Lee Myongsoo, Kim Jung-Woo, Peleshanko Sergiy, Larson Kirsten, Yoo Yong-Sik, Vaknin David, Markutsya Sergei, Tsukruk Vladimir V
Department of Chemistry, Yonsei University, Seoul 120-749, Korea.
J Am Chem Soc. 2002 Aug 7;124(31):9121-8. doi: 10.1021/ja017553+.
Amphiphilic discotic molecules with hydrophilic side branches consisting of hexaphenyl hexa-peri-hexabenzocoronene and hexabiphenyl hexa-peri-hexabiphenylcoronene as the aromatic core and hexa-substituted oligoethers as the branched peripheral chains have been synthesized, and their microstructure has been characterized. The discotic molecules based on dibranched oligoether side chains have been observed to self-organize into a well-ordered hexagonal columnar structure within liquid crystalline phases, which possessed an exceptionally high thermal stability and an unusually wide temperature range over >300 degrees C. We suggest that a combination of the large lateral dimensions of the rigid cores and disordered structure of the oxygen-containing branches tails is a driving force to the formation of a highly ordered columnar structure in the bulk state with enhanced molecular segregation. In contrast to the thermotropic phase behavior that favors the formation of highly ordered columnar aggregates through a strong stacking interaction, the hexabenzocoronene cores are packed in a face-on arrangement at the air/water interface and on solid surfaces with surface domains composed of an array of 7 x 7 molecules. We suggest a crablike molecular conformation and cluster-segregated monolayers with 6-fold symmetry and unusual face-on packing on a solid surface. Preliminary spectroscopic studies in the bulk state have shown that the molecules based on a hexaaromatic-substituted core may serve as functional supramolecular materials with high energy transfer characteristic within the columns due to near-perfect columnar ordering, which is unchanged over a wide temperature range. We believe that an absence of the crystallization phenomenon of side-branched oligoether chains is critical for the formation of long-range columnar ordering with strong intracolumnar correlation of conjugated disks important for high carrier mobility.
已合成了以六苯基六并六苯并蔻和六联苯六并六联苯蔻为芳香核、六取代低聚醚为支化外围链的具有亲水侧链的两亲性盘状分子，并对其微观结构进行了表征。基于双支化低聚醚侧链的盘状分子在液晶相中自组装成有序的六方柱状结构，该结构具有极高的热稳定性和超过300摄氏度的异常宽的温度范围。我们认为，刚性核的大横向尺寸和含氧支链尾部的无序结构相结合是在本体状态下形成具有增强分子分离的高度有序柱状结构的驱动力。与通过强堆积相互作用有利于形成高度有序柱状聚集体的热致相行为相反，六苯并蔻核在空气/水界面和固体表面以面朝上的排列方式堆积，表面域由7×7分子阵列组成。我们提出一种蟹状分子构象和具有六重对称性且在固体表面具有异常面朝上堆积的簇状分离单层。本体状态下的初步光谱研究表明，基于六芳基取代核的分子可作为功能性超分子材料，由于近乎完美的柱状排列，在柱内具有高能量转移特性，且在很宽的温度范围内不变。我们认为，侧支化低聚醚链不存在结晶现象对于形成具有对高载流子迁移率重要的共轭盘之间强柱内相关性的长程柱状有序至关重要。
