Spectral Studies on the Cyclodextrin Inclusion Complexes of Toluidine Blue O and Meldola's Blue in Aqueous Solution - Journal of Inclusion Phenomena and Macrocyclic Chemistry

The absorption and emission spectral properties of toluidine blue O (TBO) and Meldola's blue (MDB) in the presence of cyclodextrins (CDs) were studied. Formation of 1 : 1 and 1 : 2 (CD-Dye) inclusion complexes were observed with β-CD and γ-CD, respectively. An increase in the emission intensity was noticed in the presence of β-CD due to the formation of 1 : 1 (CD-Dye) inclusion complexes. However, a decrease in the emission intensity was observed in the presence of γ-CD due to the formation of 1 : 2 (CD-Dye) inclusion complexes. Dimerization of dye molecules in the presence of γ-CD lead to a decrease in the emission intensity. The formation constants for the 1 : 1 and 1 : 2 (CD-Dye) inclusion complexes were calculated.