Synthesis, structure, spectroscopic properties, electrochemistry, and DFT correlative studies of N-[(2-pyridyl)methyliden]-6-coumarin complexes of Cu(I) and Ag(I)

In vitro anti-proliferative, and in silico ribonucleotide reductase and pharmacokinetics studies of heteroleptic silver(I), nickel(II) and copper(II) complexes of 4-methyl-3-thiosemicarbazones and ibuprofen

OBJECTIVES

The present research focuses on the in vitro anti-proliferative, and in silico ribonucleotide reductase and pharmacokinetics studies of twelve heteroleptic metal complexes of the general formulae [Ag(L^1-4)(ibu)] (1-4) and [M(L^1-4)(ibu)₂] (5-12), where L^1-4 = 2-(1-(4-substitutedphenyl)ethylidene)-N-methylhydrazinecarbothioamide, ibu = non-steroidal anti-inflammatory drug (ibuprofen), and M = Cu(II) and Ni(II).

METHODS

Various spectroscopic techniques were used to authenticate the structure of the synthesized complexes. UV-Vis and cyclic voltammetry techniques were used to analyse the stability and the reducing ability of the complexes. In vitro anti-proliferative studies by MTT assay, apoptotic behaviour and cellular uptake studies were investigated followed by the in silico interaction with ribonucleotide reductase (RNR) enzyme.

RESULTS

The spectral studies predicted distorted tetrahedral geometry around silver(I) ion and distorted octahedral geometry around nickel(II) and copper(II) ions. The reducing ability of the copper(II) complexes was analysed using ascorbic acid by UV-Vis and cyclic voltammetry techniques, which authenticate the reducing ability of the complexes and the possible interactions within the cells. The in vitro anti-proliferative activity of the synthesized complexes against three cancerous (estrogen positive (MCF-7), estrogen negative (MDA-MB-231) and pancreatic (PANC-1)) and one normal (MCF-10a) cell lines by MTT assay showed enhanced activity for copper(II) complexes 11 and 12 containing the hydrophobic substituents. The apoptotic and cellular uptake studies showed that the complex 12 is readily taken up by PANC-1 cell lines and induces ROS-mediated mitochondrial and caspase-dependent apoptosis. The in silico studies indicated hydrogen bonding, hydrophobic and π-pair (π-π, π-σ and π-cation) interactions between the complexes and the ribonucleotide reductase (RNR) enzyme. The in silico pharmacokinetics studies of the complexes predicted the drug-likeness characteristics of the complexes.

CONCLUSION

The synthesized complexes are found to be less toxic to normal cells and inhibit the growth of cancerous cells by inducing mitochondrial-mediated and caspase dependent apoptotic pathway in PANC-1 cells.

New Copper(I) Complex with a Coumarin as Ligand with Antibacterial Activity against Flavobacterium psychrophilum

A new copper (I) complex, [Cu(NN₁)₂](ClO₄)_, was synthesized, where NN₁ was a imine ligand 6-((quinolin-2-ylmethylene)amino)-2H-chromen-2-one obtained by a derivatization of natural compound coumarin. The structural characterization in solution was done by NMR techniques, UV-Vis and cyclic voltammetry. The potential antibacterial effect of [Cu(NN₁)₂](ClO₄)_, was assessed for F. psychrophilum isolated 10094. F. psychrophilum is a Gram-negative bacterium which causes diseases such as bacterial cold-water disease and rainbow trout fry syndrome, causing large economic losses in the freshwater salmonid aquaculture industry. This complex show to have antibacterial activity against F. psychrophilum 10094 at non-cytotoxic concentration in cell line derived from trout (F. psychrophilum 10094 IC₅₀ 16.0 ± 0.9; RT-GUT IC₅₀ 53.0 ± 3.1 µg/mL).

Silver(I) metallodrugs of thiosemicarbazones and naproxen: biocompatibility, in vitro anti-proliferative activity and in silico interaction studies with EGFR, VEGFR2 and LOX receptors

Four new heteroleptic silver(I) complexes with the general formula [Ag(L1-4)(nap)] (1-4), where L1-4 =  2-(1-(4-substitutedphenyl)ethylidene)hydrazinecarbothioamide and nap = naproxen, have been synthesized and characterized. The geometric parameters determined from density functional theory and UV-Vis studies indicate distorted tetrahedral geometry around silver(I) ion. Fourier transform infrared (FT IR) spectra evidenced asymmetric bidentate coordination mode of carboxyl oxygen atoms of naproxen with silver(I) ion. The complexes are stable for 72 h and biocompatibility was analysed towards normal human dermal fibroblast cells, which showed non-toxic nature up to 100 ng/ml. In vitro anti-proliferative activity of the complexes by MTT assay was tested against three human cancerous cell lines and one non-tumorigenic human breast epithelial cell line (MCF-10a) in which the complex 4 exhibited enhanced activity. The morphological changes observed by acridine orange/ethidium bromide and Hoechst 33258 staining method reveal apoptosis-inducing ability of the complexes. The molecular docking studies suggest hydrogen bonding, hydrophobic and π-pair interactions with the active site of epidermal growth factor receptor, vascular endothelial growth factor receptor 2 and lipoxygenase receptors.

An enolato-bridged dinuclear Cu(ii) complex with a coumarin-assisted precursor: a spectral, magnetic and biological study

Coumarin assisted dinuclear [Cu₂(L)₂(DMF)₂] (1) shows weak ferromagnetic interaction and a geometric distortion occurs while lowering the temperature in EPR.

Synthesis and Characterisation of Copper(II) Complexes with Tridentate NNO Functionalized Ligand: Density Function Theory Study, DNA Binding Mechanism, Optical Properties, and Biological Application

The photo physical properties of two mononuclear pentacoordinated copper(II) complexes formulated as [Cu(L)(Cl)(H2O)] (1) and [Cu(L)(Br)(H2O)] (2) HL = (1-[(3-methyl-pyridine-2-ylimino)-methyl]-naphthalen-2-ol) were synthesized and characterized by elemental, physicochemical, and spectroscopic methods. The density function theory calculations are used to investigate the electronic structures and the electronic properties of ligand and complex. The interactions of copper(II) complexes towards calf thymus DNA were examined with the help of absorption, viscosity, and fluorescence spectroscopic techniques at pH 7.40. All spectroscopy's result indicates that complexes show good binding activity to calf thymus DNA through groove binding. The optical absorption and fluorescence emission properties of microwires were characterized by fluorescence microscope. From a spectroscopic viewpoint, all compounds strongly emit green light in the solid state. The microscopy investigation suggested that microwires exhibited optical waveguide behaviour which are applicable as fluorescent nanomaterials and can be used as building blocks for miniaturized photonic devices. Antibacterial study reveals that complexes are better antimicrobial agents than free Schiff base due to bacterial cell penetration by chelation. Moreover, the antioxidant study of the ligand and complexes is evaluated by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) free-radical assays, which demonstrate that the complexes are of higher antioxidant activity than free ligand.

Exploring molecular structures, orbital interactions, intramolecular proton-transfer reaction kinetics, electronic transitions and complexation of 3-hydroxycoumarin species using DFT methods

Optimal structures and electronic properties of various species of 3-hydroxycoumarin (3-HCou) have been explored using density functional theory (DFT) methods under polarizable continuum model (PCM) of solvation. Electron transfer from pyrone to benzene moieties is enhanced upon deprotonation. Anionic and radical species have similar orbital-interaction characteristics but the charges in the former are distributed more uniformly. The rate of intramolecular proton transfer for the neutral species increases many folds upon excitation. The HOMO-LUMO transition with π→π* character mainly accounts for the UV absorption of most 3-HCou species in solution. The wavelengths of maximal absorption predicted using TD-DFT method are in agreement with the previous experiment. For the charged species, calculations with the range-corrected functional yield better agreement with the previous experiment. Anionic 3-HCou species shows high degrees of complexation with chromium(III) and copper(II) compared with oxovanadium(IV) and zinc(II). Either oxovanadium(IV) or zinc(II) prefers forming two isomeric complexes with comparable degrees of formation.

Syntheses, Structures, Characterisation, and Spectroscopic Properties of CuI and AgI Complexes with Extended C–H···π and π···π Interactions

Based on the ligands N,N′-bis(pyridin-2-ylmethylene)benzene-1,4-diamine (pmb) and N,N′-bis(pyridin-2-ylmethylene)biphenyl-4,4′-diamine (pmbb), the three compounds [Cu2(pmb) (PPh3)2(Cl)2] (1), [Cu2(pmbb)(CH3CN)2(PPh3)2](BF4)2·2DMF (2), and [Ag2(pmbb)(PPh3)2] (ClO4)2 (3) have been synthesised and characterised. Structural analysis reveals that all of these complexes contain 1D supramolecular arrays, with different variations in π-stacking patterns and intermolecular C–H···π interactions. Crystal structures of 1 and 2 contain 1D tape-like arrays formed by C–H···π and π···π interactions, and an ordered-layer-lattice of DMF and BF4– in 2 is located between the one-dimensional array. For 3, π-stacking interactions lead to the construction of 1D supramolecular arrays and a 2D network. The results indicate that C–H···π and π···π interactions play an important role in the construction of the supramolecular structure. In addition, the absorption peaks of complexes 1 and 3 in the solid state at room temperature show intraligand charge transfer and metal-to-ligand charge transfer absorptions. The optical and fluorescent properties of 2 were also studied in acetonitrile solution at room temperature.