Spectra Of Cu Research Articles

Synthesis, Characterization and Electrical conductivities of the Complexes of Nickel(II), Copper(II) and Zinc(II) with 2,5-diamino-3,6-dichloro-1,4-benzoquinone

Complexes of the type [M(dadb)] (M = Ni(II), Cu(II) and Zn(II)) with ligand 2,5-diamino-3,6-dichloro-1,4-benzoquinone (dadb) have been synthesized and characterized by microanalysis, magnectic susceptibility, electronic, IR, ESR spectroscopy techniques, thermogravimetric analysis (TG), differential thermal analysis (DTA), X-ray powder diffraction (XRD) and solid phase conductivity measurements. The room temperature ESR spectra of Cu(II) complex yield ‹g› values, characteristics of square planar geometry. The solid state electrical conductivities of the complexes increase as the temperature increases from 311-383 K, with a band gap of 0.11- 0.21 eV, indicating their semiconducting behaviour.

Study of threshold energy [formula omitted] in EXAFS

This work demonstrates that the threshold energy E0 can be obtained from a simple tentative rule and the bond length R can be obtained correctly by running the FIT program while fixing E0. The extended X-ray absorption fine structure (EXAFS) spectra for Cu, W, and Au metal foils are tested and for the anharmonic system, the experimental Cu spectra measured at temperatures of 50, 150, 295, 400, 500, 600 and 700K. From the tests, it is confirmed that a more precise bond length R comparable to the crystallographic data can be obtained for both cases. Moreover, it is deduced that the new running mode of the conventional EXAFS FIT program yields satisfactory results for the anharmonic system.

How the nature and charge of metal cations affect vibrations in acetone solvent molecules.

Vibrational spectra of a series of gas-phase metal 1+ and 2+ ions solvated by acetone molecules are collected to investigate how the metal charge, number of solvent molecules and nature of the metal affect the acetone. The spectra of Cu+(Ace)(N2)2, Cu+(Ace)4, and M2+(Ace)4, where M = Co, Ni, Cu, and Zn are measured via photodissociation by monitoring fragment ion signal as a function of IR wavenumber. The spectra show a red shift of the CO stretch and a blue shift of the C-C antisymmetric stretch. DFT calculations are carried out to provide the simulated spectra of possible isomers to be compared with the observed vibrational spectra, and specific structures are proposed. The red shift of the CO stretch increases as the number of acetone molecules decreases. Higher charge on the metal leads to a larger red shift in the CO stretch. Although all of the M2+ complexes have very similar red shifts, they are predicted to have different geometries due to their different electron configurations. Unexpectedly, we find that the calculated red shift in the CO stretch in M+/2+(Ace) is highly linearly correlated with the ionization energy of the metal for a wide range of metal cations and dications.

Structural and optoelectronic properties of electrodeposited CdSe thin films: Effect of Cu-dopant

Cadmium selenide (CdSe) is a promising semiconductor extensively used in manufacturing optoelectronic devices. Compared to the undoped CdSe (Cu 1), the crystallite size of Cu 2 (1 % at. Cu-doped CdSe) increases from 27 to 29 nm , further Cu-doping into CdSe reduced crystallite size to 5 nm. The absorbance behavior exhibited improvement after Cu-doping. Additionally, the reflectance spectrum of Cu 2 displayed enhancement compared to the Cu 1 attributed to increase in crystallite size. The band gap (Eg) of undoped CdSe was measured at 1.78 eV, showing an increase to 1.89 eV after Cu-doping. Optical conductivity of CdSe samples exhibited an increase following Cu-doping. Consequently, Cu 2 exhibited optimal characteristics for photodetection among all samples, attributed to its higher crystalline quality, lower lattice strain, reduced defect density, and higher carrier concentration. This study reveals the influence of Cu-doping on CdSe, highlighting essential characteristics to enhance its application in optoelectronics.

Effect of laser energy on temporal evolution of self-absorption at different air pressures

The self-absorption effect is one of the key factors influencing the accuracy of quantitative analysis. Laser energy is the key influencing factor of laser-induced breakdown spectroscopy (LIBS), and the mechanism of its influence on temporal evolution of self-absorption under different air pressures is still not fully understood due to complex physical processes. In this study, the temporally resolved spectra of Cu I 521.82 nm were acquired from the direction of laser incidence and the influence of laser energy on the temporal evolution of self-absorption in a low-vacuum (at pressures of 105, 104 and 103Pa) and high-vacuum (at pressures of 10, 10−1 and 10−3Pa) environment was studied. The experimental results indicate that the self-absorption effect of spectral line Cu I 521.82 nm is enhanced with an increase in delay time and laser energy in both high-vacuum and low-vacuum environments in this study. This is because increasing the delay time and laser energy leads to an increase in plasma column density. An intriguing phenomenon observed in this experiment is that at a pressure of 105Pa, the self-absorption of Cu I 521.82 nm initially increases but eventually weakens with laser energy, while at air pressures of 104Pa and 103Pa the self-absorption monotonically weakens with increasing laser energy during the measurement. This is because temporal evolution of plasma at 104Pa and 103Pa is significantly faster than that at 105Pa, and an increase in laser energy can delay the enhancement of self-absorption, the self-absorption has rapidly evolved to decrease with laser energy during spectral measurement at air pressure of 104 Pa and 103 Pa. This work is helpful in understanding the influence of air pressure and laser energy on the self-absorption effect of spectral lines and optimizing experimental parameters, and provides a reference for LIBS application.

SYNTHESIS, CHARACTERIZATION AND XRD ANALYSIS OF COPPER (II) AND IRON (II) COMPLEXES OF BENZOIC ACID HYDRAZIDE.

Schiff bases are an important class of organic compounds, which play an important role in medicinal and pharmaceutical applications. Metal complexes formed by the reactions of keto forms of Benzoic acid hydrazide (BAH) with Cu(II) and Fe(II) sulphate ions were prepared and characterized by X-ray Diffraction analysis (XRD), Fourier Transform Infrared (FTIR) and electronic absorption spectra studies. The results showed that the hydrazides reacted with the metal salts in 1:2 molar ratio in all the complexes and acts as neutral bidentate ligands. The X-ray diffraction (XRD) pattern of the metal complexes provides a detailed comparative account of the behavior of the metal complexes of hydrazide ligand metal complexes. The pattern of BAH complexes shows the main characteristics peak and broad shoulder. In view of the relative half value width (FWHM), it may be concluded that the BAH-Cu is partially crystalline and while the BAH-Fe shows an amorphous nature. The broad characteristic peak indicates the amorphous nature of the polymers. The solubility test on the ligands and its metal (II) complexes revealed their solubility in ethanol and dimethylsulphoxide (DMSO). The infrared spectra of the hydrazide showed that ?(C=O), the carbonyl stretching mode, the coupling between the in-plane bending ?(N-H) and ?(C-N) and the stretching frequency for the amino group ?(NH2) all experienced shifts to lower wave numbers in the complexes suggesting the coordination of the moieties to the metal ions. The electronic absorption spectra of Cu(II) complexes showed absorption band located at 36,496 cm-1 showing a tetrahedral geometry while Fe(II) BAH and BAH ligand show absorption band at a shoulder around 16051 cm-1 with 4A2 ? 4T1 (P) respectively consistent with a four coordinate tetrahedral geometry.

Kβ X-ray Emission Spectroscopy of Cu(I)-Lytic Polysaccharide Monooxygenase: Direct Observation of the Frontier Molecular Orbital for H2O2 Activation.

Lytic polysaccharide monooxygenases (LPMOs) catalyze the degradation of recalcitrant carbohydrate polysaccharide substrates. These enzymes are characterized by a mononuclear Cu(I) active site with a three-coordinate T-shaped "His-brace" configuration including the N-terminal histidine and its amine group as ligands. This study explicitly investigates the electronic structure of the d10 Cu(I) active site in a LPMO using Kβ X-ray emission spectroscopy (XES). The lack of inversion symmetry in the His-brace site enables the 3d/p mixing required for intensity in the Kβ valence-to-core (VtC) XES spectrum of Cu(I)-LPMO. These Kβ XES data are correlated to density functional theory (DFT) calculations to define the bonding, and in particular, the frontier molecular orbital (FMO) of the Cu(I) site. These experimentally validated DFT calculations are used to evaluate the reaction coordinate for homolytic cleavage of the H2O2 O-O bond and understand the contribution of this FMO to the low barrier of this reaction and how the geometric and electronic structure of the Cu(I)-LPMO site is activated for rapid reactivity with H2O2.

Structural and Optical Characterisation of Size-Selected Glutathione-Capped Colloidal Cu–In–S Quantum Dots

Size-selected series of copper-deficient colloidal Cu–In–S quantum dots (QDs) stabilized with glutathione are obtained by the exchange reaction in aqueous solutions under mild synthesis conditions. The optical bandgap and photoluminescence maximum position shift toward higher energies with decreasing QD size. Based on X-ray diffraction data, the QDs are assigned to a tetragonal chalcopyrite-type structure. The average size of QDs, estimated from the Scherrer formula and from the comparison with the absorption edge-based sizing curves, exhibits a fair agreement, being in the interval of 1.2–2.9 nm. The Raman spectra of Cu–In–S QDs are analyzed with the account for the QD structure, confinement-related effects, non-stoichiometry, and possible existence of secondary phases.

Green synthesis of highly efficient and stable copper oxide nanoparticles using an aqueous seed extract of Moringa stenopetala for sunlight-assisted catalytic degradation of Congo red and alizarin red s

Environmental pollution by organic pollutants because of population growth and industrial expansion is a global concern. Following this, the fabrication of single and efficient nanomaterials for pollution control is highly demanded. Under this study, highly efficient and stable copper oxide nanoparticles (CuO NPs) were synthesized through the green method using Moringa stenopetala seed extract. XRD, UV–vis, FT-IR, and SEM were applied to characterize the synthesized material. From XRD data, the average particle size was found to be 6.556 nm, and the nanoparticles are crystalline in nature. The formation of CuO NPs was demonstrated by FT-IR spectra of Cu–O in different bending vibration bands at 535 cm-1 and 1122 cm-1, as well as stretching vibration of Cu–O at 1640 cm-1. From UV–visible spectroscopic measurements, the energy band gap of greenly synthesized CuO NPs was found to be 1.73 eV. The SEM result shows that the nanoparticles' surfaces are rough, with some of the particles having spherically random orientation. The photodegradation efficiency of green synthesized CuO NPs photocatalyst was found to be 98.35% for Congo red at optimum experimental parameters (initial concentration, 25 mg/L; exposure time, 120 min; catalyst dose, 0.2 g; and pH, 5) and 95.4% for Alizarin Red S at optimum experimental parameters (catalyst dose, 0.25 g; initial concentration, 40 mg/L; exposure time, 120 min; and pH, 4.6). The COD values determined for the degraded product strongly support the complete mineralization of the dyes toward nontoxic materials. Reusability of the catalyst was investigated for five cycles, and the results clearly indicate the green synthesized CuO NPs are highly stable, can be used for several times, and are cost-effective as well. The degradation of Congo red and Alizarin red S on the surface of the CuO NPs follows the MBG kinetic model.

Efficient full frequency GW for metals using a multipole approach for the dielectric screening

The properties of metallic systems with important and structured excitations at low energies, such as Cu, are challenging to describe with simple models like the plasmon pole approximation (PPA), and more accurate and sometimes prohibitive full frequency approaches are usually required. In this paper we propose a numerical approach to $GW$ calculations on metals that takes into account the frequency dependence of the screening via the multipole approximation (MPA), an accurate and efficient alternative to current full-frequency methods that was recently developed and validated for semiconductors and overcomes several limitations of PPA. We now demonstrate that MPA can be successfully extended to metallic systems by optimizing the frequency sampling for this class of materials and introducing a simple method to include the $\mathbf{q}\to 0$ limit of the intra-band contributions. The good agreement between MPA and full frequency results for the calculations of quasi-particle energies, polarizability, self-energy and spectral functions in different metallic systems confirms the accuracy and computational efficiency of the method. Finally, we discuss the physical interpretation of the MPA poles through a comparison with experimental electron energy loss spectra for Cu.

Effective degradation of tetracycline via recyclable free-standing three-dimensional copper-based graphene as a persulfate catalyst.

Water pollution by antibiotics is a serious and growing problem. Given this challenge, a free-standing three-dimensional (3D) reduced graphene oxide foam supported copper oxide nanoparticles (3D-rGO-CuxO) was synthesized using GO as a precursor and applied as an efficient persulfate activator for tetracycline (TC) degradation. The influences of CuxO mass, solution pH, persulfate dosage, and common anions on the TC degradation were investigated in detail. Analytical techniques indicated that the 3D-rGO-CuxO showed a cross-linking three-dimensional network structure, and CuxO particles with irregular shapes were uniformly loaded on graphene pore walls. The XPS and Auger spectra of Cu confirmed that Cu2O was the main component in solid copper compounds. The addition of CuxO was vitally important for the activation of the oxidation system, and the removal rate reached 98% with a CuxO load of 7:1. The pH showed little influence on the activation effect on TC degradation. For common anions, Cl- and CO32- had little influence on the system, while humic acid had a great inhibitory effect. The EPR test and quenching experiment revealed that the active substances in the oxidative degradation process mainly include SO4-·, ·OH, 1O2, and reactive Cu(III). Additionally, the 3D-rGO-CuxO material proved highly stable according to the replicated test results and was promising for the remediation of antibiotic-contaminated water.

DFT study of UV–vis-properties of thiophene-containing Cu(β-diketonato)2 – Application for DSSC

Experimental and theoretically calculated UV–vis properties of three Cu(β-diketonato)2 complexes are presented. The Cu(β-diketonato)2 contains β-diketones without (β-diketone = acetylacetone, (CH3)COCH2CO(CH3), complex (1)), with one (β-diketone = thenoyltrifluoroacetone, (CF3)COCH2CO(C4H3S), complex (2)) and with two thiophene (β-diketone = (CF3)COCH2CO(C4H2S) (C4H3S), complex (3)) groups. More thiophenes on the β-diketonato ligand of Cu(β-diketonato)2, lead to a red shift of the experimental absorbance maxima of the UV–vis of the complex, from 295 nm for complex (1), to 340 nm for complex (2) to 390 nm for complex (3). Theoretical time dependant density functional theory calculations indicate that both the two strongest absorbance peaks of the ultraviolet–visible spectrum of Cu(acetylacetonato)2 are mainly ligand-to-metal charge-transfer excitations. However, the absorbance maxima of the UV–vis of thiophene-containing Cu(β-diketonato)2 are mainly ligand-to-ligand charge-transfer excitations. Calculated properties such as light harvesting energy (LHE = 0.47, 0.94 and 0.99 for (1)–(3) respectively), driving force for electron injection (ΔGinject = 1.43, 0.76 and 0.63 for (1)–(3) respectively), and driving force of dye regeneration (ΔGregenerate = 1.85, 2.16 and 1.49 for (1)–(3) respectively), are favourable for (1)–(3) to be considered as dyes in DSSCs. However, some structural modifications are needed to prevent intramolecular charge recombination after excitation.

DC erosion jets for the production of composite graphene particles

We studied the synthesis of composite Cu/graphene nanoparticles using the radiative characteristics of copper-containing plasma jets of a helium/hydrocarbon mixture, flowing from the nozzle of the output copper electrode of a DC plasmatron. A mixture of propane and butane was used as the hydrocarbon source. To determine the conditions for nanoparticle formation during the conversion of hydrocarbons in erosive jets, the concentration of copper was estimated by analyzing the optical emission spectra of Cu I lines observed in the spectrum. We found that the maximum saturation of graphene by copper (0.03 mass %) is reached at the copper concentration in plasma [Cu] = Nabs ≈ 3 × 1013 cm−3, which is sufficient to form a chemical bond of copper with sp2 carbon in a nanoparticle.

Synthesis, Spectral Characterization, Electrochemical, Antioxidant and Antimicrobial Evaluation of 3d-Metal Complexes of 3-Mercapto-4-(Pyren-1-ylmethylene)Amino-1,2,4-Triazin-5-One

New transition metal complexes of cobalt(II), nickel(II), copper(II) and zinc(II) with new Schiff base [HLp] derived from pyrene-1-carbaldehyde and 4-Amino-3-mercapto-5-oxo-1,2,4-triazine were synthesized and characterized by elemental analysis, 1H-NMR, FT-IR, UV-Visible, ESR spectral studies, magnetic moment measurements and cyclic voltammetry. Results prove that [HLp] acts as bidentate ligand. Low conductance data reveal non-electrolytic nature of the complexes. The spectroscopic data and magnetic moment values along with elemental analytical data support octahedral geometries for Co(II), Ni(II), Zn(II) complexes and square planar geometry for Cu(II) complexes. ESR spectra of Cu(II) complexes exhibited g values trend as g ∥ > g ⊥ > g e . The nephelauxetic ratio (β) along with orbital reduction factors (K values) report the covalent nature of the metal-ligand bonds in complexes. Thermal analysis was also carried out to propose the composition of complexes and to determine their thermal stability. Coats-Redfern method was employed to evaluate some kinetic parameters of thermal degradation processes. In vitro antimicrobial properties of all synthesized compounds were investigated. After assessing the inhibition zones, metal complexes have been found more antimicrobial active than the Schiff base against both bacterial as well as fungal strains. Metal complexes also showed remarkable fluorescence and antioxidant properties.

Synthesis, Physicochemical Studies and Powder X‐Ray Diffraction Analyses for New Niclosamide Metal Complexes with Significant Bioactive Behavior

AbstractThis work underlines some important features for the research on metal complexes of Niclosamide as antioxidants and antimicrobial evaluation of some of these compounds as possible therapeutic agents. Niclosamide metal complexes show a significant leap in the study of antibiotic resistance bacteria including Methicillin Resistant S.aureus (MRSA). The synthesized metal complexes of niclosamide in our current innovation are highly effective at eliminating this destructive sort of bacteria. Niclosamide metal complexes were synthesized then characterized by elemental analysis, Infra‐Red, electronic spectra, magnetic susceptibility, Mass spectra and ESR spectra of Cu (II) complex to know their geometries and mode of bonding, with stoichiometry, 1 : 1 (M : L). All the Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) metal ions complexes were proposed to be with distorted octahedral geometry. Powder X‐Ray Diffraction technique is being utilized to further investigation of synthesized Niclosamide metal complexes. Expo2014 software was also employed to solve the structure of these novel complexes which proven the distortion of crystal structure. The TGA and DTA curves were employed to derive the kinetic thermodynamic parameters. The thermal decomposition of the complexes ended with the formation of divalent metal oxide, MO or trivalent, M2O3 as a final product except in case of Hg complex. The results of the antimicrobial activity of tested new metal complexes compounds exhibited potent antibacterial and antifungal activities in comparison to the Niclosamide ligand as reference. Quantum chemical parameters were estimated and provided noticeable values which completely matched with antimicrobial results that [Mn(NIC)(Cl2)(H2O)2] ⋅ 0.4H2O has higher biological activity than ligand and other novel complexes. low concentration value of MIC results by 125 μg/ml for both niclosamide (NIC) complexes [Ni(NIC)(Cl2)(H2O)2] and [Cu(NIC)(Cl2)(H2O)2] ⋅ 2.5H2O with Methicillin Resistant S.aureus (MRSA) genus maybe a valuable data used to produce novel therapeutic agent. Depending on their structure and on the source of the oxidative stress, metal complexes of Niclosamide might act as antioxidants or pro‐oxidants.

Structural change dynamics of heteroleptic Cu(I) complexes observed by ultrafast emission spectroscopy.

[Cu(I)(dmp)(P)2]+ (dmp = 2,9-dimethyl-1,10-phenanthroline derivatives; P = phosphine ligand) is one of the most promising photosensitizers used in a photo-catalytic system for reducing CO2, for which the quantum yield is as high as 57%. In this work, time-resolved emission spectra of Cu(I) complexes in solutions were investigated using femtosecond fluorescence up-conversion and nanosecond time-resolved emission spectroscopic systems. The temporal profiles of emission intensities less than 10 ps in acetonitrile solution were reproduced using a tri-exponential function with three-time constants of 0.040 ps, 0.78 ps and 8.0 ps. We found that only the second time constant is dependent on the solvent (acetonitrile: 0.78 ps, butyronitrile: 1.4 ps), indicating that the 0.78 ps spectral change is attributed to the structural change of the Cu(I) complex. The oscillator strengths of transition species are derived from the intensities in the time-resolved emission spectra (species-associated spectra). Based on the oscillator strengths, we concluded that the 0.040 ps process is the Sn → S1 internal conversion and the 0.78 ps process is a structural change in the S1 state. The final time constant of 8.0 ps is assigned to the S1 → T1 intersystem crossing because the 3MLCT state (τT1 = 97 ns) is generated after the decay. The DFT calculation showed that the 0.78 ps spectral change (∼600 cm-1 redshift) is attributed to Jahn-Teller distortion around the metal center, and there is a large structural change in the ligand, which results in a large Stokes shift in the Sn state (7.3 × 103 cm-1).

Synthesis, Physico-chemical, Spectral And Molecular Docking studies of 4-[(E)benzylideneamino]-5-methyl-4H-1,2,4-triazole-3-thiol and Its Metal Complexes with Cu(II), Ni(II), Co(II) and Zn(II)

Heterocyclic compounds like Triazoles have great medicinal value. There metal complexes have also shown a vide range of biological activity. In the present research, a triazole derived ligand, 4-[(E)-benzylideneamino]-5methyl-4H-1,2,4-triazole-3-thiol and its metal complex with Cu(II), Ni(II), Co(II) and Zn(II) metal ions were prepared in solid state. The ligand and its metal complexes were characterized by elemental analysis and spectral techniques like IR spectra and UV-Visible spectra. The shift in the infrared spectral band indicates bonding of metal ion with ligand through deprotonated thiol group and imine ( C=N) Nitrogen atom. The ligand is bidentate. The IR spectral analysis also showed that a large amount of lattice water is present in Ni(II) and Co(II) complex. All the metal complexes and ligand are neutral species soluble in organic solvents like DMF and DMSO. UV-Visible spectra of Cu(II), Ni(II) and Co(II) complexes indicate that their geometry is distorted octahedral. The molecular docking of the synthesized compounds was performed using CB Dock 2 server against 1JIJ protein derived from Staphylococcus Aureus. The vina score obtained indicates that compounds inhibits the protein and are potentially anti-bacterial

Schiff base coordination compounds including thiosemicarbazide derivative and 4-benzoyl-1,3-diphenyl-5-pyrazolone: Synthesis, structural spectral characterization and biological activity

A new thiosemicarbazone ligand containing an allyl group and a 5-pyrazolone derivative has been prepared. The reaction of this ligand (H2L) with chloride and nitrate salts of Co(II), Cu(II), Pd(II), and Ni(II), Cu(II) ions resulted in the formation of different chelates having variable chemical formulas. Structural characterization of H2L ligand and its chelates has been established employing microanalytical, molar conductivity, magnetic moment measurements as well as spectral techniques including IR, UV–vis, NMR, mass, XRD, and ESR spectra. The spectral and microanalytical data achieved the monobasic tridentate binding mode with the metal(II) ion through SNO and NNO donor sites in complexes (2,5) and (3,4), respectively. In addition, the thiosemicarbazone ligand acts as a neutral bidentate species (NS) and neutral or mononegative bidentate species (NO) in complexes (6) and (1), respectively. Based on electronic spectra analyses (UV–vis) and magnetic moment measurements, all chelates, with the exception of those of Co(II) and Pd(II) ions, which have square planar geometrical structures, revealed a square pyramidal structure. Furthermore, the ESR spectra of Cu(II) chelates (3–5) have been investigated, yielding 2B1g as an axial ground state. The chemical formulae for the metal chelates were determined using thermogravimetric investigations (TG and DTG), demonstrating both their thermal stability and the presence of various crystalline solvents. Metal oxide (MO) or metal with traces of carbon was the residue of the thermal degradation processes. Based on XRD analysis, the structures of allopalladium (O-dopped Pd), monoclinic CuO, and tetragonal metallic cobalt nanoparticles obtained thermally from chelates (1,3,4,6) were elucidated. Copper(II) chelates (3) and (4) display the highest anticancer activity against hepatocellular carcinoma cells (Hep G-2) testes, according to the biological studies for the ligand and some of its chelates.

New benzoyl acetohyrazone based metal complexes with Viral DNA binding and cleavage and antimicrobial treatments: Synthesis and biological activities

Some transition metal ions as Co(II), Ni(II), Cu(II) and Zn(II) form complexes with Benzoyl Acetohyrazone ligand, (1) [HL] was synthesized and characterized using physical and spectroscopic methods. Analytical data showed that the complexes found in (1:1) ligand: metal ratio. Spectral studies revealed that the ligand bonded to the metal ion in neutral bidentate or monobasic bidentate manner through azomethine nitrogen atom, protonated/deprotonated hydroxyl group. From the electronic spectral data together with magnetic susceptibility values a distorted octahedral geometry can be proposed for all complexes except complexes (4, 9, 13) which have square planar structure. Electron spin resonance spectra for Cu(II) complex (2) revealed axial symmetry with g|| >g⊥>ge, indicating distorted octahedral or square planar geometries and the unpaired electron exists in a d(x2−y2) orbital with marked covalent bond feature. The synthesized complexes presented good to excellent antimicrobial activity, and the most active complexes against Aspergillus niger were (5, 10, 14) with inhibition zone of 20, 23 and 25 mm, respectively. Complex (2) showed interesting activity against Escherichia coli with inhibition zone value 18.2 mm. Gel electrophoresis experiments using viral B- DNA were performed with the ligand and its complexes and show great effect in viral B cleavage.

Copper complexes of strongly electron rich and deficient salen ligands

Three copper(II) salen compounds (Cu(SalR)) bearing strongly electron donating (Cu(SalNMe2)), electronically neutral (Cu(SaltBu)) and strongly electron withdrawing (Cu(SalNMe3)) para-substituents were prepared. Their geometric structures were evaluated by single crystal X-ray diffraction and supported by theoretical DFT calculations. The electronic spectra of Cu(SalR) revealed LMCT bands at 23 000 cm−1–27 000 cm−1 with varying para-substituents, while the d-d bands remain around 17 600 cm−1. The electrochemical behaviour of Cu(SalR), evaluated by cyclic voltammetry, reveal the expected positive shift in redox waves for more electron deficient compounds (Cu(SalNMe2) (CH2Cl2): −0.08, 0.03, 0.55, 0.64 V; Cu(SaltBu) (CH2Cl2): 0.59, 0.74 V; Cu(SalNMe3) (DMF): 0.78 V versus ferrocene/ferrocenium). The additional reversible oxidative couples observed for Cu(SalNMe2) are likely due to the strongly electron donating NMe2 moieties that either enable additional oxidation events to occur, and/or shifting any additional oxidation events within the experimental electrochemical window. One-electron oxidation of Cu(SalNMe2) and Cu(SaltBu) were monitored using low temperature UV–vis spectroscopy: characteristic spectra for metal oxidized [CuIII(SaltBu)]+ and ligand oxidized [CuII(SalNMe2)•]+ species were observed.