Helix-sense tunability induced by achiral diene ligands in the chiral catalytic system for the helix-sense-selective polymerization of achiral and bulky phenylacetylene monomers
Helix-sense tunability induced by achiral diene ligands in the chiral catalytic system for the helix-sense-selective polymerization of achiral and bulky phenylacetylene monomers
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DOI：
10.1021/ma0713963
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发表时间：
2007-10-02
期刊：
影响因子：
5.5
通讯作者：
Aoki, Toshiki
中科院分区：
文献类型：
--
作者：
Kaneko, Takashi;Umeda, Yasuhiro;Aoki, Toshiki
[Rh(cod)Cl](2)和[Rh(nbd)Cl](2)催化剂促进{4-[(3,5-二叔丁基-4-羟基苯基)(3,5-二叔丁基-4-氧代-环六-2,5-二亚基)甲基]苯基}乙炔(简称(4-乙炔基苯基)氢加尔万氧基)的螺旋选择性聚合(R)-(+)-1-苯乙胺或(S)-(-)-1-苯乙胺(PEA)的存在。 [Rh(cod)C](2) 催化剂体系得到红色聚合物，其 CD 光谱显示出更强的棉花效应，但产率 (2-3%) 和分子量 (M-n = (1.1 - 1.4) x 10(4)) 低于 [Rh(nbd)Cl](2) 得到的聚合物。此外，我们还研究了在 (R)-PEA 存在下，催化剂、助催化剂和单体的体积对 (4-乙炔基苯基)氢加万氧基螺旋选择性聚合的影响。 [Rh(nbd)Cl](2) 和 [Rh(cod)Cl](2) 获得的聚合物的 CD 图案几乎彼此镜像，尽管信号大小不同，但尽管手性条件相同，即在 (R)-PEA 存在下。即，[Rh(nbd)Cl](2)和[Rh(cod)Cl](2)催化剂分别产生P-螺旋和M-螺旋。这是一个新颖的结果，因为螺旋正义的控制通常是通过用于螺旋正义选择性聚合的催化剂或引发剂的对映体部分来实现的。
Helix-sense-selective polymerization of {4-[(3,5-di-tert-butyl-4-hydroxyphenyl)(3,5-di-tert-butyl-4-oxo-cyclohexa-2,5-dienylidene)methyl]phenyl}acetylene (abbreviated as (4-ethynylphenyl)hydrogalvinoxyl) was promoted by [Rh(cod)Cl](2) and [Rh(nbd)Cl](2) catalyst in the presence of (R)-(+)-1-phenylethylamine or (S)-(-)-1-phenylethylamine (PEA). The [Rh(cod)C](2) Catalyst system gave red polymers whose CD spectra showed the stronger Cotton effect though the yield (2-3%) and molecular weight (M-n = (1.1 - 1.4) x 10(4)) were lower than those of polymers obtained by [Rh(nbd)Cl](2). Moreover, we investigated the effect of bulkiness of the catalyst, cocatalyst, and monomer on helix-sense-selective polymerization of (4-ethynylphenyl)hydrogalvinoxyl in the presence of (R)-PEA. The CD patterns of polymers obtained by [Rh(nbd)Cl](2) and [Rh(cod)Cl](2) were nearly mirror image of each other, except for the magnitudes of the signals in spite of the same chiral condition, i.e., in the presence of (R)-PEA. That is, [Rh(nbd)Cl](2) and [Rh(cod)Cl](2) catalysts generated P-helix and M-helix, respectively. This is a novel result, since the control of helix sense is usually achieved by enantiomeric moieties of catalysts or initiators for the helix-sense-selective polymerization.