New 15-membered macrocyclic Schiff base ligand; synthesis some Cd(II), Mn(II) and Zn(II) complexes, crystal structure, cytotoxicity, antibacterial and antioxidant activity

Abstract

Herein, we aim at preparing 15-membered-ring symmetrical pentaaza macrocyclic Schiff base complexes using a template approach, based on the condensation reaction of an amine containing piperazine moiety, 2,2-(piperazine1,4-diyl)dianiline, and 2,6-diacetylpyridine in 1:1 mol ratio while Cd(II), Mn(II) and Zn(II) metal ions are present. Moreover, FT-IR, mass spectrometry, magnetic susceptibility measurements, UV–Vis and, 1H and 13C NMR spectroscopy were used to characterize these Schiff base complexes. Besides, the structure of [C25H25N5CdBr][ClO4] was determined using a single crystal X-ray structural analysis. Being in a pentagonal planar coordination environment, the Cd atom is surrounded by a Br atom in the apical position and 5 nitrogen atoms in the pentagonal plane. We also aimed at screening the synthesized complexes to investigate their antioxidant activities applying the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging assay. also, their bactericidal activity was evaluated using a paper disk diffusion method against both Gram-negative and Gram-positive bacteria, revealing a strong antioxidant activity and moderate effectiveness against all the tested bacteria. Finally, it is worth mentioning that the complex cytotoxicity was evaluated against MCF-7 (breast) and A549 (lung) adenocarcinoma cells. Generally, as compared to [ZnLBr]ClO4 possessed a greater cytotoxic effect against the tested cells.