Homochiral helices of oligonaphthalenes inducing opposite-handed cholesteric phases.
Homochiral helices of oligonaphthalenes inducing opposite-handed cholesteric phases.
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DOI：
10.1002/chem.200500683
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发表时间：
2006-01
期刊：
影响因子：
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通讯作者：
S. Pieraccini;A. Ferrarini;K. Fuji*;G. Gottarelli;S. Lena;K. Tsubaki;G. Spada
中科院分区：
文献类型：
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作者：
S. Pieraccini;A. Ferrarini;K. Fuji*;G. Gottarelli;S. Lena;K. Tsubaki;G. Spada
通过在手性溶剂中掺杂手性非外消旋化合物而得到的手性手性非外消旋相（胆甾相）的螺旋结构是溶质手性的宏观证明。在1，4-位连接的低聚萘（四-，六-，八-）衍生物已被用作手性掺杂剂：当手性轴构型均匀（即，全S）时，分子结构对应于右手螺旋。然而，我们已经发现了一系列衍生物，其具有令人惊讶的性质，即在从四萘到六萘再到八萘的过程中，诱导的α-相的手性从正到负再到正交替。与低聚萘衍生物，不表现出这种扭曲能力的比较，点的重要性的取代模式。通过表面手性模型进行的计算，证实了诱导不同长度的同手性螺旋的反相的可能性，以及取代基所起的作用。
The helical structure of the chiral nematic phases (cholesterics) obtained by doping nematic solvents with chiral non-racemic compounds is a macroscopic proof of the solute chirality. Oligonaphthalene (tetra-, hexa-, octa-) derivatives linked at the 1,4-positions have been used as chiral dopants: When the chirality axes are configurationally homogeneous (that is, all-S), the molecular structures correspond to right-handed helices. Yet, we have found series of derivatives with the surprising property that the handedness of the induced cholesteric phase alternates from positive to negative and to positive again, on passing from tetra- to hexa- and to octanaphthalene. A comparison with oligonapthalene derivatives, which do not exhibit this twisting ability, points to the importance of the substitution pattern. Both the possibility of inducing oppositely-handed cholesteric phases by homochiral helices of different length, and the role played of substituents, are confirmed by calculations performed with the surface chirality model.