Polynuclear complexes of a new macrocyclic oxamide metalloligand: Syntheses, crystal structures and deoxyribonucleic acid cleavage and magnetic properties

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• 作者：Xiao-Ming Shi ; Chang-Xin Li ; Xiao-Zeng Li ; ^{lixiaozeng321@tju.edu.cn} ; Shi Ren ; Li-Na Zhu
• 关键词：Polynuclear complex ; Synthesis ; Crystal structure ; Metalloligand ; DNA cleavage ; Magnetism
• 刊名：Inorganica Chimica Acta
• 出版年：2013
• 出版时间：30 January, 2013
• 年：2013
• 卷：395
• 期：Complete
• 页码：197-202
• 全文大小：729 K

文摘

A mononuclear macrocyclic oxamide complex CuL was used as a new metalloligand to prepare polynuclear complexes, by which a new tetranuclear complex {Mn[CuL(ClO₄)]₃}¡¤H₃O¡¤2.5H₂O (1) and a new trinuclear complex {Cu[CuL(CH₃OH)]₂(ClO₄)₂} (2) were obtained (H₂  L = dimethyl 5,6,7,8,15,16-hexahydro-6,7-dioxodibenzo-[1,4,8,11]tetraazacyclotetradecine-13,18-dicarboxylate). X-ray single crystal analysis revealed that every Cu(II) centre of the CuL metalloligand is coordinated by the four N atoms from the macrocyclic oxamide ligand and an O atom from a ClO₄^? anion in 1 or a CH₃OH molecule in 2, with the four N atoms forming the square base and the O atom occupying the vertex of the distorted square pyramidal coordination geometry. Plasmid DNA cleavage experiments showed that complexes CuL, 1 and 2 all have cleavage activities in the absence of any added oxidizing agents and that 2 has the highest cleavage efficiency among the three complexes in Tris-HCl buffer. Synergistic effects between the Cu(II) centers may contribute to the higher DNA cleavage efficiency of 2 in Tris-HCl buffer. Magnetism studies over the temperature range 2-300 K showed pronounced antiferromagnetic interactions between the oxamido-bridged metal centers in both 1 and 2.