Oligo‐Ortho‐Chloroazomethinephenol and its Metal Complexes: Synthesis, Characterization, Antimicrobial and Thermal Properties

Abstract

The new Schiff base oligomer (oligo‐ortho‐chloroazomethinephenol) was synthesized by the condensation of ortho‐chloroaniline with oligosalicylaldehyde (OSA). Oligomer‐metal complexes of oligo‐ortho‐chloroazomethinephenol (OKAP) with Cu(II), Zn(II) and Co(II) were synthesized. The properties of OKAP and oligomer‐metal complexes were studied by elemental, UV‐Vis, ¹H‐NMR, FT‐IR, magnetic susceptibility analyses. The number average molecular weight and mass average molecular weight OKAP were found to be 1494 g · mol⁻¹ and 5418 g · mol⁻¹, respectively. Elemental analyses of oligomer‐metal complexes suggest that the ratio of metal to oligomer is 1∶2. The results indicate that the OKAP coordinate through azomethine nitrogen and phenolic oxygen to the metal ions. Antimicrobial activity of OKAP was tested against S. cerevisiae, B. subtilis, E. coli, K. pneumoniae, M. luteus and S. aureus. The thermal stabilities of the OKAP and oligomer‐metal complexes were compared by thermogravimetric (TG) analyses. According to TG, OKAP, and oligomer‐metal complexes were stable against temperature and thermooxidative decomposition. The weight losses of OKAP and oligomer‐metal complexes were found to be at 400 and 800°C at 20.2 and 50.0 (OKAP), 17.1 and 41.1 (Cu(II)), 13.4 and 38.5 (Zn(II)), 18.3 and 68.2 (Co(II)), %, respectively. Based on half degradation temperature (T_50%) parameters, Cu(II) and Zn(II) complexes were more resistant than the OKAP and Co(II) complex.

Keywords:

• Schiff base oligomer
• thermal properties
• antimicrobial properties
• metal complexes