Structural Variation and Magneto-Structural Correlation in Two New Dinuclear Bis(µ2-Phenoxo)-Bridged CuII Schiff-Base Complexes: Catalytic Potential for the Peroxidative Oxidation of Cycloalkanes

2010 ◽  
Vol 63 (3) ◽  
pp. 479 ◽  
Author(s):  
Subhra Basak ◽  
Soma Sen ◽  
Partha Roy ◽  
Carlos J. Gómez-García ◽  
David L. Hughes ◽  
...  
Keyword(s):  
Schiff Base ◽  
Exchange Interactions ◽  
Coupling Constants ◽  
Schiff Base Complexes ◽  
Schiff Base Ligands ◽  
Paramagnetic Resonance ◽  
Catalytic Potential ◽  
Elemental Analyses ◽  
Distorted Trigonal Bipyramid ◽  
Electron Paramagnetic

Two new dinuclear bis(μ2-phenoxo)-bridged copper(ii) complexes [Cu(NCS)L1]2 (1) and [Cu(NCS)L2]2 (2) have been synthesized using two tridentate NNO-donor Schiff-base ligands, L1H (Me2N(CH2)3N=CHC6H3(OMe)(OH)) and L2H (Me2N(CH2)3N=C(CH3)C6H4(OH)), respectively. They have been characterized by elemental analyses, IR, UV-visible, and electron paramagnetic resonance (EPR) spectroscopy, cyclic voltammetry, and magnetic susceptibility measurements. X-Ray single-crystal structures reveal a central Cu2O2 core in each complex with an isothiocyanate ligand coordinated terminally to each metal centre. The coordination environments around the CuII ions in 1 and 2 are a distorted trigonal bipyramid and a quasi-regular square pyramid, respectively, with significant differences in the Cu–O–Cu bridging angles (100.22(5)° for 1 and 95.64(7)° for 2). Although both CuII dimers present intradimer antiferromagnetic exchange interactions, the magnitudes of the coupling constants in 1 and 2 (J = –119(1) and –0.361(3) cm–1, respectively) are quite different as a result of the different coordination geometries and Cu–O–Cu bridging angles. Both complexes act as promising catalysts or catalyst precursors for the efficient peroxidative oxidation of cycloalkanes (cyclohexane and cycloheptane) to the corresponding cyclic alcohols and ketones, with maximum overall yields of 53% and 56% for 1 and 2, respectively.

Spectroscopic and Magnetic Properties of Gadolinium Macroacyclic and Macrobicyclic Complexes

2007 ◽  
Vol 128 ◽  
pp. 199-205
Author(s):  
G. Leniec ◽  
Slawomir M. Kaczmarek ◽  
J. Typek ◽  
Beata Kołodziej ◽  
Eugeniusz Grech ◽  
...  
Keyword(s):  
Schiff Base ◽  
Metal Ion ◽  
Molecular Spectroscopy ◽  
Schiff Base Complex ◽  
Schiff Base Complexes ◽  
Magnetic Interactions ◽  
Paramagnetic Resonance ◽  
Complex Samples ◽  
Integrated Intensity ◽  
Electron Paramagnetic

As a result of the Schiff base condensation the gadolinium macroacyclic and macrobicyclic Schiff base complexes have been synthesized and investigated by infrared spectroscopy (IR) and electron paramagnetic resonance (EPR). Both electron ionization and electron spray Molecular Spectroscopy spectra confirmed the [1:1] proportion of a ligand to metal in gadolinium macrocyclic and mocrobicyclic Schiff base complex samples. The thermogravimetrydifferential thermal analysis (TG-DTA) indicated the presence of two water molecules in the innersphere of the macrobicyclic complex and confirmed no water coordination of the metal ion in the macroacyclic complex. The temperature dependence of the integrated intensity of the EPR spectra enabled the magnetic interactions in the spin system of these compounds to be revealed.

Preparation, characterization, and biologic evaluation of copper(II) – Schiff base complexes derived from anthranilic acid and aldoses

1993 ◽  
Vol 71 (5) ◽  
pp. 629-633 ◽  
Author(s):  
Mohammad S. Iqbal ◽  
Syed J. Khurshid ◽  
Mohammad Z. Iqbal
Keyword(s):  
Schiff Base ◽  
Anthranilic Acid ◽  
Spectroscopic Data ◽  
Spectral Lines ◽  
Schiff Base Complexes ◽  
Paramagnetic Resonance ◽  
Paw Oedema ◽  
Square Planar ◽  
Rhombic Distortion ◽  
Electron Paramagnetic

Cu(II) – Schiff base complexes containing anthranilic acid and aldoses (sugars) as part of the base were prepared and characterized by microanalytical, thermogravimetric, magnetic, and spectroscopic data. The complexes are four-coordinate, anhydrous, and ML2 type. The electron paramagnetic resonance spectral lines exhibited rhombic distortion from axial symmetry in the square-planar Cu(II) complexes with [Formula: see text] The complexes were found to be active against kaolin paw oedema and standard strains of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa.

scholarly journals Efficient Catalytic Reduction of 4-Nitrophenol Using Copper(II) Complexes with N,O-Chelating Schiff Base Ligands

Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 5876
Author(s):  
Hassan Wafi Garba ◽  
Muhammad Sabiu Abdullahi ◽  
Mohamad Shazwan Shah Jamil ◽  
Nor Azam Endot
Keyword(s):  
Schiff Base ◽  
Catalytic Activity ◽  
Catalytic Reduction ◽  
Schiff Base Ligands ◽  
Paramagnetic Resonance ◽  
Nitrophenol Reduction ◽  
Ft Ir ◽  
Uv Visible ◽  
Electron Paramagnetic ◽  
Excellent Reproducibility

The reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride was used as a model to test the catalytic activity of copper(II) complexes containing N,O-chelating Schiff base ligands. In this study, a series of copper(II) complexes containing respective Schiff base ligands, N′-salicylidene-2-aminophenol (1), N′-salicylidene-2-aminothiazole (2), and N,N′-bis(salicylidene)-o-phenylenediamine (3), were synthesized and characterized by elemental analysis, Fourier transform infrared (FT-IR), and UV-Visible (UV-Vis) and electron paramagnetic resonance (EPR) spectroscopies. The results from the 4-nitrophenol reduction showed that 3 has the highest catalytic activities with 97.5% conversion, followed by 2 and 1 with 95.2% and 90.8% conversions, respectively. The optimization of the catalyst amount revealed that 1.0 mol% of the catalyst was the most optimized amount with the highest conversion compared to the other doses, 0.5 mol% and 1.5 mol%. Recyclability and reproducibility tests confirmed that all three complexes were active, efficient, and possess excellent reproducibility with consistent catalytic performances and could be used again without a major decrease in the catalytic activity.

Electronic Structure of Pseudotetrahedral Copper(II) Schiff Base Complexes

1977 ◽  
Vol 32 (5) ◽  
pp. 551-561 ◽  
Author(s):  
John R. Wasson ◽  
H. Wayne Richardson ◽  
William E. Hatfield
Keyword(s):  
Electronic Structure ◽  
Schiff Base ◽  
Schiff Bases ◽  
Opposite Direction ◽  
Hyperfine Coupling ◽  
Coupling Constants ◽  
Schiff Base Complexes ◽  
Hyperfine Coupling Constants ◽  
Structure Correlations

Copper(II) complexes with the Schiff bases formed by condensing t-butyl-, isopropyl-, cyclohexyl- and diphenylmethylamines with salicylaldehyde and 3-methoxy- and 5-nitrosalicyl-aldehyde have been prepared and characterized. The isotropic nuclear hyperfine coupling constants increase in the order t-butyl < isopropyl < cyclohexyl < diphenylmethyl for the N-substituents in the three series of complexes while isotropic g-values increased in the opposite direction. Spectra structure correlations were examined and discussed.

scholarly journals Synthesis , Spectroscopic and Antibacterial Studies of Zinc(II) Complexes Derived from Salicylaldehyde, Leucylalanine and Glycylglycine

2012 ◽  
Vol 9 (3) ◽  
pp. 532-540 ◽  
Author(s):  
Baghdad Science Journal
Keyword(s):  
Schiff Base ◽  
Bacterial Species ◽  
Conductivity Measurement ◽  
Growth Inhibitor ◽  
Molar Conductance ◽  
Diffusion Method ◽  
Schiff Base Ligands ◽  
Elemental Analyses ◽  
L1 And L2

Two Schiff base ligands L1 and L2 have been obtained by condensation of salicylaldehyde respectively with leucylalanine and glycylglycine then their complexes with Zn(II)were prepared and characterized by elemental analyses , conductivity measurement , IR and UV-Vis .The molar conductance measurement indicated that the Zn(II) complexes are 1:1 non-electrolytes. The IR data demonstrated that the tetradentate binding of the ligands L1 and L2 . The in vitro biological screening effect of the investigated compounds have been tested against the bacterial species Staphlococcus aureus, Escherichia coil , Klebsiella pneumaniae, Proteus vulgaris and Pseudomonas aeruginosa by the disc diffusion method . A comparative study of inhibition values of the Schiff base ligands and their complexes indicated that the complexes exhibit higher antimicrobial activity than the free ligands . Zinc ions are proven to be essential for the growth-inhibitor effect. The extent of inhibition appeared to be strongly dependent on the initial cell density and on the growth medium .

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