Self-assembly of multinuclear complexes with enantiomerically pure chiral binaphthoxy imine ligands: effect of the alkyl spacer connecting two binaphthyl units on the metal binding.
Self-assembly of multinuclear complexes with enantiomerically pure chiral binaphthoxy imine ligands: effect of the alkyl spacer connecting two binaphthyl units on the metal binding.
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DOI：
10.1002/chir.20308
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发表时间：
2006
期刊：
影响因子：
2
通讯作者：
Takeshi Maeda;Yoshio Furusho;M. Shiro;T. Takata
中科院分区：
文献类型：
--
作者：
Takeshi Maeda;Yoshio Furusho;M. Shiro;T. Takata
研究了具有两个末端联萘单元(L1和L2)的手性纯α，omega-二亚胺基烷烃的金属络合行为。由光学纯的2‘-丁氧基-3-甲酰基-2-羟基-1，1’-联萘与丙烷和戊二胺反应制备了配体L1和L2。L1和L2与等摩尔量的铜(OAc)2反应，得到定量的多核配合物1。其结构经MALDI-TOF MS、X-射线单晶结构分析、UV/Vis和CD光谱确证。具有1，3-丙二基间隔物的L1反应生成了一个自组装产物，命名为对映体三核螺旋状化合物1a，而具有1，5-戊二基间隔物L2的配体则得到了不同的自组装产物，双核并排配合物1b。1a在溶液中的圆二色谱(CD)表明，在萘单元的pi-pi*跃迁和N，O-螯合部分的LMCT区域都有强烈的Cotton效应。1b的CD光谱与1a的CD光谱完全不同，尤其是LMCT区的棉花效应与1a的相反。这些结果表明，1a即使在溶液中也保留了在N，O-螯合部分上诱导的手性，而在1b上诱导的手性不是很明显，这与X射线单晶结构研究的结果一致。
Metal complexing behavior of enantiomerically pure alpha,omega-diiminoalkanes possessing the two terminal binaphthyl units (L1 and L2) was studied. The ligands L1 and L2 were prepared by the reaction of optically pure 2'-butoxy-3-formyl-2-hydroxy-1,1'-binaphthyl with propane and pentane diamines. Reactions of L1 and L2 with equimolar amount of Cu(OAc)2 afforded quantitatively multinuclear complexes 1. The structure of 1 was confirmed by MALDI-TOF MS spectroscopy, X-ray single-crystal-structure analysis, and UV/vis and CD spectroscopic analyses. The reaction of L1 having a 1,3-propanediyl spacer resulted in the formation of a self-assembled product, which was assigned as enantiopure trinuclear circular helicate 1a, while the ligand having a 1,5-pentanediyl spacer L2 gave a different self-assembled product, dinuclear side-by-side complex 1b. The circular dichroism (CD) spectrum of 1a in solution showed intense Cotton effects in both the pi-pi* transition of the naphthalene units and the LMCT region of the N,O-chelate moieties. The CD spectrum of 1b was completely different from that of 1a; in particular the Cotton effects in the LMCT region were very weak, contrary to those of 1a. These results suggest that 1a retains some chirality induced on the N,O-chelating moieties even in solution, while the induced chirality on the N,O-chelating moieties in 1b is not very significant, being consistent with the consequences of the X-ray single-crystal-structure studies.