Naked-eye recognition of CuII, ZnII 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, 1H NMR and mass spectrometric analysis. The synthesized receptor 1 was able to recognize CuII, ZnII and acetate ion through visible color changes in its DMSO and DMSO-H2O (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 1H NMR spectral studies.