Fluorimetric study on the charge transfer behavior of trans-ethyl-(p-dimethylamino cinnamate) and its derivative in cyclodextrin cavities

• DOI: 10.1007/s10847-008-9527-0
• Publication Date: 2009-01-09T12:14:20Z
• Authors: T. Sanjoy Singh; Sivaprasad Mitra
• Keywords: 01 natural sciences; 0104 chemical sciences

The intramolecular charge transfer (ICT) property of trans-ethyl p-(dimethylamino) cinnamate (EDAC) and its acid derivative, p-(dimethylamino) cinnamic acid (DMACA), is used to monitor the encapsulation behavior of these probes into the cyclodextrin (CD) nanocavities by steady state and picosecond time-resolved fluorescence spectroscopy. The ICT fluorescence band intensity was found to increase with concomitant blue shift in presence of cyclodextrins. The encapsulation behavior was further characterized by increase in emission yield, fluorescence anisotropy as well as lifetime values. Detailed analysis of the spectroscopic data indicate that the probes enter through the dimethyl amino group pointing to the secondary rim of the doughnut-shaped hydrophobic cavities to form 1:1 complex at different pH, however, the extent of penetration is more for EDAC compared with DMACA.