Synthesis and structure of complexes (NiII, AgI) of substituted benzaldehyde thiosemicarbazones and antitubercular activity of NiII complex

Copper(I) and silver(I) complexes of anthraldehyde thiosemicarbazone: synthesis, structure elucidation, in vitro anti-tuberculosis/cytotoxic activity and interactions with DNA/HSA

A reaction of copper(i) halides (X = I, Br, Cl) and silver(i) halides with 9-anthraldehyde thiosemicarbazone (9-Hanttsc, H1L) and triphenylphosphine produced halogen-bridged dinuclear complexes, [M2(μ2-X)2(η1-S-9-Hanttsc)2(Ph3P)2] (M = Cu, X = Cl, 1; Br, 2; I, 3; M = Ag, X = Cl, 4; Br, 5). A similar reaction of 9-anthraldehyde-N1-methyl thiosemicarbazone (9-Hanttsc-N1-Me, H2L) with Ph3P and silver(i) halides yielded sulfur-bridged dimers, [Ag2X2(μ2-S-9-Hanttsc-N1-Me)2(Ph3P)2] (X = Cl, 9; Br, 10), however with copper(i) halides insoluble compounds were formed, which upon the addition of one extra mole of Ph3P gave mononuclear complexes of the formula [CuX(η1-S-9-Hanttsc-N1-Me)(Ph3P)2] (X = Cl, 6; Br, 7; I, 8). All of the complexes have been characterized by elemental analysis, NMR (1H, 13C) spectroscopy and single crystal X-ray crystallography (2, 5, 6, and 9). Both the ligands (H1L and H2L) and their complexes (1-10) were tested for their anti-tubercular and anticancer activities. The interactions of the ligands and their complexes (copper and silver) with calf thymus DNA (ct-DNA) and human serum albumin (HSA) were examined through UV-visible and fluorescence spectroscopy. Results showed that copper complex 2 displayed strong interactions with ct-DNA and HSA having binding constant values of 6.66 × 104 M-1 and 3.28 × 104 M-1, respectively, followed by silver complex 10 which gave binding constant values of 4.60 × 104 M-1 and 3.06 × 104 M-1, respectively. All of the complexes also showed good interactions with DNA in docking studies.

Guedes da Silva MF, Marzano C. Synthesis, Characterization and Biological Activity of Novel Cu(II) Complexes of 6-Methyl-2-Oxo-1,2-Dihydroquinoline-3-Carbaldehyde-4n-Substituted Thiosemicarbazones

Three new 6-methyl-2-oxo-1,2-dihydroquinoline-3-carbaldehyde-thiosemicarbazones-N-4-substituted pro-ligands and their Cu(II) complexes (1, -NH2; 2, -NHMe; 3, -NHEt) have been prepared and characterized. In both the X-ray structures of 1 and 3, two crystallographically independent complex molecules were found that differ either in the nature of weakly metal-binding species (water in 1a and nitrate in 1b) or in the co-ligand (water in 3a and methanol in 3b). Electron Paramagnetic Resonance (EPR) measurements carried out on complexes 1 and 3 confirmed the presence of such different species in the solution. The electrochemical behavior of the pro-ligands and of the complexes was investigated, as well as their biological activity. Complexes 2 and 3 exhibited a high cytotoxicity against human tumor cells and 3D spheroids derived from solid tumors, related to the high cellular uptake. Complexes 2 and 3 also showed a high selectivity towards cancerous cell lines with respect to non-cancerous cell lines and were able to circumvent cisplatin resistance. Via the Transmission Electron Microscopy (TEM) imaging technique, preliminary insights into the biological activity of copper complexes were obtained.