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Synthesis, characterization, density functional theory calculations, and in vitro antibacterial activity of novel transition metal complexes containing an O 3 ‐tridentate amoxicillin‐based Schiff base: A silver(II) complex as alternative against Pseudomonas aeruginosa resistant to amoxicillin
Author(s) -
Anacona J.R.,
Loroño Marcos,
Marpa Daniela,
Ramos Cesar,
Celis Freddy
Publication year - 2020
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.5755
Subject(s) - chemistry , schiff base , antibacterial activity , salicylaldehyde , nuclear chemistry , density functional theory , transition metal , square pyramidal molecular geometry , metal , stereochemistry , inorganic chemistry , organic chemistry , catalysis , computational chemistry , bacteria , genetics , biology
Transition metal complexes containing an amoxicillin‐based Schiff base (H 2 L, 3 ) obtained from the condensation of amoxicillin 1 with salicylaldehyde 2 were prepared. Spectroscopic and physicochemical techniques, namely, UV–visible, Fourier‐transform infrared spectroscopy, 1 H NMR, electron paramagnetic resonance, transmission electron microscopy, mass spectrometry, magnetic susceptibility, molar conductance, density functional theory (DFT) calculations, together with elemental and thermal analyses were used to characterize the synthesized complexes. Based on these studies, the general formulae [ML(H 2 O) 3 ], where M = Mn 4 , Ni 5 , Zn 6 , and [ML(H 2 O)], where M = Cu 7 , Ag 8 , were proposed for the complexes. The amoxicillin‐based Schiff base ligand behaved as a dianionic O 3 ‐tridentate chelating agent. DFT studies and magnetic and spectral data revealed octahedral geometries for Mn, Ni, and Zn atoms and distorted tetrahedral geometries for Cu(II) and Ag(II) complexes. Synthesized compounds were tested for antibacterial activity by both agar disk diffusion method and the minimum inhibitory concentration. in vitro bacterial viability revealed that complex 5 had similar antibacterial activity as 1 against Staphylococcus aureus and Staphylococcus epidermidis , whereas Pseudomonas aeruginosa , resistant to amoxicillin, was sensitive to complex 8 . The antibacterial activity of complex 8 could be attributed to its greater catalytic activity as shown by DFT calculations. Toxicity bioassay of the tested compounds showed LC 50 values > 1000 ppm, indicating their nontoxicity against brine shrimp nauplii ( Artemia salina ).