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EN
A series of new ruthenium(II) complexes were synthesized with Schiff bases derived from salicylaldehyde / o-hydroxyacetophenone/ o-vanillin / 2-hydroxy-1-naphthaldehyde with thiosemicarbazide and acetyl furan. They are characterized by elemental analysis, IR, electronic, 1H NMR, 13C NMR and mass spectral studies. The elemental analysis suggests the stoichiometry to be 1:1 (metal:ligand). Four of these complexes were tested for its binding with CT-DNA using absorption spectroscopic studies and two of these complexes exhibit efficient DNA cleavage activity. [...]
EN
Corrosion inhibition performance of mild steel in nitric acid solution containing different concentration of anisalidine derivative Schiff bases viz. N- (4-nitro phenyl) p-anisalidine (SB1), N- (4-chloro phenyl) p-anisalidine (SB2), N- (4-phenyl) p-anisalidine (SB3), N- (4-methoxy phenyl) p-anisalidine (SB4), N- (4-hydroxy phenyl) p-anisalidine (SB5) has been investigated using mass loss, thermometric and potentiostate polarization technique. Inhibition efficiencies of Schiff bases have been evaluated at different acid strength. The inhibition efficiency was found larger than their parent amines. Inhibition efficiencies of synthesized Schiff bases increase with inhibitor concentration. Inhibition efficiency increases up to 98.32% with ansalidine derivative Schiff base.
EN
Two novel complexes, [La(HL)(H2O)2NO3] · NO3 · H2O and [Gd(HL)(H2O)2NO3] · NO3 · H2O, where HL is a Schiff base derived from o-vanillin and lysine, have been synthesized and characterized by elemental analysis, conductivity measurements, IR, 1H NMR and thermogravimetric analyses (TGA). The Schiff base ligand behaves as a tetradentate, coordinating through azomethine nitrogen, phenolic oxygen and two carboxylic oxygen atoms. The interaction of these complexes with calf thymus DNA (CT-DNA) was also investigated by spectrometric titration and viscometric measurements. The faint hypochromism of the complexes in the absorption spectra, the remarkable reduction of fluorescence intensity of ethidium bromide (EB) bound DNA, together with a small decrease in the viscosity of the DNA suggest that a partial intercalation may be the preferred binding mode between these two complexes and DNA. The antibacterial activity testing revealed that the complexes and their precursor Schiff base show a weak to moderate activity against Bacillus subtilis, Staphylococcus aureus and Escherichia coli. [...]
EN
The Mn₂O₃ nanoparticles have been prepared using solid state thermal decomposition of MnL¹ and MnL², L¹=N,N'-bis(2-hydroxy-4-methoxybenzophenone)-1,3-propanediamine and L²=N,N'-bis(2-hydroxy-4-methoxybenzophenone)-1,2-cyclohexanediamine, at 500°C for 3 h and characterized by the Fourier transform infrared spectroscopy, X-ray powder diffraction and scanning electron microscopy. The Fourier transform infrared spectroscopy and X-ray powder diffraction confirm that the formed product at 500°C is Mn₂O₃. The MnL¹ and MnL² complexes were prepared from the one-pot reaction of MnCl₂·H₂O, diamine and 2-hydroxy-4-methoxybenzophenone and characterized by elemental analyses, the Fourier transform infrared spectroscopy and thermogravimetry.
EN
Four Schiff base ligands, salabza-H2 = N,N′-bis(salicylidene)-2-aminobenzylamine, were synthesized by condensation of one mole of 2-aminobenzylamine and two moles of salicylaldehyde and/or two moles of substituted salicylaldehyde (5-OMe, 5-Br, 5-NO2). All the four Schiff bases and their Mn(II), Co(II), Cu(II) and Zn(II) complexes are characterized by UV-Vis, FT-IR, 1H NMR spectroscopy, mass spectrometry and elemental analysis. The formation constants and the Gibbs free energies were measured spectrophotometrically for 1:1 complexes in methanol in constant ionic strength (I = 0.1 mol dm−3 NaClO4) and at 25°C. The data refinement was carried out with the SQUAD program. The trend of formation constants of H2L1 with M(II) follows the order: Mn(II) (3.97) Also, the trend of formation constants of ligand toward a given metal (for example Mn) is as follows: H2L1 (p-OMe) (3.97) > H2L2 (p-H) (3.65) > H2L3 (p-Br) (3.37) > H2L4 (p-NO2) (3.04) [...]
EN
A novel tetradentate N2O2 type Schiff base, synthesized from 1-phenyl-2,3-dimethyl-4-aminopyrazol-5-one(4-aminoantipyrine) and 3-salicylidene-acetylacetone, forms stable complexes with transition metal ions such as CuII, NiII, CoII and ZnII in ethanol. Microanalytical data, magnetic susceptibility, IR, UV-Vis.,1H-NMR, ESR and Mass spectral techniques were used to confirm the structures. Electronic absorption spectra of the complexes suggest a square-planar geometry around the central metal ion. These complexes show higher conductance values, supporting their electrolytic nature. The monomeric nature of the complexes was confirmed from their magnetic susceptibility values. Cyclic voltammogram of the copper(II) and nickel(II) complexes in DMSO solution at 300 K were recorded and the results are discussed. The X-band ESR spectra of the copper complex were recorded and the molecular orbital coefficient values were calculated from the spectra. The in vitro antimicrobial activities of the investigated compounds were tested against bacteria such as Klebsiella pneumoniae, Staphylococcus aureus, Bacillus subtilis and Escherichia coli and fungi like Aspergillus niger and Rhizoctonia bataicola. Most of the metal chelates show higher antimicrobial activity for the above microorganisms than that of the free ligand.
EN
A new Schiff base ligand of 5-bromo-2-hydroxybenzaldehyde S-ethyl-isothiosemicarbazone (H2L) was synthesized and its mixed-ligand Cu(II) complex was also prepared by reaction of Cu(NO3)2·3H2O with H2L and imidazole. Their structures were fully characterized by elemental analysis, FT-IR, molar conductivity and UV-Vis methods. The analytical data suggest that the metal, H2L and imidazole ratios in the Schiff base complex are 1:1:1. Single crystal diffraction was also used to better understand the molecular structure of the Cu(II) complex. The results of physico-chemical analyses of the Schiff base complex reveal the coordination geometry around the central atom is square planar. The H2L ligand (NNO donor) is coordinated to the metal center as a tridentate bionegatively agent. Another position of the square planar geometry is occupied by the imidazole ligand. Furthermore, computational studies of the new complex were performed by carrying out DFT calculations. Geometry optimization and natural band analysis of the complex is discussed in further detail. [...]
EN
Complexes ZnL2 with novel fluorinated benzazines as tridentate ligands (HL = 6,7-difluoroquinoxalinand 6,7-difluoroquinolincarboxalidin-2-aminophenol) have been prepared. The photophisical properties of the ligands and the complexes has been studied.
EN
A binuclear copper complex [{Cu(L)2}2], C68H48Cu2N4O12C (where L is 4-methyl-7-(salicylideneamino)coumarin), has been synthesized and characterized using elemental analysis, molar conductance measurements, and infrared, ultraviolet and ESR spectrosopy. The molecular structure of title compound, determined by single-crystal X-ray diffraction studies, reveals that the two symmetric Cu(L)2 units are associated into a dimer by rather long Cu...O bonds. The Cu(II) ions are bridged via the phenolic oxygen of one of the monomers and have distorted trigonal bipyramidal conformation geometry. Within each monomer the two methylsubstituted coumarin skeletons are trans to one another, but adopt a parallel arrangement with respect to the other monomer. Only half of the complex molecule can be found in the asymmetric unit, Z′ = 0.5, the other half is generated by the symmetry centre. [...]
EN
Two novel Schiff base ligands, 2,2'-((pentane-2,4-diylidene)bis(azanylylidene))bis(4-chlorophenol) and 2,2'-((pentane-2,4-diylidene)bis(azanylylidene))bis(4-methylphenol) were prepared by condensation reaction of acetylacetone with 2-amino-4-chlorophenol and 2-amino-4-methylphenol, respectively. Mononuclear Cu(II) complex of each ligand was also synthesized. These compounds were characterized by elemental analyses, inductively coupled plasma optical emission spectrometry, the Fourier transform infrared spectra, UV-Vis, molar conductivity, and magnetic susceptibility measurements. The ligands have been further characterized by ¹H- and ¹³C-NMR. The results suggest that the metal complexes of the ligands have a metal:ligand ratio of 1:1 and the Cu(II) ions are coordinated by the phenolic oxygen atoms and imine nitrogen atoms of the ligands. Moreover, the quantum chemical calculations of the compounds have been performed using the density functional theory. It has been found that the calculated spectroscopic values are in a good agreement with experimental data.
EN
We have reported herein the synthesis of a novel quinone derivative ligand containing the Schiff base and its Cu(II) complex starting from 1,4-naphthoquinone. Synthesized compounds were characterized using the Fourier transform infrared, UV-Vis, elemental analysis, inductively coupled plasma optical emission spectrometry, molar conductivity, and magnetic susceptibility measurements. The free ligand was also characterized by ¹H- and ¹³C-NMR spectra. Elemental analyses, stoichiometric and spectroscopic data indicated that the metal:ligand ratio is 1:2 and octahedral structure is proposed for the metal complex of the Schiff base ligand. Computational quantum calculations were also performed using DFT/B3LYP level of theory with 6-311++G(d,p) basis set for the synthesized ligand. It was found that the experimental and theoretical spectroscopic data were consistent.
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