Synthesis and Crystal Structures of Schiff-Base Cobalt(III) Complexes with Antibacterial Activity

Abstract

Cobalt complexes derived from Schiff-bases usually possess various biological activities. In this article, two new Schiff-base cobalt(III) complexes, [CoL¹L²N₃] (1) and [CoL³(NCS)₂ (OH₂)] (2), where L¹, L², and L³ are 2-[1-(2-dimethylam- inoethylimino)ethyl]phenolate, 1-(2-hydroxyphenyl)ethanone, and 2-[(2-dimethylaminoethylimino)methyl]-6-methylphenolate, respectively, have been prepared and characterized by physicochemical methods and single crystal X-ray determination. Complex 1 crystallizes in monoclinic system space group P2₁/c, with a = 14.845(2) Å, b = 6.6605(7) Å, c = 20.740(2) Å, β = 98.027(3)°, V = 2030.6(4) ų, Z = 4, R ₁ = 0.0862, and wR ₂ = 0.1798. Complex 2 crystallizes in monoclinic system space group P2₁/c, with a = 8.824(2) Å, b = 10.957(2) Å, c = 18.708(2) Å, β = 94.749(2)°, V = 1802.4(5) ų, Z = 4, R ₁ = 0.0506, and wR ₂ = 0.1205. Single crystal X-ray diffraction analysis reveals that the Co atoms in the complexes are six-coordinated in octahedral geometry. The complexes have from moderate to strong activities against Bacillus subtillis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aereuguinosa, which are stronger than the free ligands.

Keywords:

• biological activity
• crystal structure
• Schiff-base
• cobalt(III) complex
• synthesis