Synthesis, characterization, and DNA-binding of enantiomers of iron(II) Schiff base complexes

Two pairs of iron(II) chiral enantiomers fac-Δ-[Fe(S-L1)3][ClO4]2 and fac-Λ-[Fe(R-L1)3][ClO4]2 (Δ-1 and Λ-1), fac-Δ-[Fe(S-L2)3][ClO4]2 and fac-Λ-[Fe(R-L2)3][ClO4]2 (Δ-2 and Λ-2), were synthesized and characterized. The X-ray structural analyses of Λ-1 and Δ-2 revealed that the iron(II) complexes possess octahedral coordination geometry for N6 donor atoms by three bidentate ligands. R-L1 ligand induces the fac-Λ isomer, while S-L2 ligand induces the fac-Δ isomer. The enantioselective binding constants of iron(II) chiral enantiomers to calf-thymus DNA (ct-DNA) range from 0.91×105 to 1.43×105M−1. Moreover, the Δ enantiomers exhibited more efficient DNA interaction with respect to the Λ enantiomers.