A counterion displacement assay with a Biginelli product: a ratiometric sensor for Hg2+ and the resultant complex as a sensor for Cl−

Chemosensors are prepared through a one pot, multicomponent organic synthesis and their activities are evaluated in a DMF : H2O (1 : 9, v/v) solvent system. One chemosensor has demonstrated selectivity for Hg2+ by quenching the fluorescence intensity at 394 nm with enhancement at 460 nm. Thus, the sensor offers an interesting opportunity for the ratiometric determination of Hg2+ in a semi aqueous solvent system with a detection limit of 0.2 μM. The resultant mercury complex of the same sensor is evaluated for anion recognition properties. The metal complex is highly selective for the determination of chloride in a semi aqueous medium through a counterion displacement assay.