Measurement of chiral recognition by fluorescence anisotropy

Chirality plays an important role in biological, pharmaceutical, agrochemical, food and environmental fields. Thus, there is a critical need for simple, fast, reliable and sensitive techniques to evaluate chiral interactions and determine enantiomeric composition. In this work, the use of fluorescence anisotropy for the examination of chiral recognition and enantiomeric excess determination has been studied theoretically and experimentally.; A theoretical model is developed in Chapter 2 to examine the correlation between anisotropy and chiral selectivity. The results reveal a linear relationship between the ratio of the anisotropy of enantiomer pairs and the enantioselectivity, allowing the rapid examination of chiral recognition. The predicted relationship was tested by anisotropy measurements using various chiral guests and selectors. The temperature dependence of fluorescence anisotropy was investigated, allowing the estimitation of the thermodynamic parameters of enantioselective binding. The mechanisms of host-guest interactions and chiral recognition were examined on the basis of the anisotropy and thermodynamic data. The results from fluorescence anisotropy study were found to be consistent with those obtained from CE experiments.; Applications of fluorescence anisotropy in the study of chiral recognition were demonstrated in Chapters 3 and 4 using cyclodextrins and vancomycin as chiral selectors, respectively. beta-cyclodextrin and vancomycin showed opposite trends in both the binding affinity and the temperature-dependence of anisotropy ratios for all enantiomers examined, suggesting different mechanisms for chiral recognition.; In Chapter 5 the use of fluorescence anisotropy for determination of enantiomeric composition is demonstrated by theoretical modeling and anisotropy measurements. The theoretical modeling results indicated that a linear relationship exists between the average anisotropy and the composition of enantiomers, allowing the rapid examination of enantiomeric purity. The predicted linear relationship was confirmed experimentally by examining various mixtures of enantiomers in the presence of different chiral selectors. The enantiomeric composition of four solutions was determined based on a 2-point calibration with an average absolute error of less than 1.7%.; A combination study of the behavior of binaphthol in aqueous solution is described in Chapter 6. The properties of binaphthol concerning molecular interactions and chiral recognition are investigated by combination of fluorescence anisotropy and spectra. The dual chiral selector systems are studied theoretically and experimentally. The results are discussed in Chapter 7.