Simple pyrene-based chemosensors 1 to 3, were synthesized from pyrene-1-carboxaldehyde and they were characterized using various spectroscopic techniques like UV-Vis, FT-IR, Mass, H NMR and C NMR. Among synthesized receptors, the receptor 1 shows high selectivity towards Hg ions. Further, the high selectivity of receptor 1 towards Hg ions in the presence of various other interfering metal ions like Ni, Zn, Mn, Co, Cu, Cr, Fe, Al, Ag, Fe, Cd, Mg, Pb, Ca, Na, K was confirmed by UV-Vis and fluorescence methods. The detection limit for Hg ions was found to be 0.270 μM. The chemodosimetric irreversible hydrolysis of the receptor 1 in the presence of Hg was studied by UV/Vis, fluorescence, FT-IR, LC-MS, H NMR and theoretical DFT study. Further, the real life applications of receptor 1 for the determination of Hg ions were demonstrated by UV-Vis method.