Quinoline based dual fluorescence chemosensor for the detection of Zn2+ and Cd2+ ions

A fluorescent chemosensor, employing quinoline (8-HQC-2PA), has been devised for the dual-channel detection of biologically significant metal ions (Zn²⁺ and Cd²⁺) in aqueous environments. The sensing of Zn²⁺ is accomplished through a fluorogenic "turn-on" mechanism, while selective binding with Cd²⁺ ions induces a noticeable red-shift in the probe’s intensity. Density functional theory (DFT) analysis affirms that the molecular energy levels and electron transitions of 8-HQC-2PA are significantly affected by the introduction of metal ions, resulting in spectral changes that facilitate the differentiation of Zn²⁺ and Cd²⁺. Moreover, 8-HQC-2PA exhibits high selectivity for Zn²⁺ and Cd²⁺ over other coexisting metal ions, achieving limits of detection (LOD) of 3.8 × 10^–8 M and 3.7 × 10⁻⁹ M, respectively. These findings offer a facile and efficient method for selectively discerning trace amounts of Zn²⁺ and Cd²⁺ ions in biological studies.