EFFECT OF SODIUM-PERCHLORATE ON THE BINDING OF 2-(4'-AMINOPHENYL)BENZOTHIAZOLE AND 2-(4'-(N,N'-DIMETHYLAMINO)PHENYL)BENZOTHIAZOLE WITH BETA-CYCLODEXTRIN IN AQUEOUS-SOLUTION

The host-guest complexation of 2-(4'-aminophenyl)- and 2-(4'-(N,N-dime thylamino)phenyl)benzothiazole (APE and DAPB, respectively) with beta- cyclodextrin (beta-CDx) were studied in aqueous solution by use of flu orescence spectroscopy. The induced circular dichroic (ICD) spectra of the inclusion complexes were also measured to confirm complexation an d to estimate the orientation of the guest molecule in the cyclodextri n cavity. The association constants for binding of the molecules with beta-CDx were estimated in phosphate buffer containing varying concent rations of NaClO4. The association constant for binding of DAPB is alm ost 4 times as high as that of APE. In the case of DAPB, the associati on constant was found to decrease with an increase in salt concentrati on. However, the association constant of APE initially increases and t hen decreases with an increase in salt concentration. The optical rota tion data of beta-CDx in the absence and presence of NaClO4 suggest co mplexation of ClO4- with beta-cyclodextrin.