Benzaldehyde thiosemicarbazone complexes of platinum: Syntheses, structures and cytotoxic properties

New Mononuclear and Binuclear Cu(II), Co(II), Ni(II), and Zn(II) Thiosemicarbazone Complexes with Potential Biological Activity: Antimicrobial and Molecular Docking Study

Herein, we report the synthesis of eight new mononuclear and binuclear Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺ methoxy thiosemicarbazone (MTSC) complexes aiming at obtaining thiosemicarbazone complex with potent biological activity. The structure of the MTSC ligand and its metal complexes was fully characterized by elemental analysis, spectroscopic techniques (NMR, FTIR, UV-Vis), molar conductivity, thermogravimetric analysis (TG), and thermal differential analysis (DrTGA). The spectral and analytical data revealed that the obtained thiosemicarbazone-metal complexes have octahedral geometry around the metal center, except for the Zn²⁺-thiosemicarbazone complexes, which showed a tetrahedral geometry. The antibacterial and antifungal activities of the MTSC ligand and its (Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺) metal complexes were also investigated. Interestingly, the antibacterial activity of MTSC- metal complexes against examined bacteria was higher than that of the MTSC alone, which indicates that metal complexation improved the antibacterial activity of the parent ligand. Among different metal complexes, the MTSC- mono- and binuclear Cu²⁺ complexes showed significant antibacterial activity against Bacillus subtilis and Proteus vulgaris, better than that of the standard gentamycin drug. The in silico molecular docking study has revealed that the MTSC ligand could be a potential inhibitor for the oxidoreductase protein.

Platinum(II) carboxylato complexes containing 7-azaindoles as N-donor carrier ligands showed cytotoxicity against cancer cell lines

The platinum(II) malonato (Mal) and decanoato (Dec) complexes of the general formulas [Pt(Mal)(naza)₂] (1-3) and cis-[Pt(Dec)₂(naza)₂] (4-7) were prepared, characterized and tested for their in vitro cytotoxicity against cisplatin-sensitive (A2780) and cisplatin-resistant (A2780R) human ovarian carcinoma cell lines and non-cancerous human lung fibroblasts (MRC-5); naza=halogeno-derivatives of 7-azaindole. Complexes 1-7 effectively overcome the acquired resistance of ovarian carcinoma cells to cisplatin. Complexes 2 (IC₅₀=26.6±8.9μM against A2780 and 28.9±6.7μM against A2780R), 4 (IC₅₀=14.5±0.6μM against A2780 and 14.5±3.8μM against A2780R) and 5 (IC₅₀=13.0±1.1μM against A2780 and 13.6±4.9μM against A2780R) indicated decreased toxicity against healthy MRC-5 cells (IC₅₀>50.0μM for 2 and >25.0μM for 4 and 5). The representative complexes 2 and 4 showed mutually different effect on the A2780 cell cycle at IC₅₀ concentrations after 24h exposure. Concretely, the complex 2 caused cell cycle arrest at G₀/G₁ phase, while 4 induced cell death by apoptosis with high population of cells in sub-G₁ cell cycle phase. The hydrolysis and interactions of the selected complexes with biomolecules (glutathione (GSH) and guanosine monophosphate (GMP)) were also studied by means of ¹H NMR and ESI+ mass spectra.

Activation of C–H bonds of thiosemicarbazones by transition metals: synthesis, structures and importance of cyclometallated compounds

Transition metals (Pd^II, Pt^II, Ru^II, Rh^IIIand Ir^III) have induced activation of C–H bonds of thiosemicarbazones and yielded mono-, di-, tri- and tetra-nuclear complexes.

Tuneable reactivity with PPh3 and SnX2 of four- and five-coordinate Pd(II) and Pt(II) complexes containing polyphosphines

The reactivity of the unusual d(8) trigonal-bipyramidal systems [MX(PP3)]X (X = Cl: M = Pd(1a), Pt(2a); X = Br: M = Pd(3a), Pt(4a); X = I: M = Pd(5a), Pt(6a); PP3 = tris[2-(diphenylphosphino)ethyl]phosphine) in CHCl3-CH3OH, the square-pyramidal compounds [MCl(NP3)]Cl (M = Pd(7a); Pt(8a); NP3 = tris[2-(diphenylphosphino)ethyl]amine) in CD3OD-DMF and the distorted square-planar mononuclear [MX(PNP)]X (M = Pd: X = Cl(10a); M = Pt: X = I(10b); PNP = bis[2-(diphenylphosphino)ethyl]amine) and the heteronuclear [PdAu2X4(PP3)] [X = I(9a), Cl(14a), Br(15a)] and [MAuX2(PP3)]X [M = Pd: X = Cl(16a); M = Pt: X = Cl(17a), Br(18a)] species in CDCl3 with PPh3 + SnX2 has been explored to establish the factors that influence the nature of the products. With the mononuclear precursors the course of the reaction is strongly dependent on the tripodal or linear arrangement of the polydentate ligand and in the former case on the halogen. Thus, while for chlorides (1a-2a, 7a-8a) and bromides (3a-4a) the reaction led to the trigonal-bipyramidal compounds [M(SnCl3)(AP3)][SnCl3] [A = P: M = Pd(1), Pt(2); A = N: M = Pd(7), Pt(8)], [MBr(PP3)][SnBr3] [M = Pd(4), Pt(6)] containing M-Sn and M-Br bonds, respectively, for iodides (5a-6a) resulted in the unknown neutral square-planar compounds [MI2(PP(PO)2)(SnI2)2] [M = Pd(9) and Pt(10)] bearing two dangling P=O-SnI2 units and P2MI2 environments. However, complexes of the type [PtCl(PP2PO)X]X' [X = SnCl2, X' = [SnCl3](-)(11)] and [M(PP(PO)2)2X4]X'2 [X = SnCl2, X' = [SnCl3](-): M = Pd(12), Pt(13)] showing P=O-SnCl2 arms were obtained by direct reaction of [PtCl(PP2PO)]Cl (11a) and [M(PP(PO)2)2]Cl2 [M = Pd(12a), Pt(13a)] with SnCl2 in CH3OH. Although complex 9 was also prepared by interaction of the heteronuclear iodide 9a with PPh3 + SnI2 in CDCl3, the use of the neutral and ionic heteronuclear chlorides and bromides (14a-18a) as starting materials afforded the distorted square-planar ionic systems [MAuX'(PP3)(PPh3)][SnX3]2 [M = Pd: X = Cl, X' = SnCl3(-)(14); X = Br, X' = SnBr3(-)(15); M = Pt: X = Cl, X' = SnCl3(-)(17); X = Br, X' = SnBr3(-)(18)] containing M-SnX3 and P-Au-PPh3 functionalities. It was found that these reactions where the heteronuclear species are the precursors proceed via the trigonal-bipyramidal halides not only with X = Cl and Br(1a-4a) but also I(5a). When the precursors were 10a and 10b the reaction occurred with formation of [Pd(PNP)(PPh3)][SnCl3]2 (23) and [Pt(PNP)(PPh3)][SnCl2I]2 (24) showing M-PPh3 units and trihalostannato counter anions.