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, Fe2+ and Cu2+ ions, in bimodal methods (colorimetric and fluorometric). It showed fluorescent enhancement for Fe2+ ion by photoinduced electron transfer mechanism and fluorescence quenching for Cu2+ ion by charge-transfer process. Binding stoichiometry for [LH-(Fe2+)2] and [LH-(Cu2+)2] was found to be 1:2 by Job's plot method and, the binding constants were calculated as 1.6638 × 1010 and 9.22929 × 108 M-1, respectively. Compound LH exhibited OR and XOR logic gate behavior with H+, Fe2+, and Cu2+ as inputs. Further, the compound LH and bovine serum albumin binding interaction showed quenching of fluorescence by Förster resonance energy-transfer mechanism.