Naked-eye recognition of Cu(II), Zn(II) and acetate ion by the first guanine-based difunctional chromoinophore.

The first guanine-based difunctional colorimetric receptor 8-[(4-nitrophenyl)azo]guanine (receptor 1) was designed, synthesized and characterized by IR, UV-vis, (1)H NMR and mass spectrometric analysis. The synthesized receptor 1 was able to recognize Cu(II), Zn(II) and acetate ion through visible color changes in its DMSO and DMSO-H(2)O (95:5, v/v) solution. The binding affinity of the receptor 1 with the chosen analytes has been estimated in terms of binding constants through non-linear fittings of corresponding UV-vis titration data while the binding mode of the same was studied through (1)H NMR spectral studies. (c) 2010 Elsevier B.V. All rights reserved.