Copper Metal Ions Research Articles

Study of the interaction Cu(II) - Carbendazim in natural waters by electrochemical techniques

In order to obtain higher agricultural yields, the use of chemical substances has been increased to prevent the proliferation of pests, as well as ensuring durability in the storage of the food produced. Such substances are known as pesticides that may well present risks to human health and the environment. In the presence of metal ions, these substances can interact forming new species with different characteristics. Carbendazim (MBC) is an example of a harmful pesticide, which has atoms of nitrogen and oxygen in its structure that can form complexes with metal ions. Thus, in this work has studied the interaction between the copper (II) metal ion and carbendazim and its formation in natural water. The Cu-MBC complex showed a reduction peak of 0.007 V and an oxidation peak of 0.500 V, with characteristics of a quasi-reversible process under a glassy carbon electrode. By anodic stripping voltammetry, a different behavior was observed in the interaction of copper and carbendazim in ultrapure water and Billings dam water; however, it was possible to observe the complex in both samples. Carbendazim in the presence of the metal shows lower oxidation potential value, indicating the influence of the metal on the electrochemical response of the pesticide.

A DFT study of isolated histidine interactions with metal ions (Ni2+, Cu2+, Zn2+) in a six-coordinated octahedral complex.

Understanding the role that metal ions play in biological and material processes is critical to addressing a number of diseases and problems facing society today. There have been a number of studies that have begun to approach this concern from a myriad of different perspectives. However, there is still a considerable lack of understanding concerning the mechanisms and structures of metal-related problems, specifically biological and medical-related issues. Understanding the mechanism of ingestion and uptake of metals into the human body is critical to addressing many diseases such as Alzheimer's and certain types of cancers. Using computational techniques, this work adds to the overall understanding of metal interactions with proteins by focusing on metal ion interactions with the amino acid, histidine, one of the most common sites of metal attachment. In this work, the geometries of single and dual histidines attached to Ni2+, Cu2+, and Zn2+ ions at B3LYP/6-311G(d) are presented. The results show stable octahedral complexes associated with each of the metal ions. Free energy calculations suggest that all three complexes are spontaneous in the formation of the dual histidine-metal complexes. Nickel and copper are spontaneous in the formation of the single histidine complex, although the copper complex undergoes slight geometric changes. Zinc is found to be nonspontaneous in forming the single histidine complex. Finally, the reduction potential of the single histidine-metal complex is presented. All of the complexes show positive reduction potentials. However, the nickel and copper complexes undergo geometrical changes to adopt a square planar conformation. Graphical abstract The impact of metal ions in biological systems is of great importance to understanding a diverse number of diseases. By understanding the fundamentals of select ions complexed with histidines, greater understanding of the mechanisms of actions these ions play in health may be elucidated. This work presents initial structures and thermodynamics of histidine complexes with nickel, copper, and zinc metal ions.

(Invited) Oxygen Reduction Reactivity at Fe- and Cu-Codoped Carbon Nanostructures

Polymer electrolyte fuel cells (PEFCs), which can efficiently convert hydrogen into electricity without using fossil fuels, are a promising energy conversion device. At the cathodes of PEFCs, oxygen reduction reaction (ORR) occurs via 4-electrons' and 4-protons' transfer. Due to its low reaction rate limiting the performance of PEFCs, the electrocatalysts are necessary and the platinum-based electrocatalysts for ORR are mainly used because of its highest electrocatalystic activity in the metals. Since platinum metal is expensive and rare, there is a need to develop non-platinum-based electricatalysts based on iron and/or copper with high ORR activity1,2,3,4). A cytochrome c oxidase (CcO), which is a metalloenzyme and contains iron and copper metal ions, catalyzes the ORR efficiently to produce ATP in mitochondria5) and its activity is higher than that of artificial platinum-based electrocatalysts6). Metalloenzymes are not practical because of their stability, size, and difficulty to isolate and purify.In this study, iron and copper co-doped carbon electrocatalysts, synthesized from the mixtures of Fe and/or Cu complexes and carbon nanotubes in heat treatment inspired by the CcO’s active center, were developed. Synthetic conditions of Fe : Cu metal ratios and heating temperatures were optimized. The ORR activity was evaluated by hydrodynamic voltammetry using a rotating ring disk electrode in 0.05 M sulfuric acid aqueous solution saturated with oxygen. The activity of Fe/Cu/CNT catalyst was compared with two catalysts: iron-doped carbon carbon catalyst (Fe/CNT) and copper-doped carbon catalyst (Cu/CNT). The Fe/Cu/CNT catalyst showed more positive onset potential for the oxygen reduction in acidic media than Fe/CNT and Cu/CNT, indicating that Fe/Cu/CNT is more active, and we figure out that the coexistence of iron and copper in CNTs contributes to the improvement of ORR activity.

Au-nanoparticle loaded nickel-copper bimetallic MOF: An excellent catalyst for chemical degradation of Rhodamine B

Synthesis, characterization and catalytic performance of Au-nanoparticle (NP) functionalized Nickel-Copper bimetallic three-dimensional MOF is presented. A three dimensional bimetallic MOF involving aromatic polycarboxylate ligands viz. benzene 1,4-dicarboxylate and benzene 1,3,5-tricarboxylate as linkers with Cu (II) and Ni (II) as metal nodes was synthesized through Solvothermal method. Structural and morphological studies of the as-synthesized material were carried out by FTIR, PXRD, SEM and TEM analysis. The elemental composition of the material was established by EDS mapping. Thermal stability of the as-prepared samples was tested by TGA analysis. The characterization details well establish the synthesis of first of its kind of bimetallic mixed metal–ligand MOF composed of nickel and copper metal ions trapped in an organic framework of bipodal and tripodal carboxylate based mixed ligands. The bimetallic MOF was successfully functionalized by Au NPs and was tested for its catalytic performance toward the chemical degradation of environmentally hazardous organic pollutant Rhodamine B. Compared to the pristine MOF, the Au doped MOF exhibited an exceptionally high catalytic activity (kapp = 13.74 × 10−2 min−1) and thermal stability, which can be attributed to the functional synergism prevailing between the Au nanoparticles and the three-dimensional bimetallic mixed ligand framework. The estimated kapp value for RhB degradation is significantly better than those reported for various state of the art nanocomposite catalysts reported in the recent past.

Electrochemical Evaluation of Pollutants in the Environment: Interaction Between the Metal Ions Zn(II) and Cu(II) with the Fungicide Thiram in Billings Dam

AbstractPesticides are organic molecules used in the control of various pests in different crops. These molecules show functional groups that can interact with metal ions, forming new species with different properties. These new compounds have been attracting attention because they can become a new environmental problem. In this work the interaction of copper and zinc metal ions with Thiram pesticide was studied using electrochemical techniques. Studies in ultrapure water showed the formation of Zn−Thiram complex with reduction potential at −1.330 V; Cu−Thiram complex showed a cathodic peak at 0.020 V. Thiram causes a different effect on the two metal ions studied. It was observed that the ligand stabilizes more the Cu(II) than Zn(II). Both systems proved to be quasi‐reversible, controlled by the adsorption of the species on the electrode surface. The formation constants of the complexes were calculated to be 2.1×105 for Zn−Thiram and 1.5×1019 for Cu−Thiram. In the samples from Billings dam, the Zn‐complex showed reduction potential at −1.403 V; Cu‐complex exhibited a reduction peak at 0.012 V. Although there are interferers in river waters, the interaction of these metals with the pesticide showed high affinity, being possible to detect them in natural samples. The Cu(II) complex showed to be more stable in natural matrices when compared to the Zn(II) complex. The sensitivity for thiram electroanalytical determination decreases in the presence of Zn(II) and Cu(II).

Exploring the copper resistance mechanism of the lipoprotein DcrB in Salmonella enterica

Salmonella enterica is a major bacterial cause of foodborne illness and invasive disease. Salmonella establishes infections by evading host macrophages; these host immune cells engulf the bacteria into a phagosome and use mechanisms to destroy the foreign body. Within the phagosome, bacteria are subjected to many harsh conditions, one possibly being toxic amounts of copper metal ions. We have previously demonstrated that the periplasmic‐anchored lipoprotein DcrB (possessed by S. enterica serovar Typhimurium) conveys resistance to toxic concentrations of copper ions, and thereby may play a role in Salmonella’s survival within the host. To gain a better understanding of the protein’s function, we have explored gene expression affected by DcrB and possible interactions between the protein and small, cellular metabolites. Using reverse‐transcriptase quantitative PCR, we have shown that DcrB plays a role in the upregulation of some cell envelope stress response genes. DcrB, however, does not significantly affect regulation of copper ion transport genes or other copper ion resistance genes. Through thermofluor assays, we have shown that purified DcrB protein has increased stability in toxic copper ion concentrations when extracellular amino acids are present in solution. This result suggests that DcrB has copper‐dependent interactions with free amino acids. Overall, these findings advance our understanding of how DcrB confers resistance to copper ions. This knowledge could be used to develop new antibiotics targeting bacterial copper resistance, ultimately decreasing the number of invasive illnesses caused by S. enterica and other gram‐negative bacteria.Support or Funding InformationThis research was supported by a UWL Faculty Research Grant to JFM.

Effect of Sodium Dodecyl Sulfate (SDS) on Polysulfone/Zeolite membrane for the removal of copper ions

The influence of anionic surfactant, Sodium Dodecyl Sulfate (SDS) on Polysulfone (PSf) polymer impregnated with zeolite adsorbent for removing copper ions from aqueous solution is the main focus of this paper. The flat sheet membrane was prepared via blending and phase inversion methods. Different amount of SDS (1 wt%, 3 wt%, 5 wt%, and 7 wt%) were added into the polymer casting solution. Batch adsorption and continuous filtration studies were carried out to study the effect of SDS dosage on PSf/zeolite membrane for the removal of copper ion. The membrane characterizations such as pure water flux (PWF), water contact angle (WCA) and mean pore size were investigated. From the study, it was found that the presence of a high amount of SDS could enhance adsorption efficiency (99 %) by shortening the equilibrium time with adsorption of 9.4 mg/g. Filtration study indicates that a lower amount of SDS (1 wt%) results in high rejection value (70 %) of copper metal ions from the solution. Besides, as the amount of SDS increase, the PWF increases from 0 L/m2h to 100 L/m2h, WCA decreases from 94.8° to 46.4° and the pore size of membrane increases from 0.082 μm to 2.530 μm.

Fabrication and characterization of polyvinyl chloride mixed matrix membranes containing high aspect ratio anatase titania and hydrous manganese oxide nanoparticle for efficient removal of heavy metal ions: Competitive removal study

AbstractIn this study, novel polyvinyl chloride (PVC) ultrafiltration mixed matrix membranes (MMMs) containing high aspect ratio anatase titania (ANT) and hydrous manganese oxide (HMO) nanoparticles were synthesized in order to decontaminate cadmium and copper metal ions. ANT and HMO nanoparticles with various loadings in a range of 5‐15 were used in the casting solution of MMMs. The characterization of fabricated MMMs was carried out with respect to the structural morphology, hydrophilicity, and composition by scanning electron microscopy (SEM), water contact angle, and Fourier transform infrared spectroscopy (FTIR), respectively. With an increase in the nanoparticle loadings, the change in other membrane characteristics such as mean pore size, pure water flux, and porosity were also evaluated. The results revealed that the mean pore size and water flux increased at a higher loading of ANT and HMO nanoparticles, while the contact angle and porosity of the membranes showed reverse trends. Moreover, the higher flux of pure water was obtained for PVC‐ANT MMMs compared to PVC‐HMO MMMs because of the larger mean pore size, higher porosity, and hydrophilicity of PVC‐ANT MMMs. In this study, the decontamination of cadmium and copper metal ions in single and binary systems of heavy metals was investigated and the effect of Mn2+ (as an interfering ion) was also studied. The evaluation of the metal ion removal data demonstrated that the affinity sequence of both the PVC‐ANT‐15 and PVC‐HMO‐15 MMMs for heavy metal removal was Cu2+ > Cd2+ > Mn2+ in the single and binary systems. It was found through ultrafiltration (UF) experiments that PVC‐ANT MMM was the most efficient membrane in the elimination of heavy metals due to the superior ANT adsorption capacity. However, the overall findings disclosed that both ANT and HMO nanoparticles are suitable candidates for the preparation of MMMs used in cadmium and copper decontamination from aqueous solutions.

Comparison of the pH-dependent formation of His and Cys heptapeptide complexes of nickel(II), copper(II), and zinc(II) as determined by ion mobility-mass spectrometry.

The analog methanobactin (amb) peptide with the sequence ac-His1 -Cys2 -Gly3 -Pro4 -Tyr5 -His6 -Cys7 (amb5A ) will bind the metal ions of zinc, nickel, and copper. To further understand how amb5A binds these metals, we have undertaken a series of studies of structurally related heptapeptides where one or two of the potential His or Cys binding sites have been replaced by Gly, or the C-terminus has been blocked by amidation. The studies were designed to compare how these metals bind to these sequences in different pH solutions of pH 4.2 to 10 and utilized native electrospray ionization (ESI) with ion mobility-mass spectrometry (IM-MS) which allows for the quantitative analysis of the charged species produced during the reactions. The native ESI conditions were chosen to conserve as much of the solution-phase behavior of the amb peptides as possible and an analysis of how the IM-MS results compare with the expected solution-phase behavior is discussed. The oligopeptides studied here have applications for tag-based protein purification methods, as therapeutics for diseases caused by elevated metal ion levels or as inhibitors for metal-protein enzymes such as matrix metalloproteinases.

Synthesis of organosilocane allied N-heteroaryl Schiff base chemosensor for the detection of Cu2+ metal ions and their biological applications

N-Heteroaryl organosilocanes-based chemosensors have been synthesized for the recognition of copper metal ions with excellent selectivity.

Engineering proton conductivity in melanin using metal doping.

Long range electrical conduction in biomaterials is an increasingly active area of research, which includes systems such as the conductive pili, proteins, biomacromolecules, biocompatible conductive polymers and their derivatives. One material of particular interest, the human skin pigment melanin, is a long range proton conductor and recently demonstrated as capable of proton-to-electron transduction in a solid-state electrochemical transistor platform. In this work, a novel "doping strategy" is proposed to enhance and control melanin's proton conductivity, potentially enhancing its utility as a transducing material. By chelating the transition metal ion Cu(ii) into the bio-macromolecular matrix, free proton concentration and hence conductivity can be modulated. We confirm these observations by demonstrating enhanced performance in a next generation electrochemical transistor. Finally, the underlying mechanism is investigated via the use of a novel in situ hydration-controlled electron paramagnetic resonance study, deducing that the enhanced proton concentration is due to controlling the internal solid-state redox chemistry of the intrinsic polyindolequinone structure. This doping strategy should be open to any transition metal ions that bind to hydroquinone systems (e.g. polydopamine). As such, the tailoring strategy could make other soft solid-state ionic systems more accessible to applications in bioelectronics, leading to the creation of higher performance ion-electron coupled devices.

Synthesis, Photophysical, Thermal and Crystallographic Studies of 3‐Aminocoumarin Based Monobasic κ3‐O,N,O‐tridentate/ κ2‐N,O‐bidentate Schiff Base Divalent Complexes

AbstractThe reaction of 3‐Amino coumarin based Schiff base ligands HL1 and HL2 with metal acetates in refluxing ethanol affords access to a new series of neutral mononuclear divalent complexes [MII‐κ3‐bis‐O,N,O‐tridentate Schiff base‐ HL1/ HL2] {HL1, MII=Co (1), Ni (2) or Zn (3); HL2, MII=Co (4), Ni (5) or Zn (6)}, [CuII‐κ2‐bis‐N,O‐bidentate Schiff base‐HL1] (7) and [CuII‐κ2‐bis‐N,O‐bidentate Schiff base‐HL2] (8). Compounds were characterized by microanalysis, standard spectroscopic (viz. MALDI‐TOF‐MS, IR, 1H and 13C NMR, UV‐visible absorption and emission) and TGA/DTA methods. The unambiguous crystal structure of HL1, HL2, complexes 2 and 3 was determined crystallographically. The IR, UV‐visible, EPR spectral and magnetic studies clearly suggest the κ3‐O,N,O‐tridentate‐ coordination mode of HL1 and HL2 towards cobalt(II), nickel(II) and zinc(II) metal ions in 1–6 and κ2‐N,O‐bidentate‐coordination mode towards copper(II) metal ions in 7 and 8. Notably, compounds fluoresce a medium to strong emissions in the visible region is observed with concomitant Stokes shifts of ≈ 90 nm. UV‐visible transmittance spectral study reveals the semiconducting nature of HL1, HL2, complexes 1–8 gave with band gap energy of 1.57‐2.24 electron volts. The molecules of HL1, HL2, 2 and 3 are stabilized by various intermolecular CH…π, CH…O and π…π contacts that efficiently managed the growth of self‐assembly in three dimensions and form infinite molecular layers in the solid state.

An investigation on geometry and metal interactions in multi metallic porphyrin complexes – EPR studies [microwave power saturation and degree of covalency

Innovative stylish materials can be synthesized and designed at the molecular level by attaching well characterized and tailored functionalities that have various applications. A series of meso-tetracuperated porphyrin-Schiff base complexes has been prepared from metallo-5,10,15,20-tetrakis(4-hydroxyphenyl) porphyrins (M = Cu(II), VO(II) and Ni(II)) and salicylideneamino-2-(N,N-dimethylamino)ethane copper(II) perchlorate under a nitrogen atmosphere and their electron paramagnetic resonance (EPR) spectra have been studied. The steric hindrance and electronic effects of the substituted groups and the characteristics of the different metal ions are the major patrons in inducing the properties of the compounds. From detailed spectral analysis and complete simulation, the results reveal a dipolar interaction between the central copper metal ion of the porphyrin and the meso-copper ions, but no interaction between the vanadyl group and the meso-copper ions. Through studying the EPR properties of these compounds, it is clear that novel EPR oximetry materials can be found and this will help to extend the applications of EPR in vivo.

Quaternized Chitosan-Coated Montmorillonite Interior Antimicrobial Metal-Antibiotic in Situ Coordination Complexation for Mixed Infections of Wounds.

Conventional drug delivery systems for natural clay materials still face critical challenges in their practical application, including multiple bacterial infections, combined infection of bacteria and fungi, and low sterilization efficiency. In this work, we address these challenges using the multifunctional montmorillonite nanosheet-based (MMT-based) drug nanoplatform, which involves the antibiotic 5-fluorocytosine (5-FC), antibacterial metal copper ions, and quaternized chitosan (QCS). Composite material QCS/MMT/5-FCCu can can strongly inhibit Staphylococcus aureus (a typical Gram-positive bacterium), Escherichia coli (a typical Gram-negative bacterium), and Candida albicans (a fungus)because 5-FC coordinates with copper ions in situ anddueto the deposition of QCS. The subsequent drug release behavior of 5-FCCu was studied, and the results show an initial high concentration kills microorganisms and long-acting sustained release inhibition. Moreover, in vivo wound experiments and toxicity experiments show the promotion of wound healing and excellent biocompatibility. As a demonstration of the utility of the latter, we have shown that the MMT-based smart platform can be used for the treatment of mixed infections of wounds.

Optical, electrochemical, thermal, biological and theoretical studies of some chloro and bromo based metal-salophen complexes

Copper, cobalt and zinc-salophen complexes 3–8 were prepared from the reaction of N,N-bis(salicylidene)4-chloro-1,2-phenylendiamine (1) or N,N-bis(salicylidene)4-bromo-1,2-phenylendiamine (2) with their respective acetate salts. All compounds were characterized with common techniques. In additional, optical, electrochemical, thermal and antibacterial properties of ligands and their complexes were studied. Schiff base ligands 1 and 2 showed the intense emission band at 476 nm in the fluorescence spectra. The emission process of these ligands is related to the excited state intramolecular proton transfer phenomenon (and also π→π* transitions). In general, after the incorporation of copper, cobalt and zinc metal ions into the structure of ligands 1 and 2, the emission intensity of the ligands totally quenched. It can be attributed to the changes in the conformational rigidity of the structure of ligands upon complexation. Thermal stability of complexes was proved by TGA analysis. The cyclic voltammogrames of Cu (II) complexes displayed quasi-reversible one electron Cu(II)/Cu(I) redox process, while those of their cobalt counterparts exhibited two reversible redox couples of Co(II)/Co(I) and Co(III)/Co(II). The investigation of antibacterial activity against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and carbapenem &colistin resistant Klebsiella pneumoniae showed both Co(II) complexes 4 and 7 have remarkable antibacterial activity. The antibacterial effect of cobalt complexes against K. pneumoniae is of high interest as the bacterium, is resistant to two most important therapeutic options for treatment of multi-drug resistant Gram-negative bacteria, including polymyxins and carbapenems. Moreover, DFT investigations were performed to obtain a better understanding of structure of compounds 1–8. The values of band gap energies revealed ability of all compounds for using in optical devices. Finally, the electronic spectra of compounds are analyzed by TD-DFT calculations at the B3LYP/6-311G level for Schiff base ligands and the B3LYP/LANL2DZ level for complexes.

Magnetic mesoporous silica of loading copper metal ions for enrichment and LC-MS/MS analysis of salivary endogenous peptides

Peptidomics research is of great significance for discovering potential biomarkers and monitoring human diseases. As a kind of common clinical biofluid, saliva known for its noninvasive collection and easy accessibility has been widely used in peptidomics research. In this article, we combined immobilized metal ions affinity chromotography (IMAC) with mesoporous material and proposed the copper ion doped magnetic mesoporous silica material (denoted as Fe3O4@mSiO2-Cu2+) which had a large surface area of 221 m2 g−1 and pore volume of 0.20 cm3 g−1. By immobilizing copper ions onto the mesopore walls, the standard peptide Angiotensin II could be identified in an extremely low concentration of 0.1 fmol μl−1 and in a mass ratio of 1:500 (Angiotensin II:BSA, m/m), which indicated significant sensitivity and a great size-exclusive ability. In addition, the introduction of polydopamine (PDA) made Fe3O4@mSiO2-Cu2+ more hydrophilic and biocompatible which could improve the profiling of endogenous peptides in bio-sample. Finally, 131 endogenous peptides were identified in human saliva after enrichment with Fe3O4@mSiO2-Cu2+. Therefore, Fe3O4@mSiO2-Cu2+ nanoparticles provided a promising candidate protocol for biomarker discovery.

Co-Doping Effects of Iron and Copper into Carbon Nanotubes on Oxygen Reduction Reaction Activity

Polymer electrolyte fuel cells (PEFCs), which can efficiently convert hydrogen into electricity without using fossil fuels, are a promising energy conversion device. In cathodes of PEFCs, oxygen reduction reaction (ORR) occurs and its low reaction rate limits the performance of PEFCs. Therefore, the electrocatalysts for the ORR are necessary. Currently, platinum-based electrocatalysts for the ORR are mainly used because platinum shows the highest electrocatalytic activity in the metals. Since platinum metal is expensive and rare, to make the fuel cells more widely used, there is a need to develop non-platinum-based electrocatalysts based on iron and/or copper with high ORR activity1,2,3,4). A cytochrome c oxidase (CcO), which is a metalloenzyme and contains iron and copper metal ions, catalyzes the ORR efficiently to produce ATP in mitochondria5) and its activity is higher than that of artificial platinum-based electrocatalysts6). Metalloenzymes are not practical because of their stability and difficulty in isolation and purification. In this study, we developed iron-copper co-doped carbon electrocatalysts (Fe/Cu/CNT) synthesized from the mixtures of Fe and/or Cu complexes and carbon nanotubes in heat treatment inspired by the CcO’s active center. Synthetic conditions of Fe : Cu metal ratios and heating temperatures were optimized. The ORR activity was evaluated by hydrodynamic voltammetry using a rotating ring disk electrode in 0.05 M sulfuric acid aqueous solution saturated with oxygen. The activity of Fe/Cu/CNT electrocatalyst was compared with two electrocatalysts: iron-doped carbon electrocatalyst (Fe/CNT) and copper-doped carbon electrocatalyst (Cu/CNT). The Fe/Cu/CNT catalyst showed more positive onset potential for the ORR than Fe/CNT and Cu/CNT, indicating that Fe/Cu/CNT is more active and the coexistence of iron and copper in CNTs contributes to the improvement of ORR activity. References Kato et al., Chem. Lett., 45, 1213–1215 (2016).Kato et al., Appl. Energy Mater., 1, 2358–2364 (2018).Chung et al., Science, 357, 479–484 (2017).Yasuda et al., Adv. Funct. Mater., 26, 738–744 (2016).Sakamoto et al., PNAS, 108, 12271–12276 (2011).Kjaergaard et al., Inorg. Chem. 49, 3567–3572 (2010).

Structural characterisation and theoretical study of a dinuclear copper(II) complex bridged by meta-phenylenediiminophenolate moiety

A dinuclear doubly bridged copper(II) complex [Cu2L2] where L represents N, N′-bis(3-ethoxysalicylidene)-4-methyl-1,3-phenylenediamine has been synthesised. The ligand was characterised by elemental analysis and spectroscopic techniques such as 1H NMR, 13C NMR, FT–IR, UV–visible and ESI–mass. The copper(II) complex was characterised using partial elemental analysis, FT-IR and UV–visible spectral techniques. The solid state structure of the complex was carried out using single crystal X-ray diffraction. The crystallographic study reveals that the two copper(II) metal ions are four coordinated (O2N2) via phenolate O and azomethine N atoms, forming an unusual geometry between tetrahedral and square-planar. Cyclic voltammetry of complex reveals two consecutive quasi-reversible one electron redox couples corresponding to CuII–CuII/CuII–CuI and CuII–CuI/CuI–CuI. Density Functional Theory (DFT) and Time-dependent density functional theory (TD–DFT) calculations were carried out for the determination of the optimized structures. The theoretically obtained fundamental vibrational frequencies show good agreement with observed values. The ligand binds to Cu(II) in 1:1 stoichiometry as determined by Job's plot and the binding constant is calculated as 6.8 × 102 M−1 in solution phase. The photoluminescence property of the complex has also been investigated to understand its emission behaviour.

Synthesis, molecular structure, anti-microbial, anti-oxidant and enzyme inhibition activities of 2-amino-6-methylbenzothiazole and its Cu(II) and Ag(I) complexes

Molecular structure of 2-amin-6-methylbenzothiazole, 1 and its coordination complexes with Ag(I) and Cu(II) were determined by X-ray diffraction. The ligand 2-amin-6-methylbenzothiazole (hereafter represented as L in general formula of complexes) and [AgL2]NO3 crystallize in orthorhombic crystal systems and CuL2(OAc)2 complex is monoclinic. Ligand and its Ag(I) complex possess space groups Pbcn and Cu(II) complex has a space group P21/c. Complex bis(2-amino-6-methylbenzothiazole)diacetatocopper(II), 2 and bis(2-amino-6-methylbenzothiazole)silver(I) nitrate, 3 were obtained by reacting ligand with respective metal salt in a molar ratio 2:1, respectively. The coordination environment of copper metal is octahedral where acetate acts as bidentate ligand and 2-amino-6-methylbenzothiazole occupies trans position with respect to each other. The ligand contains three possible coordination sites (endocyclic nitrogen, exocyclic nitrogen and sulphur). Among three nucleophilic centers the endocyclic nitrogen is more basic and readily coordinates to the metal ion (both Cu and Ag). Nitrate group plays an important role in stabilizing the supramolecular structure of Ag complex wherein NO…H2N- interactions are very effective. Non-covalent interactions in molecules make them efficient medicines. On the basis of certain secondary interactions, compounds 1–3 were expected to be biologically active and were studied as antibacterial, antifungal, antioxidant agents and enzyme inhibitors. Moderate activities against selected strains were observed for the ligand and its complexes. It was observed that the antibacterial and antifungal potentials of the ligand were enhanced by complexation with copper(II) and silver(I) metal ions.

Effectiveness of a Cassava Peel Adsorbent on the Absorption of Copper (Cu2+) and Zinc (Zn2+) Metal Ions

Cassava peel waste can be used as an adsorbent to remove heavy metal pollution from industrial liquid waste. This study aims to determine the effect of the mesh size and operational temperature of a cassava peel adsorbent on the adsorption of heavy metal ions of copper (Cu2+) and zinc (Zn2+). This study concerns on the ability to absorb the heavy metals copper (Cu2+) and zinc (Zn2+), the characteristics of the adsorbent (functional group), and the adsorption capacity for isothermal adsorption using the Langmuir and Freundlich models. The cassava peels were crushed, dried, ground and sieved with 80, 100 and 120 mesh sieves. The cassava peel powder was activated with HNO3 and used to absorb metal ions from the model liquid waste at different temperatures of 35°C, 45°C and 55°C. The cassava peel adsorption process was analyzed using AAS, SEM and FT-IR analyses. The results of the study showed that the optimum conditions for the cassava peel adsorbent to absorb copper (Cu2+) and zinc (Zn2+) metal ions are 120 mesh in size and an operating temperature of 35°C to obtain adsorption values of 55.19% for copper (Cu2+) and 41.7% for zinc (Zn2+). Functional groups present in the cassava peel adsorbent include O-H, N-H, C=O, and C-N. Among the two widely used isotherms tested (i.e., Langmuir and Freundlich models), the experimental data were found to mostly closely resemble the Freundlich isotherm.