Photophysics of 4-(N,N-dimethylamino)cinnamaldehyde/ alpha-cyclodextrin inclusion complex

This paper reports the probing of alpha-cyclodextrin (alpha-CD) cavities with the help of dual emission properties of 4-N,N dimethylamino cinnamaldehyde (DMACA) in aqueous solution. An interesting feature could be observed that due to 1:1 complexation DMACA is encapsulated within alpha-CD in two distinctly different types of orientation as revealed from the relative positions and the intensity of locally excited state localized within donor and acceptor subunits (LE) and twisted intramolecular charge transfer (TICT) bands. In one situation the dimethylamino group is directed towards the larger rim of the cavity and in other the orientation is just the opposite. The different types of complexes were found to be excited selectively in different wavelength regions.