DNA-binding and cleavage studies of chiral Mn(III) salen complexes

Chiral bridge-substituted manganese(III) complexes of N,N'-bis-(2-hydroxynaphthalene-1-carbaldehyde)-(1R,2R)-(-)-diaminocyclohexane and N,N'-bis-(2-hydroxynaphthalene-1-carbaldehyde)-(1S,2S)-(+)-diaminocyclohexane have been synthesized. The interaction of these complexes with calf thymus DNA(CT-DNA) was investigated by spectroscopic, thermal denaturation studies, circular dichroism (CD), and viscosity measurements. Results of spectroscopic and viscosity measurements suggest that the two complexes bind to DNA via an intercalative mode and display enantioselectivity. These Mn(III) complexes have been found to promote the cleavage of plasmid DNA pBR322 in the presence of H(2)O(2).