A method of obtaining high selectivity for copper ions on triglycine decorated surfaces

Abstract

We report a method of controlling the conformations of immobilized triglycine and improving its selectivity for copper ion by mixing equal molar of triglycine and copper ion during the immobilization step. Our attenuated total reflectance-Fourier transformation infrared (ATR-FTIR) spectroscopy shows that, when triglycine molecules are immobilized in the presence of copper ions, both amide I and amide II bands of triglycine increase, which can be attributed to the conformational change of triglycine from a random coil to a loop structure. Interestingly, even after copper ion is removed, the loop structure is still maintained, possibly due to the formation of intermolecular hydrogen bonds between adjacent triglycine molecules. Immobilized triglycine molecules with a loop structure show excellent complexation capability and selectivity for copper ion. Even in the presence of 100 × other metal ions such as zinc and nickel, surface immobilized triglycine with a loop structure still preferentially binds to copper ions. No zinc or nickel ions can be detected on the surface. © 2008 American Chemical Society.