Manganese,cobalt and nickel complexes with a novel 17-membered macrocycle containing an N5 donor set

Summary The synthesis of a new macrocycle containing phenanthroline and pyridine subunits is described. The reaction of 2,9-bis(hydrazone)-1,10-phenanthroline with 2,6-bis-(bromomethyl) pyridine in the presence of Mn^II, Co^II or Ni^II ion templates leads to the isolation, in high yield, of the seven-coordinate complexes [M(L³)Br₂] (L³ = 4,5, 6,7,8,9-phenanthrolino-14,15,16-pyridino-1,2,5,8,11,12,15 heptaazacycloheptadecane,2,10-diene). The compounds were characterized by physical measurements, which indicated that in all the complexes the ligand is acting as a pentadentate N₅ chelating agent.     

Two polymorphs of bis(2‐bromophenyl) di­sulfide

Colourless crystals of the title compound, bis(2‐bromo­phenyl) di­sulfide, C₁₂H₈Br₂S₂, are obtained from the reaction of 2‐bromo­phenyl­mercaptan with metallic sodium and either zinc chloride or cadmium chloride in methanol. In the presence of Zn^II ions, the crystals are orthorhombic (space group Pbca, with Z′ = 1); with Cd^II ions present, the product is triclinic (space group , with Z′ = 4). Both polymorphs exhibit significant intramolecular C—H⋯S hydrogen bonds. In the ortho­rhombic form, mol­ecules are linked by intermolecular C—H⋯Br hydrogen bonds, while in the triclinic form, mol­ecules exhibit Br⋯Br contacts.     

Crystal Structure and Superoxide Dismutase Activity of [Cu(ethylenediamine)<Subscript>2</Subscript>Cl][PF<Subscript>6</Subscript>]

Summary. The preparation, spectroscopic properties, and crystal structure of chlorobis(ethylenediamine)copper(II) hexafluorophosphate [Cu(en)₂Cl][PF₆], (en=ethylendiamine) are reported. The complex crystallizes in the monoclinic system, space group P2₁/c, with cell constants a=6.1488(9) Å, b=12.696(2) Å, c=17.7424(17) Å, =97.265(12)°, and Z=4. The copper(II) ion is coordinated to two bidentate en molecules, to one chlorine ion, and to a more distant fluorine atom of the PF₆ group, leaving the copper ion in a distorted octahedral coordination geometry. The superoxide dismutase mimetic activity of the complex was investigated using the indirect xanthine-xanthine oxidase- nitroblue tetrazolium method and compared to that of the native enzyme.     

Potential constants and Coriolis coupling constants of perhalogenated ethylenes: Part 2. cis-ClFC=CFCl, cis-ClBrC=CBrCl and cis-FBrC=CBrF

Potential energy constants and Coriolis coupling constants, calculated for cis-dichlorodifluoroethylene, cis-dichloro-dibromoethylene and cis-difluorodibromoethylene, reproduced the vibrational frequencies and fulfilled the sum rules respectively. Inertial defect calculated values for the ground vibrational state of these molecules show good correspondence with the reported values for similar ethylene-type molecules.     

Synthesis of transition metal complexes containing a Schiff base ligand derived from 1,10-phenanthroline-2,9-dicarboxaldehyde and 2-aminobenzenethiol

The synthesis of a new Schiff base containing 1,10-phenanthroline-2,9-dicarboxaldehyde and 2-aminobenzenethiol subunits is described. The reaction of 1,10-phenanthroline-2,9-dicarboxaldehyde with 2-aminobenzenethiol leads to the isolation of 2,9-bis(2-benzothiazolinyl)-1,10-phenanthroline (I) which undergoes rearrangement when reacted with cobalt, nickel, copper or zinc ions to produce complexes of the tautomeric Schiff base 2,9-bis[2-(2-mercaptophenyl)-2-azaethene]-1,10-phenanthroline (L). The [Cu(L)ClO₄][ClO₄] and [M(L)X₂] complexes (where M = Co(II), Ni(II) and Zn(II) and X = Br) were characterized by physical and spectroscopic measurements which indicated that the ligand is acting probably as a tetradentate N₄ chelating agent.     

Crystal structure of the first SH-containing tetrahedral cobalt(II) complex, [Co(quinoline)2(SH)2]. Superoxide dismutase activity

The preparation, spectroscopic properties and crystal structure of the bis-quinoline–bis-mercaptocobalt(II) complex [Co(quinoline)₂(SH)₂] are reported. The complex is tetrahedral with nitrogen donor atoms from two quinoline ligands and sulphur donor atoms from two mercapto groups. The superoxide dismutase mimetic activity of the complex was investigated using the indirect xanthine–xanthine oxidase–nitroblue tetrazolium method and compared to that of the native enzyme.     

Synthesis and antibacterial activity of metal complexes of cefazolin

Cefazolin (Hcefaz) interacts with transition metal(II) ions to give [M(cefaz)Cl] complexes (M = Mn^II, Co^II, Ni^II, Cu^II, Zn^II, Pd^II) and [Ag₂(cefaz)₂Cl₂] which were characterized by physicochemical and spectroscopic methods. Their i.r. and the ¹H-n.m.r. spectra suggest that cefazolin behaves as a monoanionic tetradentate ligand. The complexes have been screened for antibacterial activity and the results are compared with the activity of cefazolin.     

Preparation and electrochemical study of manganese(II) macrocycles containing terpyridine

The macrocycle, L, prepared by template condensation of bis-6,6-(-methylhydrazino)-4-phenyl-2,2:6,2-terpyridine with glyoxal, forms a stable crystalline Mn^II complex, [Mn(L)(H₂O)₂][PF₆]₂, which has been used as a starting material for electrochemical studies on a series of seven coordinate Mn^II complexes [Mn(L)X₂]²⁺ (X = pyridine, 4-cyanopyridine, 4-aminopyridine, 4-dimethylaminopyridine, pyrazine, imidazole 1-methylimidazole, 2-dimethylimidazole or Ph₃P). Cyclic voltammetry of the complexes in MeCN shows a reversible one electron reduction wave in the range –1.32 to –1.42 V versus the Ag/AgBF₄ reference electrode.     

Potential constants and Coriolis coupling constants of perhalogenated ethylenes: Part 3. trans-ClFC=CFCl, trans-ClBrC=CBrCl and trans-FBrC=CBrF

Based on vibrational frequencies a calculation of a general quadratic force field has been carried out for trans-ClFC=CFCl, trans-ClBrC=CBrCl and trans-FBrC=CBrF via an iterative method. The resulting transformation L matrices were used to evaluate the Coriolis coupling constants and these were used to calculate inertial defects. The calculated values of the inertial defects are lower than those of the respective cis-ethylene-type molecules.     

Synthesis,characterization, density functional theory calculations,and in vitro antibacterial activity of novel transition metal complexes containing an O3-tridentate amoxicillin-based Schiff base: A silver(II) complex as alternative against Pseudomonas aeruginosa resistant to amoxicillin

Transition metal complexes containing an amoxicillin-based Schiff base (H₂L, 3 ) obtained from the condensation of amoxicillin 1 with salicylaldehyde 2 were prepared. Spectroscopic and physicochemical techniques, namely, UV–visible, Fourier-transform infrared spectroscopy, ¹H NMR, electron paramagnetic resonance, transmission electron microscopy, mass spectrometry, magnetic susceptibility, molar conductance, density functional theory (DFT) calculations, together with elemental and thermal analyses were used to characterize the synthesized complexes. Based on these studies, the general formulae [ML(H₂O)₃], where M = Mn 4 , Ni 5 , Zn 6 , and [ML(H₂O)], where M = Cu 7 , Ag 8 , were proposed for the complexes. The amoxicillin-based Schiff base ligand behaved as a dianionic O₃-tridentate chelating agent. DFT studies and magnetic and spectral data revealed octahedral geometries for Mn, Ni, and Zn atoms and distorted tetrahedral geometries for Cu(II) and Ag(II) complexes. Synthesized compounds were tested for antibacterial activity by both agar disk diffusion method and the minimum inhibitory concentration. in vitro bacterial viability revealed that complex 5 had similar antibacterial activity as 1 against Staphylococcus aureus and Staphylococcus epidermidis, whereas Pseudomonas aeruginosa, resistant to amoxicillin, was sensitive to complex 8 . The antibacterial activity of complex 8 could be attributed to its greater catalytic activity as shown by DFT calculations. Toxicity bioassay of the tested compounds showed LC₅₀ values > 1000 ppm, indicating their nontoxicity against brine shrimp nauplii (Artemia salina).