Characterization of chiral interactions by fluorescence anisotropy and development of fluorescence sensors for recognition of molecular species

Enantioselective separation is a major concern in the fields of drug development and enantioselective synthesis. Hence, there is need for simple, fast, reliable and sensitive techniques to evaluate chiral interactions. In this work, steady-state fluorescence anisotropy was used to characterize chiral interactions using fluorescent enantiomer pairs with various chiral selectors. Preliminary studies have shown fluorescence anisotropy to be an effective tool for evaluating chiral recognition. In Chapter 2, four chiral selectors were examined to explore correlation between separation and anisotropy ratio of enantiomers under similar conditions. A strong correlation between separation and fluorescence anisotropy data was observed, prompting an investigation into the feasibility of using fluorescence anisotropy to predict optimal conditions for chiral separations in HPLC. In Chapter 3, chiral interactions of slurries of five chiral phases and several enantiomers were examined as a function of temperature and solvent composition and the feasibility of predicting optimal conditions for chiral separations was discussed. Comparison of fluorescence anisotropy and published liquid chromatographic data of 1'1-bi-2-naphthol on a Kromasil chiral phase under similar conditions showed that the fluorescence results were consistent with those obtained from HPLC experiments. In Chapter 4, chiral interactions of propranolol with three Kromasil chiral phases were evaluated and the chiral recognition process was found to be different.; In a second project, the development of fluorescent sensors for molecular species was addressed. An evaluation of the binding response of fluorescent photoinduced electron transfer (PET) sensors to three carboxylate anions was presented in Chapter 6. One of the sensors showed a binding response to the anions under physiological conditions while the other responded only in organic media. In Chapter 7, the fluorescence sensing ability of a trans-stilbene derivative exploits conformational quenching was examined. Its fluorescence intensity increased as a function of viscosity proving the effect of restricted rotation on its sensing ability. Chapter 8 discusses the results of studies that showed selectivity and strong binding for Zn2+ compared to Ca2+, Mg2+ and Hg2+.