Journal of the American Chemical Society
Communication
performed on beamline BL19B2 at SPring-8 with the approval
of JASRI (2009B1785, 2010A1721).
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in the Gaussian 09 program. See the Supporting Information for
details.
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substituted aromatics are −4.6 and −6.3 ppm. See: Bosdet, M. J. D.;
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(12) UV−vis, fluorescence, and CD measurements were performed
for rac-A and enantiopure (P)-A and (M)-A. See the Supporting
Information for details.
(13) Dibromination of A took place selectively at the para position of
the aniline moiety in the presence of 2 equiv of N-bromosuccinimide.
See the Supporting Information for details.
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E.; McDonald, R.; Branda, N. R. Org. Lett. 2000, 2, 3169−3172.
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Figure 3. Electronic couplings V (in meV) between HOMOs of
neighboring molecules in the X-ray crystal structures of (a) rac-A (P in
blue, M in pink) and (b) (P)-A. The electronic couplings between
LUMOs are shown in parentheses.
mobilities determined by the TOF method,18 suggesting the
possibility that the molecular orientations in the amorphous
films might be similar to those in the crystals.19
In summary, we have synthesized azaboradibenzo[6]helicene
(A) via a tandem bora-Friedel−Crafts-type reaction. Charge
mobility measurements by the time-of-flight (TOF) method
suggested that the racemate and single enantiomer of A are
good p- and n-type semiconductors, respectively. This
unprecedented carrier inversion can be explained by differences
in the packing structures of the hetero- and homochiral crystals
of A, as revealed by electronic coupling calculations. The results
indicate the potential of these chiral organic semiconductors in
electronic applications such as bipolar junction transistors and
morphology-controlled bulk-heterojunction solar cells.
ASSOCIATED CONTENT
* Supporting Information
■
S
Experimental procedures; characterization, photophysical,
electrochemical, and crystallographic data and CIF files for
the products; and computational methods and data. This
material is available free of charge via the Internet at http://
AUTHOR INFORMATION
Corresponding Author
■
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This research was supported by the PRESTO Program of JST
and a Grant-in-Aid for Young Scientists (23685020) from the
Ministry of Education, Culture, Sports, Science and Technol-
ogy (MEXT) of Japan. The study was also supported by the
NEXT Program of the Japan Society for the Promotion of
Science (JSPS) and the Asahi Glass Foundation. We thank Mr.
Toshiaki Ikuta and Dr. Jingping Ni (JNC Petrochemical
Corporation) for TOF and IP measurements and Professors
Mao Minoura (Kitasato University) and Hikaru Takaya and
Takahiro Sasamori (Kyoto University) for their guidance in the
X-ray crystallography experiments. For initial investigations,
synchrotron X-ray powder diffraction measurements were
C
dx.doi.org/10.1021/ja310372f | J. Am. Chem. Soc. XXXX, XXX, XXX−XXX