Intramolecular charge transfer and solvation dynamics of coumarin 152 in aerosol-OT, water-solubilizing reverse micelles, and polar organic solvent solubilizing reverse micelles

摘要

The relative retardation of intramolecular charge transfer (ICT) and the solvation dynamics of coumarin 152 in pure AOT, water, methanol, acetonitrile, and formamide reverse micelles have been investigated using picosecond time-resolved emission spectroscopy. The rate of ICT has been retarded almost 7 times at w(0) = 4 and 4 times at w(0) = 32 compared to that in pure water. The rate of retardation of ICT is also observed in the methanol and acetonitrile reverse micelles in comparison to that in pure methanol and acetonitrile. In pure AOT, the solvation time is 12.22 ns, but at w(0) = 4 of water reverse micelles the solvation. time is 7.27 ns. The slow dynamics in methanol, acetonitrile, and formamide reverse micelles is also observed. The relative retardation of the ICT rate is much smaller compared to the several thousand fold decrease in the solvation dynamics in the pool of the reverse micelles. The w dependency of solvation time is observed for water and methanol reverse micelles, but it is little for acetonitrile and none for formamide reverse micelles. The various w dependencies of solvation dynamics in water, methanol, and acetonitrile reverse micelles are explained on the basis of the presence, and the absence of hydrogen-bonding networks in water, methanol, and acetonitrile, respectively. [References: 45]