2,6-Substituted pyridine derivative-containing conjugated polymers: Synthesis, photoluminescence and ion-sensing properties

This paper describes a strategy to design and synthesize novel 2,6-substituted pyridine derivative-containing conjugated polymers for metal ion sensing. Two polymers P-1 and P-2 were prepared and the ion sensing properties of the monomers and the polymers were examined by UV-Vis absorption and fluorescence spectra respectively. It was found that polymer sensor P-1 exhibited a high selectivity for palladium ions among various transitional metals. The main absorbance peak was enhanced and a new peak appeared with the addition of palladium ions, meanwhile a linear calibration curve was observed. Moreover, the fluorescence intensity of emission maximum also decreased dramatically with a detection limit of 1 × 10^-6 M in aqueous solution. These results indicate the polymer P-1 can be used as a novel sensor for Pd²⁺ detection with high sensitivity and selectivity. The excellent performance of the polymer for Pd²⁺ detection can be attributed to the structure of the modular-based conjugated polymer with the meta-substituted pyridine, which provides a proper spatial matching for selective binding of metal ions and this is very important for designing polymer sensors for metal ions.