A series of transition and non-transition metal complexes from a N₄O₂ hexadentate Schiff base ligand: Synthesis, spectroscopic characterization and efficient antimicrobial activities

Some transition and non-transition metal complexes of the hexadentate N₄O₂ donor Schiff base ligand 1,8-N-bis(3-carboxy)disalicylidene-3,6-diazaoctane-1,8-diamine, abbreviated to H₄fsatrien, have been synthesized. All the 14 metal complexes have been fully characterized with the help of elemental analyses, molecular weights, molar conductance values, magnetic moments and spectroscopic (UV-Vis, IR, NMR, ESR) data. The analytical data helped to elucidate the structures of the metal complexes. The Schiff base, H₄fsatrien, is found to act as a dibasic hexadentate ligand using N₂N₂O₂ donor set of atoms (leaving the COOH group uncoordinated) leading to an octahedral geometry for the complexes around all the metal ions except VO²(+) and UO₂²(+). However, surprisingly the same ligand functions as a neutral hexadentate and neutral tetradentate one towards UO₂²(+) and VO²(+), respectively. In case of divalent metal complexes they have the general formula [M(H₂fsatrien)] (where M stands for Cu, Co, Hg and Zn); for trivalent metal complexes it is [M(H₂fsatrien)]X·nH₂O (where M stands for Cr, Mn, Fe, Co and X stands for CH₃COO, Cl, NO₃, ClO₄) and for the complexes of VO²(+) and UO₂²(+), [M(H₄fsatrien)]Y (where M=VO and Y=SO₄); M=UO₂ and Y=2 NO₃). The Schiff base ligand and most of the complexes have been screened in vitro to judge their antibacterial (Escherichia coli and Staphylococcus aureus) and antifungal (Aspergillus niger and Pencillium chrysogenum) activities.

New route to the synthesis of bis[N-(2-aminoethyl) salicylaldiminato] chromium(III) chloride monohydrate Spectroscopic characterization, crystal structure and interaction with DNA

The reaction of [Cr(urea)(6)]Cl(3).3H(2)O with H(2)salen (H(2)salen=N,N(')-ethylenebis(salicylaldimine) in water-methanol mixture (40:60v/v) under reflux yielded the complex bis[N-(2-aminoethyl)salicylaldiminato]chromium(III) chloride monohydrate, [Cr(aesaldmn)(2)]Cl.H(2)O. The complex was characterized by elemental analysis, molar conductance, magnetic susceptibility, spectroscopic (UV-vis and IR) data and X-ray diffraction studies. The new ligand, N-(2-aminoethyl)salicylaldimine, Haesaldmn, possibly resulted from the hydrolytic cleavage of one end of the H(2)salen ligand during reflux. Binding of this chromium(III) complex to CT DNA has been studied using UV-vis spectroscopy with an apparent binding constant of 2.68 x 10(3)M(-1). It shows that the binding mode is electrostatic while the emission of ethidium bromide to CT DNA in the absence and in the presence of the complex show that it binds DNA with partial intercalation.