Synthesis and spectral investigation of colorimetric receptors for the dual detection of copper and acetate ions: application in molecular logic gates

Colorimetric receptors L1, L2 and L3 possessing -OH functionality as binding site and -NO2 as signalling unit with varied positional substitution of -OMe functionality has been designed and synthesised by simple Schiff base condensation reaction. Receptors L1, L2 and L3 showed selective response towards AcO(-)ion among other interfering monovalent anions viz., F-, Cl-, Br-, I-, NO3-, HSO4- and H2PO4-. L2 imparts high selectivity towards AcO- ion assisted by push-pull effect of -NO2 and -OMe functionality in conjugation with imine linkage. The binding constant for L2-OAc complex was found to be 9.04x10(4)M(-2). L2 exhibited a detection limit of 0.61ppm towards NaOAc. The selectivity of L1 towards Cu2+ ions with a lower detection limit of 1.81ppm implies the role of electron donating -OMe in favouring the coordinative interaction of hetero atoms of L1 with Cu2+ ions. The selective detection of AcO- and Cu2+ ions is further established with OR and INHIBIT logic gate application of receptors L1, L2 and L3 correspondingly. The colorimetric studies reveal the role of OMe functionality in the selective detection of AcO- and Cu (2+) ions in aqueous media.