Synthesis and characterization of polyphenols containing pyridine and pyrimidine groups

In this study, three different polyaldehydes (poly-2-hydroxybenzaldehyde, poly-4-hydroxybenzaldehyde and poly-2-hydroxy-1-naphthaldehyde) have been synthesized from three aldehyde monomers(2-hydroxybenzaldehyde, 4-hydroxybenzaldehyde and 2-hydroxy-1-naphthaldehyde) by using oxidative polymerization method in an aqueous alkaline medium in the presence of NaOCl and H2O2 oxidants. Then, six poly Schiff bases were prepared from the polyaldehydes by grafting each of them total six different amines containing pyridine and pyrimidine groups. The polymers were characterized by FT-IR, 1H-NMR, 13C-NMR spectroscopy, SEC and SEM analyses, their optical properties were determined by UV-Vis and fluorescence spectroscopy, their electrochemical properties by CV analysis, solid state conductivity measurements by the four-point probe technique, their thermal behavior by TG, DTA, DSC measurements.The electrical conductivity of the polymers was also measured and it was found that they are semiconductive. Average molecular weight of the polymers in number(Mn), average molecular weight in weight(Mw) and polydispersity index(PDI) values were found according to SEC analysis. Mw, Mn, and PDI values of P-2HBA, P-2NAF and P-4HBA polymers were found to be 46750, 35400 and 1.32; 43400, 35600 and 1.22; 24420 16805 and 1.45, respectively. Electrochemical energy gap(E'g) was found by CV, where as optical band gap(Eg) was determined by UV-Vis measurements. Fluorescence analysis of the polymers was performed in DMF solvent medium and it was observed that fluorescence intensity of the pyridine moieties was significantly higher than that of the pyrimidine groups.