Solvation dynamics of Coumarin 490 in methanol and acetonitrile reverse micelles

Abstract

The solvation dynamics of methanol and acetonitrile in n-heptane /AOT/ methanol and n-heptane/ AOT/acetonitrile reverse micelles have been investigated by picosecond time resolved emission spectroscopy using Coumarin 490 (C-490) as a probe. We have observed a substantially slower dynamics (order of a few ns) of methanol and acetonitrile reverse micelles compared to pure solvents. The solvation time is dependent on the w value (w = [polar solvent]/[AOT]) in the case of methanol reverse micelles but there is little w dependence in the case of acetonitrile reverse micelles. The different w dependence of solvation dynamics of methanol and acetonitrile reverse micelles is explained on the basis of the presence and absence of a hydrogen bonding network.