Complexation of some aromatic compounds with cyclic nigerosyl-(1-6)-nigerose
2009
Ishikawa, H.(Kyushu Univ., Fukuoka (Japan)) | Kuwano, A. | Chaen, H. | Matsumoto, K.
The fluorescence of hydrophylic and hydrophobic aromatic compounds in aqueous solution was investigated in the presence of cyclic nigerosyl-(1-6)-nigerose (CNN). The fluorescence intensity of vanillin was enhanced by the addition of CNN and the intensity increased with increasing the CNN concentration. Benesi-Hildebrand (BH) plot based on the fluorescence data showed the linear relationship between 1/(I-Isub(0) and 1/[CNN]sub(0), where Isub(0) and I are the fluorescence intensities in the absence and presence of CNN, respectively, and [CNN]sub(0) is initial concentration of CNN. The plot suggested that 1:1 vanillin-CNN complex would be formed under the experimental condition. The binding constant of vanillin to CNN was estimated as 7.1x10E1/M. Similar results were obtained on the complexations of cinnamaldehyde and eugenol. Both BH plots for these compounds showed the linear relationship, while the plot for raspberry ketone gave two different lines. It suggested that 1:1 and 1:2 guest-CNN complexes would be formed by depending on the CNN concentration. For these complexes, the binding constants were estimated 3.8x10E2 and 3.7x10E1/M, respectively. In addition, the linear relationship between the binding constant of the hydrophobic compounds and their log P values was observed, and thus, indicated that the hydrophobic interaction would be the predominant factor on the formation of guest-CNN complex.
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