Photoisomerisation near a hydrophobic surface. Diethyloxadicarbocyanine iodide in a reverse micelle

A picosecond study indicates that inside the water pool of the aerosol-OT (AOT) microemulsion in n-heptane the photoisomerisation of 3,3'-diethyloxadicarbocyanine iodide (DODCI) is nearly three times slower compared to that in ordinary water. The slower isomerisation at the AOT-water interface implies greater friction experienced by DODCI compared to bulk water and is attributed to the electrostatic attraction between the DODC cation and AOT anion. This is in sharp contrast to the threefold faster photoisomerisation of DODCI at the air-water interface compared to bulk water. (C) 1997 Elsevier Science B.V.