Structure and O2 uptake properties of a novel nickel(II) complex of pyridyl-pendant dioxocyclam [1-(2-pyridyl)methyl-5,7-dioxo-1,4,8,11-tetraazacyclotetradecane]
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- 作者：E. Kimura ; Masatoshi Sasada ; Mitsuhiko Shionoya ; Tohru Koike ; Hiromasa Kurosaki and Motoo Shiro
- 关键词：Key words ; Nickel complex ; DNA cleavage ; O2 activation ; Biomimetic chemistry ; Macrocyclic polyamine
- 刊名：Journal of Biological Inorganic Chemistry
- 出版年：1997
- 出版时间：February 1997
- 年：1997
- 卷：2
- 期：1
- 页码：74-82
- 全文大小：315 KB
文摘
Novel potentially five-coordinate pyridyl–pendant dioxocyclam [1-(2-pyridyl)methyl-5,7-dioxo-1,4,8,11-tetraazacyclotetradecane (H2L) and its homologs (6-methyl and 6,6-dimethyl derivatives)] have been synthesized to study nickel(II) complexation. A purple nickel(II) complex with a deprotonated amide (NiHL) was isolated from aqueous equimolar solution of H2L and Ni(ClO4)2. A yellow nickel(II) complex with two deprotonated amides (NiL) was crystallized from an H2O/CH3CN solution of H2L and Ni(OH)2. The X-ray crystal study of NiL showed a square-planar nickel(II) complex with the pyridyl–pendant remaining uncoordinated. It is concluded from the visible absorption and NMR study of NiL in aqueous solution that the four-coordinate NiL is in equilibrium with a five-coordinate square-pyramidal nickel(II) complex with the apical coordination of the pyridyl–pendant. A voltammetric study disclosed a low nickel(II/III) redox potential of +0.29 V vs SCE for NiL at pH 9.5 and 25 ¡ãC with 0.10 M Na2SO4. The nickel(II) complex NiL absorbed an equimolar amount of O2 at pH 9.5 and 25 ¡ãC, and the O2 was activated to cleave plasmid DNA.