Di-amido-derivatives of 1,1′-methylene-bis(2-naphthol) (mbn), viz.; L1 to L6 and L7, have been synthesized and characterized. The single crystal X-ray structure of L2 has been established. All these derivatives have been studied for metal ion recognition by fluorescence and absorption techniques. Among these, L6 and L 7 were found to be selective towards Cu2+ even in the presence of other metal ions in aqueous acetonitrile owing to the presence of the N,O-binding core up to the lowest concentration of 210 ± 11 and 144 ± 3 ppb, respectively. The binding region has been identified by 1H NMR studies. The proposed mode of binding has been modelled by DFT computations. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.