Heterocyclic ring based colorimetric and fluorescent chemosensor for transition metal ions in an aqueous medium

Heterocyclic ring based R1-R3 have been synthesized from the simple condensation method. R1-R3 exhibit highly selective and sensitive recognition towards transition metal ions in an aqueous medium via visual color change and were further confirmed by UV-vis and fluorescent spectroscopic methods. Fluorescent turn on and turn off behavior was observed for receptors tested with transition metal ions. The interaction of transition metal ions and receptors R1-R3 was confirmed to adopt 1:1 binding stoichiometry. Micromolar detection limit was found for R1-R3 with metal ions. DFT theoretical calculations were employed to understand the sensing mechanism of the sensors towards the metal ions. R1 and R2 were also successfully demonstrated as a fluorescent probe for detecting Cu2+ ions in living cells.