Liquid-Crystalline Kagome
Liquid-Crystalline Kagome
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DOI：
10.1002/anie.200802957
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发表时间：
2008-01-01
影响因子：
16.6
通讯作者：
Tschierske, Carsten
中科院分区：
文献类型：
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作者：
Glettner, Benjamin;Liu, Feng;Tschierske, Carsten
戈薇（来自日语; kago= basket，me= hole，eye：意思是一个有孔的篮子）表示规则六边形和三角形以1：2的比例周期性的2D平铺（见图1c）。这种图案，也被称为三六边形镶嵌，不仅因为其美学吸引力而引起人们的极大兴趣，而且特别是因为它与自旋受抑磁性材料有关。[1]然而，kagome模式在分子尺度上是罕见的，并且主要限于黄钾铁矾[2]和少数金属有机框架（MOF），即固态材料。[3]可果美网也可以在许多金属合金[4]中作为原子平面发现，最近通过在固体表面上组织DNA链[5]或有机分子获得了2D可果美网。[6]具有T形的三元两亲物（含有三种不相容类型的链段的分子）已被示出自发地组装成液晶（LC）相，其表示镶嵌的无限长的三角形、正方形、五边形或六棱柱的周期性阵列。[7-9]在这些新型LC相中，棱柱壁由棒状芳香链段形成（图1a）。棱柱形单元充满了横向连接到棒状芯的流体链。在本文中，这个概念被扩展并用于设计一种新的能够自组装成LC kagome的亲水性嵌段分子，LC kagome是一种代表三角形和六边形单元格相结合的周期性阵列的流体超结构。为此目的特别设计的化合物1（方案1）通过一系列制备步骤合成，其中Sonogashira交叉偶联反应[10]作为关键步骤（参见方案2）。两个化学上不同的链，脂肪族烃链和半全氟化链，横向连接在π-共轭的1，4-双（苯乙炔基）苯基芳族棒的相对侧，甘油基团，能够形成协同氢键，固定在每个末端。因此，该化合物代表Janus型，[11] X形季铵两亲物。两个不同的侧链结合在一起，通过显微偏析形成两个不同的隔室;需要不同体积的链[12]来填充
The kagome (from Japanese; kago= basket, me= hole, eye: meaning a basket with holes) represents a periodic 2D tiling of regular hexagons and triangles in a 1: 2 ratio (see Figure 1c). This pattern, also known as trihexagonal tiling, is of outstanding interest not only for its aesthetic appeal, but especially as it is of relevance for spin-frustrated magnetic materials.[1] However, the kagome pattern is rare on a molecular scale, and is mainly restricted to Jarosites [2] and a few metal–organic frameworks (MOFs), that is, to solid-state materials.[3] Kagome nets can also be found as atomic planes in a number of metal alloys [4] and recently 2D kagome nets were obtained by the organization of DNA strands [5] or organic molecules on solid surfaces.[6] Ternary amphiphiles (molecules containing three incompatible types of segments) with a T shape have been shown to spontaneously assemble into liquid-crystalline (LC) phases representing periodic arrays of tessellated infinitely long triangular, square, pentagonal, or hexagonal prisms.[7–9] In these new types of LC phases, the prism walls are formed by rodlike aromatic segments (Figure 1a). The prismatic cells are filled with fluid chains attached laterally to the rodlike cores. Herein, this concept is extended and used to design a new polyphilic block molecule capable of self-assembly into the LC kagome, a fluid superstructure representing a periodic array combining triangular and hexagonal cells. Compound 1 (Scheme 1), specifically designed for this purpose, was synthesized by a sequence of preparative steps with a Sonogashira cross-coupling reaction [10] as the key step (see Scheme 2). Two chemically different chains, an aliphatic hydrocarbon chain and a semiperfluorinated chain, were attached laterally at opposite sides of a π-conjugated 1, 4-bis (phenylethynyl) benzene-based aromatic rod to which glycerol groups, capable of forming cooperative hydrogen bonds, were fixed at each end. Hence, this compound represents a Janus-type,[11] X-shaped quaternary amphiphile. Two distinct lateral chains were combined to enable the formation of two different compartments by microsegregation; a different volume of the chains [12] was required to fill