Synthesis, Characterization, Thermal Behavior, and DNA‐Cleaving Studies of Cyano‐Bridged Nickel(II)Copper(II) Complexes of 4‐(Pyridin‐2‐ylazenyl)resorcinol

We present here the syntheses of a mononuclear Cu II complex and two polynuclear Cu II Ni II complexes of the azenyl ligand, 4‐(pyridin‐2‐ylazenyl)resorcinol (HL; 1). The reaction of HL ( 1 ) and copper(II) perchlorate with KCN gave a mononuclear complex [CuL(CN)] ( 4 ). Using 4 , one pentanuclear complex, [{CuL(NC)} 4 Ni](ClO 4 ) 2 ( 5 ) and one trinuclear complex, [{CuL(CN)} 2 NiL]ClO 4 ( 6 ), were prepared and characterized by elemental analyses, magnetic susceptibility, molar conductance, IR, and thermal analysis. Stoichiometric and spectral results of the mononuclear Cu II complex indicated that the metal/ligand/CN ratio was 1 : 1 : 1, and the ligand behaved as a tridentate ligand forming neutral metal chelates through the pyridinyl and azenyl N‐, and resorcinol O‐atom. The interaction between the compounds (the ligand 1 , its Ni II and Cu II complexes without CN, i.e. , 2 and 3 , and its complexes with CN, 4 – 6 ) and DNA has also been investigated by agarose gel electrophoresis. The pentanuclear Cu 4 Ni complex ( 5 ) with H 2 O 2 as a co‐oxidant exhibited the strongest DNA‐cleaving activity.