Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
Chemistry. 2010 Feb 15;16(7):2258-71. doi: 10.1002/chem.200902416.
Two novel nonsymmetrical disc-shaped molecules 1 and 2 based on 3,3'-bis(acylamino)-2,2'-bipyridine units were synthesized by means of a statistical approach. Discotic 1 possesses six chiral dihydrocitronellyl tails and one peripheral phenyl group, whereas discotic 2 possesses six linear dodecyloxy tails and one peripheral pyridyl group. Preorganization by strong intramolecular hydrogen bonding and subsequent aromatic interactions induce self-assembly of the discotics. Liquid crystallinity of 1 and 2 was determined with the aid of polarized optical microscopy, differential scanning calorimetry, and X-ray diffraction. Two columnar rectangular mesophases (Col(r)) have been identified, whereas for C(3)-symmetrical derivatives only one Col(r) mesophase has been found. In solution, the molecularly dissolved state in chloroform was studied with (1)H NMR spectroscopy, whereas the self-assembled state in apolar solution was examined with optical spectroscopy. Remarkably, these desymmetrized discotics, which lack one aliphatic wedge, behave similar to the symmetric parent compound. To prove that the stacking behavior of discotics 1 and 2 is similar to that of reported C(3)-symmetrical derivatives, a mixing experiment of chiral 1 with C(3)-symmetrical 13 has been undertaken; it has shown that they indeed belong to one type of self-assembly. This helical J-type self-assembly was further confirmed with UV/Vis and photoluminescence (PL) spectroscopy. Eventually, disc 2, functionalized with a hydrogen-bonding acceptor moiety, might perform secondary interactions with molecules such as acids.
两种基于 3,3'-双（酰氨基）-2,2'-联吡啶单元的新型非对称盘状分子 1 和 2 通过统计方法合成。盘状分子 1 具有六个手性二氢香茅基尾和一个外围苯基，而盘状分子 2 具有六个线性十二烷氧基尾和一个外围吡啶基。通过强分子内氢键和随后的芳香相互作用的预组织诱导盘状分子的自组装。利用偏光显微镜、差示扫描量热法和 X 射线衍射确定了 1 和 2 的液晶性。已经确定了两种柱状矩形中间相（Col(r)），而对于 C(3)-对称衍生物，仅发现一种 Col(r)中间相。在溶液中，在氯仿中研究了分子溶解状态，而在非极性溶液中使用光学光谱研究了自组装状态。值得注意的是，这些缺少一个脂肪楔形的非对称盘状分子的行为类似于对称母体化合物。为了证明盘状分子 1 和 2 的堆积行为类似于报道的 C(3)-对称衍生物，进行了手性 1 与 C(3)-对称 13 的混合实验；结果表明它们确实属于一种自组装类型。这种螺旋 J 型自组装进一步通过 UV/Vis 和光致发光（PL）光谱得到证实。最终，带有氢键受体部分的功能化盘 2 可能与酸等分子发生二次相互作用。
