C O M M U N I C A T I O N S
proceeded under the conditions of Negishi coupling to afford the
octaphenylindacene 6c in 94% yield. Similarly, addition of ben-
zophenone to 5 afforded the diol 6d (92%). Intramolecular
Friedel-Crafts reaction using BF3 ·OEt2 gave diindenoindacene 7,
which has a carbon-bridged phenylenevinylene skeleton, in 99%
yield as a yellow solid.
a lower temperature (mp 268 °C).17 We consider that the planarity
of the compounds contributes to the high mobilities and the high
stability.
In conclusion, we have developed efficient modular syntheses
of 1H-indenes, dihydro-s-indacenes, and a diindenoindacene con-
taining a carbon-bridged phenylenevinylene framework. Because
of the beneficial presence of the robust diphenylmethylene bridges,
these compounds showed clear signs of enhanced π-conjugation:
red-shift in absorption, high quantum yield of light emission, high
carrier mobilities, and high thermal stability. The balanced ambi-
polar mobility profile of 7 is noteworthy and suggests the potential
of the indacene class of materials for use in organic semiconductor
devices.
Scheme 2. Modular Synthesis of Dihydro-s-indacenes 6 and
Diindenoindacene 7
Acknowledgment. We thank Dr. Yoshiharu Sato for helpful
discussions and MEXT for financial support (KAKENHI for E.N.,
no. 18105004, H.T., no. 20685005, and the Global COE Program
for Chemistry Innovation). Z.X. thanks the JSPS for a Postdoctoral
Fellowship for Foreign Researchers (no. P 09046). C.M. thanks
JSPS for the Research Fellowship for Young Scientists (No.
21·9262).
Supporting Information Available: Experimental details and
photophysical and electrochemical data. This material is available free
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