Crown ethers with lateral ortho-terphenyl units: effect of ester groups and sodium salts on the mesomorphic properties
Crown ethers with lateral ortho-terphenyl units: effect of ester groups and sodium salts on the mesomorphic properties
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具有侧邻三联苯单元的冠醚：酯基和钠盐对介晶性质的影响
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
S. Laschat
中科院分区：
文献类型：
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作者：
Nelli Steinke;Michael Jahr;M. Lehmann;Angelika Baro;W. Frey;Stefan Tussetschläger;S. Sauer;S. Laschat
以甲氧甲基(MOM)保护的溴苯3和8为起始原料，分别转化为4和9，与二溴苯并[15]冠-5偶联，酸脱保护，最后与不同的烷基氯化物或没食子酸进行酯化反应，合成了具有不同酯基的不对称冠醚衍生物7和12。与NaI反应生成了配合物[NaI·(7a-g)]和[NaI·(12a-d)]。未络合的冠醚及其配合物[NaI·7a-c]和[NaI·12a-d]是非介晶性的。然而，在[NaI·(7d-g)]的情况下，络合诱导了中间相的形成。如[NaI·7d]的示例性显示，冷却时观察到不同的织构，扇形织构，这是柱状六方相中间相的典型织构，以及条带扇形织构，表明在低温下存在第二个中间相Colx。从SAXS衍射图可知，该中间相为柱状矩形。对于[NaI·7G]，发现了不同的衍射谱，由此得出的低温中间相可能是软晶或具有正交对称性的高度有序的柱状中间相。
Unsymmetrical crown ether derivatives 7 and 12 with one lateral o-terphenyl unit bearing different ester substituents were synthesized starting from methoxymethyl (MOM) protected bromobenzenes 3 and 8 by conversion into the respective borolanes 4 and 9, twofold Suzuki coupling with dibromobenzo[15]crown-5, acidic deprotection and finally esterification either with various alkanoic chlorides or gallic acids. Reaction with NaI provided the complexes [NaI·(7a–g)] and [NaI·(12a–d)], respectively. Uncomplexed crown ethers as well as their complexes [NaI·7a–c] and [NaI·12a–d] are non-mesogenic. In the case of [NaI·(7d–g)], however, the complexation induced a mesophase formation. As exemplarily shown for [NaI·7d], different textures were observed upon cooling, a fan-shaped texture, which is typical for a columnar hexagonal mesophase, and a striped fan-shaped texture, indicating a second mesophase Colx at low-temperature. From the SAXS diffraction pattern this mesophase was assigned to be columnar rectangular. For [NaI·7g] a different diffraction pattern was found, from which the low-temperature mesophase might be attributed to a soft crystal or a highly ordered columnar mesophase with orthorhombic symmetry.