ORGANIC
LETTERS
2006
Vol. 8, No. 21
4699-4702
Donor−Acceptor−Donor-Type Liquid
Crystal with a Pyridazine Core
Yeon Sil Park, Dohyung Kim, Hoosung Lee, and Bongjin Moon*
Department of Chemistry, Sogang UniVersity, Seoul 121-742, Korea
Received July 12, 2006
ABSTRACT
A new liquid crystalline material having an ethylenedioxythiophene
−pyridazine−ethylenedioxythiophene (EDOT−PDZ−EDOT) core with two
peripheral long alkyl chains was prepared. The designated donor acceptor
−
−donor (D−A−D)-type core structure induced a distinct smectic
liquid crystalline phase due to the strong intermolecular interaction. The photophysical property and the layer structure of the liquid crystal
were investigated by differential scanning calorimetry, polarized light microscopy, X-ray diffraction, and cyclic voltammetry.
The π-conjugated organic materials have been the subject
of recent research work in relation to their optical and
electronic properties as well as their electronic applications
in many fields such as electroluminescent diodes (OLED),1
thin-film organic field-effect transistors (OFET),2 photovol-
taic cells, sensors, semiconductors, and displays.3 If one
introduces a π-conjugated moiety into a liquid crystalline
system, the resulting material can have many advantages
arising from the inherent self-assembling propensity.4 In the
past few years, considerable efforts have been made to
design, synthesize, and characterize various π-conjugated
liquid crystalline materials. In particular, smectic liquid
crystals have been a promising alternative approach to
organic semiconductors because of their spontaneous align-
5
ment behavior and good solubility.
We have been focusing on new π-conjugated materials
with a donor-acceptor-donor (D-A-D) system containing
electron-rich 3,4-ethylenedioxythiophene (EDOT) and electron-
deficient pyridazine and found that this system shows strong
intermolecular interaction.6 Although many nitrogen-contain-
ing heteroaromatic rings such as pyridine,7 pyrazine,8 and
pyrimidine9 have been employed as an electron acceptor, the
use of a pyridazine ring as an acceptor in a conjugated system
has not been studied until Yamamoto and co-workers
reported thiophene-pyridazine-thiophene D-A-D conju-
(1) (a) Mitschke, U.; Bauerle, P. J. Mater. Chem. 2000, 10, 1471. (b)
Geiger, F.; Stoldt, M.; Schweiser, R.; Ba¨uerle, P.; Umbach, E. AdV. Mater.
1993, 5, 922. (c) Barbarella, G.; Favaretto, L.; Sotgiu, G.; Zambianchi, P.;
Bongini, A.; Arbizzani, C.; Mastragostino, M.; Anni, M.; Gigli, G.;
Cingolani, R. J. Am. Chem. Soc. 2000, 122, 11971. (d) Barbarella, G.;
Favaretto, L.; Sotgiu, G.; Antolini, L.; Gigli, G.; Cingolani, R.; Bongini,
A. Chem. Mater. 2001, 13, 4112.
(2) (a) Dimitrakopoulos, C. D.; Malenfant, P. R. L. AdV. Mater. 2002,
14, 99. (b) Garnier, F. Acc. Chem. Res. 1999, 32, 209. (c) Horowitz, G.
AdV. Mater. 1998, 10, 3. (d) Katz, H. E. J. Mater. Chem. 1997, 7, 369. (e)
Barbarella, G.; Zambianchi, M.; Antolini, L.; Ostoja, P.; Maccagnani, P.;
Bongini, A.; Marseglia, E. A.; Tedesco, E.; Gigli, G.; Cingolani, R. J. Am.
Chem. Soc. 1999, 121, 8920. (f) Halik, M.; Klauk, H.; Zschieschang, U.;
Schmid, G.; Ponomarenko, S.; Kirchmeyer, S.; Weber, W. AdV. Mater. 2003,
15, 917.
(4) Peeters, E.; van Hal, P. A.; Meskers, S. C. J.; Janssen, R. A. J.; Meijer,
E. W. Chem.-Eur. J. 2002, 8, 4470.
(3) (a) Vlachos, P.; Mansoor, B.; Aldred, M. P.; O’Nell, M.; Kelly, S.
M. Chem. Commun. 2005, 5337. (b) Aldred, M. P.; Eastwood, A. J.; Kelly,
S. M.; Vlachos, P.; Contret, A. E. A.; Farrar, S. R.; Mansoor, B.; O’Nell,
M.; Chung Tsoi, W. Chem. Mater. 2004, 16, 4928. (c) Barche, J.; Janietz,
S.; Ahles, M.; Schmechel, R.; von Seggern, H. Chem. Mater. 2004, 16,
4286. (d) van de Craats, A. M.; Stutzmann, N.; Bunk, O.; Nielsen, M. M.;
Watson, M.; Mullen, K.; Chanzy, H. D.; Sirrnghaus, H.; Friend, R. H. AdV.
Mater. 2003, 15, 495. (e) Mochizuki, H.; Hasui, T.; Kawamoto, M.; Shiono,
T.; Ikeda, T.; Adachi, C.; Taniguchib, Y.; Shirotac, Y. Chem. Commun.
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(5) (a) Cammidge, A. N.; Bushby, R. J. Handbook of Liquid Crystals;
Wiley-VCH: Weinheim, 1998. (b) Funahashi, M.; Hanna, J. AdV. Mater.
2005, 17, 594. (c) Funahashi, M.; Hanna, J.-I. Mol. Cryst. Liq. Cryst. 2001,
366, 369. (d) Me´ry, S.; Haristoy, D.; Nicoud, J.-F.; Guillon, D.; Diele, S.;
Monobe, H.; Shimizu, Y. J. Mater. Chem. 2002, 12, 37. (e) Funahashi, M.;
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(6) We have synthesized 3,6-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-
yl)pyridazine (EDOT-pyridazine-EDOT) and found that this compound
is very insoluble in any solvent once it forms a solid upon concentration.
It is presumed that the lattice energy of this material is substantially high.
10.1021/ol061711q CCC: $33.50
© 2006 American Chemical Society
Published on Web 09/20/2006