Hisaki Ichiro, Sakamoto Yuu, Shigemitsu Hajime, Tohnai Norimitsu, Miyata Mikiji, Seki Shu, Saeki Akinori, Tagawa Seiichi
Department of Material and Life Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.
Chemistry. 2008;14(14):4178-87. doi: 10.1002/chem.200800228.
To develop a novel pi-conjugated molecule-based supramolecular assembly, we designed and synthesized trisdehydrotribenzo[12]annulene ([12]DBA) derivative 2 with three carboxyl groups at the periphery. Recrystallization of 2 from DMSO gave a crystal of the solvate 23 DMSO. Crystallographic analysis revealed, to our surprise, that a face-to-face pi-stacked one-dimensional (1D) assembly of 2 was achieved and that the DMSO molecule played a significant role as a "structure-dominant element" in the crystal. This is the first example of [12]DBA to stack completely orthogonal to the columnar axis. To reveal its superstructure-dependent optical and electrical properties, 2 and its parent molecule 1, which crystallizes in a herringbone fashion, were subjected to fluorescence spectroscopic analysis and charge-carrier mobility measurements in crystalline states. The 1D stacked structure of 2 provides a red-shifted, broadened, weakened fluorescence profile (lambda(max) = 545 nm, phi(F) = 0.01), compared to 1 (lambda(max) = 491 nm, phi(F) = 0.12), due to strong interactions between the p orbitals of the stacked molecules. The charge-carrier mobility of the single crystal of 23 DMSO, as well as 1, was determined by flash photolysis time-resolved microwave conductivity (FP-TRMC) measurements. The single crystal of 23 DMSO revealed significantly-anisotropic charge mobility (sigma(mu) = 1.5x10(-1) cm(2) V(-1) s(-1)) along the columnar axis (crystallographic c axis). This value is 12 times larger than that along the orthogonal axis (the a axis).
为了开发一种新型的基于π共轭分子的超分子组装体，我们设计并合成了在周边带有三个羧基的三脱氢三苯并[12]轮烯（[12]DBA）衍生物2。2从二甲基亚砜（DMSO）中重结晶得到溶剂化物2·3DMSO的晶体。晶体学分析显示，令我们惊讶的是，实现了2的面对面π堆积一维（1D）组装，并且DMSO分子在晶体中作为“结构主导元素”发挥了重要作用。这是[12]DBA完全垂直于柱状轴堆积的首个例子。为了揭示其超结构依赖的光学和电学性质，对以人字形方式结晶的2及其母体分子1进行了晶体状态下的荧光光谱分析和电荷载流子迁移率测量。与1（λmax = 491 nm，φF = 0.12）相比，2的1D堆积结构由于堆积分子的p轨道之间的强相互作用，提供了红移、变宽、减弱的荧光光谱（λmax = 545 nm，φF = 0.01）。通过闪光光解时间分辨微波电导率（FP - TRMC）测量确定了2·3DMSO以及1的单晶的电荷载流子迁移率。2·3DMSO的单晶沿柱状轴（晶体学c轴）显示出显著的各向异性电荷迁移率（σμ = 1.5×10−1 cm2 V−1 s−1）。该值比沿正交轴（a轴）的值大12倍。
