Selective detection of Cu2 + and Co2 + in aqueous media: Asymmetric chemosensors, crystal structure and spectroscopic studies.

Two new azo-azomethine receptors, H 2 L 1 and H 2 L 2 , containing hydrazine, naphthalene and different electron withdrawing groups, Cl and NO 2 , have been designed and synthesized for qualitative and quantitative detection of Cu 2 + and Co 2 + in aqueous media. The crystal structure of H 2 L 1 is reported. The H 2 L 1 was used as a chemosensor for selective detection of trace amount of Cu 2 + in aqueous media. H 2 L 2 was also applied to naked-eye distinction of Cu 2 + and Co 2 + from other transition metal ions in aqueous media. Detection limit of Cu 2 + is 1.13 μM and 1.26 μM, in water, for H 2 L 1 and H 2 L 2 , respectively, which are lower than the World Health Organization (WHO) recommended level. The binuclear Cu 2 + and Co 2 + complexes of the receptors have been also prepared and characterized using spectroscopic methods and MALDI-TOF mass analysis. Furthermore, the binding stoichiometry between the receptors upon the addition Cu 2 + and Co 2 + has been investigated using Job's plot. Moreover, the fluorescence emission spectra of the receptors and their metal complexes are also reported. [ABSTRACT FROM AUTHOR]