Synthesis and characterization of Schiff base, Co(II) and Cu(II) metal complexes and poly(phenoxy-imine)s containing pyridine unit


KAYA İ. , Daban S., Senol D.

INORGANICA CHIMICA ACTA, vol.515, 2021 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 515
  • Publication Date: 2021
  • Doi Number: 10.1016/j.ica.2020.120040
  • Title of Journal : INORGANICA CHIMICA ACTA

Abstract

In the first stage, two different Schiff base ligands were prepared by the condensation of 2-amino-5-bromopyridine and 2-amino-5-chloropyridine with salicylaldehyde in methanol at the molar ratio of 1:1. Ligands: C12H9ON2Br (L1), C12H9ON2Cl (L2). In the second stage, four different metal complexes were obtained from Schiff bases with Co(OAc)(2)4H(2)O and Cu(OAc)(2)2H(2)O Molecular formulas of the metal complexes obtained were [Co-2(L1)(2)(H2O)(OCH3)]H2O, [Cu-2(L1)(2)(H2O)(OCH3)]H2O, [Co-2(L2)(2)(H2O)(OCH3)]H2O and [Cu-2(L2)(2)(H2O) (OCH3)] H2O. In the third stage, ortho-vanillin (VAN) was polymerized via oxidative polycondensation in aqueous alkaline medium with air as oxidant. Then, poly(phenoxy-imine)s were synthesized from condensation reactions of poly (ortho-vanillin) (PVAN) with 2-amino-5-bromopyridine and 2-amino-5-chloropyridine in THF medium at 60 degrees C. All synthesized compounds were characterized by spectral and electrochemical techniques. Thermal properties of the compounds were determined by TGA-DTA and DSC analyses. The molecular weights of the polymers were calculated from SEC analyses. Poly[2-((5-bromopyridin-2-yl-imino)methyl)-6-methoxyphenol] (PVANBr) and poly[2-((5-chloropyridin-2-yl-imino)methyl)-6-methoxyphenol] (PVANCl) were determined to have electrical conductivity of 10-3 S cm(-1). Electrochemical band gaps (Eg') of PVANBr and PVANCl were calculated as 2.10 and 1.95 eV, respectively. Initial decomposition temperatures of [Co-2(L1)(2)(H2O)(OCH3)]H2O, [Cu-2(L1)(2)(H2O)(OCH3)]H2O, [Co-2(L2)(2)(H2O)(OCH3)]H2O and [Cu-2(L2)(2)(H2O) (OCH3)]H2O were found to be 309, 271, 305 and 259 degrees C, respectively.