INDOLE ALKANOIC ACIDS and TRYPTAMINE IN REVERSE MICELLES OF SODIUM DIOCTYL SULFOSUCCINATE

Abstract— The fluorescence spectra and emission lifetimes of several 3-alkanoic indoles of different chain length and tryptamine (TA) were studied in sodium dioctyl sulfosuccinate (AOT)/heptane reverse micelles over a wide range of water/AOT ratio (R - 5 to 44). Fluorescence quenching experiments were done using carbon tetrachloride and acrylamide as quenchers. Experiments with TA were carried out using water at pH 3 in order to assure its protonation. Under these conditions, the results indicate that the indole moiety of TA remains at the micellar interface over all the range considered. Furthermore, the results can be interpreted assuming for the TA population a single microenvironment whose properties remain almost invariant when R increases from 11 to 44. The studies employing the 3-alkanoic indoles were carried out at pH 10. Under these conditions, the anions are progressively displaced to the water pool when the R value increases. This displacement is determined by the length of the side alkyl chain of the 3-indole derivatives. For these compounds, the quenching experiments indicate that, even at low R values, the excited indole moieties are distributed among different microenvironments.