Study on the interaction of methylene blue with cyclodextrin derivatives by absorption and fluorescence spectroscopy.
The ability of beta-cyclodextrin (beta-CD), hydroxypropyl-beta-cyclodextrin (HP-beta-CD), and carboxymethyl-beta-cyclodextrin (CM-beta-CD) to break the aggregate of the methylene blue (MB) and to form 1:1 inclusion complexes has been studied by absorption and fluorescence spectroscopy. Experimental conditions including concentrations of various cyclodextrins (beta-CD, HP-beta-CD and CM-beta-CD) and media acidity were investigated for the inclusion formation in detail. The formation constants are calculated by using steady-state fluorimetry, from which the inclusion capacity of different cyclodextrins (CDs) is compared. The results suggest that the charged beta-cyclodextrin (CM-beta-CD) is more suitable for inclusion of the cationic dye MB than the neutral beta-cyclodextrins (beta-CD, HP-beta-CD) at pH>5. A mechanism is proposed which is consistent with the stronger binding of MB with CM-beta-CD compared with the other CDs at pH>5.
Zhang
Guomei
G
Department of Chemistry, Shanxi University, Shanxi, Taiyuan 030006, China.
Shuang
Shaomin
S
Dong
Chuan
C
Pan
Jinghao
J
D003505:Cyclodextrins / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008751:Methylene Blue / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D013329:Structure-Activity Relationship
D003505:Cyclodextrins; D008751:Methylene Blue