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Chiral Coalition in Helical Sense Enhancement of Copolymers: the Role of the Absolute Configuration of Comonomers
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2018-01-02 , DOI: 10.1021/jacs.7b09965
Sandra Arias 1 , Rafael Rodríguez 1 , Emilio Quiñoá 1 , Ricardo Riguera 1 , Félix Freire 1
Affiliation  

Both the role of the absolute configuration and the tendency of a chiral monomer to promote a certain helical scaffold in a poly(phenylacetylene) (PPA) have been evaluated to study the communication between two chiral monomers within a copolymer chain. Nineteen different PPA copolymer series-47 helical copolymers altogether-were prepared to explore the existence of a chiral-to-chiral communication mechanism. From the data obtained, we found that communication between two different chiral monomers emerges when both exhibit two special features: (a) a different conformational composition-one must exist in a single low-energy conformation ("chiral Sergeant") and the other must present two conformers ("chiral Soldier")-and (b) the induction of a similar scaffold in the PPA, either cis-cisoidal or cis-transoidal. In the selected systems, the chiral Soldier includes the 4-ethynylanilide (para position) of either (R)- or (S)-2-methoxy-2-phenylacetic acid pendants characterized by their conformational flexibility (equilibrium between synperiplanar and antiperiplanar conformations). The chiral Sergeant contains the same chiral groups but linked to the backbone in meta position [3-ethynylanilide of (R)- or (S)-2-methoxy-2-phenylacetic acid] and is selected on the basis of its restricted antiperiplanar conformation. Incorporation of a very small amount (1%) of the Sergeant into a chain composed of just the Soldier transforms the originally axially racemic chain into a helix with strong sense preference (either M or P) that is determined by the absolute configuration of the Soldier.

中文翻译:

共聚物螺旋感增强中的手性联盟:共聚单体绝对构型的作用

已经评估了绝对构型的作用和手性单体在聚(苯乙炔)(PPA)中促进某种螺旋支架的趋势,以研究共聚物链内两种手性单体之间的通讯。共制备了 19 种不同的 PPA 共聚物系列 - 47 螺旋共聚物,以探索手性-手性通讯机制的存在。从获得的数据中,我们发现当两种不同的手性单体都表现出两个特殊特征时,就会出现两种不同的手性单体之间的通信:(a)不同的构象组成——一个必须存在于单一的低能构象中(“手性中士”),另一个必须存在提出两个构象异构体(“手性士兵”)-和(b)在 PPA 中诱导类似的支架,顺式-顺式或顺式-反式。在选定的系统中,手性士兵包括 (R)- 或 (S)-2-甲氧基-2-苯乙酸悬垂物的 4-乙炔苯胺(对位),其特征在于它们的构象灵活性(共平面和反平面构象之间的平衡) . 手性 Sergeant 包含相同的手性基团,但连接到间位 [(R)- 或 (S)-2-甲氧基-2-苯乙酸的 3-乙炔基苯胺] 的骨架,并根据其受限的反平面构象进行选择. 将极少量 (1%) 的中士并入仅由士兵组成的链,将原本轴向外消旋的链转变为具有强烈感官偏好(M 或 P)的螺旋,这由士兵的绝对构型决定. 手性士兵包括 (R)- 或 (S)-2-甲氧基-2-苯乙酸悬垂物的 4-乙炔苯胺(对位),其特征在于它们的构象灵活性(共平面和反平面构象之间的平衡)。手性 Sergeant 包含相同的手性基团,但连接到间位 [(R)- 或 (S)-2-甲氧基-2-苯乙酸的 3-乙炔基苯胺] 的骨架,并根据其受限的反平面构象进行选择. 将极少量 (1%) 的中士并入仅由士兵组成的链,将原本轴向外消旋的链转变为具有强烈感官偏好(M 或 P)的螺旋,这由士兵的绝对构型决定. 手性士兵包括 (R)- 或 (S)-2-甲氧基-2-苯乙酸悬垂物的 4-乙炔苯胺(对位),其特征在于它们的构象灵活性(共平面和反平面构象之间的平衡)。手性 Sergeant 包含相同的手性基团,但连接到间位 [(R)- 或 (S)-2-甲氧基-2-苯乙酸的 3-乙炔基苯胺] 的骨架,并根据其受限的反平面构象进行选择. 将极少量 (1%) 的中士并入仅由士兵组成的链,将原本轴向外消旋的链转变为具有强烈感官偏好(M 或 P)的螺旋,这由士兵的绝对构型决定.
更新日期:2018-01-02
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