Study on Synthesis, Characterization, Thermal Stability and Conductivity Properties of a New Conjugated Oligoazomethine and some of its Metal Complexes


JOURNAL OF INORGANIC AND ORGANOMETALLIC POLYMERS AND MATERIALS, vol.19, no.4, pp.443-453, 2009 (SCI-Expanded) identifier identifier


A novel azomethine oligomer of 2,3-bis[(2-hydroxyphenyl)methylene]diaminopyridine (HPMDAP) was first synthesized by oxidative polycondensation reaction using air and NaOCl as oxidative agents. Optimum reaction conditions for the oxidative polycondensation and the main parameters of the process were established. At optimum reaction conditions, the yield of the product was found to be 69%. Oligomeric complexes of 2,3-bis[(2-hydroxyphenyl)methylene]diaminopyridine with Cd(II), Co(II), Cu(II), Ni(II), Fe(II), Pb(II), Cr(III) and Zn(II) were successfully prepared. Structures of monomer, oligomer and some oligomer metal complexes obtained were confirmed by FT-IR, UV-vis, H-1- and C-13-NMR and elemental analysis. Characterization was carried out by TG-DTA, size exclusion chromatography (SEC), magnetic moment and solubility tests. The H-1- and C-13-NMR data showed that polymerization proceed by C-C coupling of ortho and para positions according to -OH group of HPMDAP. Elemental analysis of chelates suggests that the metal ligand ratio is about 1:2. Molecular weight distribution values of the products were determined by size exclusion chromatography (SEC). According to TG analyses, the carbonaceous residues of HPMDAP and OHPMDAP were found to be 34.94 and 29.36% at 1000 A degrees C, respectively. Thermal analyses of Cd, Co, Cu, Ni, Fe, Pb, Cr and Zn oligomer-metal complexes were also investigated under N-2 atmosphere between 15 and 1000 A degrees C. Electrical conductivities of OHPMDAP and its metal complexes were also measured with four probe technique.