Graduation Semester and Year
Summer 2026
Language
English
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Chemistry
Department
Chemistry and Biochemistry
First Advisor
Frank W. Foss Jr.
Second Advisor
Junha Jeon
Third Advisor
Rasika Dias
Fourth Advisor
Fred Macdonnell
Abstract
Fluorescent chemosensors, built from an ion-binding receptor conjugated to a fluorophore, are a versatile platform for the selective detection of cations in solution. The receptor domain of such a sensor can take the form of a crown ether, cryptand, calixarene, or acyclic podand, each offering its own balance of binding strength, ion selectivity, and synthetic accessibility. When the choice of receptor and fluorophore, as well as the mode of fluorescence response, is tuned appropriately, these conjugates can be developed into highly selective, turn-on chemosensors for a target cation. Neutrinoless double beta decay is a proposed particle phenomenon in which two neutrons within a nucleus spontaneously convert to two protons and eject two electrons, without the accompanying ejection of two neutrinos. In a model system pursued by the NEXT collaboration, 136Xe is used as the isotope of interest, decaying to 136Ba2+. A fluorescent sensor capable of selectively capturing and reporting on single Ba2+ ions is central to the NEXT BOLD barium tagging effort, providing the means to confirm this decay at the single- molecule level. Despite this promise, the first generations of Ba2+ chemosensors built around photoin- duced electron transfer (PET) suffer from small Stokes shifts, incomplete quenching of the unbound ”off” state, and a lack of any handle for covalent attachment to a surface. Here, in Chapter 2, we describe the synthesis and fluorescence studies of commercially available i IPG dyes that employ crown ether and cryptand ionophores to sense Ba2+ in a fully aqueous system. In Chapter 3, we detail efforts toward spiropyran and spirooxazine photoswitches, whose light-driven isomerization offers an alternative, structurally gated route to a quiet off state. In Chapter 4, we present a rhodamine-aza-crown-ether chemosensor, in which Ba2+ binding at the crown ether directly drives opening of the rhodamine spirolactam to produce a large fluorescent turn-on response. An unrelated project is detailed in Chapter 5, in which we examine a family of acyclic, PAH-capped glycol podands as chelation-enhanced fluorescence (CHEF) sensors for Cs+.
Keywords
chemistry, synthesis, fluorescence, chemosensors
Disciplines
Organic Chemistry
License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
Miller, Reagan L., "Development and Characterization of Fluorescent Chemosensors for Cation Detection" (2026). Chemistry & Biochemistry Dissertations. 14.
https://mavmatrix.uta.edu/chemistry_dissertations2/14