The Different Effects of Metal Ions on the Synthesis of Macroacyclic Compounds: X-ray Crystal Structure, Theoretical Studies, Antibacterial and Antifungal Activities

Abstract

In this work, we have been involved studying the synthesis of some new macroacyclic complexes I–VIII, so we tried to get propoesed results in all cases but in the case of compound I, according to X-ray crystal structure, the product is a protonated Schiff base. By the reaction of a 1 : 1 (metal : ligand) stoichiometry of two known Schiff base ligands, 1,2-bis(2-((2-hydroxy ethylimino)methyl)phenoxy)ethane (H₂L¹) or 1,3-bis(2-((2-hydroxyethylimino)methyl) phenoxy)propane (H₂L²) and appropriate metal salts in methanol in the case of Ni²⁺, Cu²⁺ and Co²⁺, macroacyclic complexes were prepared. When using Mn²⁺ only protonated Schiff base ligands is the final product. All compounds were characterized by microanalysis and IR spectroscopy, whereas compound I was also characterized by single crystal X-ray. The X-ray structure of compound I showed that both protonated imines are neutralized by two perchlorate ions. Computational calculations of relevant complexes are done by using one of the hybrid density functional theories which are a B3LYP method with 6-31G(d) basis set in a vacuum. Also, the synthesized compounds were screened for their antibacterial activities against nine bacterial strains and showed antibacterial effects. These complexes also showed antifungal effects on two species of Candida.