Spectroscopic studies on copper(II) complexes derived from a substituted 2-acetylpyridine thiosemicarbazone

Structure and anticancer activity of Cu(II) complexes with (bromophenyl)thiourea moiety attached to the polycyclic imide

A series of nine copper complexes were synthesized by reacting 1,3-disubstituted thioureas with copper(II) chloride. The new compounds were characterized by elemental analysis, infrared, ultraviolet-visible and X-ray absorption spectroscopies as well as molecular modelling. The molecular structure of complexes in the solid state consists of two thiourea ligands chelated to the Cu(II) ion through the S and deprotonated N atoms (CuN₂S₂). The coordination polyhedron of metal cation in powdered samples exhibits two different geometries. Pseudo-tetrahedral structure is observed for noncentrosymmetric complexes with cis-N₂S₂ arrangement around Cu(II). A distorted square planar geometry is characteristic for centrosymmetric compounds with trans arrangements of chelating atoms around the central ion. All complexes after dissolving in dimethyl sulfoxide adopt a centrosymmetric coordination, while after diluting this solution with water, the reorganization of atoms around the metal cation is observed, leading to the formation of a tetrahedral compounds. Initial ligands and Cu(II) complexes were evaluated for their cytotoxicity. Two complexes with 4- and 3-bromophenyl attached to the (1,7,8,9,10-pentamethyl-3,5-dioxo-4-azatricyclo[5.2.1.0^2,6]dec-8-en-4-yl)thiourea moiety (Cu1, Cu3) are cytotoxic against SW480 and PC3 cells (IC₅₀ 4-19 μm), and non-cytotoxic against HaCaT cells (IC₅₀ ≥ 84 μm), being more selective than doxorubicin and cisplatin used as references. The compounds induced apoptosis in cancer cells, however, Cu3 was estimated to be highly active inducer of late apoptosis in SW480 and PC3 cells at lower toxicity against normal cells. The likely mechanism of action of complexes is correlated with decreasing release of IL-6 in cancer cell lines.

Binuclear copper(II), cobalt(II) and nickel(II) complexes of N1-ethyl-N2-(pyridin-2-yl) hydrazine-1,2-bis(carbothioamide): structural, spectral, pH-metric and biological studies

Binuclear Cu(II), Co(II) and Ni(II) complexes derived from N(1)-ethyl-N(2)-(pyridin-2-yl) hydrazine-1,2-bis(carbothioamide) (H(2)PET) have been prepared and characterized by elemental analysis, spectral (IR, UV-vis, EI mass, ESR and (1)HNMR) and magnetic measurements. The isolated complexes assigned the general formula, [M(HPET)(H(2)O)(n)Cl](2)·xH(2)O where M=Cu(II), Co(II) and Ni(II), n=2, 1, 0 and x=0, 0.5 and 0, respectively. IR data revealed that the ligand behaves as monobasic tridentate through (CN)(py), (C-S) and new azomethine, (NC)(∗) groups in the Co(II) complex but in Cu(II) complex, the ligand coordinate via both (CS) groups, one of them in thiol form as well as the new azomethine group. In Ni(II) complex, H(2)PET acts as NSNS monobasic tetradente via (CN)(py), (C-S), (CS) and the new azomethine, (NC)(∗) groups. An octahedral geometry is proposed for all complexes. pH- metric titration was carried out in 50% dioxane-water mixture at 298, 308 and 318 °K, respectively and the dissociation constant of the ligand as well as the stability constants of its complexes were evaluated. Also the kinetic and thermodynamic parameters for the different thermal decomposition steps of the complexes were determined by Coats-Redfern and Horowitz-Metzger methods. Moreover, the anti-oxidant, anti-hemolytic, and cytotoxic activities of the compounds have been tested.

Synthesis, Characterization and In Vitro Antibacterial Studies of Organotin(IV) Complexes with 2-Hydroxyacetophenone-2-methylphenylthiosemicarbazone (H(2)dampt)

Five new organotin(IV) complexes of 2-hydroxyacetophenone-2-methylphenylthiosemicarbazone [H₂dampt, (1)] with formula [RSnCl_n-1(dampt)] (where R = Me, n = 2 (2); R = Bu, n = 2 (3); R = Ph, n = 2 (4); R = Me₂, n = 1 (5); R = Ph₂, n = 1 (6)) have been synthesized by direct reaction of H₂dampt (1) with organotin(IV) chloride(s) in absolute methanol. The ligand (1) and its organotin(IV) complexes (2–6) were characterized by CHN analyses, molar conductivity, UV-Vis, FT-IR, ¹H, ¹³C, and ¹¹⁹Sn NMR spectral studies. H₂dampt (1) is newly synthesized and has been structurally characterized by X-ray crystallography. Spectroscopic data suggested that H₂dampt (1) is coordinated to the tin(IV) atom through the thiolate-S, azomethine-N, and phenoxide-O atoms; the coordination number of tin is five. The in vitro antibacterial activity has been evaluated against Staphylococcus aureus, Enterobacter aerogenes, Escherichia coli, and Salmonella typhi. The screening results have shown that the organotin(IV) complexes (2–6) have better antibacterial activities and have potential as drugs. Furthermore, it has been shown that diphenyltin(IV) derivative (6) exhibits significantly better activity than the other organotin(IV) derivatives (2–5).

Synthesis and spectral investigations of Mn(II) complexes of pentadentate bis(thiosemicarbazones)

Five Mn(II) complexes of bis(thiosemicarbazones) which are represented as [Mn(H(2)Ac4Ph)Cl(2)] (1), [Mn(Ac4Ph)H(2)O] (2), [Mn(H(2)Ac4Cy)Cl(2)].H(2)O (3), [Mn(H(2)Ac4Et)Cl(2)].3H(2)O (4) and [Mn(H(2)Ac4Et)(OAc)(2)].3H(2)O (5) have been synthesized and characterized by elemental analyses, electronic, infrared and EPR spectral techniques. In all the complexes except [Mn(Ac4Ph)H(2)O], the ligands act as pentadentate neutral molecules and coordinate to Mn(II) ion through two thione sulfur atoms, two azomethine nitrogens and the pyridine nitrogen, suggesting a heptacoordination. While in compound [Mn(Ac4Ph)H(2)O], the dianionic ligand is coordinated to the metal suggesting six coordination in this case. Magnetic studies indicate the high spin state of Mn(II). Conductivity measurements reveal their non-electrolyte nature. EPR studies indicate five g values for [Mn(Ac4Ph)H(2)O] showing zero field splitting.

Synthesis, characterization, molecular modeling and antimicrobial activity of 2-(2-(ethylcarbamothioyl)hydrazinyl)-2-oxo-N-phenylacetamide copper complexes

Six Cu(II) complexes of 2-(2-(ethylcarbamothioyl)hydrazinyl)-2-oxo-N-phenylacetamide (H(3)APET) have been prepared and characterized by elemental analyses, spectral (IR, UV-vis, (1)H NMR and ESR) as well as magnetic and thermal measurements. The data revealed that the ligand acts as ON bidentate, ONS tridentate or ONNS tetradentate forming structure in which each copper atom is a tetrahedral or tetragonal environment. The bond length, bond angle, HOMO, LUMO, dipole moment and charges on the atoms have been calculated to confirm the geometry of the ligand and the investigated complexes. Kinetic parameters were determined for each thermal degradation stage of the Cu(II) complexes using Coats-Redfern and Horowitz-Metzger methods. Moreover, the ligand and its complexes were screened against bacteria Staphylococcus aureus, Escherichia coli, Candida and fungi, Albicans and Aspergillus flavus using the inhibitory zone diameter.

Spectral studies and structure of a 2-hydroxyacetophenone 3-hexamethyleneiminyl thiosemicarbazonate(-2) copper(II) complex containing 1,10-phenanthroline

The spectral studies and structure of a ternary complex of copper(II) with 2-hydroxyacetophenone 3-hexamethyliminylthiosemicarbazonate (L(2-)) and 1,10-phenanthroline (phen) are reported. The thiosemicarbazone binds to the metal as a dianionic ONS-donor (L(2-)) ligand, and forms a complex of the stoichiometry [CuLphen]. The copper(II) complex was characterized by IR and UV/Vis spectroscopies, as well as by solid state room-temperature magnetic susceptibility. Spin Hamiltonian and bonding parameters of the compound are calculated from the EPR spectra. Computer simulation of EPR spectrum in DMF at 77 K aided the calculation of magnetic and bonding parameters of the compound. The structure of the compound is solved by single crystal X-ray diffraction. The geometry around copper is distorted square pyramidal.