The mechanism of fluorescence quenching of naphthalimide A/C leak detector by copper (II).

BACKGROUND: Fluorescence quenching is an interesting phenomenon with the potential to be applied across various fields. The mechanism is commonly used across analytical applications for monitoring the concentration of trace substances. Naphthalimide and its family of compounds are commonly used as fluorescent detectors. This work investigated an analytical technique through which naphthalimide-based dyes could be quantified. A commercial A/C leak detector was used as the dye and Cu2+ ions as the quencher. Experiments were also conducted to investigate the effect of temperature on quenching. To study the mechanism of quenching further, density functional theory (DFT) was used.

RESULTS: The method detection limit obtained in this work is 1.7 × 10-6 mol/L. The results from the quenching experiments demonstrated a pattern which fit a modified Stern-Volmer (SV) model, with an R2 value of 0.9886. From the experiments on the effect of temperature, a dynamic quenching behavior was observed given the emission spectra demonstrated an inverse relationship with temperature.

CONCLUSIONS: The quenching of the commercial A/C dye by Cu2+ ions can be used to develop a rapid and sensitive detection method for metal ions such as Cu2+, and for future fabrication of chemosensors for Cu2+.