On/Off Fluorescent Chemosensor for Selective Detection of Divalent Iron and Copper Ions: Molecular Logic Operation and Protein Binding

Here, naphthalene diamine-based β-diketone derivative (compound LH) was successfully used as a dual signaling probe for divalent cations, Fe 2+ and Cu 2+ ions, in bimodal methods (colorimetric and fluorometric). It showed fluorescent enhancement for Fe 2+ ion by photoinduced electron transfer mechanism and fluorescence quenching for Cu 2+ ion by charge-transfer process. Binding stoichiometry for [LH-(Fe 2+ ) 2 ] and [LH-(Cu 2+ ) 2 ] was found to be 1:2 by Job's plot method and, the binding constants were calculated as 1.6638 × 10 10 and 9.22929 × 10 8 M -1 , respectively. Compound LH exhibited OR and XOR logic gate behavior with H + , Fe 2+ , and Cu 2+ as inputs. Further, the compound LH and bovine serum albumin binding interaction showed quenching of fluorescence by Förster resonance energy-transfer mechanism.