Esref Tas

Preparation, characterisation and redox properties of four new tetradentate salicylaldimines with their Cu(II) complexes

Some new tetradentate salicylaldimine ligands of Schiff bases were synthesised by treating 3,5-di-tert-butyl-2-hydroxybenzaldehyde with 1,2-bis-(o-aminophenoxy)ethane, 1,4-bis-(o-aminophenoxy)butane, 1,4-bis-(m-aminophenoxy)buthane and 1,4-bis-(p-aminophenoxy)butane. The compounds were characterised by IR, UV-vis, 1H NMR, 13C NMR, magnetic susceptibility measurements, elemental analysis, molar conductance (ΛM), thermogravimetric analysis (TGA) and cyclic voltammetry. The metal to ligand ratios of the Cu(II) complexes were found to be 1:1. The coordination of the novel tetradentate salicylaldimines appears to occur through the two azomethine nitrogens and two o-OH groups. Cyclic voltammetric studies showed that all of the Cu(II) complexes undergo quasi reversible one-electron transfer redox processes attributed the Cu(II)/Cu(I) couples in dimethylsufoxide. The electron donor affinity of copper(II) complexes increases in order Cu(L4)>Cu(L3)>Cu(L2)>Cu(L1).

Electrical and optical properties of newly synthesized glyoxime complexes

Abstract In this study, the electrical and optical properties of newly prepared Ni(L 1 H 2 ) and Ni(L 2 H 2 ) complexes have been investigated and the results obtained were analyzed. It is seen that these complexes have inorganic semiconductor properties. The activation energies ( E a ) for the complexes were calculated by using Arrhenius plots and their optical band gaps have been determined through the optical spectra. Thermal probe measurements indicated that these samples have n -type of electrical conductivity.

Solid state electrical conductivity properties of copper complexes of novel oxime compounds containing oxolane ring

Abstract In this study, a novel dioxime having the 1,3-oxolane group, 1,2-dihydroxyimino-3,7-diaza-9,10-O-cyclohexylidenedecane (L1H2) and 9,10,bis(hydroxyimino)-4-8,11,15-tetraaza-1,2,17,18-O-dibenzaloctadecane (L2H2), were synthesised from 1,2-O-benzal-4-aza-7-aminoheptane, which was prepared from a reaction of 1-choloro-2,3-O-benzalpropane and dichlorogloxime. The electrical properties of complexes of those ligands with Cu(II) salts were investigated and obtained results were analyzed. It was seen that these complexes had semiconducting properties. The activation energies (Ea) were calculated for the complexes by using the Arrhenius plot. Thermal probe measurement indicated that these complexes had an n-type electrical conductivity.

Synthesis, spectral characterization and electrochemical studies of copper(II) and cobalt(II) complexes with novel tetradentate salicylaldimines

Several new complexes of Schiff bases obtained by the condensation of 1,2-bis(p-aminophenoxy)ethane and 1,2-bis(m-aminophenoxy)ethane with 3,5-di-tert-butyl-2-hydroxybenzaldehyde have been synthesized, and characterized by elemental analyses, FT-IR, UV–VIS, 1H NMR spectroscopy, magnetic susceptibility measurements and cyclic voltammetry. The metal to ligand ratios of the Co(II) and Cu(II) complexes were found to be 1 : 1. The coordination of the Schiff base appears to occur through the two azomethine nitrogens and two o-OH groups. Electrochemical data suggest the existence of copper(II)/copper(I) and cobalt(II)/cobalt(I) redox couples in DMSO along with an irreversible oxidation peak assigned to the oxidation of ligands for all of the complexes.

Synthesis, spectroscopic and electrochemical studies of copper(II) and cobalt(II) complexes of three unsymmetrical vic -dioximes ligands

Cobalt(II) and copper(II) complexes with three dioxime ligands cyclohexylamine-p-tolylglyoxime (L1H2), tert-butyl amine-p-tolylglioxime (L2H2) and sec-butylamine-p-tolylglyoxime (L3H2), have been prepared. The metal to ligand ratios of the complexes were found to be 1 : 2. The Cu(II) complexes of these ligands are proposed to be square planar; the Co(II) complexes are proposed to be octahedral with water molecules as axial ligands. Ligands and complexes are soluble in common solvents such as DMSO, DMF, CHCl3 and C2H5OH. The ligands have been characterized by elemental analysis, IR, UV-VIS, 1H NMR, 13C NMR and thermogravimetric analysis (TGA). The complexes were characterized by elemental analysis, IR, UV-VIS, magnetic susceptibility measurements, thermogravimetric analysis (TGA) and electrochemistry. Electrochemical properties of metal complexes show quasi-reversible one-electron redox processes. However, Co(L1H)2 and Cu(L1H)2 complexes show another oxidation peak in the positive region. This single irreversible oxidation peak is caused by the cyclic ring of the ligand. Data also revealed that the electron transfer rates of metal complexes with L1H2 are higher than the other complexes.

Transition metal complexes with tridentate salicylaldimine derived from 3,5-di-t-butylsalicylaldehyde

Several new binuclear CuII, NiII, OVIV and MnII complexes of tridentate salicylaldimine (H2L), obtained from 3,5-di-t-butylsalicylaldehyde and o-aminophenol, have been prepared and characterized by analytical, spectroscopic (i.r., u.v.–vis., e.s.r.) techniques, magnetic and thermal measurements. The adduct formation or dissociation of these complexes in the presence of strongly coordinating solvents like pyridine and DMSO did not take place. The complexation of CoII with H2L is accompanied by intramolecular electron transfer from the metal to the coordinated ligand yielding the radical ligand CoIII complex (g = 2.003, ACo = 10 G). The e.s.r. spectra of the CuII, OVIV and MnII complexes in the solid state and in solution are very broad due to intramolecular dipolar antiferromagnetic interactions.

Synthesis, characterization and electrochemical properties of copper(II) complexes with novel bidentate salicylaldimines derived from 3,5-di-t-butyl-2-hydroxybenzaldehyde

Mononuclear copper(II) complexes of novel bidentate salicylaldimines (L x H) have been synthesized by the addition of Cu(Ac)2·2H2O to a mixture of 3,5-di-t-butyl-2-hydroxybenzaldehyde (3,5-DTB) and biologically active amines, 4-(3-aminopropyl)morpholine, 1-(3-aminopropyl)-2-pyrrolidinone and 1-(3-aminopropyl)-2-methylpiperidine. In this study N-[1-(3-aminopropyl)imidazole]-3,5-di-t-butylsalicylaldimine (L1H) was synthesized by reaction of 3,5-DTB and 1-(3-aminopropyl)imidazole followed by complexation with copper(II). The complexes were characterized by FTIR, UV–VIS, ESR, MS, 1H and 13C NMR spectroscopy, magnetic susceptibility measurements and thermogravimetric analysis (TGA) and also by electrochemistry. The room-temperature powder ESR spectra of these complexes are similar and exhibit axially symmetric g-tensor parameters with g ‖ > g ⊥ > g e suggesting that the copper(II) atom has a ground state characteristic of square-planar or square-pyramidal stereochemistry. Thermal analysis indicated that Cu(L3)2 had the highest thermal stability of the complexes and Cu(L2)2 the lowest. Cyclic voltammetric experiments showed that all of the Cu(II) complexes underwent one-electron transfer, mainly diffusion controlled, as indicated by the dependence of the peak current on the square root of the scan rate.

Preparation and spectral characterization of new macrocyclic Ni(II) and Co(II) complexes derived from 1,4- bis (2-carboxyaldehydephenoxy)butane and various diamines

Six new macrocyclic complexes were synthesized by the template effect from reaction of 1,4-bis(2-carboxyaldehydephenoxy)butane, Ni(NO3)2 · 6H2O or Co(NO3)2 · 6H2O and various diamines. The metal-to-ligand ratios of Ni(II) or Co(II) metal complexes were found to be 1 : 1. Coordination of the Schiff base to Ni(II) and Co(II) through the two nitrogen and two oxygen atom (ONNO) are expected to reduce the electron density in the azomethine link and hydroxyl group. The Ni(II) and Co(II) complexes are proposed to be tetrahedral and are 1 : 2 electrolytes as shown by their molar conductivities (ΛM) in DMF (dimethyl formamide) at 10−3 M. The structures are proposed from elemental analysis, FT-IR, UV-VIS, magnetic susceptibility measurements, molar conductivity measurements, and mass spectra.

The synthesis, spectroscopic and voltametric studies of new metal complexes containing three different vic-dioximes

The synthesis, spectroscopic, and redox properties of some metal complexes with three novel vic-dioxime ligands, N-(1-(2-aminoethyl)piperazine)-phenylglyoxime (L1H2), N-(1-(2-aminoethyl)piperazine)-glyoxime (L2H2), and N,N′-bis(1-(2-aminoethyl)piperazine)-glyoxime (L3H2)], prepared from different glyoxime and 1-(2-aminoethyl)piperazine are reported. The structure of these vic-dioximes have been determined as the anti-form according to 1H NMR, 13C NMR, and FT-IR data. The metal to ligand ratios of Co(II), Ni(II), and Cu(II) complexes were found to be 1 : 2. The Cu(II) complexes of these ligands are proposed to be square planar and Ni(II) complexes of these ligands are proposed to be square planar or octahedral, while the Co(II) complexes are proposed to be octahedral with water molecules as axial ligands. Ni(II), Co(II), and Cu(II) metal complexes are non-electrolytes as shown by their molar conductivities (ΛM) in DMF (dimethyl formamide) at 10−3 M. The structure of ligands and their complexes is proposed from elemental analysis, FT-IR, UV-VIS, 1H NMR, 13C NMR, magnetic susceptibility measurements, and molar conductivity measurements. The cyclic voltammetric measurements of the mononuclear complexes provide an understanding of the electrochemical behaviour of the reduced or oxidized species in DMSO solution.

Synthesis of a Novel Oxime Ligand: Characterization and Investigation of Its Complexes with Some Metal Ions

Abstract A novel dioxime, 1,2‐dihydroxyimino‐3‐aza‐6‐morpholine heptane (H2L) was synthesized by the reaction of anti‐monochloroglyoxime and 4‐(3‐aminopropyl)morpholine in absolute THF. Mononuclear complexes with a metal:ligand ratio of 1:2 were prepared with Co(II), Cu(II), and Ni(II). The ligand and complexes were characterized by elemental analyses, FT‐IR, UV‐Vis, 1H NMR and 13C NMR spectra, magnetic susceptibility measurements. The thermal behavior of the compounds has been studied by thermogravimetry (TGA).