Austin Carlson / Chemistry & Biochemistry / Faculty Mentor: Frank Foss Jr.
Neutrinoless double beta decay is a theoretical process converting two neutrons into two protons, releasing two electrons and self-annihilating neutrinos. Though proven mathematically, it remains unobserved experimentally. A theorized model for this process involves the decay of Xenon(Xe) to a charged Barium(Ba2+) ion, which can be detected using small-molecule fluorescent sensors. As shown in previous works, fluorophores containing aza-crown ether ionophores are particularly sensitive and selective turn-on chemosensors. We characterize the ability of three commercially-available Potassium(K+) chemosensors with similar ionophores to act as sensors for Ba2+. We utilized a multifaceted approach to spectrofluorimetry by making bulk fluorescence measurements in aqueous solution while also running single-molecule fluorescence microscopy. We analyzed their fluorescence mechanism in tandem through computation. Bulk fluorescence studies show consistent selectivity toward Ba2+ ions and better fluorescent response to Ba2+ versus K+ ions. Single-molecule fluorescence further showcases the strong response to Ba2+, and characteristic photobleaching associated with single-molecule fluorescence. We found an interesting case with our computational analyses. Due to the over-representation of electron-transfer in DFT, functionals and basis sets screened revealed that commonly-used methods lead to conflicting results. Despite this, our calculations point toward a Photoinduced-Electron-Transfer(PET) fluorescence mechanism, consistent with similar small-molecule sensors.
Leave a Reply