Carbon quantum dots (CQD's) are semiconducting nanoparticles that fluoresce upon excitation with ultraviolet light. They are an emerging topic in chemistry due to their simple construction, biocompatibility and low toxicity in comparison to other non-carbon based dots. The surface ligand of the synthesized carbon quantum dots can be manipulated to sense the presence of different ions based on the intensity of this excitation. Here, the photoluminescent (PL) properties of CQD's with varying ligands are tested to determine a relationship between ion concentration and PL peak intensity. We show that dots synthesized with different ligands resulted in dots of varying color and different affinities for specific ions. Regardless of color, the fluorescence of the dots drop at different rates depending on the concentration and identity of metal ions. This shows that specific ligands quenches PL differently depending on the metal cation identity. Metal ions that compose car motors leach off into the oil inside due to degradation which still leaves the status of the motor a question. These dots can be added into the solution of the oil and can be used to detect the degradation of a motor based on the fluorescence of the dots. The surface of CQD’s can be easily changed to become tailored to the composition of certain car motors.

Equation that shows relationship between peak intensity and concentration of ions

PL that shows the progression of flourescent decay in the presence of a higher concentration of ions in solution

Kyle Magee

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