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Many Schiff bases prepared from 2-hydrazinobenzothiazole and isatin have been used to produce Co (II) complexes of the form [ML 2 ]Cl 2. Nitrogen from azomethine, oxygen from lactonyl, and nitrogen atoms of the thiazole ring contribute to coordinating the metallic ion. Complexes made entirely of metal have geometrical octahedrons, according to analytical, magnetic studies and spectroscopic (Infrared, Ultraviolet-Visible, ESR, FAB-mass) investigations. The conductivity measurements show the electrolytic behaviour of the metal complexes. The redox behaviour of the metal complexes is investigated using cyclic voltammetry. The antibacterial and antifungal activities of the Schiff bases and their metal complexes were examined using the Minimum Inhibitory Concentration method against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and S. typhi. Investigations into DNA cleavage were conducted using the agarose gel electrophoresis technique, and significant DNA cleavage was found. [ABSTRACT FROM AUTHOR]

Copper(II) complexes with Schiff bases derived from linear and branched amines with 2-hydroxy-1-naphthaldehyde and 3-hydroxy-2-naphthaldehyde were synthesized and characterized by IR and electronic spectroscopies, magnetic susceptibilities, electrochemistry, cyclic voltammetry (CV), X-ray diffraction, and theoretical calculations. Electronic spectra are a function of the R group on the imine nitrogen of the ligand that determines steric effects. Complexes obtained from 3-hydroxy-2-naphthaldehyde ligand are more distorted from planarity in dimethylformamide solutions than those of 2-hydroxy-1-naphthaldehyde for the same R group. As a result, the former are easier to reduce to the related copper(I) complexes than those of 2-hydroxy-1-naphthaldiminate. The structure of bis(N-i-propyl-3-hydroxy-2-naphthaldiminato)copper(II) was determined by single-crystal X-ray diffraction. Its molecular structure can be described as distorted flat tetrahedral influenced by important packing effects and is flatter than that calculated with density functional theory methods. Additional related flat tetrahedral complexes were studied by theoretical calculations and it has been found that electronic effects also play a significant role. [ABSTRACT FROM AUTHOR]

A successful preparation of a Schiff base copper complex was carried out directly in rap oil, using a W/O microemulsion reactor. The prepared Schiff base copper complex dispersed equably and spontaneously in the oil. Owing to a modification of the rap oil, by addition of 2%wt of Cu (II) chelate of bissalicylaldehyde-ethylenediamine, the friction coefficient decreased by 80% compared to that of the original one. It was verified by energy dispersive spectroscopy (EDS) and x-ray photoelectron spectroscopy (XPS) analyses that steel/steel rubbing pairs underwent a selective transferring process with such modified lubricants. It was suggested that the mechanism for the improvement in the tribological characteristics of the modified lubricants was due to a selective transferring effect. The Cu (II) chelate of bissalicylaldehyde-ethylenediamine not only served as an additive in the rap oil, but also self-assembled on the surface of the 100Cr6 steel. The self-assembled monolayer (SAM) was examined using SEM techniques. The SAM was characterized with cyclic voltammetry (CV). It indicated that the SAM could activate the rubbing surface of 100Cr6 steel, which benefited the tribological chemical reaction. [ABSTRACT FROM PUBLISHER]

A new series of acyclic mononuclear copper(II) complexes have been prepared by Schiff-base condensation derived from 5-methylsalicylaldehyde, diethylenetriamine, tris(2-aminoethyl) amine, triethylenetetramine, N,N-bis(3-aminopropyl)ethylene diamine, N,N-bis(aminopropyl) piperazine, and copper perchlorate. All the complexes were characterized by elemental and spectral analyses. Electronic spectra of the complexes show a d-d transition in the range 500-800 nm, electrochemical studies of the complexes show irreversible one-electron-reduction process around -1.10 to -1.60 V. The reduction potential of the mononuclear copper(II) complexes shifts toward anodic direction upon increasing the chain length of the imine compartment. ESR spectra of the mononuclear copper(II) complexes show four lines, characteristic of square-planar geometry, with nuclear hyperfine spin 3/2. The copper(II) complexes show a normal room temperature magnetic moment value μeff = 1.72-1.76 BM, close to the spin-only value of 1.73 BM. Electrochemical and catalytic studies of the complexes were compared on the basis of increasing the chain length of the imine compartment. All the complexes were screened for antifungal and antibacterial activities. [ABSTRACT FROM AUTHOR]

A series of Co(II), Ni(II), and Cu(II) complexes of the type ML.2H2O have been synthesized with Schiff bases derived from 8-formyl-7-hydroxy-4-methylcoumarin and o-phenylenediamine/ethylenediamine. The structure of the complexes has been proposed in the light of analytical, spectral (IR, UV-Vis, ESR, and FAB-mass), magnetic, thermal, and fluorescence studies. The complexes are soluble in DMF and DMSO. The measured molar conductance values indicate that the complexes are non-electrolytes in nature. In view of IR, UV-Vis, and magnetic studies, it has been concluded that all the complexes possess octahedral geometry, in which ligand is coordinated to metal ion through the azomethine nitrogen and phenolic oxygen via deprotonation. Thermal studies provide useful information about the coordination of water molecules to the metal ion and the stability of the complexes. The redox behavior of the complexes has been investigated by an electrochemical method using cyclic voltammetry. The Schiff bases and their metal complexes have been screened for their antibacterial ( Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella typhi) and antifungal activities ( Aspergillus niger, Aspergillus flavus, and Cladosporium) by the minimum inhibitory concentration method. DNA binding with Co(II) and Cu(II) complexes has been studied by the agarose gel electrophoresis method. [ABSTRACT FROM AUTHOR]

A new Schiff base ligand (KH2L) was synthesized using potassium salt of glycine and 2,4-dihydroxybenzaldehyde. A binuclear complex of this ligand [Cu2 (HL)2] 2H2O was synthesized and characterized by elemental analyses, IR, UV, TG-DTG, and molar conductance. The fundamental electrochemical characteristics of the Cu(II) complex have been studied, and the interaction of the copper complex and DNA was also studied by cyclic voltammetry and fluorescence spectra. The results of the cyclic voltammetry showed that the Cu(II) complex had an oxidation peak with the oxidation potential at -0.345 V. After the DNA was added, the peak current declined with the peak potential shifting positively. This suggested that the complex combined with DNA in the form of intercalative binding, which was also proved by the fluorescence analysis. [ABSTRACT FROM AUTHOR]