Molecular docking and biological activities of Ni(II), Cu(II) and Co(II) complexes with a new potentially hexadentate polyamine ligand; X-ray crystal structure of the Cu(II) complex

Three new metal complexes have been obtained from the reaction of a new polyamine (L) with Ni(II), Cu(II), and Co(II) ions. The X-ray structural analysis of the Cu(II) complex shows that the copper atom is in a very distorted square pyramidal environment, coordinated by five of the six nitrogen donor atoms of the potentially hexadentate ligand. To evaluate the biological potential of the ligand and the synthesized metal complexes, their binding behavior with DNA was studied by molecular modeling methods. The Molecular docking studies showed that the free ligand and its complexes were bound to the major groove of DNA. The antioxidant activities of the ligand and its metal complexes were also assessed, in vitro, using 2,2-diphenyl-1-picrylhydrazyl. The synthesized compounds were tested for activity against lung carcinoma epithelial cells (A549) using the MTT cell viability assay. A comparative study of the IC50 values indicated that the Cu(II) complex exhibited the highest activity, while the Co(II) and Ni(II) complexes showed more potent antiproliferative activity than the ligand. The antibacterial activities of the synthesized complexes were evaluated using micro-broth dilution and disk diffusion methods. The complexes showed greater antibacterial activity than the free ligand.Communicated by Ramaswamy H. Sarma.

Theoretical and solid-state structures of three new macroacyclic Schiff base complexes and the investigation of their anticancer, antioxidant and antibacterial properties

Three symmetrical macroacyclic Schiff base complexes were prepared from a ligand derived from the condensation reaction of 1,4-bis(2-aminophenyl)piperazine and salicylaldehyde (L) with Cu(ii), Ni(ii) and Co(ii) perchlorates. The ligand and the Schiff base complexes were characterized by elemental analyses, UV-vis, FT-IR and mass spectrometry, with the structure of [CoL] being determined by a single crystal X-ray structural analysis. In this complex, the cobalt is in a distorted trigonal prismatic coordination environment, surrounded by the six donor atoms of the deprotonated hexadentate ligand. In order to compare the experimental and theoretical data and determine structure parameters in all complexes, Density Functional Theory (DFT) calculations at the B3lyp and BP86 levels with Def2-TZVP basis set have been carried out. NBO and QTAIM analyses have been used to describe the nature of M-O and M-N bonding in these complexes. The synthesized complexes were screened for their antioxidant activities using the DPPH free radical scavenging assay while their bactericidal activity was evaluated by the paper disc diffusion method against both Gram-negative and Gram-positive bacteria, revealing strong antioxidant activities and moderate effectiveness against all bacteria tested. The cytotoxicity of the metal complexes was also investigated against AGS (gastric) and A549 (lung) adenocarcinoma cells.

A novel self-assembled Na{Cu12Zn4} multifunctional material: first report of a discrete coordination compound for detection of Ca2+ions and selective adsorption of cationic dyes in water

A novel discrete Na{Cu₁₂Zn₄} unit is discovered with the ability to sense calcium ions (with ultra-low detection limit) as well as to adsorb cationic dyes in the aqueous phase with high performance.

Designing antiferromagnetically coupled mono-, di- and tri-bridged copper(ii)-based catecholase models by varying the ‘Auxiliary Parts’ of the ligand and anionic co-ligand

The role of the auxiliary part of ligands towards the architecture of copper(ii)-based catecholase models were unveiled with the help of DFT study.

Transition metal complexes of a versatile polyalkoxy oxazolidine-based ligand derived from in situ cyclization

One-pot reaction between 8-hydroxyquinoline-2-carboxaldehyde (HQC) and tris(hydroxymethyl)aminomethane (TRIS) followed by in situ cyclization yielded an oxazolidine based ligand which produced four mononuclear complexes of MnII(1), CoII(2), NiII(3), ZnII(4), a tetranuclear iron (FeIII4) complex (5) and a trinuclear cobalt (CoIICoIII2) complex (6). Magnetic studies show dominant antiferromagnetic interaction in tetranuclear iron (FeIII4) complex 5 and presence of the slow relaxation of magnetisation in 6. The compounds were also studied for their antibacterial properties. The oxazolidine ligand (H3L2) of this study showed good antimicrobial activity not only against Gram-positive bacteria but against Gram-negative bacteria too. The antimicrobial efficacy of the metal complexes (1-6) is also reported.

Experimental and theoretical investigations of copper (I/II) complexes with triazine-pyrazole derivatives as ligands and their in situ C-N bond cleavage

Two copper complexes, Cu(SCN)(Mpz(∗)T-(EtO)2) (1) (Mpz(∗)T-(EtO)2=L3) and CuCl(H2O)(Mpz(∗)T-O2) (2) (Mpz(∗)T-O2=L4) were synthesized by the reaction of 2,4,6-tri(3,5-dimethylpyrazol-1-yl)-1,3,5-triazine (L1) or 2,4,6-tri(1H-pyrazol-1-yl)-1,3,5-triazine (L2) with CuCl2·2H2O in anhydrous ethanol and methanol, respectively. The complexes were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, single crystal X-ray diffraction and X-ray powder diffraction. The structural characterizations and quantum mechanical calculations of the two complexes were analyzed in detail. It was found that an in site reaction occurred during the synthesis process of complexes 1 and 2, likely due to catalytic property of copper ions which leads to the C-N bond cleavage to generate new organic species, namely, Mpz(∗)T-(EtO)2 (L3) and Mpz(∗)T-O2 (L4).

Coordination polymers of a multipyridyl and pyrazolyl ligand with conformational flexibility: syntheses, structures and luminescence

Eight novel coordination polymers were obtained by the coordination of a multipyridyl and pyrazolyl ligand, which shows rich conformational changes.

Recent advances in the design strategies for porphyrin-based coordination polymers

Strategies to construct the porphyrin-based coordination polymers are summarized based on utilization of metal nodes, porphyrin ligands, inorganic polyoxometalates and post-synthetic modification.