Macrocyclic Co Complexes Research Articles

Novel amide based macrocyclic complexes of Co(II): Synthesis, structural characterization, thermal, DFT, molecular docking studies, in vitro cytotoxic, antimicrobial and antioxidant evaluation

The novel cobalt (II) macrocyclic complexes [Co(N4O4MacL1)Cl2]-[Co(N4O4MacL3)Cl2] have been synthesized by using the macrocyclic ligands [N4O4MacL1], [N4O4MacL2] and [N4O4MacL3] that have an N4O4 core. To investigate Co(II), metal complexes [Co(N4O4MacL1)Cl2]-[Co(N4O4MacL3)Cl2] with new ligands, elemental analyses, infrared, magnetic measurements, UV–visible, 1H NMR, 13C NMR, and XRD studies were utilised. According to the spectrum data, the ligands perform as a mononegative tetradentate. Based on magnetic and electronic spectrum data, an octahedral structure for Co(II) metal complexes has been postulated. The Coats-Redfern and FWO techniques are used to determine the thermodynamic characteristics of ligands and their complexes. The molecular modelling using the DFT technique displays bond angles, bond lengths, and quantum chemical factors. To determine their ability to prevent the growth of harmful fungus and bacteria, the ligands [N4O4MacL1]- [N4O4MacL3] and their complexes were tested in vitro against A. Niger, C. albicans and B. subtilis, S. aureus, E. coli and S. typhi fungal and bacterial organisms, respectively. By using DPPH free radical scavenger assays, the in vitro antioxidant capabilities of each compound were evaluated. The [Co(N4O4MacL3)Cl2] antioxidative capabilities revealed significant radical scavenging power. All of the compounds under research were examined for cytotoxicity using the MTT assay on MCF-7 and HepG-2 cells, and the findings revealed that [Co(N4O4MacL2)Cl2] show outstanding cytotoxic activity against HepG-2 with IC50 17.94 ± 045 at a concentration of 25 ppm. Additionally, docking investigations of the produced compounds were carried out in order to validate the biological outcomes. Considerably, the current Co (II) complexes with their effective antimicrobial, antioxidant, and cytotoxicity activity would be probably appraised for further medicinal and pharmaceutical applications.

Synthesis, spectroscopic and surface morphological investigations of Co(II), Ni(II), Cu(II), and Zn(II) Schiff base macrocyclic complexes

The tetraiminediphenol macrocyclic complexes of Co(II), Ni(II), Cu(II), Zn(II) were synthesized by employing [2 + 2] Schiff base condensation of 2,6–diformyl–4–methylphenol and 1,2–diaminobenzene in the presence of hydrated metal(II) nitrates as templates in the molar ratio of 1:1:1 in methanol. All the synthesized complexes were found to be dark in color, stable in air and non–hygroscopic. The characterization of the complexes has been performed by the elemental analyses such as IR, UV–Visible, 1H NMR spectroscopy, mass spectrometry, magnetic susceptibility and molar conductivity measurements. X–ray diffractional studies suggest that the complexes are crystalline in nature. Energy dispersive X–ray spectroscopy (EDS) explores the complexes in terms of their chemical purity. The effects of metal ions on the surface morphology of macrocyclic complexes have been successfully analyzed by making use of a scanning electron microscopy (SEM).

Electrochemical, Antimicrobial, and Theoretical Investigations of Synthetic tetra-aza/penta-aza-Macrocyclic Complexes

The tailoring of the coordination environment around a central metal ion by changing ligands in macrocyclic complexes is one of the key approaches to monitoring their functions in various applications. Herein, two macrocyclic complexes of Co(II) transition metal ion, tetra-aza and penta-aza, were synthesized using a condensation reaction between different diamine and dicarboxylic precursors. The prepared complexes were analyzed using various characterization techniques. Further, the electrochemical behavior of both the tetra-aza and penta-aza complexes was investigated using cyclic voltammetry. The Co(II)-penta-aza-complex exhibited a quasi-reversible redox couple for Co(III)/Co(II) transition in the more anodic region as compared to Co(II)-tetra-aza-complex. According to theoretical calculations, the fifth N-coordination transferred a high electron density in the eg-orbital of Co-atom of penta-aza-complex, resulting in an anodic shift in the Co(III)/Co(II) redox potential when compared to the Co(II)-tetra-aza-complex. Furthermore, both complexes were tested for antimicrobial activity against P. aeruginosa, E. coli, S. aureus, and B. subtilis, with the results indicating that Co(II)-penta-aza-complex had higher antimicrobial activity against these bacteria than Co(II)-tetra-aza-complex. This study offers new insight into tailoring the electrochemical and biological features of macrocyclic complexes by tuning the coordination environment around the central metal ion.

Synthesis, characterization and in vitro anticancer activity of 18-membered octaazamacrocyclic complexes of Co(II), Ni(II), Cd(II) and Sn(II)

An effective series of 18 membered octaazamacrocyclic complexes of the type [MLX2], where X=Cl or NO3 have been synthesized by template condensation reaction of oxalyl dihydrazide with dibenzoylmethane and metal salt in 2:2:1 molar ratio. The formation of macrocyclic framework, stereochemistry and their overall geometry have been characterized by various physico-chemical studies viz., elemental analysis, electron spray ionization–mass spectrometry (ESI–MS), I.R, UV–Vis, 1H NMR, 13C NMR spectroscopy, X-ray diffraction (XRD) and TGA/DTA studies. These studies suggest formation of octahedral macrocyclic complexes of Co(II), Ni(II), Cd(II) and Sn(II). The molar conductance values suggest nonelectrolytic nature for all the complexes. Thermogravimatric analysis shows that all the complexes are stable up to 600°C. All these complexes have been tested against different human cancer cell lines i.e. human hepatocellular carcinoma (Hep3B), human cervical carcinoma (HeLa), human breast adenocarcinoma (MCF7) and normal cells (PBMC). The newly synthesized 18-membered octaazamacrocyclic complexes during in vitro anticancer evaluation, displayed moderate to good cytotoxicity on liver (Hep3B), cervical (HeLa) and breast (MCF7) cancer cell lines, respectively. The most effective anticancer cadmium complex (C34H28N10CdO10) was found to be active with IC50 values, 2.44±1.500, 3.55±1.600 and 4.82±1.400 in micro-molar on liver, cervical and breast cancer cell lines, respectively.

Studies of Synthetic Macrocyclic Complexes of Co (II) and Mn( II) in the Catalytic Oxidation of Hydroquinones

Studies of Synthetic Macrocyclic Complexes of Co (II) and Mn( II) in the Catalytic Oxidation of Hydroquinones

Synthesis and characterization of N2S2-tin macrocyclic complexes of Co(II), Ni(II), Cu(II) and Zn(II)

AbstractComplexes of Co(II), Ni(II), Cu(II), and Zn(II) containing N

Ab Initio quantum chemical calculation of the structures of coordination compounds arising at template synthesis in ion M(II)-hydrozinomethane thiohydrazide-acetone (M = Co, Ni, Cu) systems

Using a hybrid B3LYP density functional method with the 6-31G(d) basis set and the Gaussian-98 program, the geometrical parameters of macrocyclic complexes of Co(II), Ni(II) and Cu(II) with NNSS-coordination of donor centers of the chelate ligand, formed due to template processes in M(II)-hydrozinomethane thiohydrazide-acetone systems, are calculated. Coordinates of atoms, selected bond lengths and angles, and dihedral angles in complexes with MN2S2 metal-chelate site are given. It is noted that for all considered M(II) ions the additional six-membered metal cycle, formed because of template stitching, is turned at a considerable angle to two five-membered cycles, and this cycle itself is not planar either.

Spectral and thermal studies of new Co(II) and Ni(II) hexaaza and octaaza macrocyclic complexes

The macrocyclic complexes of Co(II) and Ni(II) having chloride or thiocyanate ions in the axial position have been synthesized and characterized. These complexes are synthesised by the template condensation of o-phenylenediamine or 2,3-butanedionedihydrazone with the appropriate aldehydes in NH4OH solution in the presence of the metal ions, Co(II) and Ni(II). The complexes were characterized by spectroscopic methods (IR, UV-Vis and ESR) and magnetic measurements as well as thermal analysis (TG and DTA). The results obtained are commensurate with the proposed formulae. Spectral studies indicate that these complexes have an octahedral structure. From conductivity measurements the complexes are non-electrolytes. The kinetic of the thermal decomposition of the complexes was studied and the thermodynamic parameters are reported.

Control of the electro-oxidation of macrocyclic complexes of Co(II) by axial coordination

Control of the electro-oxidation of macrocyclic complexes of Co(II) by axial coordination