Dimeric “paddle-wheel” carboxylates of copper(II): Synthesis, crystal structure and electrochemical studies

New copper carboxyl-ate pyrene dimers: synthesis, crystal structure, Hirshfeld surface analysis and electrochemical characterization

Two new copper dimers, namely, bis-(dimethyl sulfoxide)-tetra-kis-(μ-pyrene-1-carboxyl-ato)dicopper(Cu-Cu), [Cu2(C17H9O2)4(C2H6OS)2] or [Cu2(pyr-COO-)4(DMSO)2] (1), and bis-(di-methyl-formamide)-tetra-kis-(μ-pyrene-1-carboxyl-ato)dicopper(Cu-Cu), [Cu2(C17H9O2)4(C3H7NO)2] or [Cu2(pyr-COO-)4(DMF)2] (2) (pyr = pyrene), were synthesized from the reaction of pyrene-1-carb-oxy-lic acid, copper(II) nitrate and tri-ethyl-amine from solvents DMSO and DMF, respectively. While 1 crystallized in the space group P , the crystal structure of 2 is in space group P21/n. The Cu atoms have octa-hedral geometries, with four oxygen atoms from carboxyl-ate pyrene ligands occupying the equatorial positions, a solvent mol-ecule coordinating at one of the axial positions, and a Cu⋯Cu contact in the opposite position. The packing in the crystal structures exhibits π-π stacking inter-actions and short contacts through the solvent mol-ecules. The Hirshfeld surfaces and two-dimensional fingerprint plots were generated for both compounds to better understand the inter-molecular inter-actions and the contribution of heteroatoms from the solvent ligands to the crystal packing. In addition, a Cu2+/Cu1+ quasi-reversible redox process was identified for compound 2 using cyclic voltammetry that accounts for a diffusion-controlled electron-donation process to the Cu dimer.

New copper(II) μ-Alkoxo-μ-carboxylato double-bridged complexes as models for the active site of catechol oxidase: Synthesis, spectral characterization and DFT calculations

A series of four copper(II) μ-Alkoxo-μ-carboxylato double bridged complexes, [{Cu₂(L)}₂][(μ–O₂C–CO₂] 1, [{Cu₂(L)}₂(μ–O₂C–(CH₂)CO₂] 2, [{Cu₂(L)}₂(μ–O₂C–CH₂–CO₂] 3 and [{Cu₂(L)}₂(μ–O₂C–C₆H₄–CO₂] 4 (H₃L = 4-bromo-2-((E)-((3-(((E)-5-chloro-2-hydroxybenzylidene) amino)-2-hydroxypropyl) imino) methyl)-6-methoxyphenol and μ-dicarboxylate ions = oxalate, malonate, succinate and terephthalate) have been synthesized and characterized using several physicochemical techniques. The tridentate nature of H₃L is interpreted from IR spectra. The Epr spectra of these complexes are characteristic of the quintet state (S = 2) in central features and the triplet state (S = 1) of these tetranuclear complexes. The electrochemical potential of these complexes was investigated using CV (cyclic voltammetry) and DPV (differential pulse voltammetry). All complexes showed quasi reversible reduction peaks in the cathodic region. To explore the stability of these complexes, quantum chemical parameters like electronegativity, ionization potential, electron affinity, global hardness and softness, and electrophilicity were estimated and discussed. The synthesized complexes have been designed as structural and functional models of the catechol oxidase enzymes to investigate the catecholase activity. Additionally, superoxide dismutase activity data of all complexes have also been evaluated and compared with known SOD mimics.

Synthesis, characterization, antioxidant, antileishmanial, anticancer, DNA and theoretical SARS-CoV-2 interaction studies of copper(II) carboxylate complexes

Copper(II) carboxylate complexes [Cu₂(OOCR)₄L₂] (1) and [Cu₂(OOCR`)<sub>4</sub>OCO(R`)CuL₂]_n (2), where L = 2-methyl pyridine, R = 2-chlorophenyl acetate and R` = 2-fluorophenyl acetate were synthesized and characterized by FT-IR spectroscopy and single crystal X-ray analysis. Complex 1 exhibits the typical paddlewheel array of a dinuclear copper(II) complex with carboxylate ligands. In complex 2, this scaffold is further extended into a polymeric arrangement based on alternate paddlewheel and square planar moieties with distinct coordination spheres. The complexes showed better 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging activities and have been found to be more potent antileishmanial agents than their corresponding free ligand acid species. UV-Vis absorption titrations revealed good DNA binding abilities {Kb = 9.8 × 10⁴ M^-1 (1) and 9.9 × 10⁴ M^-1 (2)} implying partial intercalation of the complexes into DNA base pairs along with groove binding. The complexes displayed in vitro cytotoxic activity against malignant glioma U-87 (MG U87) cell lines. Computational docking studies further support complex-DNA binding by intercalation. Molecular docking investigations revealed probable interactions of the complexes with spike protein, the nucleocapsid protein of SARS-CoV-2 and with the angiotensin converting enzyme of human cells.

New triorganotin(iv) compounds with aromatic carboxylate ligands: synthesis and evaluation of the pro-apoptotic mechanism

Three new organotin(iv) carboxylate compounds were synthesized and structurally characterized by elemental analysis and FT-IR and multinuclear NMR (1H, 13C, 119Sn) spectroscopy. Single X-ray crystallography reveals that compound C2 has a monoclinic crystal system with space group P21/c having distorted bipyramidal geometry defined by C3SnO2. The synthesized compounds were screened for drug-DNA interactions via UV-Vis spectroscopy and cyclic voltammetry showing good activity with high binding constants. Theoretical investigations also support the reactivity of the compounds as depicted from natural bond orbital (NBO) analysis using Gaussian 09. Synthesized compounds were initially evaluated on two cancer (HeLa and MCF-7) cell lines and cytotoxicity to normal cells was evaluated using a non-cancerous (BHK-21) cell line. All the compounds were found to be active, with IC50 values less than that of the standard drug i.e. cisplatin. The cytotoxic effect of the most potent compound C2 was confirmed by LDH cytotoxicity assay and fluorescence imaging after PI staining. Apoptotic features in compound C2 treated cancer cells were visualized after DAPI staining while regulation of apoptosis was observed by reactive oxygen species generation, binding of C2 with DNA, a change in mitochondrial membrane potential and expression of activated caspase-9 and caspase-3 in cancer cells. Results are indicative of activation of the intrinsic pathway of apoptosis in C2 treated cancer cells.

Synthesis and Crystallographic, Absorption and Emission Studies of 4-Pyridine Carboxamide of Zn(II) 4-Chlorophenylacetate

A new zinc(II) complex, [Zn(CB)₂(INA)₂] (where CB is 4-chlorophenylacetate and INA is 4-pyridine carboxamide) was synthesized. The structure of the complex was characterized by elemental analysis, FT-IR spectroscopy and single-crystal X-ray diffraction technique. Besides, the thermal stability of the complex was investigated by TGA/DTA analysis method. Moreover, the optical absorption and the emission features of the complex were examined by using UV-Vis and fluorescence spectrophotometers, respectively. Furthermore, Density Functional Theory (DFT) calculations were carried out to support the experimental results. Accordingly, it was determined that the complex crystallized in a monoclinic system with space group Pc, a = 8.3329 (2) Å, b = 25.6530 (4) Å, c = 13.5048 (3) Å, α = 90°, β = 91.703 (3)° and γ = 90°. The complex consists two crystallographically independent molecules. In each molecule, the Zn^II ion adopts a distorted trigonal pyramidal coordination formed by two O atoms from the two 4 chlorophenylacetate ligand and two N atoms of the two 4-pyridine carboxamide ligands. It was observed that the linear absorption spectra of the complex were similar to linear absorption spectra of the semiconductors. In addition, two emission peaks were observed in the fluorescence spectra which could be due to the formation of excimer and the interactions of the benzene and pyridine rings. The energy gap (ΔE_gap = E_LUMO - E_HOMO) of the complex has been calculated as 3.712 eV and this value is very close to the experimentally measured value (3.86 eV). Therefore, because of higher fluorescence intensity of emission peak that was observed between 309 and 556 nm wavelength besides other traits, the complex could potentially be used in the blue light OLED application by filtering of the emission peak around 710 nm wavelength. Graphical Abstract It was reported synthesis and spectroscopic, structural and optical characterization of a new complex that is Zn(II) of 4-Chlorophenylacetate with isonicotinamide. The complex characterized by elemental analysis, Single crystal X-ray diffraction and FT-IR Spectroscopy. Thermal stabilities of the complex have also been investigated. The studying of the optical absorption and fluorescence spectra of the prepared complex is very important for the determination of the optical application areas. The fluorescence measurements showed that these materials are much suitable for application area of the detection of nitroaromatic explosives. In addition to the Density Functional Theory (DFT) calculations were carried out to support the experimental results. It was reported synthesis and spectroscopic, structural and optical characterization of a new complex that is Zn(II) of 4-Chlorophenylacetate with isonicotinamide. The complex characterized by elemental analysis, Single crystal X-ray diffraction and FT-IR Spectroscopy. Thermal stabilities of the complex have also been investigated. The studying of the optical absorption and fluorescence spectra of the prepared complex is very important for the determination of the optical application areas. In addition to the Density Functional Theory (DFT) calculations were carried out to support the experimental results.

Synthesis, characterization, and anticancer activity of Schiff bases

Five Schiff bases, 2-((3-chlorophenylimino)methyl)-5-(diethylamino)phenol (L1), 2-((2,4-dichlorophenylimino)methyl)-5-(diethylamino)phenol (L2), 5-(diethylamino)-2-((3,5-dimethylphenylimino)methyl)phenol (L3), 2-((2-chloro-4-methylphenylimino)methyl)-5-(diethylamino)phenol (L4), and 5-(diethylamino)-2-((2,6-diethylphenylimino)methyl)phenol (L5) were synthesized and characterized by elemental analysis, FT-IR, ¹H and ¹³C NMR spectroscopy. Three of the compounds (L1, L2, and L4) were analyzed by single crystal X-ray diffraction: L1 and L2 crystallized in orthorhombic P2₁2₁2₁ and Pca2₁ space group, respectively, while L4 crystallized in monoclinic P2₁/c space group. Theoretical investigations were performed for all the synthesized compounds to evaluate the structural details. Drug-DNA interaction studies results from UV-Vis spectroscopy and electrochemistry complement that the compounds bind to DNA through electrostatic interactions. The cytotoxicity of the synthesized compounds was studied against cancer cell lines (HeLa and MCF-7) and a normal cell line (BHK-21) by means of an MTT assay compared to carboplatin, featuring IC₅₀ values in the micromolar range. The pro-apoptotic mechanism for the active compound L5 was evaluated by fluorescence microscopy, cell cycle analysis, caspase-9 and -3 activity, reactive oxygen species production, and DNA binding studies that further strengthen the results of that L5 is a potent drug against cancer.Communicated by Ramaswamy H. Sarma.

Amphiphile-like self assembly of metal organic polyhedra having both polar and non-polar groups

Mixed linker metal-organic polyhedra (MOPs) with polar and non-polar groups on the same MOP have been synthesized. This yields two types of MOPs, one where the ligands are evenly and symmetrically distributed over each polyhedron, as confirmed crystallographically and the other where respective groups segregate. The segregation is confirmed by the amphiphile-like behavior of the latter MOP in different polarity solvents, as seen through transmission electron microscopy (TEM) even though the anchor points of the functional groups are ∼10 Å apart on the MOP surface.

A tetranuclear copper (II) complex with pyrazole-3,5-dicarboxylate ligands: synthesis, characterization and electrochemical properties

A tetranuclear copper (II) complex with pyrazole-3,5-dicarboxylate ligands (pdc3−), [Me2NH2]4[Cu4(pdc)4], was synthesized using solvothermal and metal oxidation routes and characterized by elemental analysis, infrared, thermogravimetry/differential thermal analysis, and room-temperature magnetic measurements. The structure of the complex was determined by single-crystal X-ray diffraction. It comprises dimethylammonium cations and complex anions containing four Cu2+ cations. The crystal structure is stabilized by N–H···O hydrogen bonds. In addition, the electrochemical behavior was studied.