Synthesis, characterization, and biological properties of N-phenolato-N′-(3-dimethylaminopropyl)oxamide and its binuclear copper(II) complexes

• Published in: Transition metal chemistry (Weinheim) 2013-02, Vol.38 (1), p.69-78
• Main Authors: Zhang, Wan-Ju, Wang, Fang, Li, Yan-Tuan, Wu, Zhi-Yong
• Format: Article
• Language: English
• Subjects: Catalysis; Chemistry; Chemistry and Materials Science; Inorganic Chemistry; Organometallic Chemistry; Physical Chemistry
• ISSN: 0340-4285; 1572-901X
• DOI: 10.1007/s11243-012-9662-8

A new asymmetric N , N ′-bis(substituent)oxamide ligand, N -phenolato- N ′-(3-dimethylaminopropyl)oxamide (H 3 pdmapo), and two of its binuclear Cu(II) complexes with different terminal ligands, namely [Cu 2 (pdmapo)(phen)(H 2 O)](ClO 4 ) ( 1 ) and [Cu 2 (pdmapo)(bpy)(CH 3 OH)](ClO 4 ) ( 2 ), where phen = 1,10-phenanthroline and bpy = 2,2′-bipyridine, have been synthesized and characterized. The crystal structures of both complexes have been determined by single-crystal X-ray diffraction. Both structures contain binuclear Cu(II) cationic complexes with pdmapo 3− ligands. The asymmetric pdmapo 3− ligands bridge two Cu(II) atoms in the cis conformation and the Cu···Cu separations through the oxamide bridge are 5.2046(18) and 5.207(2) Å for complexes 1 and 2 , respectively. The coordination environments of the two Cu(II) atoms in each binuclear complex are different. The copper occupying the inner site of the pdmapo 3− ligand is four-coordinated in a CuN 3 O distorted square-planar environment, while the other is five-coordinated in a square pyramid geometry. In complex 1 , O–H···O and C–H···O hydrogen bonds link the complex into a one-dimensional chain. In complex 2 , O–H···O hydrogen bonds link the molecules to form a dimer, together with two types of strong π – π interactions, giving a two-dimensional network structure. The cytotoxicities and DNA-binding properties of H 3 pdmapo and the two complexes were studied. The experimental evidence suggests that the ligand binds to DNA via a groove binding mode, while the binuclear complexes bind intercalatively to DNA.