Dejan Jeremić

Synthesis and characterization of new Pt(II) and Pd(II) complexes with 2-quinolinecarboxaldehyde selenosemicarbazone: Cytotoxic activity evaluation of Cd(II), Zn(II), Ni(II), Pt(II) and Pd(II) complexes with heteroaromatic selenosemicarbazones

New complexes of Pt(II) and Pd(II) with 2-quinolinecarboxaldehyde selenosemicarbazone were synthesized and characterized by elemental analysis, NMR and IR spectroscopy and molar conductivity measurements. The assumed geometry of Pt(II) and Pd(II) complexes was square planar where the ligand was tridentately coordinated via the quinoline and imine nitrogen atoms and the selenium atom. The cytotoxic activity of the new Pt(II) and Pd(II) compounds, as well as of some previously synthesized Cd(II), Zn(II) and Ni(II) complexes with the same or analogous ligand, was tested against a panel of three human cancer cell lines: human cervix carcinoma cells (HeLa), human melanoma cells (FemX) and breast cancer cells (MDA-361). All investigated compounds, except Pt(II) complex, possess a strong dose-dependent cytotoxic activity of the same order of magnitude as cisplatin (CDDP). The investigation of potential of these compounds to induce HeLa cell cycle perturbations was also evaluated.

An Fe(III) Complex with the Dianionic form of 2,6-Diacetylpyridine Bis(Acylhydrazone). The Crystal Structure of [Diaqua-2′,2′′′-(2,6-PyridinediyldiEthylidyne)Dioxamohydrazide]Iron(III) Perchlorate Trihydrate, [Fe(dapsox)(H2O)2]ClO4·3H2O

The title compound was prepared by a template synthesis from 2,6-diacetylpyridine, dioxamohydrazide and Fe(ClO4)3·6H2O(mol ratio 1:2:1) in MeOH/H2O(3:1) solution and its structure determined by single-crystal X-ray diffraction; triclinic, space group P1, a = 7.5186(7), b = 10.9730(9), c = 14.6110(10) Å, α = 95.866(1), β = 100.252(1), γ = 92.895(1), z = 2. The polydentate ligand is coordinated as a dianionic pentadentate while water molecules occupy apical positions in the structure. This is the first example of a monomeric, pentagonal bipyramidal structure of an Fe(III) complex with a dianionic bis(acylhydrazone) derivative of 2,6-diacetylpyridine.

Synthesis and structural characterization of copper(II) complexes with the 2′-[1-(2-pyridinyl)ethylidene]oxalohydrazide ligand

The octahedral copper(II) complex with two 2′-[1-(2-pyridinyl)ethylidene]oxalohydrazide molecules was synthesized from bis(acetylacetonato)copper(II) and 2′-[1-(2-pyridinyl)ethylidene]oxamohydrazide (Hapsox). The complex is unstable when not in solution. X-ray analysis confirmed the tridentate coordination of the ligands in the monoanionic form. In addition, the stable tetrahedral copper(II) complex with one ligand molecule coordinated as a tridentate in the dianionic form was prepared by direct synthesis from Cu(NO3)2·3H2O and Hapsox, and characterized by elemental analysis, magnetic measurements and by i.r. and u.v./vis. spectrophotometry.

Synthesis and Structural Characterization of the Co(III) Complex with 2'-[1-(2-Pyridinyl)-Ethylidene]-Oxamohydrazide (Hapsox): The Crystal Structure of Bis-{2'-[1-(2-Pyridinyl)-Ethylidene]-Oxamohydrazido} Cobalt(III) Perchlorate, [Co(apsox)2]ClO4

The synthesis of a novel ligand 2′-[1-(2-pyridinyl)-ethylidene]-oxamohydrazide (Hapsox), from a series of 2-acetylpyridine acylhydrazones, and its complex with Co(III), which is the first in this series of complexes are described. Both the ligand and the complex were characterized by elemental analysis, IR, 1H-NMR, and 13C-NMR spectra, and the structure of the complex [Co(apsox)2]ClO4 was determined by X-ray structural analysis. It was established that [Co(apsox)2]ClO4 has an octahedral geometry with two tridentate apsox ligands in monoanionic form. Structural characteristics, lengths of the bonds, and angles between the bonds were typical for Co(III) complexes of distorted octahedral geometry. Both direct and template synthesis afforded the same geometrical isomer of the complex with two apsox ligands meridionally bound to the central metal ion, even in the case when equimolar quantities of Co(ClO4)2 and Hapsox were applied.

Synthesis, Characterization and Biological Activity Evaluation of Novel Pd(II) and Pt(II) Complexes with Heterocyclic Hydrazone Ligands

New complexes of Pt(II) with condensation derivatives of ethyl hydrazinoacetate and either 2-acetylpyridine or 2-quinolinecarboxaldehyde, and of Pd(II) with the condensation derivative of ethyl hydrazinoacetate and 2-quinolinecarboxaldehyde were synthesized and characterized by elemental analysis, IR, 1H- and 13C-NMR spectroscopy, and molar conductivity measurements. The complexes have a square planar geometry, ligands binding as bidentates in the neutral form, and the remaining two coordination sites being occupied by chloride ions. Biological activity of new complexes, and of previously synthesized Pd(II), Cd(II), Co(III) and Zn(II) complexes with this ligand type was evaluated by the brine shrimp test. All the complexes showed a moderate activity.

Hexaaqua­magnesium(II) bis­(d-camphor-10-sulfonate)

The structure of the title complex, [Mg(H2O)6](C10H15O4S)2, consists of regular octahedral [Mg(H2O)6]2+ cations and d-camphor-10-sulfonate anions. A three-dimensional supramolecular architecture is formed via hydrogen-bond interactions [O—H⋯O = 2.723 (2)–2.833 (2) Å] to give alternating layers of [Mg(H2O)6]2+ cations and d-camphor-10-sulfonate anions. The title compound is isomorphous with the zinc, copper, cadmium and nickel analogues.

Tetraaquabis(D-camphor-10-sulfonato)calcium(II).

The structure of the title compound, [Ca(C(10)H(15)O(4)S)(2)(H(2)O)(4)], is the first example in which two D-camphor-10-sulfonate anions are coordinated to a metal ion, in this case with direct Ca-O bonding. The molecule has crystallographically imposed twofold symmetry with the Ca atom on the twofold axis. Hydrogen bonds are formed between the coordinated water molecules and the O atoms of the SO(3)(-) groups of adjacent molecules, leading to the formation of a two-dimensional layered network. The compound displays sharp wavelength-selective transparency in the UV-visible spectrum, offering the potential for application as an optical filter.

Investigation of Thermal Stability of Zn(II), Pt(II) and Pd(II) Complexes with (E)-2-oxo-2-{N'-[1-(pyridin-2-yl)ethylidene]hydrazino}acetamide

Thermal stability of neutral Zn(II), Pd(II) and Pt(II) complexes of formulae [Zn(apsox)2]·3H2O and [M(apsox)Cl] (M=Pd(II), Pt(II), HL=(E)-2-oxo-2-{N ’-[1-(pyridin-2- yl)ethylidene]hydrazino}acetamide) were studied. The results of DSC and TG analyses within the temperature range from 20 to 600 °C in nitrogen atmosphere showed that the loss of crystal water represents the first step during decomposition of the octahedral Zn(II) complex followed by structural rearrangement of its anhydrous form. After that the complex remained stable to about 330 °C. Different from neutral square-planar Pd(II) and Pt(II) complexes, a satisfactory resolution of the peaks in DSC of the Zn(II) complex enabled determination of the activation energies of its structural transformation and thermal degradation.