Synthesis and characterization of transition metal complexes with a Schiff base derived from cephalexin and 1,2–diaminobenzene. antibacterial activity

Abstract

From the reaction of 1,2-diaminobenzene 1 with cephalexin 2 antibiotic a cephalexin–based Schiff base (HL) 3, was obtained and the transition metal Schiff base complexes were synthesized. The products were characterized by physical and spectral techniques, namely, UV–Vis, FT-IR, ¹H-NMR, EPR, MALDI mass spectrometry, magnetic susceptibility, molar conductance, molecular modeling, together with elemental and thermal analysis. The general composition [M(L)(OAc)(H₂O)₂], M(II) = Mn²⁺ 4, Co²⁺ 5, Ni²⁺ 6, Cu²⁺ 7, Zn²⁺ 8, where L represents deprotonated tridentate NNO Schiff base, have been assigned to the adducts. Direct calcinations of the complexes 6 and 8 at 700 °C resulted high-quality metal oxide (MO) nanoparticles. Paper disc diffusion method was used to test the bactericidal activity of the synthesized products.

Keywords:

• Transition metal complexes
• cephalexin-based Schiff base
• IR spectroscopy
• DFT calculations; metal oxide (MO) nanoparticles

Acknowledgements

The authors thanks to the Universidad de Oriente (UDO) and Universidad de Playa Ancha (UPLA) for continuous support.