The 8-Silyloxyquinoline Scaffold as a Versatile Platform for the Sensitive Detection of Aqueous Fluoride

Authors

Xinqi Zhou, University of Nebraska-LincolnFollow

Date of this Version

4-24-2015

Document Type

Article

Comments

A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Chemistry, Under the Supervision of Professor Cliff I. Stains. Lincoln, Nebraska: April 2015

Copyright (c) 2015 Xinqi Zhou

Abstract

As one of the most essential elements in nature, fluoride has been well known and extensively studied since the 16^th century. Since then the two-edged nature of fluoride in biological systems has been well described. Specifically, moderate fluoride exposure can aid in tooth and bone development, while fluoride overexposure results in the depilating disease known as fluorosis. Because of the side effects upon overexposure of fluoride, there is a need to develop fast and straight forward methods to sensitively and selectively detect and quantify fluoride concentration in drinking water. With this goal in mind and by taking advantage of the high sensitivity of fluorescence, we designed fluorescent probes to selectively detect inorganic fluoride (NaF) in aqueous sample using the novel 8-silyloxyquinoline scaffold. Our initial probe design is capable of detecting inorganic fluoride in aqueous solution, with a detection limit of 3.8 μM (72 ppb), well below the EPA recommended levels for drinking water (4 ppm), placing the probe among the most sensitive inorganic fluoride sensors reported to date. Since the 8-silyloxyquinoline template showed high sensitivity to fluoride and the structure could be easily modified, we were able to design and synthesize a second fluoride probe that had a red-shifted excitation and emission wavelength and was capable of detecting aqueous fluoride concentrations as low as 50 μM (0.95 ppm) utilizing a straightforward test-strip assay. In conclusion, this work provides a novel fluorogenic platform for detecting fluoride with high selectivity and sensitivity in the laboratory and in the field.

Advisor: Cliff I. Stains