Search Results (32)

Background/Objectives: Leishmaniasis constitutes one of the most fatal parasitic diseases globally, adversely impacting the health of individuals residing in both intertropical and temperate zones. In these geographical areas, the administration of treatment is often inconsistent and largely ineffective with the available pharmaceuticals, as these exhibit more pronounced side effects than the therapeutic advantages they purport to provide. Methods: Consequently, the current investigation seeks to engage in molecular modeling of novel pharmacological candidates incorporating 1,2,3 disubstituted triazole moieties, coordinated with Cu^II metal centers, in pursuit of promising bioactive properties. Results: Two complexes were prepared and X-ray analysis revealed a comparable structural configuration surrounding the copper (II) atom. The planar square coordination geometry was elucidated through the assessment of the ${\tau }_4=0$ (tau four) parameters. The comprehensive characterization encompasses HRMS-ESI (+), NMR, elemental analyses, mid-infrared, and UV-vis spectroscopic techniques. Time-dependent density functional theory (TD-DFT) analyses will substantiate the findings obtained through UV-vis spectroscopy. Crucially, the biological assays against Leishmania (L.) amazonensis revealed that Complex 1 exhibited outstanding potency against the intracellular amastigote form, demonstrating a half-maximal inhibitory concentration (IC₅₀) of 0.4 µM. This activity was 6-fold higher than that of amphotericin B (IC₅₀ = 2.5 µM) and 33-fold higher than pentamidine (IC₅₀ = 13.3 µM). Furthermore, Complex 1 showed a promising selectivity index (SI = 9.7) against amastigotes, surpassing the reference drugs and meeting the criteria for a lead compound. While less active on promastigotes, both complexes demonstrated high stability in DMSO solution, a prerequisite for biological testing. Conclusions: These results unequivocally identify Complex 1 as a highly promising candidate for the development of new antileishmanial therapies, warranting further in vivo studies. Full article

In the current research a series of new copper(II) complexes with novel acylhydrazone ligands were synthesized and their antibacterial and anticancer activities were determined. The complexes were characterized by molecular spectroscopy (FT-IR and UV-Vis) and conductivity measurements. Additionally, their structure was confirmed by single-crystal X-ray analysis. The crystallographic data revealed that all compounds are mononuclear Cu(II) species. The Cu(II) ion is four-coordinated by the ONO donor set from mono-deprotonated hydrazone ligand and one Cl^¯ anion, forming distorted square-planar geometry. The biological studies revealed that the compounds exhibit high antimicrobial activity, especially against Gram-positive bacteria, in some cases greater than the reference substances, and better activity than free ligands. The tested complexes possessed the lowest MIC and MBC values towards Staphylococcus epidermidis ATCC 12228 and Micrococcus luteus ATCC 10240. Furthermore, they showed no toxicity towards normal cell lines. Full article

This study systematically investigates the solvent-dependence of copper(II) extraction using di-2-ethylhexyl phosphoric acid (D2EHPA) across a range of polar and non-polar diluents, including chloroform, dichloromethane, carbon tetrachloride, cyclohexane, 1-octanol, and methyl isobutyl ketone (MIBK). Through analysis of extraction constants and distribution coefficients at varying pH levels, it was demonstrated that solvent polarity and dipole moment critically influenced the coordination geometry and extraction efficiency of the Cu(II)-D2EHPA complex. Notably, the highest extraction efficiencies were exhibited by 1-octanol and cyclohexane. A solvent-dependent structural transition was revealed by Ultraviolet–Visible (UV) spectroscopic evidence: tetrahedral coordination was dominated in polar media, while square planar geometries prevailed in non-polar environments. These findings establish a direct correlation between diluent properties and the extractant’s performance, offering a mechanistic framework for optimizing industrial-scale copper recovery processes. The insights gained highlight the importance of solvent selection in tailoring metal extraction systems for specific applications. 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

Current breast cancer therapies are unable to positively impact the lives of a significant proportion of diagnosed patients (24% based on 10-year survival rate). Breast cancer relapse and metastasis, the leading cause of breast cancer-associated deaths, is linked to the existence of breast cancer stem cells (CSCs). Redox-modulating metal complexes have been used to perturb the redox balance in breast CSCs and effect cell death. Here, we sought to expand this promising class of anti-breast CSC agents. Specifically, we report the synthesis, and anti-breast CSC properties of a series of copper(II) complexes bearing regioisomeric vanillin Schiff base ligands (1–4). X-ray crystallography studies show that the copper(II) complexes 1–4 adopt square planar geometries with the copper(II) centre coordinated to two vanillin Schiff base ligands. The most effective copper(II) complex within the series 4 displays low micromolar potency towards breast CSCs, up to 4.6-fold higher than salinomycin and cisplatin. Mechanistic studies indicate that copper(II) complex 4 elevates reactive oxygen species levels in breast CSCs, leading to activation of the JNK/p38 pathway and caspase-dependent apoptosis. Overall, this work expands the library of anti-breast CSC copper(II) complexes and provides insight into their mode of action. Full article

To increase the number of potential materials for application as MRI contrast agents, several Cu(II) complexes were synthesized. Cu(II) complexes were chosen because they are less expensive in comparison with the presently used Gd(III), Mn(II) and other agents. Pyridine-2-carboximidamide (1), pyrimidine-2-carboximidamide (2) and pyrazole-2-carboximidamide (3) in the form of different salts along with CuCl₂ and NaCl or CuBr² and NaBr were used to obtain four Cu(II) complexes: dichloro-pyrimidine-2-carboximidamide copper(II) (4), dibromo-pyrimidine-2-carboximidamide copper(II) (5), dichloro-pirazole-2-carboximidamide copper(II) (6), and dibromo-pirazole-2-carboximidamide copper(II) (7). X-ray diffraction analysis revealed that molecular complexes 4–7 contain square planar coordinated Cu(II) atoms and their structures are very similar, as well as their packing in crystals, which allows us to consider them isomorphs. The same synthetic approach to complex preparation where NaCl or NaBr was not used brought us to the formation of dimeric complexes μ-chloro{chloro(pyridine-2-carboximidamide)copper(II)} (8) and μ-chloro{chloro(pyrimidine-2-carboximidamide)copper(II)} (9). In the dimeric complexes, two fragments which were the same as in monomeric complexes 4–7 are held together by bridging Cu-Cl bonds making the coordination of Cu equal to 5 (square pyramid). In dimeric complexes, axial Cu-Cl bonds are 2.7360 and 2.854 Å. These values are Cu-Cl bonds on the edge of existence according to statistical data from CSD. Synthesized complexes were characterized by IR spectroscopy, TGA, PXRD, EPR, and quantum chemical calculations. The higher thermal stability of monomer pyrimidine-based complexes with Cl and Br substituents makes them more prospective for further studies. Full article

The 3d transition metal (Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II)) complexes, supported by anions of sterically demanding β-diketones, 1,3-dimesitylpropane-1,3-dione (HL^Mes) and 1,3-bis(3,5-bis(trifluoromethyl)phenyl)-3-hydroxyprop-2-en-1-one (HL^CF3), were synthesized and evaluated for their antitumor activity. To assess the biological effects of substituents on phenyl moieties, we also synthesized and investigated the analogous metal(II) complexes of the anion of the less bulky 1,3-diphenylpropane-1,3-dione (HL^Ph) ligand. The compounds [Cu(L^CF3)₂], [Cu(L^Mes)₂] and ([Zn(L^Mes)₂]) were characterized by X-ray crystallography. The [Cu(L^CF3)₂] crystallizes with an apical molecule of solvent (THF) and features a rare square pyramidal geometry at the Cu(II) center. The copper(II) and zinc(II) complexes of diketonate ligands, derived from the deprotonated 1,3-dimesitylpropane-1,3-dione (HL^Mes), adopt a square planar or a tetrahedral geometry at the metal, respectively. We evaluated the antitumor properties of the newly synthesized (Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II)) complexes against a series of human tumor cell lines derived from different solid tumors. Except for iron derivatives, cellular studies revealed noteworthy antitumor properties, even towards cancer cells endowed with poor sensitivity to the reference drug cisplatin. Full article

The new diprotic ligand 3,5-di-tert-butylsalicylaldehyde 4-ethyl-3-thiosemicarbazone, abbreviated H₂(3,5-t-Bu₂)-sal4eT, exists as the thio-keto tautomer and adopts the E-configuration with respect to the imine double bond, as evidenced by single-crystal X-ray analysis and corroborated by spectroscopic characterisation. Upon treatment with Cu(OAc)₂·H₂O in the presence of either 2,9-dimethyl-1,10-phenanthroline (2,9-Me₂-phen) or 1,10-phenanthroline (phen) as a co-ligand in MeOH, this thiosemicarbazone undergoes conformational transformation (relative donor-atom orientations: syn,anti → syn,syn) concomitantly with tautomerisation and double deprotonation to afford the ternary copper(II) complexes [Cu{(3,5-t-Bu₂)-sal4eT}(2,9-Me₂-phen)] (1) and [Cu₂{3,5-t-Bu₂)-sal4eT}₂(phen)] (2). Crystallographic elucidation has revealed that complex 1 is a centrosymmetric dimer of mononuclear copper(II) complex molecules brought about by intermolecular H-bonding. The coordination geometry at the copper(II) centre is best described as distorted square pyramidal in accordance with the trigonality index (τ = 0.14). The co-ligand adopts an axial–equatorial coordination mode; hence, there is a disparity between its two Cu–N coordinate bonds arising from weakening of the apical one as a consequence of the tetragonal distortion. The axial X-band ESR spectrum of complex 1 is consistent with retention of this structure in solution. Complex 2 is a centrosymmetric dimer of dinuclear copper(II) complex molecules exhibiting intermolecular H-bonding and π-π-stacking interactions. The two copper(II) centres, which are 4.8067(18) Å apart and bridged by the thio-enolate nitrogen of the quadridentate thiosemicarbazonate ligand, display two different coordination geometries, one distorted square planar (τ₄ = 0.082) and the other distorted square pyramidal (τ₅ = 0.33). Such dinuclear copper(II) thiosemicarbazone complexes, which are crystallographically characterised, are extremely rare. In vitro, complexes 1 and 2 outperform cisplatin as antiproliferative agents in terms of potency and selectivity towards HeLa and MCF-7 cancer cell lines. Full article

The treatment of 2-(ArNC(H))C₆H₄-HNC₉H₆N with n-BuLi and the subsequent addition of CuCl₂ afforded the anilido-aldimine Cu(II) complexes 1-5 Cu[{2-[ArN=C(H)]C₆H₄}N(8-C₉H₆N)]Cl (Ar = 2,6-ⁱPr₂C₆H₃ (1), 2,4,6-(CH₃)₃C₆H₂ (2), 4-OCH₃C₆H₄ (3), 4-BrC₆H₄ (4), 4-ClC₆H₄ (5)), respectively. All the copper complexes were fully characterized by IR, EPR and HR-MS spectra. The X-ray diffraction analysis reveals that 2 and 4 are mononuclear complexes, and the Cu atom is sitting in a slightly square-planar geometry. These Cu(II) complexes have exhibited excellent catalytic activity in the Chan–Lam coupling reactions of benzimidazole derivatives with arylboronic acids, achieving the highest yields of up to 96%. Full article

The first single crystal structure of the homoleptic copper (II) ML₂ complex (M=Cu (II), L = curcumin) was obtained and its structure was elucidated by X-ray diffraction showing a square planar geometry, also confirmed by EPR. The supramolecular arrangement is supported by C-H···O interactions and the solvent (MeOH) plays an important role in stabilizing the crystal packing Crystallinity was additionally assessed by XRD patterns. The log P value of the complex (2.3 ± 0.15) was determined showing the improvement in water solubility. The cytotoxic activity of the complex against six cancer cell lines substantially surpasses that of curcumin itself, and it is particularly selective against leukemia (K562) and human glioblastoma (U251) cell lines, with similar antioxidant activity to BHT. This constitutes the first crystal structure of pristine curcumin complexed with a metal ion. Full article

The growth of antibiotic resistance is a matter of worldwide concern. In parallel, cancer remains one of the main causes of death. In the search for new and improved antiproliferative agents, one of the strategies is the combination of bioactive ligands and metals that are already consolidated in the synthesis of metallopharmaceutical agents. Thus, this work deals with the synthesis, characterization, and study of naproxen (Nap)-based complexes of copper(II) and platinum(II) as antiproliferative agents. The copper complex (Cu–Nap) presents a binuclear paddle-wheel structure in a 1 Cu:2 Nap:1 H₂O molar composition, in which Cu(II) is bonded to the carboxylate oxygens from naproxenate in a bidentate bridging mode. The platinum complex (Pt–Nap) was identified as the square planar cis-[Pt(Nap)₂(DMSO)₂] isomer, in which Pt(II) is bonded to the carboxylate oxygen atom of Nap in a monodentate fashion. Both complexes were inactive against the Gram-positive and Gram-negative bacterial strains assessed. Pt–Nap presented low cytostatic behavior over a set of tumor cells, but good viability for normal cells, while Cu–Nap was cytotoxic against all cells, with a cytocidal activity against glioma tumor cells. Full article

A combination of 4-styrylpyridine (spy) and 1-adamantanecarboxylic acid (Hadc) was employed in the assembly reactions with Zn(II) and Cu(II) nitrates. The photoreactivity of the products was compared and discussed on the basis of the structure–function relationship. Zinc(II) complex 1 is a trinuclear species of type [Zn₃(spy)₂(adc)₆] in which three zinc(II) atoms are linearly arranged, with two adjacent zinc(II) atoms linked by three bridging carboxylates. Two spy ligands occupy both terminal positions, yielding the overall structure of a six-bladed windmill. Copper(II) complex 2, [Cu(spy)₂(adc)₂][Cu₂(spy)₂(adc)₄]·2DMF, is an inorganic cocrystal comprising a mononuclear complex with a trans square planar geometry and a dinuclear complex with a paddle-wheel structure. In the photoreaction experiments characterized by ¹H NMR spectroscopy, the zinc(II) complex was found to be photoinert, while the copper(II) complex was photoreactive to form a cyclobutene ring via the [2+2] photodimerization between two spy ligands, resulting in the preparation of a one-dimensional chain as a coordination polymer. The separations of the C=C bond pair obtained from the crystal structures for both products also support their photoreactivity. For example, the spy ligands from two adjacent monocopper(II) complexes are aligned in a head-to-tail manner with the separation of 3.899 Å between the C=C bond pair, satisfying the so-called Schmidt criteria (<4.2 Å). However, no other products satisfy this condition. Full article

Two new isomeric complexes [CuBr₂(R-bian)] (R = 4-Me-Ph (1), 2-Me-Ph (2)) were obtained by reacting copper(II) bromide with 1,2-bis[(2-methylphenyl)imino]acenaphthene ligands and characterized. The crystal structure of 2 was determined by X-ray diffraction analysis. The copper atom has a distorted square-planar environment; the ω angle between the CuN₂ and CuBr₂ planes is 37.004°. The calculated ω parameters for optimized structures 1 and 2 were 76.002° and 43.949°, indicating significant deviations from the ideal tetrahedral and square-plane geometries, respectively. Molecules 2 form dimers due to non-covalent Cu···Br contacts, which were analyzed by DFT calculations. The complexes were also characterized by cyclic voltammetry and UV-Vis spectroscopy. A quasi-reversible Cu(II)/Cu(I) redox event with E_1/2 potentials of 0.81 and 0.66 V (vs. SHE) was found for 1 and 2, respectively. The electronic absorption spectra showed the presence of Cu(I) species as a result of the partial reduction of the complexes in the acetonitrile solution. Both complexes were tested as homogenous catalysts for the oxidation of isopropylbenzene (IPB) in acetonitrile at low temperatures. Differences in the mechanism of the catalytic reaction and the composition of the reaction products depending on the oxidizing ability of the catalyst were revealed. Full article

Three new tripod tetradentate phenolate-amines (H₂L¹, H₂L⁴ and H₂L⁹), together with seven more already related published ligands, were synthesized, and characterized. With these ligands, two new dinuclear doubly-bridged-phenoxido copper(II) complexes (3, 4), and six more complexes (1, 2, 5–8), a new trinuclear complex (9) with an alternative doubly-bridged-phenoxido and –methoxido, as well as the 1D polymer (10) were synthesized, and their molecular structures were characterized by spectroscopic methods and X-ray single crystal crystallography. The Cu(II) centers in these complexes exhibit distorted square-pyramidal arrangement in 1–4, mixed square pyramidal and square planar in 5, 6, and 9, and distorted octahedral (5+1) arrangements in 7 and 8. The temperature dependence magnetic susceptibility study over the temperature range 2–300 K revealed moderate–relatively strong antiferromagnetic coupling (AF) (|J| = 289–145 cm⁻¹) in complexes 1–6, weak-moderate AF (|J| = 59 cm⁻¹) in the trinuclear complex 9, but weak AF interactions (|J| = 3.6 & 4.6 cm⁻¹) were obtained in 7 and 8. No correlation was found between the exchange coupling J and the geometrical structural parameters of the four-membered Cu₂O₂ rings. Full article

This article provides detailed redox data on nine differently substituted benzophenones and ten square planar copper(II) complexes containing 2-hydroxyphenones obtained by cyclic voltammetry (CV) experiments. The information provided is related to the published full research articles “An electrochemical and computational chemistry study of substituted benzophenones” (Electrochim. Acta2021, 373, 137894) and “Electrochemical behaviour of copper(II) complexes containing 2-hydroxyphenones” (Electrochim. Acta2022, 424, 140629), where the CVs and electrochemical data at mainly one scan rate, namely at 0.100 Vs⁻¹, are reported. CVs and the related peak current and voltage values, not reported in the related research article, are provided in this article for nine differently substituted benzophenones and ten differently substituted copper-2-hydroxyphenone complexes at various scan rates over more than two orders of magnitude. The redox data presented are the first reported complete set of electrochemical data of nine 2-hydroxyphenones and ten copper(II) complexes containing 2-hydroxyphenone ligands. Full article