Formation constants and thermodynamic parameters of α-pyridoin thiosemicarbazones with divalent metal ions

The proton–ligand stability constants of -pyridoin thiosemicarbazone, -pyridoin 2–methylthiosemicarbazone, -pyridoin 4–methylthiosemicarbazone and -pyridoin (4–phenylthiosemicarbazone) as well as the formation constants of their chelates with CuII, NiII, CoII, ZnII and MnII have been determined. The Calvin–Bjerrum pH titration techniques, as modified by Irving and Rossotti, were employed in aqueous media at different ionic strengths and temperatures. The stability constants of the complexes follow the order: CuII > NiII > CoII > ZnII >MnII which is in accord with the Irving–Williams series. The chelates derived from -pyridoin 4–phenylthiosemicarbazone have relatively higher stability constants, which may be attributed to the presence of the benzene ring in the chain.     

Synthesis, crystal structure and luminescent property of the novel μ-thiocyanato-bis[(2-acetylpyridinethiosemicabazonato)(thiocyanate)] cadmium(II) complex

A dinuclear cadmium(II) complex, containing 2-acetylpyridinethiosemicarbazone (Hatsc) and thiocyanate ligands of general formula Cd₂(SCN)[L(SCN)₂] (L = Hatsc), has been prepared and characterized by elemental analysis, IR and single crystal X-ray diffraction methods. The crystal structure determination reveals the formation of a one dimensional chain in this complex. The photophysical properties have been investigated and two emission peaks at 468 and 510 nm observed for the title complex in the solid state.     

Copper(II) malonate coordination frameworks with amino-1,2,4-triazole: Crystal structures and magnetic properties of [Cu2(mal)2(datz)2(H2O)]·5H2O and [Cu2(mal)2(atz)2(H2O)]·3H2O

Two new malonato-bridged copper(II) complexes of the composition [Cu₂(mal)₂(datz)₂(H₂O)]·5H₂O (1) and [Cu₂(mal)₂(atz)₂(H₂O)]·3H₂O (2) (mal = malonate, atz = 4-amino-1,2,4-triazole, datz = 3,5-diamino-1,2,4-triazole) are prepared and characterized by X-ray crystal structure determination and magnetic studies. The environment of each copper atom in 1 and 2 has distorted square pyramidal and octahedral geometries. The intrachain copper-copper separation is 6.305 Å and 3.640 Å across the carboxylates and trizolates bridges respectively for complexes 1 and 2. The magnetic properties of 1 and 2 are investigated in the temperature range 2–300 K. The overall antiferromagnetic behavior is observed in both cases.     

Antimicrobial activities of 1-phenyl-3-methyl-4-trichloroacetyl-pyrazolone: Experimental,DFT studies,and molecular docking investigation

The rate of bacterial resistance to antibiotics is faster than the rate of discovery of new antibiotic classes. However, development of novel compounds with similar behavior but with a better therapeutic action has posed a serious challenge to researchers. Therefore, discovering of new novel drugs is of great importance in combating health problems and improving the quality of human life. In this research, first principle density functional theory (DFT) along with molecular docking approach were utilized for the investigation of 1-phenyl-3-methyl-4-trichloroacetyl-pyrazolone-5 (HTcP) to address some factors that are linked to this phenomenon. The theoretical computations were carried out utilizing the Becke-3-Parameter-hybrid model of Lee-Yang-Parr (B3LYP) with the 6-31+G (d, p) basis set. The most active site of the studied compound was studied within the framework of molecular electrostatic potential (ESP) meanwhile the strength and nature of the bond was studied using quantum theory of atoms in molecules (QTAIM). The antibacterial activities of the title structure was tested in this study using three proteins, 4YNT, 4YNU, and 5UZ9, with the help of Bio – via discovery studio and Auto dock vina tool via molecular docking simulations. The compound had a higher binding energy with the 4YNT and 4YNU proteins (?7.7 kcal/mol). Also controlled model was used in the docking analysis which shows no much significant different between the modelled structure and the commercial drug Kanamycin. In addition, a computer simulation was used to predict the absorption, distribution, metabolism, excretion, and toxicity profiles of the compound under investigation (ADMET). The result obtained from the ADMET studies indicated that the structure under study has moderate antibacterial activities.     

Di‐μ‐acetato‐bis­[(2‐acetyl­pyridine thio­semicarbazonato)zinc(II)]

The title compound, [Zn₂(C₂H₃O₂)₂(C₈H₉N₄S)₂], is a centrosymmetric dinuclear mol­ecule with two acetate bridging ligands in a syn–syn arrangement. The Zn^II atom is five‐coordinated in a trigonal–bipyramidal configuration by three thio­semicarbazone atoms (two N and one S) and by an O atom from each of the two acetate groups.     

Studies on the stereochemistry of diphenyl diketone monothio-semicarbazone and its transition metal complexes

Summary The stereochemistry and complexation behaviour of diphenyl diketone monothiosemicarbazone (DKTS) with Cu^II, Co^II, Ni^II, Cd^II, Zn^II, Pd^II, Pt^II, Ru^III, Rh^III and Ir^III have been investigated by means of chemical, magnetic and spectral (i.r., Raman, ¹H- and ¹³C-n.m.r. and electronic) studies. The ligand forms complexes of the M(DKTS)₂ type with Ni^II, Cu^II and Co^II having a distorted octahedral geometry. The absence of a v(M—X) band in the i.r. spectra, coupled with their 1:1 electrolytic conductances, suggests that Ru^III, Rh^III and Ir^III form octahedral complexes of the [M(DKTS)₂]Cl type. A four-coordinate structure involving bridging halides is proposed for the Zn^II, Cd^II, Pd^II and Pt^II complexes, which have relatively low v(M—X) vibration modes.     

Stereochemistry and antitumour activity of platinum metal complexes of 2-acetylpyridine thiosemicarbazones

Complexes, [M(HL)2], where M = PdII, PtII and HL = neutral 2-acetylpyridine-(2-methylthiosemicarbazone), 2-acetylpyridine-(4-methylthiosemicarbazone) and 2-acetylpyridine-(4-phenylthiosemicarbazone), as well as [M(HL)2]Cl3, where M = RuIII, RhIII and IrIII, have been prepared and characterized by elemental analyses, conductivity measurements, magnetic susceptibility measurements and spectroscopic (i.r., Raman, u.v.-vis. and 1H and 13C-n.m.r) studies. The ligands behave as neutral bidentate components in the PdII and PtII complexes, whereas in RuIII, RhIII and IrIII complexes the ligands exist as neutral tridentates. Various ligand and nephelauxetic parameters have been calculated for the metal complexes. The RuIII, RhIII and IrIII complexes are six-coordinate distorted octahedral, whereas PdII and PtII are four coordinated. The ligands and their platinum group complexes exhibit a potent cytotoxic activity against Ehrlich ascites tumour cells in vitro but appear to be more in vivo.     

Synthesis,spectral and cytotoxicity studies of palladium(II) and platinum(II) amino acid Schiff base complexes

Novel Pd^II and Pt^II complexes of substituted o-hydroxyacetophenone-glycine have been synthesized, and characterized by conductivity measurements, i.r., electronic and ¹H-n.m.r. spectra. The spectral data indicate that the ligands are monobasic bidentate, coordinating through imino nitrogen and the carboxylate group. A four coordinate square planar configuration has been proposed for all the complexes. The ligands, as well as their Pd^II and Pt^II complexes, exhibit potent cytotoxic activity against Ehrlich ascites tumour cells in vitro, but appear to be more active in vivo. This revised version was published online in June 2006 with corrections to the Cover Date.