EVIDENCE FOR THE FORMATION OF A BENZO[A]PHENOTHIAZINE 2-HYDROXYPROPYL-BETA-CYCLODEXTRIN INCLUSION COMPLEX USING A FLUORESCENCE METHOD/

The inclusion complex of benzo[a]-12H-phenothiazine (BPHT) and 2-hydro xypropyl-beta-cyclodextrin (HP-beta-CD) was investigated in an aqueous solution containing 1% ethanol, It was found that the fluorescence em ission intensity of the complexed fluorophore is six times larger than that of uncomplexed species and 1.5 times higher than that in pure et hanol, BPHT forms a 1:1 complex when included in the HP-beta-CD, An as sociation constant of the complex of 100+/-20 M-1 was calculated by us ing the Benesi-Hildebrand treatment of fluorescence emission data, A d iscussion based on AM1 semiempirical calculation of BPHT geometry indi cates that the inclusion of BPHT in HP-beta-CD is partially achieved, probably by the hydrophobic aromatic moiety of the molecule.