Co(III) N,N′‐diarylformamidine dithiocarbamate complexes: Synthesis, characterization, crystal structures and biological studies

Abstract

Three symmetric N,N‐diarylformamidine dithiocarbamates, N,N′‐bis(2,6‐dimethylphenyl)formamidine dithiocarbamate (DTL1), N,N′‐bis(2,6‐disopropylphenyl)formamidine dithiocarbamate (DTL2) and N,N′‐dimesitylformamidine dithiocarbamate (DTL3), and three unsymmetric ones, N′‐(2,6‐dichlorophenyl‐N‐(2,6‐dimethylphenyl)formamidine dithiocarbamate (DTL4), N′‐(2,6‐dichlorophenyl)‐N‐(2,6‐diisopropylphenyl)formamidine dithiocarbamate (DTL5) and N′‐(2,6‐dichlorophenyl)‐N‐mesitylformamidine dithiocarbamate (DLT6), were reacted with chloridocobalt(III) in water to give Co‐(DTL1)3 (1), Co‐(DTL2)3 (2), Co‐(DTL3)3 (3), Co‐(DTL4)3 (4), Co‐(DTL5)3 (5) and Co‐(DTL6)3 (6). All the dithiocarbamates and complexes were characterized using 1H NMR, 13C NMR, Fourier transform infrared, UV–visible and mass spectra and the purity confirmed by elemental analysis. In addition, crystal structures of complexes 1, 2, 4 and 5 were determined, confirming the formation of mononuclear species in which the Co(III) centers coordinated to six sulfur atoms from three dithiocarbamate ligands resulting in distorted octahedral geometries. All complexes showed moderate to good antibacterial activities against Gram‐negative bacteria Escherichia coli, Salmonella typhimurium, Klebsiella pneumoniae and Pseudomonas aeruginosa even at low concentrations. None of the six were active against Gram‐positive bacterium methicillin‐resistant Staphylococcus aureus and only active against S. aureus at high concentrations. Complexes 5 and 6 were found to be more active than ciprofloxacin against S. typhimurium, E. coli, P. aeruginosa and K. pneumoniae and complexes with chloro‐substituted ligands generally had enhanced activities. Antioxidant activities of the dithiocarbamate salts and their Co(III) complexes were also investigated using DPPH assay and the complexes were found to be more efficient. Complex 2 with an IC50 value of 2.84 × 10−4 mM displayed the highest activity of all compounds tested, even outdoing ascorbic acid. The radical scavenging ability of the complexes followed the order 2 > 1 > ascorbic acid >3 > 4 > 6 > 5.

Design of New Schiff-Base Copper(II) Complexes: Synthesis, Crystal Structures, DFT Study, and Binding Potency toward Cytochrome P450 3A4

“…Earlier, Cu compounds used as therapeutic agents suffered some drawbacks, , such as solubility issues, which could be solved as recently proposed by Wehbe et al However, Cu-based complexes have resurfaced lately in inorganic synthesis investigations with rapt attention in which researchers have prepared Cu complexes for various medical indications. ,− For instance, Cu­(II)–indomethacin complexes have found application in veterinary science as anti-inflammatory medicine. , This re-emergence is partly inherent from copper’s existence in many natural biological pathways that could control Cu levels and metabolize it appreciably …”

4‐Aryl‐2‐Imino‐1,3‐Dithiolanes from the Room Temperature Coupling of Sodium Dithiocarbamates with Sulfonium Salts

“…The spectroscopic characterization of the compounds, being rather sparse in the literature, has been performed for all the compounds described in the paper and it is detailed in the Experimental section. The IR spectra (solid state) display an absorption assigned to the {CS 2 } moiety in the range 984–949 cm −1 , [31] while the thioureide {N−CS 2 } carbon‐nitrogen bond stretching is observed in the interval 1526–1479 cm −1 , suggesting a bond order in between a single (1350–1250 cm −1 ) and a double one (1690–1640 cm −1 ) [32,33] . Resonances around 210 ppm due to the {CS 2 } carbon are observed in the 13 C NMR spectra (in CDCl 3 ).…”

“…Note that cyclic dithiocarbamates are isomers of dithiolanes and their {SC=S} group is typically featured by a 13 C resonance at ca. 200 ppm, [32–36] whereas a diagnostic signal was found around 165 ppm in products spectra and assigned to the C=N moiety of dithiolanes [9,16] . All the IR spectra of prepared 2‐amino‐1,3‐dithiolanes display an intense absorption from 1590 to 1605 cm −1 due to the C=N stretching.…”

N,N′-Diarylformamidine Dithiocarbamate Ag(I) Cluster and Coordination Polymer

“…With the CS 2 moieties added on, a propeller like core is formed (Figure 2c). In the electronic spectra of 1 and 2, two bands were observed at 238 and 312, and 314 nm and these are attributed to intraligand π→π* transition associated with N-C=S and π→π* transition within S-C=S groups of the coordinated dithiocarbamate ligands [37].…”