Recently, we found that n-type semiconducting hexaaza-
1
1
triphenylenes (HATs) can be self-assembled both in solu-
tion and bulk state to form one-dimensional columnar-type
Scheme 1. Preparation of 5a-c
1
2
aggregates. This finding led us to design and prepare new
n-type semiconducting large-sized aromatics based on the
combination of the HAT core and other electron-deficient
aromatics to improve both aggregation ability and electron
affinity. A combination of the HAT core and three phenan-
throline rings results in large n-type semiconductor tri-
13
(
phenanthrolino)hexaazatriphenylene (TP-HAT), which is
composed of 13 fused six-membered rings as many as that
of hexabenzocoronene.7 Here, we report that TP-HAT
derivatives provide high electron affinity as n-type semi-
conductor as well as strong self-assembling nature to form
well-ordered one-dimensional aggregates.
TP-HATs 5a and 5b with six butyl and dodecyl groups,
respectively, were prepared by condensation reactions of the
corresponding 1,10-phenanthroline-5,6-diketones 2a and 2b,
12
respectively, with hexaaminobenzene 4 in refluxing ethanol
in the presence of potassium carbonate (Scheme 1). In 5c
with 4-octylphenyl groups, the condensation reaction was
performed in an ethanol/THF mixture system because of the
poor solubility of 2c in ethanol. The key synthetic intermedi-
ate diketones 2a and 2b were derived from 1,10-phenan-
throline via 2,9-dialkyl derivatives 1a and 1b, respectively.
Two alkyl groups (butyl in 1a and dodecyl in 1b) were
introduced at the 2 and 9 positions of the phenanthroline
ring by addition reaction of the corresponding alkyllithium
with 1,10-phenanthroline followed by hydrolysis with water
1
4
and oxidation with manganese oxide to give 1a and 1b.
The dodecyllithium reagent was prepared in situ from
dodecyl iodide by treatment with tert-butyllithium at -65
°
C, before use.15 The 5 and 6 positions in 1a and 1b were
oxidized by treatment with nitric acid/sulfuric acid to give
(
8) van de Craats, A. M.; Warman, J. M. AdV. Mater. 2001, 13, 130-
33.
9) (a) Struijk, C. W.; Sieval, A. B.; Dakhorst, J. E. J.; van Dijk, M.;
1
(
Kimkes, P.; Koehorst, R. B. M.; Donker, H.; Schaafsma, T. J.; Picken, S.
J.; van de Craats, A. M.; Warman, J. M.; Zuilhof, H.; Sudh o¨ lter, E. J. R. J.
Am. Chem. Soc. 2000, 122, 11057-11066. (b) Balakrishnan, K.; Datar,
A.; Oitker, R.; Chen, H.; Zuo, J.; Zang, L. J. Am. Chem. Soc. 2005, 127,
1
6
2a and 2b. The poor isolated yields, in particular of 5% in
b, are attributed to the violent oxidation conditions where
2
1
0496-10497.
the alkyl chains in 1a and 1b were oxidized. On the other
hand, another key synthetic intermediate 2c was conveniently
obtained from coupling reaction of 2,9-dichloro-1,10-
(
10) Nitrogen-functionalized and fluorine-substituted hexabenzocoronenes
were reported: (a) Draper, S. M.; Gregg, D. J.; Madathil, R. J. Am. Chem.
Soc. 2002, 124, 3486-3487. (b) Zhang, Q.; Prins, P.; Jones, S. C.; Barlow,
S.; Kondo, T.; An, Z.; Siebbeles, L. D. A.; Marder, S. R. Org. Lett. 2005,
1
7
7
, 5019-5022.
phenanthroline-5,6-dione (3) with 4-octylphenylboronate
in the presence of a palladium (0) catalyst. This synthetic
route has the advantage of avoiding the alkyl-chain oxidation.
In 5a-c, any mesophases could not be observed. DSC and
TG measurements indicated decomposition above 350 °C.
TP-HATs 5b and 5c can dissolve in various solvents from
polar to nonpolar ones such as cyclohexane, toluene, dichlo-
romethane, chloroform, 1,1,2,2-tetrachloroethnae, and THF.
In contrast, 5a showed poor solubility in these solvents except
(
11) (a) Arikainen, E. O.; Boden, N.; J. Bushby, R.; Lozman, O. R.;
Vinter, J. G.; Wood, A. Angew. Chem., Int. Ed. 2000, 39, 2333-2336. (b)
Gearba, R. I.; Lehmann, M.; Levin, J.; Ivanov, D. A.; Koch, M. H. J.;
Barber a` , J.; Debije, M. G.; Piris, J.; Geerts, Y. H. AdV. Mater. 2003, 15,
1
614-1618. (c) Lehmann, M.; Kestemont, G.; Aspe, R. G.; Buess-Hermann,
C.; Koch, M. H. J.; Debije, M. G.; Piris, J.; de Haas, M. P.; Warma, J. M.;
Watson, M. D.; Lemaur, V.; Cornil, J.; Geerts, Y. H.; Gearba, R.; Ivanov,
D. A. Chem. Eur. J. 2005, 11, 3349-3362.
(12) (a) Ishi-i, T.; Hirayama, T.; Murakami, K.; Tashiro, H.; Thiemann,
T.; Kubo, K.; Mori, A.; Yamasaki, S.; Akao, T.; Tsuboyama, A.; Mukaide,
T.; Ueno, K.; Mataka, S. Langmuir 2005, 21, 1261-1268. (b) Ishi-i, T.;
Murakami, K.; Imai, Y.; Mataka, S. Org. Lett. 2005, 7, 3175-3178.
(13) Parent tri(phenanthrolino)hexaazatriphenylene without any alkyl
chains was reported as a ligand of tris-ruthenium complexes without any
discussion on self-assembling ability: W a¨ rnmark, K.; Heyke, O.; Thomas,
J. A.; Lehn, J.-M. Chem. Commun. 1996, 2603-2604.
(15) (a) Bailey, W. F.; Punzalan, E. R. J. Org. Chem. 1990, 55, 5404-
5406. (b) Boivin, R. P.; Luu-The, V.; Lachance, R.; Labrie, F.; Poirier, D.
J. Med. Chem. 2000, 43, 4465-4478.
(16) Margiotta, N.; Bertolasi, V.; Capitelli, F.; Maresca, L.; Moliterni,
A. G. G.; Vizza, F.; Natile, G. Inorg. Chem. Acta 2004, 357, 149-158.
(17) Yamada, M.; Tanaka, Y.; Yoshimoto, Y. Bull. Chem. Soc. Jpn. 1992,
65, 1006-1011.
(
14) (a) Dietrich-Buckecker, C. O.; Marnot, P. A.; Sauvage, J. P.
Terahedron Lett. 1982, 23, 5291-5294. (b) Felder, D.; Nierengarten, J.-
F.; Barigelletti, F.; Ventura, B.; Armaroli, N. J. Am. Chem. Soc. 2001, 123,
6
291-6299.
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Org. Lett., Vol. 8, No. 4, 2006