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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
Author(s) -
Hisaki Ichiro,
Sakamoto Yuu,
Shigemitsu Hajime,
Tohnai Norimitsu,
Miyata Mikiji,
Seki Shu,
Saeki Akinori,
Tagawa Seiichi
Publication year - 2008
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200800228
Subject(s) - crystallography , molecule , crystal structure , annulene , materials science , crystal (programming language) , single crystal , supramolecular chemistry , monoclinic crystal system , stacking , chemistry , stereochemistry , organic chemistry , computer science , programming language
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).