Metal Complexes of New Tetraazamacrocyclic Constrained Oxadiazole Ring as Subunits: Synthesis, DNA Binding and Photonuclease Activity

Abstract

Abstract A new tetraazamacrocyclic ligand, L (C24H16N12O6) and its complexes of type, [MLCl2] and [CuL]Cl2 (Where M = Co(II), Fe(II); L = N,N′-(benzene-1,3-diyldi-1,3,4-oxadiazole-5,2-diyl)bis{2-[(5-benzene-1,3-diyl-1,3,4-oxadiazol-2-yl)amino]acetamide}) were synthesized and characterized by elemental analysis including IR, 1H NMR, 13C NMR, mass and electronic spectral data. An octahedral geometry has been proposed for Fe(II) and Co(II) complexes except the Cu(II) complex which have a square planar environment. The binding property of the complexes with CT-DNA was studied by absorption spectra, viscosity measurement and thermal denaturation studies. The absorption spectral results indicate that the complexes binds with the base pairs of DNA with an intrinsic binding constant Kb of Cu(II), Co(II) and Fe(II) complexes were found to be 4.5 × 104 M−1, 5.7 × 104 M−1 and 2.6 × 104 M−1, respectively in 5 mM Tris-HCl/50 mM NaCl buffer at pH 7.2. The photo induced cleavage studies revealed that the complexes show photonuclease property against pUC19 DNA under UV-visible irradiation. Keywords: Tetraazamacrocyclic ligandmetal complexesDNA binding and cleavage Acknowledgment This work is supported by Major Research Project (F.No.33-322 /2007 (SR) Dated: 28-02-2008) from the University Grants Commission, New Delhi.