ISSN:
1573-1111
Keywords:
Cyclodextrin
;
rhodamine B
;
equilibrium
;
kinetics
;
temperature-jump
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract A UV/visible spectrophotometric temperature-jump study of the inclusion of the rhodamine B zwitterion (RB) by β-cyclodextrin (βCD) to form a 1:1 complex (RB·βCD) in aqueous 1.00 mol dm−3 NaCl at pH 6.40 and 298.2 K yields:k 1=(1.3±0.2)×108 dm3 mol−1 s−1,k −1=(2.2±0.5)×104 s−1, andK 1=(5.9±2.3)×103 dm3 mol−1 for the equilibrium: $${\text{RB + }}\beta {\text{CD}}{\text{RB}} \cdot \beta {\text{CD}} K_1 $$ Under the same conditions the dimerization of RB: $${\text{2}} {\text{RB}}({\text{RB}})_2 K_d $$ is characterized byK d =(1.8±1.0)×103 dm3 mol−1. The interaction of RB with αCD and γCD is weaker than with βCD, and is discussed in terms of the relative sizes of RB and the cyclodextrin annulus. Comparisons are made with the inclusions of other dyes by cyclodextrins.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00656590
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