Pyrene excimer-based fluorescent chemosensor for cascade detection of Zn(II) and phosphate ions and its applications

Pyrene-naphthaldehyde derivative PNY was synthesized and employed for the cascade fluorescent ‘On-Off’ detection of Zn2+ and H2PO4-. [Display omitted] •A pyrene-naphthaldehyde based Schiff base PNY was synthesized and characterized.•PNY was employed for cascade fluorescent ‘Off-On-Off’ detection of Zn2+ and phosphate ions.•PNY showed a distinct fluorescence enhancement at 450 nm for Zn2+ due to the formation of a pyrene excimer.•The in-situ formed PNY-Zn2+ complex gets decomplex upon the addition of phosphate ions.•PNY and PNY-Zn2+ were explored to quantify Zn2+ and phosphate ions in real samples. There is growing research on developing fluorescent chemosensors that can detect multiple analytes. Herein, a pyrene-naphthaldehyde based Schiff base PNY was synthesized, characterized, and employed for the cascade fluorescent ‘Off-On-Off’ detection of Zn2+ and phosphate ions. The interaction of PNY with Zn2+ led to a distinct fluorescence enhancement at 450 nm, and the fluorescent color of PNY was changed from blue to cyan-blue due to the complexation-induced formation of a pyrene excimer. PNY, as a fluorescent turn-on sensor can be employed to detect Zn2+ down to 2.20 × 10−7 M. Subsequently, the in-situ formed PNY-Zn2+ complex gets decomplex upon the addition of phosphate ion among other tested anions with a detection limit of 3.42 × 10−7 M. With the addition of phosphate ion, fluorescence intensity of PNY-Zn2+ at 450 nm was quenched with the concomitant formation of an emission peak at around 396 nm. The excimer-monomer mechanism was used to explain the sensing ability of PNY. Further, to complement the phosphate ion selectivity, the ability of PNY-Zn2+ to detect adenosine triphosphate (ATP) was explored. At last, the analytical novelty of PNY and PNY-Zn2+ was explored by quantifying Zn2+ and phosphate ions in real environmental and biological samples.