Synthesis, Spectra and Electrochemistry of Ru(III) Complexes with Tetradentate Schiff Bases

Large interaction energy for the homodimer and the heterodimer extracted from the supramolecular chain of a bent trinuclear zinc(ii) complex with a reduced Schiff base ligand

The coordinated amino groups in a trinuclear zinc complex participate in strong H-bonding interactions that have been analysed. The dimerization energy is very large for both the homodimer and the heterodimer in the 1D supramolecular chain.

Synthesis, characterization, and DNA binding study of ruthenium(II/III) complexes containing ONS donor Schiff base

A chelating ligand of thioether with ONS donor Schiff base HL [(E)-2-(((2-(benzylthio)phenyl)imino)methyl)napthalen-1-ol] and its metal complexes (RuL₁ and RuL₂) have been synthesized. They have been characterized by UV-Vis, FTIR, ¹H NMR, ¹³C NMR, mass spectrometry methods. The formulas of the synthesized compounds have been confirmed by elemental analysis and magnetic susceptibility measurements. The binding ability studies of the ligand (HL) and its Ru complexes (RuL₁ and RuL₂), with calf-thymus DNA have been explored by the absorption titration method. The binding interaction study reveals that the ligand (HL) and the complex RuL₁ interact with CT-DNA through an intercalative mode of binding whereas the complex RuL₂ does not show any interaction with CT-DNA due to steric effect.

Synthesis, Characterization and Biological Studies of Metal(II) Complexes of (3E)-3-[(2-{(E)-[1-(2,4-Dihydroxyphenyl) ethylidene]amino}ethyl)imino]-1-phenylbutan-1-one Schiff Base

Co(II), Ni(II), Zn(II) and Cu(II) complexes of (3E)-3-[(2-{(E)-[1-(2,4-dihydroxyphenyl)ethylidene]amino}ethyl)imino]-1-phenylbutan-1-one (DEPH2) derived from ethylenediamine, 2',4'-dihydroxyacetophenone and 1-phenylbutane-1,3-dione have been synthesized and characterized by elemental analysis, FTIR, UV-Visible spectroscopy, and screened to establish their potential as antibacterial agents, antioxidants and DPPH radical scavengers. The FTIR spectra showed that the ligand behaves as a dibasic tetradentate ligand with the dioxygen-dinitrogen donor atom system oriented towards the central metal ion. The analytical and spectroscopic data suggest a square planar geometry for Cu(II) and Ni(II) complexes and an octahedral geometry for the Co(II) complex. The ligand and their metal complexes were screened for antibacterial activity against Gram (+) and Gram (-) bacteria by the agar well diffusion method. In addition, the antioxidant activities of the complexes were also investigated through their scavenging effect on DPPH and ABTS radicals. The obtained IC50 value of the DPPH activity for the copper complex (2.08 ± 0.47 µM) and that of the ABTS activity for the copper complex (IC50 = 2.11 + 1.69 µM) were higher than the values obtained for the other compounds.

Synthesis, spectral characterization, and biological evaluation of transition metal complexes of bidentate N, o donor schiff bases

New series of three bidentate N, O donor type Schiff bases (L (1) )-(L (3) ) were prepared by using ethylene-1,2-diamine with 5-methyl furfural, 2-anisaldehyde, and 2-hydroxybenzaldehyde in an equimolar ratio. These ligands were further complexed with Co(II), Cu(II), Ni(II), and Zn(II) metals to produce their new metal complexes having an octahedral geometry. These compounds were characterized on the basis of their physical, spectral, and analytical data. Elemental analysis and spectral data of the uncomplexed ligands and their metal(II) complexes were found to be in good agreement with their structures, indicating high purity of all the compounds. All ligands and their metal complexes were screened for antimicrobial activity. The results of antimicrobial activity indicated that metal complexes have significantly higher activity than corresponding ligands. This higher activity might be due to chelation process which reduces the polarity of metal ion by coordinating with ligands.

Synthesis and spectroscopic characterization of copper(II) complexes with the polydentate chelating ligand 4,4'-[1,4-phenylenedi(nitrilo)dipente-2-one

A new series of complexes of 4,4'-[1,4-phenylenenedi(nitilo)]dipenten-2-one, (H(2)L) with CuX(2) x nH(2)O, X = Cl, Br, ClO(4), NO(3) and OAc; n = 1-6 as well as their ethylenediamine adducts have been synthesized and characterized by different physical techniques. The formulation of the complexes is assumed based on their elemental analysis and the molar conductivity. The products are found to be pH-dependent. The IR data showed that the ligand acts as dibasic tetradentate coordinated to copper(II) ions through the enolato-oxygen and the azomethine nitrogen atoms. Electronic, ESR spectra and room temperature magnetic moments indicate that complexes 1-9 are square planar while complexes 10 and 11 are square based pyramidal. The different electronic spectral and ESR parameters are calculated and used to describe the nature of ligand-metal bonding (sigma and pi) as well as to estimate the extent of distortion. A macrocyclic containing copper(II) complex, 12 have been isolated by the reaction of Schiff-base with copper(II)-ethylenediamine mixture. The ligand (H(2)L) is designed as a building block for larger molecules and superamolecular assemblies.

Synthesis, spectra, dioxygen affinity and antifungal activity of Ru(III) Schiff base complexes

The reaction of ruthenium(III) complexes, [RuX(3)(EPh(3))(3)] (E=As, X=Cl or Br; E=P, X=Cl) and [RuBr(3)(PPh(3))(2)(CH(3)OH)] with bidendate Schiff base ligands derived by condensing salicylaldehyde with methylamine (Hsalmet), cyclohexylamine (Hsalchx), 2-aminopyridine (Hsalampy) have been carried out. The complexes were characterized by analytical and spectral studies (IR, electronic and EPR) and are formulated as [RuX(EPh(3))(LL')(2)] (where LL'=monobasic bidentate Schiff base ligand; E=P or As, X=Cl or Br). An octahedral geometry has been tentatively proposed for the new complexes. Dioxygen affinity of some of the Ru(III) Schiff base complexes was studied by cyclic voltammetry. The representative Schiff bases and their complexes were tested in vitro to evaluate their activity against fungi, namely, Aspergillus flavus (A. flavus) and Fusarium species.