Syntheses, crystal structures, and properties of two macrocyclic dinuclear Ni(II) complexes bearing 2-pyridylmethyl pendant-arms

Synthesis, spectral and extended spectrum beta-lactamase studies of transition metal tetraaza macrocyclic complexes

Urinary tract infections commonly occur in humans due to microbial pathogens invading the urinary tract, which can bring about a range of clinical symptoms and potentially fatal sequelae. The present study is aimed at addressing the development of a new antimicrobial agent against extended spectrum beta lactamase (ESBL) producing E. coli bacteria. We have synthesised some biologically potent (NNNN) donor macrocycles (L ₁  = dibenzo[f,n]dipyrido[3,4-b:4',3'-j][1,4,9,12]tetraazacyclohexadecine-6,11,18,23(5H,12H, 7H, 24H)-tetraone, and L ₂  = 6,12,19,25-tetraoxo-4,6,11,12,16,18,23,24-octahydrotetrabenzo [b,g,k,p][1,5,10,14]tetra azacyclooctadecine-2,13-dicarboxylic acid) and their Ti and Zr metal complexes in alcoholic media using microwave protocol. Macrocyclic ligands were synthesised by incorporating of 3,5-diaminobenzoic acid, phthalic acid and 3,4-diaminopyridine in 1:1:1 molar ratio. The macrocyclic ligands and their metal complexes have been characterised by elemental analysis, conductance measurement, magnetic measurement and their structure configurations have been determined by various spectroscopic (FTIR, ¹H/¹³C NMR, UV-Vis, LC-MS mass, XRD and TGA) techniques. [ZrL₂Cl₂]Cl₂ metal complex shows excellent antibacterial activity against ESBLs. A zone of inhibition and minimum inhibitory concentration was determined by McFarland and the dilution method, respectively. The spectral studies confirm the binding sites of the nitrogen atom of the macrocycles. An octahedral geometry has been assigned to the metal complexes based on the findings.

Cobalt (II) complex with novel unsymmetrical tetradentate Schiff base (ON) ligand: in vitro cytotoxicity studies of complex, interaction with DNA/protein, molecular docking studies, and antibacterial activity

[C₂₀H₁₇N₃O₂] and cobalt (II) complex [Co(L²)(MeOH)₂].ClO₄, (L² = 4-((E)-1-((2-(((E)-pyridin-2-ylmethylene) amino) phenyl) imino) ethyl) benzene-1, 3-diol) novel Schiff base has been synthesiszed and chracterized by Fourier transform infrared, UV-vis, ¹H-NMR spectroscopy, and elemental analysis techniques. The interaction of Co(II) complex with DNA and BSA was investigated by electronic absorption spectroscopy, fluorescence spectroscopy, circular dichroism, and thermal denaturation studies. Our experiments indicate that this complex could strongly bind to CT-DNA via minor groove mechanism. In addition, fluorescence spectrometry of BSA with the complex showed that the fluorescence quenching mechanism of BSA was of static type. The complex exhibited significant in vitro cytotoxicity against three human cancer cell lines (JURKAT, SKOV3, and U87). The molecular docking experiment effectively proved the binding of complex to DNA and BSA. Finally, antibacterial assay over gram-positive and gram-negative pathogenic bacterial strains was studied.

Structure, DNA binding and cleavage of a new Zn(II)Mn(II) macrocyclic complex

A new heterodinuclear complex of an unsymmetrical macrocycle [ZnMnL(CH(3)O)(2)]·H(2)O has been synthesized by the cyclocondensation between N,N'-bis(3-formyl-5-chlorosalicylidene)ethylenediimine and 2-hydroxyl-1,3-propanediamine in the presence of the metal ions, and characterized by elemental analyses, IR spectra and X-ray determination. The interactions of the complex with DNA have been investigated by UV absorption, fluorescence spectroscopy, viscosity measurements and electrochemical studies. Absorption spectroscopic investigation reveals that the complex has good binding propensity to calf thymus DNA by intercalation with a binding constant of 2.52 × 10(5)M(-1). Fluorescence spectroscopy shows that the complex can displace ethidium bromide and bind to DNA, with a quenching constant of 4.37 × 10(3)M(-1). The agarose gel electrophoresis studies show that pBR322 plasmid DNA can be transformed to nicked form and linear form in air by the complex.