Synthesis, Crystal Structures, Antimicrobial Activity, and Acute Toxicity Evaluation of Chiral Zn(II) Schiff Base Complexes

Four mononuclear bioefficient zinc coordination complexes [Zn(NN)₃](ClO₄)₂ (<b>A</b>-<b>D</b>) involving chiral bidentate Schiff base ligands have been synthesized and characterized by IR, ¹H, and ¹³C NMR spectroscopy and mass spectrometry. X-ray crystal structures of three of the zinc complexes revealed that the zinc metal ion is hexacoordinated, exhibiting a distorted octahedral geometry where both the nitrogen atoms (NN = pyridyl and imine) of imines are coordinated to the central zinc ion. The isolated zinc complexes were evaluated for their antimicrobial activity in vitro against <i>Escherichia coli</i>, <i>Pseudomonas aeruginosa</i>, and <i>Staphylococcus aureus</i>, displaying varying levels of growth inhibition. An acute toxicity test conducted using <i>Artemia salina</i> and Swiss albino mice showed that the zinc complexes <b>A</b>-<b>D</b> were non-toxic towards <i>A. salina</i> at concentrations below 414, 564, 350, and 385 µM, respectively, and did not affect liver biochemical parameters, although pyknosis was induced in hepatocytes of the treated mice.