Synthesis, characterization, structural investigation, and antimicrobial studies of mononuclear Zn(II), Cd(II), and Ag(I) complexes of an N₃O Schiff base

Abstract

L O N Ph Ph N C H N ZnBr2 RT CdI2 RT A Zn(II), Cd(II) and Ag(I) mononuclear complexes of an N 3 O Schiff base have been synthesized. The crystal structures of these complexes have been determined. The complexes have antibacterial activity against the bacteria K. pneumoniae 114, E. coli K88, S. typhi ATCC 34, B. subtilis UC564, and S. aureus ATCC25923 and antifungal activity against A. niger, A. oryzae, P. notatum, and S. cerevisiae. An N 3 O Schiff base (L), 1 : 1 condensate of benzil monohydrazone and 4-pyridine carboxaldehyde, and its Zn(II), Cd(II), and Ag(I) complexes were synthesized and characterized by elemental analyses and various spectroscopic techniques. The crystal structures of [ZnL 2 Br 2 ] (1), [CdL 2 I 2 ]·CH 2 Cl 2 ,(2)·CH 2 Cl 2 , and [Ag(L) 2 ]ClO 4 (3) have been determined using X-ray crystallography. The Zn(II) and Cd(II) complexes show a tetrahedral configuration whereas in the asymmetric unit of 3, two independent coordination units of Ag(I) are present. Carbonyl-silver interaction, weak C-H⋯O interaction, and also π-π interaction are present in 3 in the solid state. The synthesized complexes have antibacterial activity against Klebsiella pneumoniae 114, Escherichia coli K88, Salmonella typhi ATCC 34, Bacillus subtilis UC564, and Staphylococcus aureus ATCC25923. The results showed that in some cases the antibacterial activities of the complexes were comparable to standard antibiotics Tetracycline and Streptomycin. The antifungal activities of the complexes were also studied for Aspergillus niger, Aspergillus oryzae, Penicillium notatum, and Saccharomyces cerevisiae. MIC values of 1, 2·CH 2 Cl 2 , and 3 are less than the Nystatin standard.

Synthesis, characterization, DFT calculations and antimicrobial activity of pentagonal-bipyramidal Zn(II) and Cd(II) complexes with 2,6-diacetylpyridine-bis(trimethylammoniumacetohydrazone)

“…In most of the cases, the coordination of ligands to Zn(II) enhanced their antimicrobial activity [44,[47][48][49]. Reported results [43][44][45][46][47][48][49][50][51][52][53] and the present work showed that stability, solubility, charge, geometry and nuclearity of Cd(II) and Zn(II) complexes determine their antimicrobial activity. is the total number of parameters refined.…”

“…The literature contains many reports dealing with antimicrobial properties of Zn(II) and Cd(II) complexes [43][44][45][46][47]. Due to the extremely toxic nature of Cd(II), its complexes mainly showed higher antimicrobial activity than Zn(II) complexes with the same ligands [48][49][50][51][52][53]. At concentration 10 -7 -10 -5 mol/L, Zn(II) is necessary for normal microbial growth, but at millimolar concentration Zn(II) exhibits toxic effects [53].…”

Crystal structures, spectroscopic, electrochemical, and antibacterial properties of a series of new copper(II) Schiff base complexes

“…The study of the antibacterial properties of Schiff bases and their metal complexes has attracted interest [33][34][35][36][37][38][39]. In our previous studies on the biological activities of the transition metal Schiff base complexes, we found that the presence of more electronegative substituents on the ancillary ligand increased the antibacterial activity of their corresponding complexes.…”