Two new copper (II) complexes with sulfanilamide as ligand: Synthesis, structural, thermal analysis, electrochemical studies and antibacterial activity

Cytotoxic Cu(II) Complexes with a Novel Quinoline Derivative Ligand: Synthesis, Molecular Docking, and Biological Activity Analysis

The utilization of metallodrugs as a viable alternative to organic molecules has gained significant attention in modern medicine. We hereby report synthesis of new imine quinoline ligand (IQL)-based Cu(II) complexes and evaluation of their potential biological applications. Syntheses of the ligand and complexes were achieved by condensation of 7-chloro-2-hydroxyquinoline-3-carbaldehyde and 2,2'-thiodianiline, followed by complexation with Cu(II) metal ions. The synthesized ligand and complexes were characterized using UV-vis spectroscopy, TGA/DTA, FTIR spectroscopy, 1H and 13C NMR spectroscopy, and pXRD. The pXRD diffractogram analysis revealed that the synthesized ligand and its complexes were polycrystalline systems, with nanolevel average crystallite sizes of 13.28, 31.47, and 11.57 nm for IQL, CuL, and CuL 2 , respectively. The molar conductivity confirmed the nonelectrolyte nature of the Cu(II) complexes. The biological activity of the synthesized ligand and its Cu(II) complexes was evaluated with in vitro assays, to examine anticancer activity against the MCF-7 human breast cancer cell line and antibacterial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacterial strains. The CuL complex had the highest cytotoxic potency against MCF-7 breast cancer cells, with an IC50 of 43.82 ± 2.351 μg/mL. At 100 μg/mL, CuL induced the largest reduction of cancer cell proliferation by 97%, whereas IQL reduced cell proliferation by 53% and CuL 2 by 28%. The minimum inhibitory concentration for CuL was found to be 12.5 μg/mL against the three tested pathogens. Evaluation of antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl revealed that CuL exhibited the highest antioxidant activity with IC50 of 153.3 ± 1.02 μg/mL. Molecular docking results showed strong binding affinities of CuL to active sites of S. aureus, E. coli, and estrogen receptor alpha, indicating its high biological activity compared to IQL and CuL 2 .

New Copper Complexes with Antibacterial and Cytotoxic Activity

The discovery of a new non-toxic metal complex with biological activity represents a very active area of research. Two Cu+2 complexes, [Cu4(L1)4(OH)4(DMF)2(H2O)] (C1) (HL1 = N-(5-ethyl-[1,3,4]-thiadiazole-2-yl)-benzenesulfonamide) and [Cu(L2)2(phen)(H2O)] (C2) (HL2 = N-(5-(4-methylphenyl)-[1,3,4]-thiadiazole-2-yl)-naphtalenesulfonamide), with two new ligands were synthesized. The X-ray crystal structures of the complexes were determined. In both complexes, Cu+2 is five-coordinated, forming a CuN2O3 and CuN4O chromophore, respectively. The ligands act as monodentate, coordinating the metal ion through a single Nthiadiazole atom; for the two complexes, the molecules from the reaction medium (phenantroline, dimethylformamide and water) are also involved in the coordination of Cu+2. The complexes have a distorted square pyramidal square-planar geometry. The compounds were characterized by FT-IR and UV-Vis spectroscopy. Using the microdilution method, the antibacterial activity of the complexes was determined against four Gram-positive and two Gram-negative bacteria, with Gentamicin as the positive control. Cytotoxicity studies were carried out on two tumor cell lines (HeLa, DLD-1) and on a normal cell line (HFL1) using the MTT method and Cisplatin as a positive control. Flow cytometric assessment of apoptosis induced by the complexes on the three cell lines was also performed. Both complexes present in vitro biological activities but complex C2 is more active.

Multi-target activity of copper complexes: Antibacterial, DNA binding, and molecular docking with SARS-CoV-2 receptor

A series of pendant-armed mixed-ligand copper(II) complexes of the type [CuL^1-3(diimine)] (1-6) have been synthesized by the reaction of pendant-armed ligands N,N-bis(2-(((E)-2-hydroxy-5-methylbenzylidene)amino)ethyl)benzamide (H₂L¹), N,N-bis(2-(((E)-2-hydroxy-5-methylbenzylidene)amino)ethyl)-4-nitrobenzamide (H₂L²) and N,N-bis(2-(((E)-2-hydroxy-5-methylbenzylidene)amino)ethyl)-3,5-dinitrobenzamide (H₂L³) with diimine = 2,2'-bipyridyl (bpy) or 1,10-phenanthroline (phen) in the presence of copper(II) chloride and analyzed using various spectroscopic methods. All the spectroscopic results support that the complexes adopt a pentagonal-bipyramidal shape around the copper ion. Gram-positive and Gram-negative bacteria were used to test all the complexes for antibacterial activity and all the complexes had greater potency against gram-negative pathogens. DNA-binding experiments of complexes with calf thymus DNA revealed a major-groove binding pattern, further supported by molecular docking studies. Complexes have significantly interacted with SARS-CoV-2 receptor via π-π, π-σ, π-alkyl, π-anion, π-cation, alkyl, hydrogen bond, van der Waals, and electrostatic interactions. The estimated binding energy and inhibition constant of these complexes are higher than standard drugs, chloroquine, and molnupiravir.

Halogen bond and polymorphism in trans-bis(2-iodo-5-halopyridine)dihalocopper(ii) complexes: crystallographic, theoretical and magnetic studies

As the halogen atom on position 5 of the 2I5YP ligand gets heavier the probability of crystallizing the syn-conformer increases; 2I5Cl-Cl crystallizes as the anti-conformer whereas 2I5Br-Cl crystallizes as syn- and anti-conformers.

Novel Zinc(II) and Copper(II) Complexes of 2-((2-Hydroxyethyl)amino)quinoline-3-carbaldehyde for Antibacterial and Antioxidant Activities: A Combined Experimental, DFT, and Docking Studies

In the present work, two novel complexes of zinc(II) and copper(II) were synthesized from the ligand 2-((2-hydroxyethyl)amino)quinoline-3-carbaldehyde (H ₂ L) in a 1:2 metal-to-ligand ratio in methanol. The complexes were characterized by UV-visible spectroscopy, fluorescence spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX), mass spectrometry (MS), nuclear magnetic resonance (NMR) spectroscopy, and thermogravimetric analysis (TGA) experimental techniques and density functional theory (DFT) calculations. The spectral data revealed that the mono-deprotonated (HL) ligand acted as a bidentate ligand, which bound to both Zn(II) and Cu(II) ions via the nitrogen atom of the amine (N-H) and the hydroxyl (O-H) groups through the deprotonated oxygen atom. Formation constants and thermal analysis indicated that both metal complexes are stable up to 100 °C with thermodynamically favored chemical reactions. The Cu(II) complex showed antibacterial activities with the zones of inhibition of 20.90 ± 2.00 mm against Pseudomonas aeruginosa, 19.69 ± 0.71 mm against Staphylococcus aureus, and 18.58 ± 1.04 mm against Streptococcus pyogenes. These results are relatively higher compared with the Zn(II) complex at the same concentration. The minimum inhibitory concentration (MIC) results for the complexes also showed similar trends against the three bacteria. On the other hand, radical scavenging activities of both Cu(II) and Zn(II) complexes showed half-maximal inhibitory concentrations (IC₅₀) of 4.72 and 8.2 μg/mL, respectively, while ascorbic acid (a positive control) has a value of 4.28 μg/mL. The Cu(II) complex exhibited better communication with the positive control, indicating its potential use for biological activities. The calculated and in silico molecular docking results also strongly support the experimental results.