Antonis Hatzidimitriou

Synthesis and characterization of new addition compounds of bis(2-hydroxyaryloximato) nickel(II) with α-diimines: Crystal and molecular structure of [Ni(saox)2phen]·H2O

Abstract A series of new addition compounds of bis(2-hydroxyaryloximato) nickel(II), [Ni(ox)2], with an α-diimine (enR), under the general formula [Ni(ox)2enR], were synthesized and characterized. The IR and electronic excitation spectra indicate that the bidentate coordination mode of the ligands consists with the chromophore NiN4O2. The octahedral environment around nickel(II) was confirmed by an X-ray structure analysis of [1,10-phenanthroline-bis(2-hydroxy-benzaldoximato)nickel(II)], [Ni(saox)2phen]·H2O. The equatorial plane, which encompasses the nickel atom, is formed by four nitrogen atoms, two coming from the phenanthroline molecule and two from the two molecules of the 2-hydroxybenzaldoxime (salicylaldoxime). In the apical positions lie the two deprotonated phenolic oxygen atoms of the two salicylaldoxime ligands. The thermal stability and decomposition mode were studied in nitrogen using the technique of thermogravimetry (TG/DTG). Mass spectrometry was also used, and possible fragmentation patterns are given and discussed.

THE CRYSTAL AND MOLECULAR STRUCTURE OF BIS(AQUO)-BIS(2-(METHYLAMINO)PYRIDINE) COPPER(II) DICHLORIDE

Abstract Spectroscopic features of [bis(aquo)bis(2-aminomethylpyridine)copper(II)] dichloride, [Cu (ampy)2(H2O)2]Cl2, are presented and its X-ray crystal structure is described. The IR spectra, ligand field spectra and conductivity measurements confirmed that the chloride anions were not coordinated to the metal ion. The copper(II) cation is coordinated by two water and two bidentate 2-aminomethylpyridine molecules. The chloride anions are rather strongly hydrogen-bonded to two hydrogen atoms of water molecules and two hydrogen atoms of the primary amino group in a distorted tetrahedral arrangement.

Solid and solution behavior of sulphonylurea complexes with ions of IIa group metals. Molecular modeling of K[Zn(ClCH4SO2NCONHC3H7)3] and Action of zinc-sulphonylurea complexes as hypoglycemic agents

Complexes of Zn2+ with deprotonated suphonylurea as ligands have been synthesized and characterized. Deprotonated sulphonylurea act as bidentate ligands using one nitrogen and one oxygen atom (the ureido oxygen) to bind Zn2+ forming K[Zn(suphonylurea)3]. Using the MMX89 program, a model for K[Zn(ClC6H4SO2NCONHC3H7)3] compound is proposed. Conductometric and potentiometric studies in methanol, for d10 metal-sulphonylurea complexes, demonstrated that zinc, cadmium and silver complexes are 1:1 electrolytes and are protonated in the range 4.2-5.6 pH. UV-Vis study shows no interaction between metal and protonated sulphonylureas in methanol solutions. At 7.34 pH the form of Zn complexes which act as a hypoglycemic agent is [ZnL3]-. Test for hypoglycemic activity reduced glycemia to a statistically significant degree compared to the corresponding free ligands.

Cadmium(II) complexes of 5-nitro-salicylaldehyde and α-diimines: synthesis, structure and interaction with calf-thymus DNA

Five Cd(II) complexes with the anion of 5-NO2-salicylaldehydeH (5-NO2-saloH) in the absence or presence of the α-diimine 1,10-phenanthroline (phen), 2,2′-dipyridylamine (dpamH), 2,2′-dipyridine (bipy), or 2,9-dimethyl-1,10-phenanthroline (neoc) were synthesized and characterized as [Cd(5-NO2-salo)2(CH3OH)2] (1), [Cd(5-NO2-salo)2(phen)]·2CH3OH·H2O (2), [Cd(5-NO2-salo)2(dpamΗ)] (3), [Cd3(5-NO2-salo)6(bipy)2] (4), and [Cd(5-NO2-salo)(neoc)(NO3)]2 (5). Based on spectroscopic results (IR, UV, NMR), elemental analysis and conductivity measurements an octahedral geometry around cadmium metal ion is suggested, with the 5-NO2-salicylaldehyde ligand having different coordination modes. The structures determined by X-ray crystallography verified neutral mononuclear 1–3 and trinuclear 4. Simultaneous TG/DTG–DTA technique was used to analyze the thermal behavior of 1, 2, and 3. The complexes bind tightly to calf-thymus DNA mainly by intercalation, as concluded by DNA viscosity measurements and exhibit significant displacement of EB from the EB-DNA complex.

Influence of substituents within bidentate nitrogenous bases on the spectra of mixed-ligand (1,1-dithiolato)copper(II) and nickel(II) chelates

Abstract A series of mixed-ligand copper(II) and nickel(II) chelates, [M(enR)(i-MNT)], containing the dianion of 1,1-dicyano-2,2-ethylenedithiole, (i-MNT)2−, and an N-alkyl substituted 1,2-diaminoethane, enR, were prepared and characterised. From the IR spectra of [M(enR)(i-MNT)] it transpires that the influence of the groups attached to the diamine on group vibrations is not as important as that of substituents linked to the >CC CC

The crystal and molecular structure of [neocuproine-bis(3-thiocyano-2,4-pentanedionato)nickel(II)]

The spectra (IR, electronic) of the addition compound [Ni(NCS-acac)2ncup] (ncup = 3,6-dimethyl-4,5-diazaphenanthrene; NCS-acac− = 3-thiocyano-2,4-pentanedionato anion) were obtained and its crystal and molecular structure were determined by X-ray diffraction studies. The unit cell is monoclinic (space group P21/c) with dimensions a = 11.693(1), b = 16.312(1), c = 14.209(1) A, β = 100.75(2)° and contains four formula units. The chelate rings are essentially planar and although the β-dionato moieties are identical, they form unequal dihedral angles with the plane of the α-diimine. The planes of the virtually linear thiocyano groups and the carbon atom they attach form with the plane of the corresponding β-dionato moieties dihedral angles of 79.9(3) and 96.8(4)°, while the dihedral angle of the thiocyano planes is 59.5(4)°.

Dinuclear copper(I) complexes of N-methylbenzothiazole-2-thione: synthesis, structures, antibacterial activity and DNA interaction

Abstract Three copper(I) halide complexes containing N-methylbenzothiazole-2-thione (mbtt) and triphenylphosphine (PPh3) have been prepared and structurally characterized by X-ray single-crystal analysis. Copper(I) halide precursors [CuΧ(PPh3)]4 (X = Cl, Br, I) react with mbtt in 1 : 4 M ratio to give complexes of formula [CuΧ(mbtt)(PPh3)]2. Hereby, dimerization is achieved in case of copper(I) chloride and bromide via halide bridges, while copper(I) iodide gives the binuclear thione-S-bridged dimer. The new complexes show moderate in vitro antibacterial activity against certain bacterial strains. The interaction of the compounds with calf-thymus DNA was monitored via UV–vis spectroscopy, DNA-viscosity measurements and their competition with ethidium bromide for the DNA intercalation sites studied by fluorescence emission spectroscopy. Intercalation was revealed as the probable mode of binding.

Synthetic investigation, physicochemical characterization and antibacterial evaluation of ternary Bi(III) systems with hydroxycarboxylic acid and aromatic chelator substrates

Due to its physical and chemical properties, bismuth (Bi(III)) is widely used in the treatment of several gastrointestinal and skin diseases, and infections caused by bacteria. Herein, its known antimicrobial potential was taken into consideration in the synthesis of two new hybrid ternary materials of Bi(III) with the physiological α-hydroxycarboxylic glycolic acid and 1,10-phenanthroline (phen), [Bi2(C2H2O3)2(C2H3O3)(NO3)]n. nH2O (1) and [Bi(C12H8N2)(NO3)4](C10H8N4) (2), aiming at improving its antibacterial properties. Their physicochemical characterization was carried out through elemental analysis, FT-IR, atomic absorption spectroscopy, single crystal X-ray diffraction, thermogravimetric analysis (TGA), photoluminescence, and 13C MAS-NMR techniques. The antimicrobial activity of the title complexes was directly linked to Bi(III) coordination environment and the incipient aqueous chemistry. For their antibacterial assessment, minimum inhibitory concentration (MIC), zone of inhibition (ZOI), and bacteriostatic-bacteriocidal activity were determined in various Gram positive (Staphylococcus aureus, Bacillus subtilis and Bacillus cereus) and Gram negative (Escherichia coli and Xanthomonas campestris) bacterial cultures, in reference to a positive control (ampicillin), encompassing further comparisons with literature data. The findings reveal that the new hybrid bismuth materials have significant antimicrobial effects against the employed bacteria. Specifically, 2 exhibits better antimicrobial properties than free Bi(NO3)3 and phen. On the other hand, 1 is bacteriostatic toward four microorganisms except X. campestris, with 2 being bacteriocidal toward four microorganisms except B. cereus. Collectively, the new hybrid, well-defined, and two of the rarely crystallographically characterized Bi(III) materials a) exhibit properties reflecting their physicochemical nature and reactivity, and b) are expected to contribute to the development of efficient metallodrugs against drug-resistant bacterial infections.

Influence of conjugated nitrogenous bases on the spectra and structure of mixed-ligand nickel(II) chelates containing β-diones

The infrared and electronic excitation spectra of a series of new nickel(II) chelates containing anα-diimine (or nitrogenous base, enR) and the anion of aΒ-dione (1,3-ketoenol or 1,3-ketoester,ΒH) were obtained in the solid state and in solution. The composition and the overall structure of the new chelates in the solid state depends on ligand concentration, the substituents within theΒ-dionato moiety and the counterion present. The IR and electronic excitation spectra of [Ni(enR)2Β]NO3 and [Ni(enR)Β(O2NO)] indicate, in conjunction with other physicochemical measurements, bidentate coordination of the ligands, while the spectral shifts reveal replacement of the (O,O′)nitrato group by basic solvents. The existence of the nickel(II) in an octahedral environment is confirmed by an X-ray structure analysis of [Ni(dpamH)2acac]NO3 · CH3OH (monoclinic, space groupP2l/n, a=17.296(1),b=7.462(1),c=21.604(3) å,Β=95.65(1)‡,Z=4, R=0.0534,Rw=0.0600), where dpamH denotes the 2,2′-dipyridylamine.

In vitro structure-specific Zn(II)-induced adipogenesis and structure-function bioreactivity correlations

The advent of Zn(II) metallodrugs in metabolic syndrome pathologies generates a strong challenge toward synthetic endeavors targeting well-defined, atoxic and biologically active binary/ternary species of Zn(II). Proper formulation of that metal ions coordination sphere sets the stage for construction of appropriately configured Schiff ligands based on tromethamine and variably modified vanillin core components. The arising Schiff ligands react with Zn(II) in a defined stoichiometry, thereby delivering new binary Zn(II)-L species with defined physicochemical properties. Analytical (elemental), spectroscopic (FT-IR, Thermogravimetric Analysis) and crystallographic techniques attest to the distinct nature of the derived binary-ternary materials, bearing defined Zn(II):L molecular stoichiometry, variable nuclearity, charge, bulk and balance mix of hydrophilicity-hydrophobicity, thereby providing the physicochemical profile based on which biological studies could ensue. The structurally based selection of species was applied onto in vitro 3T3-L1 cultures, essentially exploring toxicity, migration, morphology, cell differentiation and maturation. The systematic effort toward comparative work on appropriately defined Zn(II) species and insulin in inducing adipogenesis reveals the salient structural features in the Schiff family of ligands configuring Zn(II) so as to promote complex formation sufficient to engage biomolecular targets during the process of initiation and maturation. Molecular targets of importance in adipogenesis were examined under the influence of Zn(II) and their expression levels suggest the structural composition that a Zn(II) ion might have to optimally pursue cell differentiation. Thus, a well-defined selection of binary Zn(II)-L species is tightly associated with the incurred bioactivity, thereby setting the stage for the development of efficient Zn(II) metallodrugs to combat Diabetes mellitus II.