Colorimetric and fluorescent sensor for selective sensing of Hg2+ ions in semi aqueous medium

► Hg2+ ions coordinate with imine and shows color turn-off from yellow to colorless. ► The binding constant of the receptor 1 (DMSO) with Hg2+ ion (DMSO) is 1.35×105. ► Hg2+ ions coordinate to the imine through NONO binding site forming 1:1 complex. ► The receptor 1 shows fluorescent 'Turn-on' behavior based on solvent polarity. ► The detection limit of receptor 1 with mercury is 1 μg L−1.