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Transition metal complexes containing a tridentate cefadroxil‐based Schiff base: An effective paramagnetic semiquinone Ag (I) complex against Staphylococcus aureus and Pseudomonas aeruginosa
Author(s) -
Anacona J.R.,
Barrios Virginia,
Bravo Alina,
Celis Freddy
Publication year - 2018
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.4562
Subject(s) - chemistry , schiff base , nuclear chemistry , electron paramagnetic resonance , salicylaldehyde , chelation , antibacterial activity , transition metal , stereochemistry , crystallography , inorganic chemistry , organic chemistry , nuclear magnetic resonance , bacteria , physics , biology , genetics , catalysis
The aim of this study was to prepare transition metal complexes containing a cefadroxil‐based Schiff base ligand (H 2 L, 3 ) obtained from the condensation of cefadroxil 1 with salicylaldehyde 2 , and to study their bactericidal activity against G(+) and G(–) strains. Spectroscopic and physicochemical techniques, namely, transmission electron microscopy, UV–Vis, Fourier transform‐infrared, electron paramagnetic resonance, 1 H NMR, mass spectrometry, magnetic susceptibility, molar conductance, molecular modelling, together with elemental and thermal analyses were used to find out the binding mode and composition of these complexes. Based on the characterization studies, the general formulae [ML (H 2 O) 3 ], where M = Mn 4 , Co 5 , Ni 6 , Zn 7 and Ag 8 , were proposed for the complexes. The Schiff base 3 behaved as a dianionic tridentate OOO chelating agent. An octahedral geometry for all the complexes was suggested on the basis of magnetic and spectral data. Free 1 , 3 and its metal complexes 4 – 8 were tested for bactericidal activity by using both agar disc diffusion method and the minimal inhibitory concentration. In vitro bacterial viability revealed that 3 and complexes 4 – 7 had similar bactericidal activity than 1 against Staphylococcus epidermidis showing that they have good activity as bactericides. Based on magnetic data, the paramagnetic complex 8 was shown to be a semiquinone complex stabilized by the metal, and exhibited much better bactericidal activity than 1 against all bacterial strains tested.