Structural studies and biological evaluation of Co (II), Ni (II) and Cu (II) complexes of carbohydrazone derived from ethyl acetoacetate in addition to crystallographic description of La (III) or Sm (III) catalytic activity abnormal product

New carbohydrazone ligand derived from the condensation of carbohydrazide and ethyl acetoacetate, diethyl 3,3′‐(carbonylbis (hydrazin‐2‐yl‐1‐ylidene))(3E,3′E)‐dibutyrate (H₄EBC), and its divalent Co, Ni and Cu chelates have been isolated and characterized utilizing convenient methods. ¹H‐NMR spectrum of H₄EBC revealed the abundance of the enol isomer in solution, which was the opposite to what was shown by the solid IR. This was supported by comparing the theoretical IR of both keto and enol forms. In [Ni(H₄EBC)Cl₂(H₂O)]·2H₂O, H₄EBC acts as a neutral NON tridentate ligand via the (C=O)_carbonyl oxygen atom besides the two (C=N)_azomethine nitrogen atoms, while in [Co(H₄EBC)Cl₂(2H₂O)]·2H₂O, H₄EBC behaves as a neutral NN bidentate ligand through the two azomethine groups. Magnetic measurements inherent to their electronic spectra show that both Ni (II) and Co (II) chelates have octahedron coordination frameworks. On the other hand, the ligand behaves as a binegative tetradentate in [Cu₂(H₄EBC)Cl₂]·H₂O via the deprotonated (C=O)_carbonyl groups of the ethyl acetoacetate framework and the two (C=N)_azomethine groups. In the latter complex, the carbonyl group of the carbohydrazide moiety is converted to hydroxyl group. Cu (II) complex has a tetrahedral geometry according to ESR and electronic spectral data. The reaction of H₄EBC with SmCl₃·6H₂O or LnCl₃·7H₂O gave single crystals of abnormal product (C₁₆H₁₆N₄O₄). The packing diagram of this crystal has a chain structure. The photoluminescence spectra of [Cu ₂ (H ₄ EBC)Cl ₂ ]·H ₂ O , [Co(H ₄ EBC)Cl ₂ (H ₂ O) ₂ ]·2H ₂ O and [Ni(H ₄ EBC)Cl ₂ (H ₂ O)]·2H ₂ O display emission broad‐bands at 342, 321 and 337 nm, respectively. The microbial behavior of the synthesized moieties was investigated against various bacterial and fungal strains. [Cu₂(H₄EBC)Cl₂]·H₂O complex shows the same activity as ampicillin towards Escherichia coli and Staphylococcus aureus with inhibition zones of 26 and 22 mm, respectively. Antioxidant activity is determined using bleomycin‐dependent DNA damage assay besides erythrocyte hemolysis. Finally, in vitro cytotoxic activities against two different cell lines have been examined.     

Self-assembled macrocyclic molecular squares of Ni(II) derived from carbohydrazones and thiocarbohydrazones: Structural and magnetic studies

Four novel molecular square grids were achieved by self-assembly using the flexible ligands bis(di-2-pyridyl ketone) thiocarbohydrazone (H₂L¹), bis(quinoline-2-carbaldehyde) thiocarbohydrazone (H₂L²), bis(di-2-pyridyl ketone) carbohydrazone (H₂L³) and bis(2-benzoylpyridine) carbohydrazone (H₂L⁴). Three complexes were given a general formula of [Ni(HL)]₄[PF₆]₄ · nH₂O and one [Ni₂(HL²)L²]₂(PF₆)₂ · 7H₂O. The MALDI-MS spectra reveal the formation of tetranuclear molecular squares. The square grid of the Ni(II) centers in all the complexes were organized by deprotonated ligands. The complex [Ni(HL¹)]₄[PF₆]₄ · 11H₂O crystallized as [Ni(HL¹)]₄(PF₆)₄ · 0.5 CH₃CH₂OH · 2.8H₂O and X-ray study revealed octahedral geometries around the Ni(II) centers. Variable temperature magnetic studies suggest intramolecular antiferromagnetic coupling between the Ni(II) electrons by a super exchange mechanism through intervening sulfur/oxygen atoms.     

Synthesis and Spectral Studies of Bisthiocarbohydrazone and Biscarbohydrazone of Quinoline-2-carbaldehyde: Crystal Structure of Bis(quinoline-2-aldehyde) Thiocarbohydrazone

Abstract Two new ligands, having flexible coordination ability, 1,5-bis(quinoline-2-carbaldehyde) thiocarbohydrazone and 1,5-bis(quinoline-2-carbaldehyde) carbohydrazone were synthesized and characterized by elemental analysis, IR, and UV spectral studies. The compounds exist in the thione/ketone tautomeric forms, as evidenced by IR spectral data. The structure of bis(quinoline-2-aldehyde) thiocarbohydrazone has been solved by single crystal XRD study. The compound C₂₁H₁₆N₆S crystallizes in triclinic form with two independent molecules in the asymmetric unit, space group , Z = 4, V = 1856.1(6) ?³ with unit cell parameters a = 11.331(2) ?, b = 11.714(2) ?, c = 15.116(3) ?, α = 100.369(4)°, β = 109.512(4)° and γ = 90.134(4)°. Both molecules exist in the thione forms and show a Z–Z configuration about both azomethine bonds, with quinoline nitrogens on opposite sides. The N–N, N–C and the C–S bond distances of the thiocarbohydrazide moiety suggest extensive electron delocalization of the whole thiocarbohydrazone moiety. Index Abstract Synthesis and spectral studies of bisthiocarbohydrazone and biscarbohydrazone of quinoline-2-carbaldehyde: Crystal structure of bis(quinoline-2-aldehyde) thiocarbohydrazone, E. Manoj, M. R. Prathapachandra Kurup, E. Suresh. Bis(quinoline-2-aldehyde) thiocarbohydrazone crystallizes in the tricliniccrystal system with two independent molecules in the asymmetric unit, and exists in the thione tautomeric form. Both molecules show a Z-Z configuration about both azomethinebonds, with quinoline nitrogens on opposite sides. The N–N, N–C and the C–S bond distances of the thiocarbohydrazide moiety suggest extensive electron delocalization of the whole thiocarbohydrazone moiety . Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.