Selective detection of Cu and Co in aqueous media: Asymmetric chemosensors, crystal structure and spectroscopic studies.

Two new azo-azomethine receptors, HL and HL, containing hydrazine, naphthalene and different electron withdrawing groups, Cl and NO, have been designed and synthesized for qualitative and quantitative detection of Cu and Co in aqueous media. The crystal structure of HLis reported. The HLwas used as a chemosensor for selective detection of trace amount of Cu in aqueous media. HL was also applied to naked-eye distinction of Cu and Co from other transition metal ions in aqueous media. Detection limit of Cu is 1.13μM and 1.26μM, in water, for HL and HL, respectively, which are lower than the World Health Organization (WHO) recommended level. The binuclear Cu and Co 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 and Co has been investigated using Job's plot. Moreover, the fluorescence emission spectra of the receptors and their metal complexes are also reported.