Iron(III) complexation behavior of benzene-centered tripodal mono-, di- and tritopic ligands carrying a repeating –Ahe–(HO)Apr– sequence [Ahe = 6-aminohexanoyl; (HO)Apr = 3-(N-hydroxy)aminopropanoyl]
作者:Akira Tsubouchi、Langtao Shen、Yukihiro Hara、Masayasu Akiyama
DOI:10.1039/b005788f
日期:——
To
investigate how three-directional molecules behave upon complexation with ferric iron, tripodal 1,3,5-benzene-centered
mono-, di- and tritopic iron-chelating ligands C6H3[COâ(Aheâ(HO)Apr)nâOH]3: 1, n
  =  1; 2, n
  =  2; 3,
n
  =  3}, composed of strands containing an âAheâ(HO)Aprâ sequence [Ahe  =  6-aminohexanoyl; (HO)Apr = 3-(N-hydroxy)aminopropanoyl],
were synthesized. These hydroxamate ligands form intramolecular six-coordinate octahedral complexes
with Fe(III): Fe1-1, Fe1-2, Fe2-2, Fe1-3, Fe2-3
and Fe3-3. The complexes formed were investigated from a topological
viewpoint and examined in terms of stability against attack by H+ and HOâ, monoprotonation equilibrium and
iron removal kinetics using a 20-molar excess of EDTA. Fe1-1, Fe1-2 and Fe2-2 have tripodal interstrand structures.
In particular, the iron removal reaction of Fe2-2 shows a consecutive first-order reaction pattern. From kinetic data
of the first-order reactions, Fe1-3, Fe2-3 and Fe3-3
are concluded to possess one, two and three discrete ferrioxamine-type
(intrastrand) structures, respectively.
为了研究三向分子在与铁络合时的行为,三元 1,3,5-苯中心单位、双位和三位铁螯合配体 C6H3[COâ(Aheâ(HO)Apr)nâOH]3:1, n  =   1; 2, n  =   2; 3, n  =   3},由含有âAheâ(HO)Aprâ序列[Ahe =  6-氨基己酰基;(HO)Apr =  3-(N-羟基)氨基丙酰基]的链组成。这些羟肟酸配体与 Fe(III) 形成分子内六配位八面体配合物:Fe1-1、Fe1-2、Fe2-2、Fe1-3、Fe2-3 和 Fe3-3。研究人员从拓扑学的角度对所形成的配合物进行了研究,并利用 20 摩尔过量的乙二胺四乙酸(EDTA)从稳定性、单质子化平衡和除铁动力学等方面考察了配合物对 H+ 和 HOâ 攻击的抵御能力。结果表明,Fe1-1、Fe1-2 和 Fe2-2 具有三足鼎立的链间结构,尤其是 Fe2-2 的除铁反应呈现出连续的一阶反应模式。根据一阶反应的动力学数据,Fe1-3、Fe2-3 和 Fe3-3 分别具有一个、两个和三个离散的铁氧胺型(链内)结构。