Nickel (II) complexes of naphthaquinone thiosemicarbazone and semicarbazone: synthesis, structure, spectroscopy, and biological activity.

Ni(II) complexes of ortho-naphthaquinone thiosemicarbazone and semicarbazone were synthesized and spectroscopically characterized. The X-ray crystal structure of both the complexes describe a distorted octahedral coordination with two tridentate mono-deprotonated ligands. In vitro anticancer studies on MCF-7 human breast cancer cells reveal that the semicarbazone derivative along with its nickel complex is more active in the inhibition of cell proliferation than the thiosemicarbazone analogue.

Molybdenum(VI) Peroxo alpha-Amino Acid Complexes: Synthesis, Spectra, and Properties of MoO(O(2))(2)(alpha-aa)(H(2)O) for alpha-aa = Glycine, Alanine, Proline, Valine, Leucine, Serine, Asparagine, Glutamine, and Glutamic Acid. X-ray Crystal Structures of the Glycine, Alanine, and Proline Compounds.

The compounds MoO(O(2))(2)(alpha-aa)(H(2)O), alpha-aa = glycine (1), alanine (2), proline (3), valine (4), leucine (5), serine (6), asparagine (7), glutamine (8), and glutamic acid (9), were prepared from the acidic aqueous solutions and characterized by examination of their IR, (1)H and (13)C NMR, and UV-visible spectra. They represent the first complexes containing a peroxo-alpha-amino acid combination in a metal ion ligand sphere. The synthesis and crystallization of these complexes was pH and concentration dependent, and their stability varied for different alpha-amino acids. X-ray structural studies of 1-3 have shown that the alpha-amino acids are coordinated as a zwitterion via one oxygen. This oxygen of the monodentate carboxylato group occupies an equatorial position in a distorted pentagonal bipyramid and encloses the pentagonal ring with the two bidentate peroxo groups. The apical positions are occupied by an oxo group and a water molecule, respectively. The Mo-O(O(2)) bonds are nonsymmetrical, differing in length by 0.009-0.045 Å. The longer bonds are located next to the coordinated carboxylato oxygen. A correlation between O-O and Mo-O bond lengths with the IR and UV-visible spectra of complexes 1-3 is discussed. Crystal structure of MoO(O(2))(2)(alanine)(H(2)O): monoclinic, space group P2(1)/c; Z = 4; a = 10.727(3) Å; b = 8.026(2) Å; c = 10.794(4) Å; beta = 110.81(2) degrees; V = 869 (Å)(3); R = 0.041. (1)H and (13)C NMR spectra in D(2)O solutions showed the presence of one complex species, which decomposed by standing in solution. Analogies and differences between Mo(VI) and V(V) peroxo complexes are outlined.

Transition metal complexes of phenanthrenequinone thiosemicarbazone as potential anticancer agents: synthesis, structure, spectroscopy, electrochemistry and in vitro anticancer activity against human breast cancer cell-line, T47D.

The thiosemicarbazone derivative of 9,10-phenanthrenequinone, 1, and its metal complexes were synthesized. The X-ray crystal structure for 1 confirms the presence of the E tautomeric arrangement in this compound. Its copper complex shows 1:1 stoichiometry while nickel and cobalt compounds show 1:2 stoichiometry. The X-ray crystal structure of the nickel complex indicates two tridentate ligands coordinating in the thiolato form yielding an octahedral geometry for the 'mer' isomer. The copper complex exhibits maximum antiproliferative activity against human breast cancer cell-line, T47D probably due to inhibition of steroid binding to the cognitive receptor or by preventing dimerization of the estrogen receptor.

Antitumor metallothiosemicarbazonates: structure and antitumor activity of palladium complex of phenanthrenequinone thiosemicarbazone.

The crystal structure of the potential antitumor metal compound, viz. chloro, mono(phenanthrenequinone thiosemicarbazonato) palladium(II) dimethyl formamide solvate, is reported. The central palladium(II) atom is in a square planar environment provided by the tridentate, monoanionic thiosemicarbazone ligand and the ancillary chloride ion. The compound exhibited remarkable activity against drug-sensitive and drug-resistant breast cancer cell lines and was relatively nontoxic toward the normal mammary epithelial cells. The drug-induced killing effect against breast cancer cell lines was predominantly mediated via apoptosis, a physiologic form of cell death.

Structural study of the thermal and photochemical spin states in the spin crossover complex [Fe(phen)2(NCSe)2].

The first structural data for [Fe(phen)(2)(NCSe)(2)] (obtained using the extraction method of sample preparation) in its high-spin, low-spin and LIESST induced metastable high-spin states have been recorded using synchrotron radiation single crystal diffraction. The space group for all of the spin states was found to be Pbcn. On cooling from the high-spin state (HS-1) at 292 K through the spin crossover at about 235 K to the low-spin state at 100 K (LS-1) the iron coordination environment changed to a more regular octahedral geometry and the Fe-N bond lengths decreased by 0.216 and 0.196 A (Fe-N(phen)) and 0.147 A (Fe-N(CSe)). When the low-spin state was illuminated with visible light at about 26 K, the structure of this LIESST induced metastable high-spin state (HS-2) was very similar to that of HS-1 with regards to the Fe-phen bond lengths, but there were some differences in the bond lengths in the Fe-NCSe unit between HS-1 and HS-2. When HS-2 was warmed in the dark to 50 K, the resultant low-spin state (LS-2) had an essentially identical structure to LS-1. In all spin states, all of the shortest intermolecular contacts (in terms of van der Waals radii) involved the NCSe ligand, which may be important in describing the cooperativity in the solid state. The quality of the samples was confirmed by magnetic susceptibility and IR measurements.