Base Copper Complexes Research Articles

Synthesis, crystal structure, characterization and antimicrobial activities of ternary chiral mononuclear Schiff base copper(II) complexes.

[CuL1-4(tmen)] is a sequence of four ternary mononuclear Schiff base copper(II) complexes that are derived from L-valine, suitable 5'-substituted-2'-hydroxyacetophenones (where the substituents are -Cl for L1, -Me for L2, -OMe for L3, and -H for L4), and tmen (where tmen-N,N,N',N' tetramethyl ethylenediamine). Without isolating the Schiff base ligand or producing any other intermediate products, all of the complexes were synthesised. These compounds were identified using elemental analysis, molar conductance, UV-Vis, FTIR, EPR, VSM-RT, and CD spectra. Single crystal XRD was used to characterise the structure of Complex 1. The crystalline structure exhibits a distorted square pyramidal shape wherein the Schiff base forms an axial bond with the Cu(II) ion through the ONO-donor, while the chelating ligand tmen exhibits both an equatorial and an axial mode of binding through the NN-donor atoms. Hydrogen bonding and non-covalent CH(methyl)π(phenyl) interaction are two intriguing aspects of compound 1's packing diagram. By calculating the minimum inhibitory concentration (MIC) against harmful bacteria, the synthesised complexes' antimicrobial activity was assessed. According to the bioactivity experiments, the microorganisms employed in this investigation were susceptible to the antibacterial and antifungal properties of copper(II) complexes 1-4. According to the bioactivity experiments, the microorganisms employed in this investigation were susceptible to the antibacterial and antifungal properties of copper(II) complexes 1-4.

In vitro study of the pro-apoptotic mechanism of amino acid Schiff base copper complexes on anaplastic thyroid cancer.

In the endocrine system, anaplastic thyroid cancer (ATC) is extremely aggressive since it inhibits the majority of medications and treatments. Therefore, there is an immediate demand to identify new treatment approaches or drugs to deal with ATC. Recently, amino acid Schiff base copper complexes have received great attention due to their excellent anti-tumor activity. In this research, three copper(II) complexes, [Cu(o-van-D-Trp)(phen)](1), [Cu(o-van-D-Trp)(bipy)](2), [Cu(naph-D-Trp)(bipy)](3), [D-Trp = D-tryptophan; o-van = o-vanillin; naph = 2‑hydroxy-1- naphthaldehyde; phen = 1,10-phenanthroline; bipy = 2,2-biprydine], have been synthesized and investigated as potential anticancer agents. The crystal structure data of the complexes demonstrate that the central copper (II) atom forms a twisted polyhedral environment with nitrogen and oxygen atoms. The MTT results demonstrated that three complexes exhibited superior cytotoxicity against five cell lines of thyroid cancer (Cal-62 cells, ARO cells, KHM-5 m cells, BHP10-3 cells and K1 cells), especially complex 1 with the IC50 values of 0.59±0.05 μM, 2.36±0.47 μM, 1.10±0.87 μM, 0.75±0.09 μM, 1.72±0.06 μM, when cisplatin was used as a control. Research on antitumor mechanisms has demonstrated that complex 1 can significantly reduce the mitochondrial membrane potential, raise autophagy, and produce reactive oxygen species (ROS) in ARO cells in a dose-dependent manner. RNA sequencing study reveals that complex 1 may cause apoptosis in ARO cells and exhibit anticancer efficacy in vitro through ROS-mediated downregulation of Akt and p38 MAPK activation.

Structural, spectroscopic, and biological properties of an asymmetric Cu (II) Schiff-base complex: Synthesis, DNA/BSA interactions, and antimicrobial potential with experimental and computational insights

A copper (II) complex with the asymmetric bidentate Schiff-base ligand (E)-2-(((4-chlorophenyl) imino) methyl) phenol was synthesized and characterized using FTIR and UV–VIS spectroscopy. Photoluminescence studies were conducted on both the copper (II) complex and the free ligand. XRD analysis revealed the copper (II) complex crystallizes in the monoclinic system, space group P21/c. The complex structure was optimized using DFT calculations with B3LYP/6-31G+(d,p) and Lanl2dz basis sets, with QTAIM and NBO analyses confirming complex formation. The energy gap of the copper (II) complex was determined to be 3.701 eV (alpha state) and 2.764 eV (beta state). MEP analysis of the optimized structure indicated a hydrophobic environment around the nitrogen atom, with the molecule exhibiting overall hydrophobicity. The chlorine atoms were identified as potential nucleophilic sites. The antimicrobial efficacy of a Schiff base copper (II) complex was evaluated against selected pathogenic bacteria (B. subtilis, B. megaterum, K. pneumoniae, E. coli) and the fungus Candida albicans. Among these C. albicans for complex showed larger zones (11–15.5 mm) at higher concentrations such as 2 and 2.5 mg/mL. Molecular docking studies suggested strong binding affinity between the complex and the target protein, this was further supported by obtained root means square deviations, root means square fluctuations, radius of gyration and hydrogen bond values during simulations. The binding free energy between BSA and the copper (II) complex was calculated as −8.7 kcal/mol, indicating significant interaction. However, only weak van der Waals interactions were observed between the complex and DNA. Toxicity studies revealed the copper (II) complex had minimal irritant effects on ocular and cutaneous tissues, with a low lethal dose. In comparison, Tricresyl phosphate showed moderate to severe ocular irritancy and modest cutaneous irritancy.

Ultrahigh-Strength Textile Fiber-Supported Schiff Base Copper Complexes for Photocatalytic Degradation of Methyl Orange

Ultrahigh-Strength Textile Fiber-Supported Schiff Base Copper Complexes for Photocatalytic Degradation of Methyl Orange

Hydroxylation of Phenol by an Azomethine Quinoxaline Schiff Base Copper (II) Complex

Introduction: A binuclear azomethine quinoxaline Schiff base copper (II) complex, [Cu2LCl2], having square-planar environment around each copper (II), has been synthesized. Method: The coordination of the azomethine quinoxaline Schiff base with copper (II) and its structure was studied by various physicochemical and spectroscopic measurements. Results: Catalytic activity of this complex in phenol hydroxylation reaction has been examined using H2O2 as a green oxidant. Conclusion: Catalytic reaction conditions were optimized and under these conditions, 18.32 % conversion of phenol has been obtained for this catalyst

An Insight Into Experimental and Theoretical Investigation of Structure, Photophysical Property by ESIPT Processes and Biological Activities of Schiff Base Copper Complex

ABSTRACTA novel Schiff base (BSSMO) and its copper complex have been synthesized, and their structure was delineated using single crystal XRD studies. Computational techniques were used to design and evaluate BSSMO‐based luminophores, revealing a significant intramolecular hydrogen bond within the molecule. Understanding ESIPT is crucial for optimizing photophysical and luminophore properties of organic molecules, especially for advancing optoelectronic devices. The study also explored the mechanisms of GSIPT and ESIPT for these BSSMO‐based luminophores using transition state theory, charge distribution, molecular orbital analysis, and quantum theory of atoms in molecules. Results advocated that BSSMO‐L2 exhibits higher absorption compared with BSSMO‐L1 and the same trend is observed in emission spectral studies. However, the intensity of enol emissions in BSSMO‐L2 is lower than that of keto (BSSMO‐L3) emissions and the S1 (Keto form) emission of BSSMO‐L3 shows significantly larger values, making it attractive for optoelectronic devices. The findings offer valuable insights for the development of ESIPT emitters with distinct photophysical properties. The in silico antidiabetic study of BSSMO‐L2 explores the interaction with PPAR‐γ protein, revealing a moderate affinity and stable complex, enhancing its bio‐potential for future applications. The in vitro anticancer study of Cu‐BSSMO‐L2 complex shows a potential anticancer effect through mitochondrial and extrinsic death receptor mediated pathways. These insights contribute to the design of novel benzenesulfonamide‐based bioactive molecules.

Verification of the Inverse Scale Effect Hypothesis on Viscosity and Diffusion by Azo-Amino Acid Schiff Base Copper Complexes

Microdroplets generated in microfluidic devices are attracting attention as a new chemical reaction field and are expected to improve reactivity. One of the effects of microscaling is that the ratio of the force that acts on the diffusion and movement of substances to gravity is different from that of ordinary solvents. Recently, we proposed a hypothesis for determining reaction acceleration through micro-miniaturization: If a reaction is inhibited by setting the volume and viscosity of the solution to conditions that are unfavorable to the reaction on a normal scale, that reaction can be promoted in microfluidics. Therefore, for the purpose of this verification, (1) we used an amino acid Schiff base copper(II) complex with an azobenzene group to demonstrate the polarization-induced orientation in a polymer film (the redirection that is mechanically maintained in a soft matter matrix). Numerical data on optical anisotropy parameters were reported. (2) When the reaction is confirmed to be promoted in laminar flow in a microfluidic device and its azo derivative, a copper(II) complex is used to increase the solvent viscosity or diffusion during synthesis on a normally large scale. We will obtain and discuss data on the investigation of changing the solvent volume as a region. The range of experimental conditions for volume and viscosity did not lead to an improvement in synthetic yield, nor did (3) the comparison of solvents and viscosity for single-crystal growth of amino acid Schiff base copper(II) complexes having azobenzene groups. A solvent whose viscosity was measured was used, but microcrystals were obtained using the diffusion method.

Investigation of Nanostructure of Schiff Base Copper (II) Complex: Synthesis, Characterization, Textural, and Thermal Property Analysis for Evaluating their Effectiveness as Cadmium Sensors with QCM-Based Sensing Method

Investigation of Nanostructure of Schiff Base Copper (II) Complex: Synthesis, Characterization, Textural, and Thermal Property Analysis for Evaluating their Effectiveness as Cadmium Sensors with QCM-Based Sensing Method

Photocatalytic dye degradation and hydrogen peroxide sensing by a novel copper-Schiff base complex prepared via mechanochemical method

ABSTRACT Water pollution, primarily caused due to hazardous organic and inorganic substances, is a cause of concern for human health and development, for it manifests adverse repercussions across health, economic, and social dimensions. The footprints of its adverse effects are also left on aquatic/marine life forms. In the light of the negative impacts of such substances, the development of efficient remediation techniques becomes pertinent. In this article, we report a water-soluble glutamic acid Schiff base copper complex (Cu-GSb) that has been synthesised by taking recourse to a mechanochemical approach, relying upon solid-state reagent interactions in a benign environmental setting, eluding a rigorous refluxing condition and overuse of solvents. The experimental results revealed that the ligand coordinates to the metal centre in a bidentate fashion through the imine nitrogen and carboxylate oxygen, respectively, adopting a distorted square planar geometry. Further, the complex’s utility in mitigating chemical hazards has been demonstrated through the studies involving degradation of organic dyes like methylene blue and bromocresol green, and decomposition/sensing of H2O2. Notably, as a photocatalyst towards the degradation of above-mentioned dyes under visible light irradiation, our study showed the photocatalytic efficiency of Cu-GSb to be ~95% in 50–60 min. The rate of degradation reaction has been found to follow first-order kinetics with rate constant values of 6 × 10−2 and 5.66 × 10−2 min−1 for MB and BCG, respectively. Furthermore, the results of H2O2 sensing evaluation revealed that the complex is capable of potentially decomposing H2O2 in about 20–30 min. The compounds have been routinely characterised by UV–visible spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and proton nuclear magnetic resonance (1H NMR).

Metallo-organic complexes as precursors for nanostructured metal oxides and their studies on protein interactions and drug loading characteristics

In the current study, we have synthesized and characterized Schiff base copper and zinc complexes based on (E)-2,4-dichloro-6-(((2-hydroxy-4-methyl-phenyl)-imino) methyl) phenol ligand obtained from 3,5-dichloro salicylaldehyde and 2-amino,4-methyl phenol. The interactions of these complexes with the protein, Bovine Serum Albumin (BSA) were monitored through the fluorescence spectral technique. The quenching of fluorescence with the incremental addition of the ligand and the complexes provides important information regarding the binding propensity of the tested compounds with the protein. Furthermore, these metal complexes are used as precursors to obtain the pure phases of copper oxide and zinc oxide nanostructures by the thermal decomposition method. The phase formation of the metal oxides was confirmed by powder X-ray diffraction (p-XRD) technique. The metal oxides prepared from their respective metal complexes have unique characteristics in terms of particle size, morphology, and band gap and are compared with the literature reports based on conventional solid-state methods. The studies on the interaction of the prepared metal oxide and curcumin with and without BSA, the drug carrier, have been investigated and the drug loading capacity is assessed.

Synthesis and Characterization of Slow-Release Chitosan Oligosaccharide Pyridine Schiff Base Copper Complexes with Antifungal Activity.

Herein, a series of chitosan oligosaccharide copper complexes modified with pyridine groups (CPSx-Cu complexes) were successfully prepared via the Schiff base reaction and ion complexation reaction for slow-release fungicide. The structures of the synthesized derivatives were characterized via Fourier transform infrared spectroscopy and 1H and 13C nuclear magnetic resonance spectroscopy, and the unit configuration of the complexes was calculated using Gaussian software. The slow-release performance experiment demonstrated that the cumulative copper ion release rate of CPSx-Cu complexes was dependent on the type of substituents on the pyridine ring. Furthermore, the in vitro and in vivo antifungal activities of the CPSx-Cu complexes were investigated. At a concentration of 0.4 mg/mL, CPSx-Cu complexes completely inhibited the growth of Pythium vexans and Phytophthora capsici. Results indicated that CPSx-Cu complexes with slow-release ability exhibited better antifungal activity than thiodiazole-copper and copper sulfate basic. This study confirmed that combining chitosan oligosaccharide with bioactive pyridine groups and copper ions is an effective approach to further developing slow-release copper fungicides, providing new possibilities for the application of copper fungicides in green agriculture. This study lays the foundation for further studies on biogreen copper fungicides.

Promising in vitro and in silico biological activity of tetradentate Schiff base copper(ii) complexes with a propylenediamine bridge

Analyzed tetradentate Schiff base copper(ii) complexes (with a propylenediamine bridge) show promising antioxidant and antiproliferative activity and the ability to bind to macromolecular targets such as HSA and DNA.

A Simple Flow Injection System for Amperometric Detection of Ascorbic Acid Using Carbon Paste/Copper Schiff Base Composite Electrode

AbstractIn this paper, a simple, sensitive, and precise flow injection system was optimized and applied to ascorbic acid determination with a carbon paste electrode modified with the Schiff base copper complex. The modified sensor showed increased sensitivity toward ascorbic acid oxidation with a decrease of oxidation potential by 200 mV. Under optimized flow parameters, working potential, gasket thickness, sample and reaction coil volumes, and flow rate, the developed flow system gave a linear response from 5 to 75 μmol/L of ascorbic acid. The calculated limit of detection was 4.5 μmol/L, calculated as 3σ/s which corresponds to the absolute value of 40 ng for the 50 μL sample coil. The precision for six consecutive injections of 5 and 75 μmol/L ascorbic acid solutions was determined as a relative standard deviation of 5.8 % and 1.5 %, respectively. The flow injection system enabled up to 120 analyses per hour. An optimized flow system was applied to the determination of ascorbic acid in dietary supplements, after simple preparation.

Anti-cancer activity of novel Schiff base copper (II) complex: synthesis and characterization

A novel thiosemicarbazone substituted schiff base ligand and its Cu(II) complex have been prepared and characterized. Schiff bases are considered as an important pro ligand in coordination chemistry because they easily form stable complexes with biologically active transition metal ions. Such as Cu 2+, Zn2+, Ni2+ etc. In this paper, novel Cu (II) complexes of thiosemicarbazone ligands were synthesised by refluxing thiosemicarbazone substituted pro ligands with copper salts in 1:1 molar ratio in absolute ethanol under thermal condition at 80o c for 5-6 hour. The resulting brown coloured copper complexes were filtered and recrystallized from petroleum ether. In this synthesis, we use absolute ethanol as a polar environment for the synthesis of copper complexes from schiff base ligands because the use of polar solvent medium in synthesis plays a very important role in reducing minimum possibilities of side reactions which hinders the proper conversion of ligands into copper complexes and also reducing the reaction time. All synthesized compounds were characterized through various spectroscopic and pharmacological techniques. FT-IR, UVVis, NMR, Mass, TGA-DTA, XRD spectra techniques were used to confirm the structures of copper complexes and ligands. All compounds are thermal stable up to 350o c. The good results of pharmacological activities of compounds like in-vitro anti -oxidant and anti - cancer activity against DPPH and cisplatin drug, explained the presence of biologically active functional groups are present in ligands as well as their copper complexes. Results found that the copper complexes were more active than the ligands. The synthesis of copper complexes from thiosemicarbazone schiff base ligands in proper stoichiometic ratio is an excellent method of preparing pharmacological active compounds which can be considered as good anti -cancer drug candidate for the treatment of cancer.

Structure elucidation {single X-ray crystal diffraction studies, Hirshfeld surface analysis, DFT} and antibacterial studies of sulfonamide functionalized Schiff base copper (II) and zinc (II) complexes

Microbial infections tremendously affect the human health and can be cured by antimicrobial agents. In this regard, the copper and zinc complexes of a sulfonamide functionalized Schiff base have been synthesized. The molecular structures confirm that the ligand has acted as N,O- chelator and stabilized the metal complexes by forming six membered ring system. The square planar and octahedral geometries have been assigned to the synthesized complexes on the basis of various spectral analyses. The crystal structure data has been utilized to calculate UV-visible, FT-IR, NMR, HOMO-LUMO energies, molecular electrostatic potential and frontier molecular orbitals using density function theory. The relative stability of the complexes was predicted using global chemical reactivity. The synthesized metal complexes were screened against different bacterial strains. It was concluded that both compounds were effective against almost all microbes. The compound 2 is more potent as compared to 1 with highest activity against Halomonas halophila (22.4 ± 1.2 mm; MIC 79 ± 5 µg). The compounds were further evaluated in terms of docking studies to find out their antimicrobial studies which confirmed that complexes have better antibacterial trends.

The Schiff base hydrazine copper(II) complexes induce apoptosis by P53 overexpression and prevent cell migration through protease-independent pathways.

Although chemotherapy has increased the life expectancy of cancer patients, its toxic side effects remain a major challenge. Recently, organometallic compounds, such as Schiff base copper complexes, have become promising candidates for next-generation anticancer drugs owing to their unique anticancer activities. In this study, binuclear copper(II) complex-1 and mononuclear copper(II) complex-2 were examined to analyze their anticancer mechanisms further. For this purpose, a viability test, flow cytometry analysis of apoptosis and the cell cycle, migration assay, and gene expression analysis were performed. According to our results, complex-1 was more cytotoxic than complex-2 at 24/48-h intervals. Our findings also demonstrated that both complexes induced apoptosis at IC50 concentrations and arrested the cell cycle at the G1-S checkpoint. However, complex-1 accelerates cell cycle arrest at the sub-G0/G1 phase more than complex-2 does. Furthermore, gene expression analysis showed that only complex-1 induces the expression of p53. Interestingly, both complexes induced Bcl-2 overexpression. However, they did not affect MMP-13 expression. More interestingly, both complexes inhibited cell migration in different ways, including amoeboid and collective, by recruiting protease-independent pathways. This study confirmed that adding several metal cores and co-ligands increased the activity of the complex. It also appeared that Cu-containing complexes could prevent the migration of cancer cells through protease-independent pathways, which can be used for novel therapeutic purposes.

Explorations on the synthesis, structure, DFT, DNA binding properties and molecular docking of tridentate Schiff base Copper (II) complexes

Copper(II) Schiff base complexes of (2-Hydroxy-benzaldehyde)-amino acid have been synthesized and characterized. The complexes' single-crystal X-ray structures were studied, and it was discovered that the 4,4-bipyridine functions as a bidentate bridging ligand connecting two Cu(II) ions. In order to assemble the complicated components into a three-dimensional chain structure and arrange the 4,4-bipyridine molecules into parallel sheets, intermolecular hydrogen bonds are essential. A robust intermolecular hydrogen bond network including water oxygen atoms strengthens the connection between water molecules and phenolate oxygen atoms from the ligand, which is produced from salicylaldehyde. The complexes' interaction with DNA was investigated by UV–Visible, fluorescence and CD spectrophotometric methods, which indicate that the complexes favourably bind to the groove in the DNA. The DNA binding affinity was confirmed by molecular docking. Additionally, DFT calculations were used to determine the stable geometry for these complexes. A thorough understanding of the interactions of these synthesized complexes was achieved through an intensive molecular docking research. These findings show that the complexes have a high affinity for DNA binding and considerable groove binding. Notably, Complex 1 showed a greater affinity for DNA than Complex 2.

Pyridine‐derived Schiff base copper (II), zinc (II), and cadmium (II) complexes: Synthesis, structural properties, biological evaluation, and docking studies

Herein, Cu (II), Zn (II), and Cd (II) complexes, [DEP(M)X2], encompassing the pyridine‐derived Schiff‐base ligand DEP, where DEP is (E)‐N,N‐diethyl‐2‐([pyridine‐2‐ylmethylene]amino)ethane‐1‐amine, are synthesized. X‐ray diffraction studies reveal distorted square pyramidal geometries for the Cd (II) and Cu (II) complexes, whereas the geometry of [DEP (Zn)Cl2] can best be described as trigonal bipyramidal. The antibacterial potential of DEP and its [DEP(M)X2] complexes were evaluated against four bacterial strains: Salmonella typhi, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa; five fungal strains: Candida glabrata, Candida albicans, Microsporum canis, Fusarium solani, and Aspergillus flavus; and Leishmania major protozoan. Complexes exhibited superior bactericidal, fungicidal, and leishmanicidal inhibition potential against all tested microbes compared with the free ligand. The preliminary cytotoxic activity of [DEP(M)X2] complexes on breast and colon carcinoma cells, that is, MCF‐7cell line and HCT‐116 cell line, respectively, revealed that studied complexes showed high cytotoxicity compared with ligand (DEP). Among the studied complexes, [DEP (Cd)Br2] exhibited an excellent inhibitory profile, as confirmed by the docking study. The molecular docking studies showed a good correlation between the biological activities of synthesized metal complexes and docking studies. We have confidence in the contribution of these complexes toward the design of new metal‐derived candidates that can treat infectious diseases.

Efficient Synthesis of a Schiff Base Copper(II) Complex Using a Microfluidic Device

The efficient synthesis of amino acid Schiff base copper(II) complexes using a microfluidic device was successfully achieved. Schiff bases and their complexes are remarkable compounds due to their high biological activity and catalytic function. Conventionally, products are synthesized under reaction conditions of 40 °C for 4 h using a beaker-based method. However, in this paper, we propose using a microfluidic channel to enable quasi-instantaneous synthesis at room temperature (23 °C). The products were characterized using UV–Vis, FT–IR, and MS spectroscopy. The efficient generation of compounds using microfluidic channels has the potential to significantly contribute to the efficiency of drug discovery and material development due to high reactivity.

In vitro and in silico study of the biological activity of tetradentate Schiff base copper(II) complexes with ethylenediamine-bridge

The biological activity of six structurally similar tetradentate Schiff base copper(II) complexes, namely [Cu(ethylenediamine-bis-acetylacetonate)] (CuAA) and five derivatives where two methyl groups are replaced by phenyl, (CuPP), CF3 (CuTT) or by mixed groups CH3/CF3 (CuAT), Ph/CF3 (CuPT), and Ph/CH3 (CuAP) has been investigated. The set of antioxidant assays was performed, and the results were expressed as IC50 and EC50 values. The series of complexes showed interesting bioactivity and were investigated for the determination of antioxidant, antifungal, antimicrobial, and cytotoxic activity. A significant antioxidant behavior was exhibited by complex CuAA, greater than Trolox in the Oxygen Radical Absorbance Capacity (ORAC) assay. Antibacterial assay over Gram-positive and Gram-negative pathogenic bacterial strains and some fungal pathogens were studied. Antiproliferative activity of complexes in two human tumor cell lines, breast adenocarcinoma MCF-7, colon adenocarcinoma LS-174, and normal fibroblast cells-MRC-5, examined the effect on cell cycle progression. The significant cytotoxic potential, comparable to cisplatin cytotoxicity, was determined in human breast cancer cell line-MCF-7 with IC50 values being 17.53–31.40 μM and human colon cancer cell line-LS-174 with IC50 values being 15.22–23.92 μM. All tested compounds showed nearly twice more selectivity toward cancer cell lines than normal cells. The interactions of complexes with human serum albumin (HSA), the most prominent protein in plasma, were investigated using spectroscopic fluorescence techniques. The complexes bind to human serum albumin at multiple sites (n = 0.2–1.9), displaying a moderate binding constant Ka = 4.1–12.4 × 104 M−1. The molecular docking experiment effectively showed complex binding to HSA and DNA molecular fragments.