Chelation-Controlled Fluorescence: A Novel Coumarin-Thiazole Probe for Zn (II) Analysis in Real Samples

In this investigation, an exceptional coumarin-thiazole-based fluorescent sensor was fabricated through a facile one-pot synthetic strategy, affording a highly emissive blue-fluorescent probe suitable for Zn (II) determination. The synthesized fluorescent probe exhibited a strong emission band at 470 nm upon excitation at 410 nm with a quantum yield of 0.95 ± 0.05. Incremental additions of Zn (II) from 2.5 to 37.5 μM induced a pronounced turn-off response in fluorescence intensity. An excellent linearity (r = 0.9999) was established between the quenching magnitude and Zn (II) concentration, with a limit of detection (LOD) reaching 0.47 μM, indicative of exceptional sensitivity. This fluorescence attenuation was ascribed to a chelation-induced static quenching mechanism, as corroborated by Stern-Volmer analysis, confirming the formation of a non-emissive Zn (II)-probe complex. The protocol demonstrated practical utility in assaying Zn (II) within commercial tablets and river water matrices, yielding recovery rates of 97.70%-102.85%. These results demonstrate the high selectivity of the fabricated probe and its negligible susceptibility to matrix interferences. Collectively, this methodology offers a facile, economical one-pot synthesis route alongside a highly sensitive spectrofluorimetric platform, thereby extending its scope for real-world environmental and pharmaceutical monitoring.