Chelation of transition metal ions by peptide nanoring

Shuichiro Kihara, Hiroyuki Takagi, Kazumasa Takechi, Kyozaburo Takeda*

*この研究の対応する著者

研究成果: Article査読

7 被引用数 (Scopus)

抄録

We have computationally studied the energetics and electronic structures of a chelate system where the guest cation is a transition metal (TM) and the host ligand is a peptide nanoring (PNR). The trapping of a TM cation by a cyclic peptide skeleton is primarily caused by the electrostatic interaction. The exchange interaction plays a secondary role in determining the relative stability in accordance with the spin multiplicity. An interesting feature of this chelate system is that a TM cation can also be trapped by the side-chain aromatic groups of the PNR via π-d hybridization. However, the spin multiplicity of the system changes the trapped form. When the chelate system has spin singlet multiplicity, a Fe2+ cation, for example, is not trapped by the single-phenyl group but is preferentially sandwiched by the two phenyl groups. In contrast, a Fe2+ cation can be trapped by single as well as by double-phenyl groups when the chelate system has higher spin multiplicity, such as triplet and quintet. These two different trapping forms are caused by the difference in the number of valence electrons of TM cations. For this chelate system, the newly occupied molecular orbital (MO) has an interbenzene antibonding character. Therefore, an electron occupying this MO state favors the mutual separation of two benzene molecules. Because the electron occupation of this MO varies in accordance with the spin multiplicity, one can predict the preference for the single-phenyl-group trapping process rather than the double-phenyl-group process systematically as well as consistently.

本文言語English
ページ(範囲)7631-7644
ページ数14
ジャーナルJournal of Physical Chemistry B
112
25
DOI
出版ステータスPublished - 2008 6月 26

ASJC Scopus subject areas

  • 物理化学および理論化学
  • 表面、皮膜および薄膜
  • 材料化学

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