Optical sensing of metal ions by using polyamide containing azo moieties

Congo Red-based polyamide was prepared by condensation polymerization reaction between Congo Red and sebacoyl chloride and its metal ion-responsive properties were investigated by UV–VIS spectroscopy. The absorption spectra showed cation-selective spectral intensity changes in the presence of specific metal ions in aqueous media due to cation complexing. Self-assembled multilayer film was prepared by means of layer-by-layer deposition technique with polyanion (Congo Red-based polymer) and polycation (poly(diallyldimethyl ammonium chloride)).