Superstructure-Dependent Optical and Electrical Properties of an Unusual Face-to-Face, π-Stacked, One-Dimensional Assembly of Dehydrobenzo[12]annulene in the Crystalline State

✍ Scribed by Ichiro Hisaki; Yuu Sakamoto; Hajime Shigemitsu; Norimitsu Tohnai; Mikiji Miyata; Shu Seki; Akinori Saeki; Seiichi Tagawa

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 801 KB
• Volume: 14
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/chem.200800228

✦ Synopsis

Abstract

To develop a novel π‐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 **2⋅**3 DMSO. Crystallographic analysis revealed, to our surprise, that a face‐to‐face π‐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 (λ~max~=545 nm, ϕ~F~=0.01), compared to 1 (λ~max~=491 nm, ϕ~F~=0.12), due to strong interactions between the p orbitals of the stacked molecules. The charge‐carrier mobility of the single crystal of **2⋅**3 DMSO, as well as 1, was determined by flash photolysis time‐resolved microwave conductivity (FP‐TRMC) measurements. The single crystal of **2⋅**3 DMSO revealed significantly‐anisotropic charge mobility (∑μ=1.5×10^−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).