Synthesis, characterization, and antimicrobial activity of 4-imidazolecarboxaldehyde thiosemicarbazone and its Pt(II) and Pd(II) complexes

Abstract

Schiff bases are versatile ligands, synthesized via condensation of primary amines with carbonyl compounds. In this study, equimolar amounts of 4-imidazolecarboxaldehyde and thiosemicarbazide were combined and the Schiff base 4-imidazolecarboxaldehyde thiosemicarbazone was prepared as a new bidentate complexing agent. The synthesized ligand was reacted with palladium (II) and platinum (II) ions yielding air-stable complexes. For characterization purpose, infrared spectra, mass spectra, electronic spectra, thermal analysis, proton nuclear magnetic resonance and 13-carbon nuclear magnetic resonance spectra studies were carried out on the obtained complexes and ligand. The characterization data showed that the ligand acts as a bidentate coordinate to the metal ions through azomethine nitrogen and sulfur atoms. An in vitro antimicrobial investigation was also carried out for the free ligand and its metal complexes against four bacteria; Bacillus cereus, Staphylococcus aureus (Gram-positive), Escherichia coli and Salmonella typhimurium (Gram-negative) and one Fungi; Candida albicans, to assess their antimicrobial properties by disc diffusion technique. Antimicrobial activity of the prepared complexes showed higher activity than the free ligand.

Comparative antimicrobial activity of Cymbopogon citratus essential oil and thiosemicarbazones derived from this oil

“…CPThio had always been shown to be more active on parasites, followed by EO and finally Cthio [24][25][26]. These results obtained on inhibition diameters are also in agreement with those obtained by other researchers who have worked on the antimicrobial activities of else thiosemicarbazones [18][19][20]. We retain from this part that certain strains of microbes used during this work are sensitive to the three substances tested.…”

“…The mechanism of action of the compounds on the parasites would be different from their mechanism on the microbes considered in the present study. Depending on the thiosemicarbazone molecules used, the results may differ because the literature reports on thiosemicarbazones molecules with very interesting antimicrobial activities [18][19][20]. The values of the Minimum Bactericidal Concentration (MBC) are grouped together in Table 4.…”

“…Among them, we can mention the antifungal [9,10], anti-HIV [11,12], anticancer [13,14], anti-inflammatory [15,16], tuberclostatic [17] activities. The antimicrobial properties of these molecules were also known [18][19][20]. The starting substrate which is the essential oil of Cymbopogon citratus according to the literature also had very interesting biological properties [21][22][23].…”