The photophysics of 7-(diethylamino)coumarin-3-carboxylic acid N-succinimidyl ester in reverse micelle: Excitation wavelength dependent dynamics

Abstract

This paper focuses on the photophysical studies of 7-(diethylamino) coumarin-3-carboxylic acid N-succinimidyl ester (7-DCCAE) in aqueous reverse micelles using steady state absorption, fluorescence emission and picosecond time resolved emission spectroscopy. We used sodium dioctylsulfosuccinate (AOT) as surfactant to prepare reverse micelles. We have observed excitation wavelength dependent photophysics of 7-DCCAE in the reverse micelles. The red edge excitation shift (REES) was found in the reverse micelles, at different w0 values. The REES gradually decreases with increase in size of the water pool. The rotational relaxation time of the dye molecule decreases with increasing the mole ratio of water to surfactant (w0) inside the reverse micelles. The fluorescence anisotropy decays were found biexponential in nature with fast and slow reorientation times, which is explained by two steps and "wobbling-in-cone model". We have observed the excitation wavelength dependent dynamics of 7-DCCAE in the reverse micelles. We have observed the difference in the photophysics 7-DCCAE with its acid form.