Spectrophotometric studies of the complexation of 2-Aryl-Imino-N-(2-Aryl)-thiazoline substrates with hydroxypropyl cyclodextrin

Abstract

Cyclodextrins molecules can form inclusion complexes with a wide variety of substrates. The relatively hydrophobic cavity of native cyclodextrins and their derivatives induces the ability to complex substrates of appropriate size and shape. Complexation of substrates with cyclodextrins can modify the solubility of the substrate and increase its stability. The most common application of CD in pharmaceutical industry is to enhance drug solubility in aqueous solutions. Inclusion complexes of 2 (2-aryl-imino-N-(2- aryl)-thiazoline) substrates: N-[(2Z)-4-methyl-3-(2-methylphenyl)-1,3-thiazol-2(3H)-ylidene]-N-(2-chlorophenyl) amine (1) and N-[(2Z)-4-methyl-3-(2-methylphenyl)-1,3-thiazol-2(3H)-ylidene]-N-(2-chloro-4 nitrophenyl) amine (2) with hydroxypropyl-γ-cyclodextrin (HPγCD) were investigated by applying a simple and rapid spectrophotometric methods. The 1 : 1 stoichiometry of substrate-CD complexes were determined by continuous variation (Job's plot) method and the overall association constants were determined by using Scott's method. The association constants were determined to be 30866 M-1 and 5765 M-1 respectively.