New dinuclear Schiff base complexes of iron(II/III) and copper(II) ions: synthesis, crystal structure, and DNA-binding studies

Pyridine-2-carboxaldehyde-semicarbazone (PCS) complex [(H₂PCS).Cl]⁺[Fe(II)(PCS)Cl₃]^–.[Fe(III)(PCS)Cl₃] · (HPCS) · (Cl) (1) and 2,3-diacetylhydrazoneoxime (DAHO) complex [Cu₂(μ-Cl)₂(DAHO)₂Cl₂] (2) have been synthesized and characterized by different spectroscopic techniques. Structures were confirmed by single crystal X-ray crystallographic technique. Complex 1 crystallizes as Fe(II)/Fe(III) coordination complex in triclinic crystal system. EPR signals of 1 at g = 4.2 and g = 1.8 show transitions within m_S = ±3/2 and m_S = ±1/2 Kramers’ doublets of high spin (S = 5/2) distorted octahedral Fe(III) complex. Complex 2 crystallizes in triclinic system as square pyramidal chloro-bridged dinuclear copper(II) complex. The complexes were found to be groove binding to calf-thymus DNA.