Date Approved

2026

Degree Type

Open Access Senior Honors Thesis

Department or School

Chemistry

First Advisor

Timothy Brewer, Ph.D.

Second Advisor

Hedeel Evans, Ph.D.

Third Advisor

Harriet Lindsay, Ph.D.

Abstract

Copper nanoclusters stabilized by polyvinylpyrrolidone (PVP) exhibit unique fluorescence properties that are highly sensitive to changes in their chemical environment, making them promising candidates for sensing applications. This study investigates the reversible fluorescence quenching and recovery behavior of PVP-supported copper nanoparticles in response to iron(III) ions and evaluates the selectivity of this response across different chemical conditions. Fluorescence quenching was examined using Fe³⁺ introduced as FeCl₃, followed by recovery experiments using ascorbic acid to assess reversibility through redox-driven interactions. To determine whether the observed response is specific to iron, potassium ferricyanide was used as an alternative Fe³⁺ source. Additional comparisons were made using group 1 and group 2 metal salts, including KCl and BaCl₂, to evaluate selectivity across different classes of ions. Fluorescence emission intensity was monitored using spectrofluorometry under consistent experimental conditions, and quenching behavior was analyzed through intensity relationships. The results demonstrate that Fe³⁺ induces significant fluorescence quenching, with partial recovery observed upon reduction. Transition metal species produced stronger quenching effects compared to group 1 and group 2 metals, suggesting that electron transfer and coordination interactions play a key role in fluorescence modulation. These findings support the potential application of PVP-supported copper nanoclusters as a fluorescence-based sensing platform for transition metal ions, while highlighting limitations in selectivity and environmental sensitivity.

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