Search Results (330)

Annually, more than 10,000 synthetic dyes are produced worldwide, generating around 280,000 tons of waste, posing risks to human and aquatic life, and potentially creating even more toxic products than the dyes themselves. This study aims to immobilize organic dyes, forming hybrid pigments using ZnO as support obtained through starch combustion. ZnO was obtained by starch (sago) combustion and characterized by XRD, SEM and the BET method. It was then used for the adsorption of orange and green textile dyes, evaluating the adsorbent dosage, initial dye concentration, contact time, and selectivity with copper ions. The removal studies indicated up to 100% removal of both dyes at low concentrations. The co-adsorption system showed excellent performance, with removal percentages exceeding 90% for both textile dyes and Cu (II) ions. Hybrid pigments were assessed for solvent resistance and durability under extended white light exposure. ZnO immobilized the dyes, showing resistance to organic solvents and good stability under prolonged white light exposure. Full article

In this study, 3-chlorothiophene-2-carboxylic acid (HL) was used as a main ligand to successfully synthesize four novel complexes: [Cu(L)₂(Py)₂(OH₂)₂] (1), [Co(L)₂(Py)₂(OH₂)₂] (2) (Py = pyridine), [{Ni(L)₂(OH₂)₄}₂{Ni(L)(OH₂)₅}]L•5H₂O (3), and [{Co(L)₂(OH₂)₄}₂{Co(L)(OH₂)₅}]L•5H₂O (4). All four compounds were identified by elemental analysis and ESI mass spectrometry, and subsequently characterized by IR spectroscopy, UV-visible diffuse reflectance spectroscopy, electron paramagnetic resonance spectroscopy, thermogravimetric analysis, single-crystal X-ray crystallography, and cyclic voltammetry. X-ray analyses revealed that complexes 1 and 2 exhibit a centrosymmetric pseudo-octahedral coordination geometry; the copper (II) and cobalt (II) metal ions, respectively, are located at the crystallographic center of inversion. The coordination sphere of the copper (II) complex is axially elongated in accordance with the Jahn–Teller effect. Intriguingly, for charge neutrality, compounds 3 and 4 crystallized as three independent mononuclear octahedrally coordinated metal centers, which are two $\left[\mathrm{M}{\mathrm{L}}_2{\left({\mathrm{O}\mathrm{H}}_2\right)}_4\right]$ complex molecules and one ${\left[\mathrm{M}\mathrm{L}{\left({\mathrm{O}\mathrm{H}}_2\right)}_5\right]}^{+}$ complex cation (M = ${\mathrm{N}\mathrm{i}}^{\mathrm{I}\mathrm{I}}$ and ${\mathrm{C}\mathrm{o}}^{\mathrm{I}\mathrm{I}}$, respectively), with the ligand anion ${\mathrm{L}}^{-}$ serving as the counter ion. The anticancer activities of these complexes were systematically assessed on human leukemia K562 cells, lung cancer A549 cells, liver cancer HepG2 cells, breast cancer MDA-MB-231 cells, and colon cancer SW480 cells. Among them, complex 4 shows significant inhibitory effects on leukemia K562 cells and colon cancer SW480 cells. Full article

The present study compared the adsorption properties of two plant materials and the waste products after their essential oil extraction for removing Cu(II) ions from contaminated water. Methods like SEM, XRD, nitrogen adsorption, DTA, TGA, FTIR, and XPS were used for characterization of the materials. All materials showed similar porosity and structure, favoring Cu(II) biosorption. The effects of contact time, pH, temperature, sample amount, and initial metal concentration on Cu(II) removal were examined. Optimal pH was 4, with equilibrium reached in less than 10 min. Temperature and sample amount do not significantly influence the biosorption. The experimental data were fitted to the Langmuir, Freundlich, and Dubinin–Radushkevich isotherm models, and maximum adsorption capacities were calculated. The four plant materials proved to be effective biosorbents for removing copper ions from contaminated water. Desorption experiments using 1 M HNO₃ and 0.1 M EDTA showed 100% recovery. The reusability of the most effective biosorbent was confirmed through four adsorption/desorption cycles with EDTA. This material was also used to study the possibilities of purifying a real sample of contaminated water. Full article

The electrochemical behavior of copper (II) on glassy carbon from an eutectic mixture of choline chloride (ChCl) and ethylene glycol (EG) was investigated using cyclic voltammetry (CV). The redox and deposition processes were studied for electrolyte concentrations of 0.01 M and 0.5 M Cu(II), with particular attention paid to the effects of different Cu(II) concentrations on the copper deposition potential and morphology of the copper deposits. The CV results showed that the Cu(II) species are reduced to Cu(0) via two separate steps. Higher Cu(II) concentrations in the electrolyte triggered the formation of differently coordinated Cuⁿ⁺ complexes next to the electrode, which shifted the electrodeposition potential of Cu(I)/Cu(0) couples towards more positive values. The Cu deposits were obtained potentiostatically from 0.01 M and 0.5 M Cu(II)-ChCl:EG electrolyte and analyzed using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The different copper concentrations in electrolytes induced different morphologies of electrodeposited copper, where the mixture of irregular grains and carrot or needle-like dendrites was obtained from 0.01 M, and rose-like forms were obtained from 0.5 M electrolytes. This study is the first to identify these rose-like forms and the mechanism of their formation, which is discussed in detail. Full article

This study investigates the adsorption and desorption efficiencies of Cu (II) and Cd (II) from industrial effluents using orange peel powder and a newly developed mixed adsorbent composed of equal parts of activated charcoal (AC) and bone charcoal (BC). The mixed adsorbent (AC + BC) exhibited significantly higher removal efficiencies for both copper and cadmium metal ions compared to orange peel powder. This can be attributed to the high surface area of AC and the negative surface charge of BC, resulting in a synergistic adsorption effect. Batch adsorption experiments were conducted in an orbital shaker at 150–180 rpm for 60 min, followed by thorough rinsing to remove any residual metal ions. The optimal pH for maximum adsorption of Cu (II) and Cd (II) was found to be 6. The effects of adsorbent dosage (ranging from 0.5 to 5 g/L) and contact time (ranging from 15 min to 4 h) on adsorption performance were systematically studied. Regeneration experiments using 0.2 M HCl demonstrated that the adsorption of Cu (II) and Cd (II) on the mixed adsorbent was highly reversible, achieving desorption efficiencies of 90% and 94%, respectively. Notably, Cd (II) consistently exhibited higher desorption rates across all tested dosages. These results confirm the potential of the proposed adsorbent and regeneration strategy for efficient and economical removal of heavy metals from industrial wastewater. Full article

Cuproptosis, a newly discovered copper-dependent programmed cell death pathway, represents a promising approach for anticancer therapy. However, the efficacy of cuproptosis critically depends on intracellular copper accumulation. Traditional copper ionophores have limited therapeutic efficacy due to their reliance on serum copper levels. Therefore, the development of novel copper ionophores to enhance intracellular copper levels is urgently needed. In this study, we targeted a melanoma model and pioneered the application of Bis(2-hydroxyethyl)dithiocarbamic acid copper(II) [Cu(HEDTC)₂] as a highly efficient copper ionophore for inducing cuproptosis in B16 melanoma cells. Compared to conventional copper ionophores, Cu(HEDTC)₂ exhibits superior intracellular copper delivery efficiency, thereby enhancing the induction of cuproptosis. We further constructed a Cu(HEDTC)₂@Soluplus-nanomicelle (CS NM) system designed to disrupt copper ion homeostasis in tumor cells and amplify cuproptosis. In this system, Cu(HEDTC)₂, as a novel copper ionophore, significantly enhanced the copper level in B16 melanoma cells. Upon cellular internalization, CS NM underwent degradation and released copper ions, which subsequently triggered cuproptosis by causing abnormal aggregation of mitochondrial lipoylated proteins. This study provides a new experimental foundation and potential therapeutic strategy for cuproptosis-based cancer treatment. Full article

Transition metal (II) complexes stabilized by 2,6-di(pyrazol-3-yl)pyridine as a novel coplanar tridentate nitrogen-donor ligand have been reported for their unusual structures and photoluminescent properties. In this work, the ligand 2,6-bis(5-isopropyl-1H-pyrazole-3-yl)pyridine (denoted as L) and its transition metal (II) halogenido complexes viz [ZnCl₂(L)] (1), [ZnBr₂(L)] (2), [CuCl₂(L)] (3), and [CuCl(L)(thf)](PF₆) (4) were synthesized and characterized by single crystal X-ray crystal analysis. Its structures contained N–H groups in its pyrazole rings and hydrogen bonds between these N–H donors and the coordinated halogenide ions and lattice solvent molecules. Tautomers between 3-pyridyl and 5-pyridyl substitutes were also observed. In L, the N–H group at the pyrazole nitrogen was located adjacent to the pyridine ring to form hydrogen bonds with adjacent pyrazoles. However, on complexation, the H atoms at the pyrazole nitrogens are shifted remotely to the pyridine. The zinc (II) complexes [ZnCl₂(L)] (1) and [ZnBr₂(L)] (2) possessed distorted trigonal pyramidal structures in the solid state. By comparison, the copper (II) complexes [CuCl₂(L)] (3) and [CuCl(L)(thf)](PF₆) (4) adopted square pyramidal geometry with a Jahn–Teller distortion resulting from their d⁹ electron configurations. Full article

The chemical interaction of salicylic acid, formaldehyde, and sulfuric acid produced a disalicylic ligand (3,3′-dicarboxy-2,2′-dihydroxydiphenylmethane, DCM), which was then allowed to coordinate with copper (II) ions. The solid compounds’ chemical structures were determined using elemental analysis, UV-Vis, FT-IR, MS, ¹H-NMR, PXRD, SEM, TEM, magnetic studies, as well as molecular modeling based on DFT (density functional theory) calculations. It was proposed that the ligand coordinates in a tetradentate fashion with the copper ion to give a square-planar binuclear complex. A significant difference in the diffraction patterns between Cu(II)–DCM (amorphous) and DCM (crystalline) was displayed using an X-ray diffraction analysis. Spherical granules were identified throughout through morphology analysis using SEM and TEM. UV-Vis spectra were used to quantify the optical characteristics such as the energy gap, optical conductivity, refractive index, and penetration depth. The band gap values that lie within the semiconductor region suggested that the compounds could be used for electronic applications. The optimized structure of the synthesized Cu(II)–DCM complex was investigated using DFT and TD-DFT (time-dependent density functional theory) at the B3LYP/6-31G(d, p) level, with the LANL2DZ basis set for Cu in an ethanol solvent and the gas environment modeled by CPCM. The experimental data suggest a square-planar geometry of the Cu(II) binuclear complex. The theoretical calculations support the proposed structure of the compound. The cytotoxicity of the DCM against HCT–116 (human colon cancer) cells was tested, and the outcome exhibited good inhibitions of growth. A molecular docking (MD) examination was carried out to illustrate the binding mode/affinity of the prepared compounds (DCM and Cu(II)–DCM) in the active site of the receptor protein [CDK2 enzyme, PDB ID: 6GUE]. The compounds formed hydrogen bonds with the amino acid residues of the protein, increasing the binding affinity from −7.2 to −9.3 kcal/mol through the coordination process. The information from this current study, particularly the copper complex, is beneficial for exploring new compounds that have anticancer potential. Full article

Coordination polymers are attractive materials for various fields of practical application. The high degree of freedom of choice of metal ions and organic ligands plays a critical role in functional diversification. In the present study, we report the liquid–liquid interfacial synthesis of a 2D bis(terpyridine)copper(II) polymer thin film, Cu-tpy. The synthesized Cu-tpy was characterized by various microscopic observations such as TEM, SEM, and AFM, and spectroscopic measurements such as XPS, Raman spectroscopy, SEM/EDS, and UV–Vis spectroscopy. Synchrotron-radiated X-ray scattering confirmed that Cu-tpy was oriented crystalline films. Moreover, Cu-tpy showed electrochemical micro-supercapacitor behavior in the solid-state owing to its ionic nature. This study expands the potential of bis(terpyridine)metal(II) polymers as electro-functional materials. Full article

Azurin is a small blue copper protein that participates in redox reactions during anaerobic respiration in Pseudomonas aeruginosa, and there are a significant number of studies employing this model to investigate the electron transfer (ET) processes or coordination sphere of metal ion in metalloproteins. Azurin naturally contains Cu(II/I) as a central ion and is redox-active for a single electron ET. Moreover, azurin with no central ion (apo-azurin) is capable of binding other metal cofactors—e.g., Zn(II)—forming redox-inactive Zn-form and many others impacting the redox potential and structural variation in the active site’s arrangement. Also, mutations of amino acid residues in the immediate vicinity of the metal ion can influence the structure and functionality of a particular metalloprotein. Therefore, this review aims to summarize the abundant information about selected topics related to redox reactions and blue copper proteins, particularly azurin, and is structured as follows: (i) introduction to the structure, properties, and physiological role of this group of metalloproteins, (ii) the role of the equatorial and axial ligands of the central metal ions, or metal species, in the active site on the metal coordination sphere’s structure and related determination of the particular azurin form’s redox potentials, and (iii) the effects of the particular amino acid’s moiety (Phe, Tyr and Trp residues together with acceleration employing Trp-Trp π-π stacking interactions contrary to ET distance dependence) on the preferable type of long-range ET mechanism in an azurin-mediated model biomolecule. We assume that azurin is a suitable model to study the structural functionality of a particular central metal ion or individual amino acid residues in the central ion coordination sphere for studying the redox potential and ET reactions in metalloproteins. Full article

The reaction of CuCl₂∙2H₂O, (E)-2-hydroxy-1,2-di(pyridin-2-yl)ethanone oxime (α-pyroxH₂) and Et₃N in refluxing MeOH gave complex [Cu₁₂Cl₁₂(mpydol)₄(pydox)₂(MeOH)₄] (1), where mpydol²⁻ is the dianion of 1,2-dimethoxy-1,2-di(pyridin-2-yl)ethane-1,2-diol and pydox²⁻ is the dianion of (E,E)-1,2-di(pyridin-2-yl)ethanedione dioxime. “Blind” experiments have proven that the transformation of α-pyroxH₂ is copper(II)-assisted. By changing the solvent from MeOH to MeCN, the polymeric compound {[Cu₄Cl₄(pic)₄]}_n (2) was isolated; pic⁻ is the pyridine-2-carboxylato(-1) ligand. The observed α-pyroxH₂ → pic⁻ transformation is also copper(II)-assisted. The topology of the metal ions in 1 can be described as consisting of four consecutive isosceles triangles in a zigzag configuration. Complex 2 is a 2D coordination polymer consisting of Cu^II₄ squares. Complete mechanistic views for the α-pyroxH₂ → mpydol²⁻, pydox²⁻ and pic⁻ transformations are critically discussed. In 1, the six Cu^II ions of the “central” triangles seem to be strongly antiferromagnetically coupled, thus cancelling out their spins ($S_{{\mathrm{Cu}}_6}$ = 0). The two local spins of S = 1/2 for each of the antiferromagnetically coupled “terminal” Cu^II₃ triangles result in an overall S = 1 ground state spin value for 1. In 2, the four Cu^II ions within each tetrameric unit are practically isolated and ferromagnetic interactions occur between these units through Cu^II–(μ-Cl)–Cu^II bridges. Full article

Chitosan was hydro-thermally extracted from grey shrimp carapaces and characterized using various techniques (degree of deacetylation (DD), viscosity, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and surface area analysis (BET)). It was then used for Cu(II) removal in a batch system, achieving a maximum capacity of 89 mg/g under standard conditions. Both pseudo-first-order and pseudo-second-order nonlinear kinetic models described the adsorption of Cu(II) ions on chitosan well, with a better fit of the pseudo-first-order model at low concentrations, while the equilibrium data suggested that the Langmuir model was suitable for describing the adsorption system, with a maximum adsorption capacity of 123 mg/g. A response surface methodology and central composite design were used to optimise and evaluate the effects of six independent parameters: initial Cu(II) concentration, pH, chitosan concentration (S/L), temperature (T), contact time (t), and NaCl concentration on the adsorption efficiency of Cu(II) by the synthesised chitosan. The proposed model was confirmed to accurately describe the phenomenon within the experimental range, achieving an R² value of 1. ANOVA indicated that the initial concentrations of Cu(II) and chitosan concentration (S/L) were the most significant factors, while the other variables had no significant effect on the process. The adsorption capacity of Cu(II) onto the prepared chitosan was also optimised and modelled using artificial neural networks (ANNs). The maximum amount, qmax = 468 mg·g⁻¹, shows that chitosan is a highly effective adsorbent, chelating and complexing for copper ions. Full article

Graphene quantum dots (GQDs) represent a class of promising nanomaterials characterized by adjustable optical properties, making them well suited for applications in biosensing and chemical detection. However, challenges persist in achieving scalable, cost-effective synthesis and enhancing detection sensitivity. In this study, we have developed a simple and environmentally friendly method to prepare blue graphene quantum dots, c-GQDs, using nitronaphthalene as a precursor, and yellow graphene quantum dots, y-GQDs, using nitronaphthalene doped acid. The quantum yield is 29.75%, and the average thickness is 2.08 nm and 3.95 nm, respectively. The synthesized c-GQDs exhibit a prominent cyan fluorescence at a wavelength of 490 nm under excitation at 380 nm, while the y-GQDs show a distinct yellow fluorescence at a wavelength of 540 nm under excitation at 494 nm. The introduction of p-aminobenzoic acid (PABA) introduced a marked red shift in fluorescence, attributed to the electron-withdrawing effect of the carboxyl groups on PABA. This key finding significantly enhanced the sensitivity of GQDs for detecting trace copper(II) ions (Cu²⁺), a heavy metal contaminant posing serious environmental risks. The fluorescence of the GQDs was selectively quenched in the presence of Cu²⁺, facilitating accurate and sensitive detection even in complex ion matrices. Mechanistic studies revealed that the quenching effect is driven by strong static quenching interactions, which inhibit non-radiative transitions. This work not only introduces a scalable method for producing high-performance GQDs but also highlights their potential as effective fluorescent probes for environmental monitoring and heavy metal ion detection. Full article

The reaction in reagent grade acetone of copper(II) nitrate hexahydrate, 2,2′-bipyrimidine (bpm) and potassium iodide in a 1:2:2 molar ratio afforded three different products: an unreduced Cu(II) species, a fully reduced Cu(I) species and a mixed-valent Cu(II)/Cu(I) species. Of these, only the unreduced Cu(II) complex of formula [Cu^II(bpm)₃](I₃)(I) (1) could be structurally characterized, the other two products being initially only isolated as amorphous powders. X-ray quality, beautifully shaped, quasi-black prismatic crystals of compound 2, namely {[Cu^I(I₃)Cu^II(I)(bpm)₂](I₃)}_n, and brick-reddish parallelepipeds of compound 3, namely {[Cu^I₂ (μ-I)₂(bpm)]}_n, were successively obtained through the slow diffusion in H-shaped tubes of aqueous solutions of the three reagents, after extensive optimization of the crystallization conditions. Compound 1 consists of a rare tris(2,2′-bipyrimidine)copper(II) monomeric dication, charge balanced by both iodide and triiodide anions. Compound 3, whose structure as well as optical and photocatalytic properties were recently disclosed, consists of a regular alternating μ-bpm/di-μ-iodide copper(I) chain. Finally, compound 2 consists of a rare, regular alternating mixed-valent Cu(II)-Cu(I) μ-bpm copper chain, showing unusual similarities in the metal coordination environment. The magnetic properties of compound 2 remarkably reveal a very weak antiferromagnetic coupling between the paramagnetic Cu(II) ions which are well separated both intra- and inter-chain. Full article

The bioavailability of dissolved copper (Cu) in seawater is influenced by the presence of natural organic matter. Changes in physicochemical conditions, such as pH, temperature, and salinity, can significantly affect the solubility and speciation of copper, thereby impacting the complexation of Cu(II)-binding organic ligands. The concentration of dissolved Cu in the coastal water of Mersing, Malaysia, was detected by anodic stripping voltammetry (ASV). The natural organic copper(II)-binding ligands (CuL) and their conditional stability constants (log K′) were determined by using the competitive ligand exchange–adsorptive cathodic stripping voltammetry method (CLE–AdCSV) in our samples. The in situ parameters, such as pH, temperature, salinity, and dissolved oxygen (DO), were found to be significantly different between sampling periods and indicated the different physical chemical conditions between the sampling periods. However, we found a consistent concentration of dissolved Cu throughout the water column between sampling periods. This suggests that the presence of a strong class of natural organic ligands (L₁) in Mersing’s coastal water maintains the dissolved Cu(II) ions in the water column and prevents the scavenging and precipitation processes under the seasonal variations. Full article