Mahmut Ulusoy

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, 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.

The synthesis, electrochemical properties and structural characterization of bis(N-(4-dimethylaminophenyl)-3,5-di-tert- butylsalicylaldiminato)copper(II)

A Cu(II) complex of a Schiff base obtained by the condensation of N,N-dimethyl-1,4-phenylenediamine with 3,5-di-tert-butyl-2-hydroxybenzaldehyde has been synthesized and characterized. The structure of the complex was determined by single-crystal X-ray methods. The four-coordinate Cu(II) ion possesses a compressed tetrahedral coordination environment.

Chemical fixation of CO2 into cyclic carbonates by azo-containing Schiff base metal complexes

Two new ligands containing a –NN– group, 4-((E)-(4-bromophenyl)diazenyl)-2-((E)-(phenylimino)methyl)phenol (L1H, 2), 4-((E)-(4-bromophenyl)diazenyl)-2-((E)-((4-ethylphenyl)imino)methyl)phenol (L2H, 3) and their metal complexes were synthesized. The synthesized metal complexes were used as catalysts for the chemical fixation of CO2 into cyclic carbonates using epoxides which were used as both substrate and solvent. According to analytical, UV-visible and IR data, the metal complexes are formed by coordination of the N and O atoms of the ligands and the metal : ligand ratio was found to be 1 : 2 for all the complexes. The TG and DTA results showed that these complexes had good thermal stability. The molecular structures of ligand 2 (L1H) and its ZnII complex 4 (Zn(L1)2) were determined by single crystal X-ray diffraction studies. After choosing the most active catalyst (Zn(L1)2, 4), optimization studies were performed by changing various parameters. Ionic liquids have been found to have a positive effect and showed the most active performance with (bmim)PF6 + Zn(L1)2 (4) as a binary catalytic system.

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).

The synthesis, characterization, and electrochemistry of molecular cobaloxime/organocobaloxime: catalysts for cycloaddition of carbon dioxide and epoxides

The new cobaloxime (1), organocobaloxime (2), and their intramolecular hydrogen (O–H⋯O) bridges replaced by Cu(II)-containing multinuclear cobaloximes (3–10) were synthesized and characterized by elemental analysis, 1H and 13C NMR spectra, FT-IR spectra, UV–vis spectra, LC-MS spectra, molar conductivity measurements, melting point measurements, and magnetic susceptibility measurements. Their electrochemical properties were investigated using cyclic voltammetric techniques in DMSO solution. The cobaloxime or organocobaloxime (1, 2) were used as precursors, replacing intramolecular O–H⋯O bridges, forming multinuclear complexes (3–10). Then, these compounds were used as homogeneous catalysts for cyclic carbonate synthesis from carbon dioxide (CO2) and epoxides. In the catalytic experiments, dimethyl amino pyridine (DMAP) was used as co-catalyst, since DMAP was a more active base with higher yield compared to other Lewis bases. It is not necessary to use solvent according to catalytic test results, important in green chemistry. Graphical Abstract In this paper, the new cobaloxime (1), organocobaloxime (2) and multinuclear cobaloximes (3–10) were synthesized and characterized. These compounds were used as homogeneous catalysts for cyclic carbonate synthesis from carbon dioxide (CO2) and epoxides.

Synthesis of the Multinuclear Cobaloxime Complexes via Click Chemistry as Catalysts for the Formation of Cyclic Carbonates from Carbon Dioxide and Epoxides

AbstractIn this study, the structurally similar multinuclear cobaloxime complexes based on dioxime ligands were synthesized and characterized as trinuclear complexes with respect to varied axial groups. The multinuclear cobaloxime complexes were characterized by 1H, 13C-NMR, FT-IR, UV-Vis, LC-MS spectra, melting point and magnetic susceptibility measurements. These multinuclear cobaloxime complexes have been successfully applied to the synthesis of cyclic carbonates from CO2 and epoxides under optimized conditions and without using any solvent. All multinuclear cobaloxime complexes obtained by click chemistry are good catalysts for the cycloaddition of CO2 to different epoxides in the presence of pyridine as a co-catalyst. Additionally, the effects of epoxides, bases, temperature, pressure, and time on the yield of cyclic carbonates were investigated. Graphical AbstractIn this study, multinuclear cobaloxime complexes based on dioxime ligands were synthesized and characterized by 1H and 13C-NMR spectra, FT-IR spectra, UV-Vis spectra, LC-MS spectra, melting point measurements and magnetic susceptibility measurements. The multinuclear cobaloxime complexes are good catalysts for the cycloaddition of CO2 to different epoxides in the presence of pyridine as a co-catalyst.

1-(4-Fluoro-benz-yl)-2-(pyridin-2-yl)-1H-benzimidazole.

In the title compound, C19H14FN3, the dihedral angles between the benzimidazole unit (r.m.s. deviation= 0.017 Å) and the pyridine and benzene rings are 24.46 (4) and 81.87 (3)°, respectively. In the crystal, molecules are stacked along the a-axis direction by C—H⋯π interactions.

Conversion of CO 2 into cyclic carbonates in the presence of metal complexes as catalysts

The sterically hindered salicylaldimine ligands N,N‘-(1,5-diaminonaphthalene)-3,5-but2-salicylaldimine (L1), N,N‘-(2,7-diaminofluaren)-3,5-but2-salicylaldimine (L2) and N,N‘-(1,8-diaminonaphthaline)-3,5-but2-salicylaldimine (L3) have been synthesised by the condensation of 1,5-diaminonaphthalene, 2,7-diaminofluarene, and 1,8-diaminonaphthaline with 3,5-di-tert-butylsalicylaldehyde, respectively. Dinuclear M(II) complexes of L1 and L2 and mononuclear M(II) complexes of L3 have been prepared using Cu(II), Ni(II), Co(II), and Mn(II) salts and characterised. The synthesised sterically-hindered, salen-type complexes were tested as catalysts for the formation of cyclic carbonates from CO2 and liquid epoxides (propylene oxide, epichlorohydrine, 1,2-epoxybutane and styrene oxide), which served as both reactant and solvent. Ligand structure and the type of metal centre have a marked influence on the catalytic activity. Mn(II) complexes showed the highest catalytic activity.

Bis{μ-2,4-di-tert-butyl-6-[3-(1H-imidazol-1-yl)propyl-imino-meth-yl]phenolato}bis-[acetatocopper(II)].

In the centrosymmetric title compound, [Cu2(C21H30N3O)2(C2H3O2)2], each Cu atom has a distorted tetrahedral coordination geometry defined by N and O atoms in a chelate ring, N of an imidazole ring, and an acetate O atom. The uncoordinated acetate O atom is disordered over two sites with occupancies 0.7:0.3.