Combination of an Aromatic Core and Aromatic Side Chains Which

In 3a−c, the aromatic side chains with terminal flexible groups make up soft regions ... structures together with the hard regions of the hexaazatri...
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Langmuir 2005, 21, 1261-1268

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Combination of an Aromatic Core and Aromatic Side Chains Which Constitutes Discotic Liquid Crystal and Organogel Supramolecular Assemblies Tsutomu Ishi-i,*,† Tomoyuki Hirayama,‡ Ko-ichi Murakami,§ Hiroshi Tashiro,§ Thies Thiemann,† Kanji Kubo,† Akira Mori,† Sumio Yamasaki,‡ Tetsuyuki Akao,| Akira Tsuboyama,⊥ Taihei Mukaide,⊥ Kazunori Ueno,⊥ and Shuntaro Mataka*,† Institute for Materials Chemistry and Engineering (IMCE), Kyushu University, 6-1 Kasuga-koh-en, Kasuga 816-8580, Japan, Faculty of Engineering, Kyushu Sangyo University, 2-3-1 Matsukadai, Higashi-ku, Fukuoka 813-8503, Japan, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasuga-koh-en, Kasuga 816-8580, Japan, Biotechnology and Food Research Institute, Fukuoka Industrial Technology Center, 1465-5 Aikawa, Kurume 839-0861, Japan, and OL Development Div. 1, Advanced Device Technology Development Center, Canon Inc., 30-2, 3 Shimomaruko, Ohta-ku, Tokyo 146-8501, Japan Received August 25, 2004. In Final Form: November 15, 2004 This paper reports unique and unusual formations of columnar liquid crystals and organogels by selfassembling discotic molecules, which are composed of an aromatic hexaazatriphenylene (HAT) core and six flexible aromatic side chains. In HAT derivatives 3a, with 4′-(N,N-diphenylamino)biphenyl-4-yl chains, 3b, with 4′-[N-(2-naphthyl)-N-phenylamino]biphenyl-4-yl chains, and 3c, with 4′-phenoxybiphenyl-4-yl chains, the two-dimensional hexagonal packings can be created by their self-assembling in the liquid crystalline phase, which were characterized by polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction analysis. In certain solvents, HAT molecules 3a-c can form the viscoelastic fluid organogels, in which one-dimensional aggregates composed of the HAT molecules are self-assembled and entangled into three-dimensional network structures. The organogel structures were analyzed by scanning electron microscopy observation, 1H NMR, UV-vis, and circular dichroism spectroscopy. In contrast to 3a-c, none of the liquid crystalline and organogel phases could be formed from 3d and 3e with short aromatic side chains including a phenylene spacer, and 3f (except a few specific solutions) and 3g without terminal diarylamino and phenoxy groups. In 3a-c, the aromatic side chains with terminal flexible groups make up soft regions that cooperatively stabilize the liquid crystalline and organogel supramolecular structures together with the hard regions of the hexaazatriphenylene core.

Introduction Supramolecular assembly composed of disk-shaped aromatic molecules has been of much interest,1-3 because it enables the formation of π-stacked columnar-type architecture, which is very useful in materials science such as organic light-emitting diodes,4 field-effect transistors,5 and photovoltaics.6 In principle, the disk-shaped molecules are composed of a central aromatic core as a * Corresponding author. E-mail: [email protected]. Tel: +81 92 583 7811. Fax: +81 92 583 7894. † IMCE, Kyushu University. ‡ Kyushu Sangyo University. § Interdisciplinary Graduate School of Engineering Sciences, Kyushu University. | Fukuoka Industrial Technology Center. ⊥ Canon Inc. (1) For reviews of discotic liquid crystals see: (a) Chandrasekhar, S. In Handbook of Liquid Crystals; Demus, D., Goodby, J., Gray, G. W., Spiess, H.-W., Vill, V., Eds.; WILEY-VCH: Weinheim, 1998; Vol. 2B, Chapter 8. (b) Guillon, D. Struct. Bonding 1999, 95, 41-82. (2) Brunsveld, L.; Folmer, B. J. B.; Meijer, E. W.; Sijbesma, R. P. Chem. Rev. 2001, 101, 4071-4097. (3) For reviews of organogels see: (a) Tereth, P.; Weiss, R. G. Chem. Rev. 1997, 97, 3133-3159. (b) Esch, J. V.; Schoonbeek, F.; de Loose, M.; Veen, E. M.; Kellogg, R. M.; Feringa, B. L. Supramol. Sci. 1999, 6, 233-259. (c) Shinkai, S.; Murata, K. J. Mater. Chem. 1998, 8, 485-495. (d) Abdallah, D. J.; Weiss, R. G. Adv. Mater. 2000, 12, 1237-1247. (e) Gronwald, O.; Shinkai, S. Chem. Eur. J. 2002, 7, 4328-4334. (4) (a) Christ, T.; Glu¨sen, B.; Greiner, A.; Kettner, A.; Sander, R.; Stu¨mpflen, V.; Tsukruk, V.; Wendorff, J. H. Adv. Mater. 1997, 9, 4851. (b) Hassheider, T.; Benning, S. A.; Kitzerow, H.-S.; Achard, M.-F.; Bock, H. Angew. Chem., Int. Ed. 2001, 39, 2060-2063.

rigid region and peripheral flexible alkyl side chains as a soft region. In addition to the central aromatic stacking, the flexible alkyl side chains play an important role in the formation of supramolecular aggregates such as discotic liquid crystals1,2 and organogels.2,3 In discotic liquid crystals, the alkyl side chains make a soft region to facilitate phase separation, leading to the formation of a mesophase.1,7 In a concentrated solution, the flexible alkyl chains disturb recrystallization to form viscoelastic organogels.3,8 Recently, exciting and surprising examples that do not follow the structural guideline for such supramolecular assembly were reported: columnar liquid (5) van de Craats, A. M.; Stutzmann, N.; Bunk, O.; Nielsen, M. M.; Watson, M.; Mu¨llen, K.; Chanzy, H. D.; Sirringhaus, H.; Friend, R. H. Adv. Mater. 2003, 15, 495-499. (6) (a) Schmidt-Mende, L.; Fechtenko¨tter, A.; Mu¨llen, K.; Moons, E.; Friend, R. H.; MacKenzie, J. D. Science 2001, 293, 1119-1122. (b) Ajayaghosh, A.; George, S. J.; Praveen, V. K. Angew. Chem., Int. Ed. 2003, 42, 332-335. (7) (a) Watson, M. D.; Fechtenko¨tter, A.; Mu¨llen, K. Chem. Rev. 2001, 101, 1267-1300 and references therein. (b) Watson, M. D.; Debije, M. G.; Warman, J. M.; Mu¨llen, K. J. Am. Chem. Soc. 2004, 126, 766-771. (c) Terasawa, N.; Monobe, H.; Kiyohara, K.; Shimizu, Y. Chem. Commun. 2003, 1678-1679. (d) Kimura, M.; Saito, Y.; Ohta, K.; Hanabusa, K.; Shirai, H. Kobayashi, N. J. Am. Chem. Soc. 2002, 124, 5274-5275. (e) Boden, N.; Bushby, R. J.; Headdock, G.; Lozman, O. R.; Wood, A. Liq. Cryst. 2001, 28, 139-144. (f) Yatabe, T.; Harbison, M. A.; Brand, J. D.; Wagner, M.; Mu¨llen, K.; Samori, P.; Rabe, J. P. J. Mater. Chem. 2000, 10, 1519-1525. (g) Mohr, B.; Wegner, G.; Ohta, K. J. Chem. Soc. Chem. Commun. 1995, 995-996. (h) Shimizu, Y.; Miya, M.; Miya, A.; Nagata, A.; Ohta, K.; Yamamoto, I.; Kusabayashi, S. Liq. Cryst. 1993, 14, 795805.

10.1021/la047874+ CCC: $30.25 © 2005 American Chemical Society Published on Web 01/12/2005

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crystals that lack side chains9 and columnar nematic liquid crystals that have only aromatic side chains.10 The created supramolecular aggregates would be considered as attractive functional materials because of their high π-electron densities and the presence of photochemically and electrochemically active aromatic side chains. Our combined interest in n-type semiconducting hexaazatriphenylene (HAT) as an electron-transporting material11 and in a new-type, columnar-type aggregate led us to design and prepare discotic HATs without alkyl side chains. Here, we report that discotic HATs with six aromatic side chains aggregate both in liquid crystalline and in organogel phases. Results and Discussion HATs with six aromatic functional groups (3a, 4′-(N,Ndiphenylamino)biphenyl-4-yl; 3b, 4′-[N-(2-naphthyl)-Nphenylamino]biphenyl-4-yl; 3c, 4′-phenoxybiphenyl-4-yl; 3e, 4-phenoxyphenyl; 3f, 4-diphenyl; 3g, phenyl) were prepared by condensation reactions of the corresponding diaryldiketones 2a-c and 2e-g with hexaaminobenzene 112 (Scheme 1). The key synthetic intermediate diaryldiketones 2a-c,f were derived from commercially available 2h by Suzuki coupling reactions with the corresponding arylboronic acids. The other synthetic intermediate 2e was obtained by benzoin condensation reaction of 4-phenoxybenzaldehyde and the subsequent oxidation reaction with bismuth nitrate and cuprous acetate. Diphenylaminophenyl-substituted diketone 2d, which was the synthetic intermediate of HAT 3d with 4-N,Ndiphenylaminophenyl groups, could not be obtained from the coupling reaction of 2h with diphenylamine in the presence of a palladium(0) catalysis. Thus, HAT 3d was derived from 3h by the coupling reaction with diphenylamine in the presence of a palladium(0) catalyst. Differential scanning calorimetry (DSC) measurement of 3a with (diphenylamino)biphenyl groups indicates the formation of mesophase at 343-385 °C (Table 1). Similarly, mesophase was confirmed at 278-398 °C in 3b with (naphthylphenylamino)biphenyl groups, although at above the melting point, 3b was gradually decomposed. For 3c with (phenoxy)biphenyl groups the mesophase was observed at 357-464 °C (Table 1). In polarizing optical microscopy of 3a, 3b, and 3c, characteristic textures such (8) (a) Ikeda, M.; Takeuchi, M.; Shinkai, S. Chem. Commun. 2003, 1354-1355. (b) Shirakawa, M.; Kawano, S.; Fujita, N.; Sada, K.; Shinkai, S. J. Org. Chem. 2003, 68, 5037-5044. (c) Tamaru, S.; Uchino, S.; Takeuchi, M.; Ikeda, M.; Hatano, T.; Shinkai, S. Tetrahedron Lett. 2002, 43, 3751-3735. (d) Ajayaghosh, A.; George, S. J. J. Am. Chem. Soc. 2001, 123, 5148-5149. (e) Engelkamp, H.; Middelbeek, S.; Nolte, R. J. M. Science 1999, 284, 785-788. (f) van Nostrun, C. F.; Picken, S. J.; Schouten, A.-J.; Nolte, R. J. M. J. Am. Chem. Soc. 1995, 117, 99579965. (9) Barbera´, J.; Rakitin, O. A.; Ros, M. B.; Torroba, T. Angew. Chem., Int. Ed. 1998, 37, 296-299 and references therein. (10) (a) Praefcke, K.; Singer, D.; Gu¨ndogan, B.; Gutbier, K.; Langer, M. Ber. Bunsen-Ges. Phys. Chem. 1993, 97, 1358-1361. (b) Praefcke, K.; Singer, D.; Langer, M.; Kohne, B. Mol. Cryst. Liq. Cryst. 1992, 215, 121-126. (11) Hexaazatriphenylene-based discotic molecules with long alkyl chains: (a) Gearba, R. I.; Lehmann, M.; Levin, J.; Ivanov, D. A.; Koch, M. H. J.; Barbera`, J.; Debije, M. G.; Piris, J.; Geerts, Y. H. Adv. Mater. 2003, 15, 1614-1618. (b) Ong, C. W.; Liao, S.-C.; Chang, T. H.; Hsu, H.-F. Tetrahedron Lett. 2003, 44, 1477-1480. (c) Pieterse, K.; van Hal, P. A.; Kleppinger, R.; Vekemans, J. A. J. M.; Janssen, R. A. J.; Meijer, E. W. Chem. Mater. 2001, 13, 2675-2679. (d) Kestemont, G.; de Halleux, V.; Lehmann, M.; Ivanov. D. A.; Watson, M.; Geerts, Y. H. Chem. Commun. 2001, 2074-2075. (e) Arikainen, E. O.; Boden, N.; Bushby, R. J.; Lozman, O. R.; Vinter, J. G.; Wood, A. Angew. Chem., Int. Ed. 2000, 39, 2333-2336. (12) (a) Mataka, S.; Eguchi, H.; Takahashi, K.; Hatta, T.; Tashiro, M. Bull. Chem. Soc. Jpn. 1989, 62, 3127-3131. (b) Mataka, S.; Shimojyo, Y.; Hashimoto, I.; Tashiro, M. Liebigs Ann. 1995, 1823-1825. (c) Komin, A. P.; Carmack, M. J. Heterocycl. Chem. 1975, 12, 829-833.

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as pseudofocal conic and dendritic textures are observable as found in hexagonal discotic liquid crystals reported so far (Figure 1).13 Around room temperature (a solid state), such characteristic textures were observable also along with lacking the fluidity. In contrast to 3a-c, no liquid crystalline phase could be formed from 3d and 3e with a phenylene spacer and from 3f and 3g without terminal diarylamino and phenoxy groups (Table 1). It can be concluded that in 3a-c the flexibility of the terminal groups and the length of the biphenylene spacer are crucial for the formation of the liquid crystalline supramolecular structure. In the self-assembling of the discotic molecules, the terminal diarylamino and phenoxy groups of the aromatic side chains should be entangled intermolecularly to facilitate phase separation. The entanglement can be controlled by the spacer moiety connecting the hexaazatriphenylene core and the terminal groups. Compared to 3d and 3e with the short phenylene spacer, 3a and 3c with the biphenylene spacer can offer suitable room around the terminal moieties to facilitate the intermolecular entanglement.14 Also, the steric hindrance of the terminal bent structure can disturb the crystallization to form a liquid crystalline mesophase. The hexagonal discotic liquid crystalline structure in 3a and 3c is confirmed by X-ray diffraction analysis. In the narrow angle region, characteristic d100, d110, d200, and d210 reflections (2.83, 1.64, 1.41, and 1.06 nm, respectively) in a two-dimensional hexagonal array are observable in 3a, indicating the formation of hexagonal columnar packing but no crystalline three-dimensional packing (Figure 2a and Table 2).15 The estimated intercolumnar distance of 3.25 nm is slightly shorter than the molecular length of ca. 3.45 nm calculated by the MM method. Similarly, the hexagonal packing with d100, d110, and d200 reflections (2.44, 1.41, and 1.21 nm, respectively) is observable in 3c (Figure 2b and Table 2).15 The hexagonal packing of 3c has a short intercolumnar distance of 2.81 nm. Compared to 3a with 12 terminal phenyl groups, 3c with 6 terminal phenyl groups has more room around the terminal moieties where the intercolumnar entanglement is favored to stabilize the hexagonal packing. The stabilization is reflected in the higher clearing point in 3c (464 °C) than in 3a (385 °C). The aggregative nature of HATs is also operative in the gelation of organic solvents. In certain organic solvents at 1.0 × 10-2 M, 3a, 3b, and 3c can form viscoelastic fluid organogels, in which one-dimensional aggregates composed of 3a, 3b, and 3c molecules are entangled into threedimensional network structures to prevent the solvents from flowing. Compound 3a can gelate aniline, nitroben(13) (a) Destrade, C.; Foucher, P.; Gasparoux, H.; Tinh, N. H.; Levelut, A. M.; Malthete, J. Mol. Cryst. Liq. Cryst. 1984, 106, 121-146. (b) Kumar, S.; Wachtel, E. J.; Keinan, E. J. Org. Chem. 1993, 58, 3821-3827. (c) Serrette, A. G.; Lai, C. K.; Swager, T. M. Chem. Mater. 1994, 6, 22522268. (d) Terasawa, N.; Monobe, H.; Kiyohara, K.; Shimizu, Y. Chem. Lett. 2003, 32, 214-215. (14) In the calculated structures by MM method, the intramolecular nonbonded N‚‚‚N distances (1.14-1.18 nm for small space, 1.51-1.59 nm for large space) in 3a with the biphenylene spacer are longer than those (0.76-0.80 nm for small space, 1.09-1.12 nm for large space) in 3d with the phenylene spacer, suggesting the possible entanglement at the terminal moieties. A similar trend was observed in the comparison of 3c with 3e. (15) A weak and broad halo was observed in the wide angle region. A shoulder detected ca. 24°degree would be attributed to the intracolumnar disk-disk distance of ca. 0.37 nm, which is comparable to those (0.35-0.36 nm) of alkyl-chain-containing aryl-substituted triphenylenes and hexaazatriphenylenes: see ref 11e and Boden, N.; Bushby, R. J.; Headdock, G.; Lozman, O. R.; Wood, A. Liq. Cryst. 2001, 28, 139-144. Around room temperature, 3a indicated weak and broad reflections, suggesting the formation of an amorphous type solid. In contrast, 3c showed the multiple reflections arising from the formation of a crystalline solid at the lower temperature.

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Scheme 1. Preparation of Hexaazatriphenylenes Having Six Aromatic Side Chains 3a-h

Table 1. Phase Transitions of 3a-g compound

phase transition T/°C (∆H/kJ mol-1) a

3ab 3b 3cb 3d 3e 3f 3g

Cr 343 (13.0), Colh 385 (3.0), I Cr 278, Colh 398, Ic Cr 357 (45.5), Colh 464 (7.8), I Cr 380 (47.5), I Cr 290 (28.7), I Cr 484 (20.3), I Cr 359 (22.5), I

a The transition temperatures and enthalpies (∆H) were measured by DSC (samples 2-3 mg in closed Al pans, heating rate 10 K min-1). Phases were assigned on the basis of polarizing optical microscopy and X-ray diffraction analysis. b Reproducible data were obtained in first, second, and third heating processes. c At above the melting point, 3b decomposed gradually.

zene, (R)/(S)-1-phenylethyl alcohols to form stable and transparent gels, whereas partial gels were formed from

benzene, toluene, p-xylene, and 1,2-dichloroethane solutions (Table 3). The temperature and concentration effects on the gelation were checked in the 3a gels in aniline and (R)-1-phenylethyl alcohol. The aniline gel of 3a was stable until 60 °C (1.0 × 10-2 M) and unstable at a dilute concentration of 1.0 × 10-3 M (20 °C). The (R)-1phenylethyl alcohol gel of 3a was stable until 80 °C at 1.0 × 10-2 M. The gel structure was still stable at 1.0 × 10-3 M, whereas it collapsed at 1.0 × 10-4 M. A birefringent character in the gel samples of 3a was confirmed in polarized optical microscopy, revealing the presence of ordered aggregate structures (Figure S1 in Supporting Information).8a In contrast, 3b can gelate aniline at only below 5 °C, and 3c can partially gelate aniline 1,2dichloroethane and (R)/(S)-1-phenylethyl alcohols. As a whole, in these solvents that can be gelated by 3a, 3b shows good solubility whereas 3c shows poor solubility

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Figure 2. X-ray diffraction patterns of hexagonal columnar mesophase for (a) 3a at 380 °C and (b) 3c at 450 °C on heating. Table 2. Observed and Calculated Parameters of X-ray Diffractions for 3a at 380 °C and 3c at 450 °C

Figure 1. Optical textures from different local alignment of the hexagonal phases formed on cooling from isotropic liquids: (a) 3a at 367 °C, (b) 3b at 390 °C, and (b) 3c at 435 °C. All photographs were viewed through cross-polarizing filters; the samples were inserted between the slide and cover slip.

(Table 3). Thus, the gelation ability is very sensitive to the structure of the terminal groups in 3a-c. HATs 3a-c can be considered as liquid crystalline molecules with gelation ability as found in limited numbers of the precedent examples reported previously.8a,f,16 Such liquid crystalline gelators take the same packing pattern such as hexagonal packing both in liquid crystalline and in organogel phases.17 On the other hand, gelation did not occur in 3d and 3e with a phenylene spacer and in 3g without terminal diarylamino and phenoxy groups, as similar to liquid (16) (a) Hashimoto, M.; Ujiie, S.; Mori, A. Adv. Mater. 2003, 15, 797800. (b) Ito, S.; Herwig, P. T.; Bo¨hme, T.; Rabe, J. P.; Rettig, W.; Mu¨llen, K. J. Am. Chem. Soc. 2000, 122, 7698-7706. (17) XRD diffraction pattern of the xerogel of 3a was similar to that observed in the liquid crystalline state, although the reflections (100 reflection and halo) were detected very slightly. The result seems to suggest the formation of the hexagonal packing also in the organogel phase. Probably, almost organogel fibrous structure was decomposed during the freeze-drying treatment to prepare the xerogel.

compound

ahex (nm)

3a

3.25

3c

2.81

hkl

observed dhkl (nm)

calculated dhkl (nm)

100 110 200 210 100 110 200

2.83 1.64 1.41 1.06 2.44 1.41 1.21

2.82 1.63 1.41 1.07 2.43 1.40 1.22

crystals (Table 3). The finding suggests the contributions of the phenylene spacer and the terminal flexible groups on the formation of the aggregates. Surprisingly, 3f can gelate (R)/(S)-1-phenylethyl alcohols and partially gelate benzene despite the lack of terminal flexible groups. Probably, the organogel structure of 3f is maintained by a subtle balance between the gelator-gelator interaction and the gelator-solvent interaction in the specific solvent media. As described above, the stable and transparent gels were obtained only from 3a. Thus, the detailed characterization of the organogel structure was performed mainly in 3a as described below. The aggregated structure of 3a can be visualized by scanning electron microscopy (SEM) observation. The SEM picture of the xerogel, which was obtained from 3a in aniline at -15 °C/0.1 Torr, showed the fibrous structure with 50-80 nm diameters (Figure 3). The π-stacking of 3a molecules in the gel phase was corroborated by means of 1H NMR, UV-vis, and circular

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solvent

3a

3b

3c

3d

3e

3f

3g

n-hexane cyclohexane methylcyclohexane benzene toluene p-xylene nitrobenzene aniline dichloromethane chloroform 1,2-dichloroethane ethanol benzyl alcohol (R)-1-phenylethyl alcohol ether THF ethyl acetate N-methylpyrrolidone

I I I pG pG pG S (G)b G S S pG (R)b I R G I S I R

I I I S S S S S (G)b S S S I R R I S I S

I I I R R R S (R)b pG (R)b I I pG I R pG (R)b I I I R

I I I S (R)b S (R)b S (R)b S S S S S (R)b I S S I S I S

I I I S S S S S S S S I R S I S I S

I I I pG R R S R R S R I S G (R)b I R I S

I I I S S S S S S S S I S S I S I S

a [3] ) 1.0 × 10-2 M; at 20 °C, G ) gel, pG ) partial gel, R ) recrystallization, S ) solution, I ) insoluble. b The data in parentheses are at 5 °C.

Figure 3. SEM picture of xerogel obtained from 3a in aniline (1.0 × 10-2 M) at -15 °C/0.1 Torr.

spectroscopy.17

1

dichroism (CD) In the H NMR spectrum, a line-broadening effect arising from the π-stacked aggregation was observed in the gel sample of 3a in anilined7 (1.0 × 10-2 M) at 20 °C (Figure S2 in Supporting Information).8d,8f,18 At the elevated temperature, the broad peaks became sharp according to the gel-to-sol phase transition. At 70 °C the 1H NMR spectrum resembled that of the sol sample at the dilute concentration of 1.0 × 10-4 M (Figures S2-d and S2-e in Supporting Information). The UV-vis spectrum of the gel sample of 3a in aniline (1.0 × 10-2 M) was considerably broadened compared to that of the sol sample (1.0 × 10-4 M), as found in π-stacked organogels reported previously (Figure 4).8,19 The concentration of the aniline gel is too high to obtain the spectral data quantitatively: the gel sample was sand(18) At 20 °C the 1H NMR spectrum indicated time-dependent shift. At the early stage for 6 min, the aromatic proton signals of Ha, Hb, and Hc appeared to higher magnetic field at 7.96, 7.46, and 7.34 ppm, respectively, compared to those (8.05, 7.51, and 7.38 ppm, respectively) at a dilute concentration of 1.0 × 10-4 M (Figures S2-a and S2-e). After prolonged standing for 3 h, the signals moved to lower magnetic field at 8.04, 7.50, and 7.37 ppm for Ha, Hb, and Hc, respectively, along with further peak broadening (Figure S2-b). The results suggest the slow gelation process based on the formation of the π-stacked aggregate and the subsequent self-assembling and entanglement. The lower magnetic field shift during the gel generation process is not clear at the moment. We feel that the first higher magnetic field shift is ascribe to the π-π stacking among the HAT core moieties and the subsequent lower magnetic field shift to the further self-assembling and the entanglement of the formed π-stacked aggregate. (19) Ishi-i, T.; Iguchi, R.; Snip, E.; Ikeda, M.; Shinkai, S. Langmuir 2001, 17, 5825-5833.

Figure 4. UV-vis spectra of 3a in aniline (at 20 °C) at 1.0 × 10-2 M (gel phase, solid line) with two quartz glass plates and at 1.0 × 10-4 M (sol phase, dotted line) in a 0.1 cm width cell.

wiched with two quartz glass plates to make a thin film. Fortunately, the gel structure of 3a in (R)/(S)-1-phenylethyl alcohols can be maintained even at a lower concentration of 1.0 × 10-3 M, at which the spectroscopic measurement can be performed in a reliable 0.01 cm width quartz cell. In the chiral solvents, the absorption intensity in a gel phase at 20 °C is smaller than that in a sol phase at 80 °C (Figure 5a). In the chiral solvents, the gel samples of 3a at 1.0 × 10-3 M at 20 °C are CD-active, and the two CD spectra in the (R)- and (S)-chiral solvent are almost perfect mirror images (Figure 5b). The gel sample in the (R)-chiral solvent gave positive, negative, positive, and negative Cotton effects at 325 (∆ ) 42.50 cm2 mmol-1), 360 (∆ ) -35.97 cm2 mmol-1), 405 (∆ ) 9.32 cm2 mmol-1), and 457 nm (∆ ) -84.30 cm2 mmol-1), respectively. Opposite CD signs were observable in the (S)-chiral solvent. The intersections at λθ)0 of 420 and 340 nm in the CD spectra were in accord with the absorption band around 420 nm and the shoulder around 340 nm, respectively, suggesting appearance of exciton splitting.20 On the other hand, the sol samples of 3a at the dilute concentration of 1.0 × 10-4 M are CDsilent. The exciton splitting patterns observed around the (20) Harada, N.; Nakanishi, K. Circular Dichroic SpectroscopyExciton Coupling in Organic Stereochemistry; University Science Book: Mill Valley, CA, 1983.

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less-ordered aggregate, which is attributed to the lack of terminal flexible groups in 3f. Conclusions In conclusion, we have demonstrated that discotic liquid crystals and organogels are actually formed by selfassembling aromatic components composed of a rigid HAT core and flexible aromatic side chains. The aggregation of the discotic HAT molecules is first stabilized by the π stacking of the central aromatic core.24 In addition, the flexibility of the terminal groups in the aromatic side chains plays an important role for the stabilization of the aggregate to facilitate phase separation and to prevent crystallization. The created columnar-type architectures are attractive candidates as new functional materials because of their semiconducting properties arising from the electrodeficient nature of the hexaazatriphenylene ring.11 We believe that the present study would provide new valuable information not only for creation of columnartype architectures but also for functional materials. Acknowledgment. We thank Dr. Yo Shimizu (AIST, Japan) for helpful discussion. This work was partially supported by a Supporting Young Researchers with Fixedterm Appointments, Special Coordination Funds for Promoting Science and Technology, and by a Grant-inAid for Scientific Priority Area (No. 15750157) from the Ministry of Education, Culture, Sports, Science and Technology of Japan. Experimental Section

Figure 5. (a) UV-vis spectra of 3a in (S)-1-phenylethyl alcohol (at 1.0 × 10-3 M in 0.01 cm width cell) at 20 °C (gel phase, solid line) and at 80 °C (sol phase, dotted line). (b) CD spectra of 3a in (R)- and (S)-1-phenylethyl alcohols (at 1.0 × 10-3 M in 0.01 cm width cell) at 20, 30, 40, 50, 60, 70, and 80 °C.

HAT chromophore region would be due to chiroptical contribution from the chirally ordered aggregates formed in the gel phase. One of the most plausible explanations of the exciton splitting is the one-dimensional stacking of the HAT molecules with twisting mode “left-handed or right-handed”,21,22 in which the transition moment lies on the axis between accepting HAT core and donating aromatic side chains. Other aggregation modes such as two-dimensional sheets are very difficult to explain the exciton splitting. Weak gelator-chiral solvent interactions can be cooperatively intensified in the gel phase to take a twisting mode.23 The magnitude of the Cotton effects was reduced with increasing temperature and reached zero at around 70 °C, indicating a gel-to-sol phase transition on the dissociation of the chiral aggregates (Figure 5b). Other chiral gels obtained from 3f in the (R)- and (S)1-phenylethyl alcohols indicated Cotton effects around the HAT chromophore region (Figure S3 in Supporting Information). In contrast to 3a, the CD intensity was relatively weak and the exciton splitting pattern could not be observed. The results suggest the formation of the (21) (a) Adam, D.; Schuhmacher, P.; Simmerer, J.; Ha¨ussling, L.; Siemensmeyer, K.; Etzbach, K. H.; Ringsdorf, H.; Haarer, D. Nature 1994, 371, 141-143. (b) Wu, J.; Watson, M. D.; Mu¨llen, K. Angew. Chem., Int. Ed. 2003, 42, 5329-5333. (22) van Gorp, J. J.; Vekemans, J. A. J. M.; Meijer, E. W. J. Am. Chem. Soc. 2002, 124, 14759-14769. (23) Palmans, A. R. A.; Vekemans, J. A. J. M.; Havinga, E. E.; Meijer, E. W. Angew. Chem., Int. Ed. Engl. 1997, 36, 2648-2651.

General. All melting points are uncorrected. IR spectra were recorded on a JASCO FT/IR-470 plus Fourier transform infrared spectrometer and measured as KBr pellets. 1H NMR spectra were determined in CDCl3 or DMSO-d6 with a JEOL EX-270 or LA 400 spectrometer. Residual solvent protons were used as internal standard, and chemical shifts (δ) are given relative to tetramethylsilane (TMS). The coupling constants (J) are reported in hertz. Elemental analysis was performed at the Elemental Analytical Center, Kyushu University. Electron impact mass spectrometry (EI-MS) spectra were recorded with a JEOL JMS70 mass spectrometer at 70 eV using a direct inlet system. Fast atom bombardment mass spectrometry (FAB-MS) were recorded with a JEOL JMS-70 mass spectrometer with m-nitrobenzyl alcohol (NBA) as a matrix. Differential scanning calorimetry was performed on a METTLER TOLEDO DSC822e at heating and cooling rates of 10 K min-1. Optical textures at cross polarizers were obtained with an Olympus BHSP BH-2 polarization microscope equipped with a Linka TH-600 RMS hot stage controller unit. X-ray diffraction measurements were performed on PANalytical X′Pert PRO and carried out with Cu(KR) radiation from a X-ray tube with a 0.4 × 12 mm2 filament operated at 45 kV × 40 mA (1.8 kW). UV-vis spectra were measured on a JASCO V-570 spectrophotometer between two glass plates (1.0 × 10-2 M) and in a 0.01 cm width cell (1.0 × 10-3 M). CD spectra were measured on a JASCO J-720W spectropolarimeter in a 0.01 cm width cell (1.0 × 10-3 M). Gel permeation chromatography (GPC) was performed with a Japan Analytical Industry LC-908 using polystyrene JAIGEL1H column (20 × 600 mm) and JAIGEL-2H column (20 × 600 mm) eluting with chloroform (3.0 mL min-1). Analytical TLC (24) Recently, it was reported that dimer of hexaazatriphenylene molecules is stabilized by complementary polytopic interactions between the hexaazatriphenylene cores, between the peripheral aromatic groups, and between the aromatic groups of one molecule and the hexaazatriphenylene core of another: Lozman, O. R.; Bushby, R. J.; Vinter, J. G. Perkin 2 2001, 1446-1452. In the present system, the complementary polytopic interactions around the extended central core including the hexaazatriphenylene ring and the biphenyl groups would play an important role to form the columnar-type aggregates whereas the terminal flexible groups of diarylamino and phenoxy groups maintain a subtle balance to stabilize the specific aggregation forms of discotic liquid crystals and organogels.

Formation of Liquid Crystals was carried out on silica gel coated on aluminum foil (Merck 60 F254). Column chromatography was carried out on silica gel (Wako C-300 or KANTO 60N). THF and toluene were distilled from sodium and benzophenone under an argon atmosphere just before use. Phenylboronic acid, 4-phenoxyphenylboronic acid, 4-phenoxybenzaldehyde, benzyl (2g), and bis(4-bromophenyl)ethanedione (2h) are commercially available. Hexaaminobenzene trihydrochloride (1),12 4-diphenylaminophenylboronic acid,25 and N-(4-bromophenyl)-2-naphthylphenylamine26 were prepared according to a method reported previously. Gelation Test. The gelator 3 and the solvent (1.0 × 10-2 M) were put in a screw-capped test tube and heated until the solid was dissolved. The solution was cooled at 5 or 20 °C. If a stable and transparent gel was observed at this stage, it was classified as gel. SEM Measurements. A Hitachi S-4500 scanning electron microscopy was used for taking the SEM pictures. A thin gel, which was prepared in a sample tube at 1.0 × 10-2 M at -15 °C, was evaporated by a vacuum pump (at 0.1 Torr) for 12 h. The dry sample thus obtained was shielded by Pd-Pt. The accelerating voltage of SEM was 5 kV, and the emission current was 10 µA. 4-[N-(2-Naphthyl)-N-phenyl]phenylboronic Acid. To a solution of N-(4-bromophenyl)-2-naphthylphenylamine26 (5.48 g, 14.6 mmol) in dry THF (35 mL) was added dropwise a 2.6 M n-butyllithium hexane solution (6.03 mL, 16.1 mmol) at -78 °C under an argon atmosphere. After the mixture was stirred at -78 °C for 1 h, trimethylborate (2.28 g, 21.9 mmol) in dry THF (5 mL) was added dropwise to the mixture. The mixture was stirred at -60 °C for 1 h and at room temperature for 12 h. After the reaction mixture was quenched by addition of aqueous 3 M hydrochloric acid solution (40 mL), it was extracted with diethyl ether (40 mL × 3). The combined organic layers were washed with brine (40 mL × 2), dried over anhydrous magnesium sulfate, and evaporated in vacuo to dryness. After the residue was suspended in n-hexane, it was collected by filtration and washed with n-hexane to give 4-[N-(2-naphthyl)-N-phenyl]phenylboronic acid in 35% yield (1.75 g, 5.16 mmol) as white powder. Without further purification, it was used for the preparation of 2b: IR (KBr) 1628, 1590, 1507, 1490, 1467, 1416, 1350 (νBO), 1277, 1180, 812, 746; 1H NMR (DMSO-d6) δ 6.96 (d, J ) 8.6 Hz, 2 H, ArH), 7.04-7.12 (m, 3 H, ArH), 7.22 (dd, J ) 2.3, 8.9 Hz, 1 H, ArH), 7.31-7.47 (m, 5 H, ArH), 7.71 (d, J ) 8.6 Hz, 2 H, ArH), 7.837.88 (m, 3 H, ArH). General Procedure for Preparation of Bis[4′-(diphenylamino)biphenyl-4-yl]ethanedione (2a). To a mixture of 2h (4.19 g, 11.3 mmol), tetrakis(triphenylphosphine)palladium(0) (780 mg, 0.68 mmol) in benzene (100 mL), and aqueous 2 M sodium carbonate solution (50 mL) was added 4-diphenylaminophenylboronic acid (6.56 g, 22.7 mmol) in ethanol (25 mL) under an argon atmosphere. The resulting mixture was heated at 80 °C for 12 h. The reaction mixture was poured into water and extracted with dichloromethane (50 mL × 3). The organic layer was washed with brine (50 mL), dried over anhydrous magnesium sulfate, and evaporated in vacuo to dryness. The residue was separated by silica gel column chromatography (Wakogel C-300) eluting with dichloromethane/n-hexane, (1:1, v/v). The main fraction was evaporated in vacuo to dryness, and the residue was purified by recrystallization from chloroform/ n-hexane (1:1, v/v) to give 2a in 78% yield (6.16 g, 8.84 mmol) as orange powder: mp 121-124 °C; IR (KBr) 1669 (νCdO), 1590, 1522, 1490, 1327, 1283, 1219, 1192, 1173, 885, 851; 1H NMR (CDCl3) δ 7.07-7.15 (m, 12 H, ArH), 7.25-7.31 (m, 12 H, ArH), 7.51 (d, J ) 7.9 Hz, 4 H, ArH), 7.70 (d, J ) 7.9 Hz, 4 H, ArH), 8.04 (d, J ) 7.9 Hz, 4 H, ArH); FAB-MS (NBA, positive) 697 [(M + H)+]. Anal. Calcd for C50H36N2O2: C, 86.18; H, 5.21; N, 4.02. Found: C, 85.88; H, 5.14; N, 4.04. Bis{4′-[N-(2-naphthyl)-N-phenylamino]biphenyl-4-yl}ethanedione (2b). According to a method similar to the preparation of 2a, 2b was obtained in 80% yield from 2h and (25) (a) Wong, K.-T.; Chien, Y.-Y.; Lian, Y.-L.; Lin, C.-C.; Chou, M.Y.; Leung, M.-K. J. Org. Chem. 2002, 67, 1041-1044. (b) Leung, M.-K.; Chou, M.-Y.; Su, Y. O.; Chiang, C. L.; Chen, H.-L.; Yang, C. F.; Yang, C.-C.; Lin, C.-C.; Chen, H.-T. Org. Lett. 2003, 5, 839-842. (26) Koene, B. E.; Loy, D. E.; Thompson, M. E. Chem. Mater. 1998, 10, 2235-2250.

Langmuir, Vol. 21, No. 4, 2005 1267 4-[N-(2-naphthyl)-N-phenylamino]phenylboronic acid. The crude product was purified by silica gel column chromatography (Wakogel C-300) eluting with dichloromethane/n-hexane (2:1, v/v). Orange solid: mp 141-143 °C; IR (KBr, cm-1) 1667 (νCdO), 1592, 1522, 1491, 1468, 1360, 1289, 1174, 883, 852; 1H NMR (CDCl3) δ 7.11 (t, J ) 7.3 Hz, 2 H, ArH), 7.18-7.21 (m, 8 H, ArH), 7.29-7.44 (m, 10 H, ArH), 7.51 (s, 2 H, ArH), 7.54 (d, 4 H, J ) 8.7 Hz, ArH), 7.63 (d, 2 H, J ) 8.9 Hz, ArH), 7.72 (d, 4 H, J ) 8.7 Hz, ArH), 7.75 (d, 2 H, J ) 8.9 Hz, ArH), 7.75 (d, 2 H, J ) 8.9 Hz, ArH), 8.05 (d, 4 H, J ) 8.7 Hz, ArH); FAB-MS (NBA, positive) 797 [(M + H)+]. Anal. Calcd for C58H40N2O2: C, 87.41; H, 5.06; N, 3.52. Found: C, 87.11; H, 5.24; N, 3.43. Bis(4′-phenoxybiphenyl-4-yl)ethanedione (2c). According to a method similar to the preparation of 2a, 2c was obtained in 84% yield from 2h and 4-phenoxyphenylboronic acid. The crude product was purified by silica gel column chromatography (Wakogel C-300) eluting with dichloromethane/n-hexane (1:1, v/v): yellow plates (chloroform/n-hexane, 1:1 (v/v)); mp 156-158 °C; IR (KBr) 1668, 1591, 1523, 1488, 1243, 1200, 1175, 1072, 1023, 1002, 876, 853, 827; 1H NMR (CDCl3) δ 7.07 (d, J ) 8.6 Hz, 4 H, ArH), 7.10 (d, J ) 8.9 Hz, 4 H, ArH), 7.16 (t, J ) 8.6 Hz, 2 H, ArH), 7.38 (t, J ) 8.6 Hz, 4 H, ArH), 7.60 (d, J ) 8.9 Hz, 4 H, ArH), 7.72 (d, J ) 8.6 Hz, 4 H, ArH), 8.07 (d, J ) 8.6 Hz, 4 H, ArH); FAB-MS (NBA, positive) 547 [(M + H)+]. Anal. Calcd for C38H26O4: C, 83.50; H, 4.79. Found: C, 83.36; H, 4.82. Bis(biphenyl-4-yl)ethanedione (2f). According to a method similar to the preparation of 2a, 2f was obtained in 86% yield from 2h and phenylboronic acid. The crude product was purified by silica gel column chromatography (Wakogel C-300) eluting with dichloromethane/n-hexane, (1:1, v/v): yellow needles (chloroform/n-hexane, 1:1 (v/v)); mp 143-145 °C (lit.27 140-141 °C); IR (KBr, cm-1) 1665 (νCdO), 1602, 1558, 1486, 1450, 1407, 1318, 1218, 1178, 1076, 1005, 962, 919, 880, 842; 1H NMR (CDCl3) δ 7.42-7.51 (m, 6 H, ArH), 7.64 (d, J ) 8.3 Hz, 4 H, ArH), 7.75 (d, J ) 8.3 Hz, 4 H, ArH), 8.08 (d, J ) 8.6 Hz, 4 H, ArH); FAB-MS (NBA, positive) 363 [(M + H)+]. Bis(4-phenoxyphenyl)ethanedione (2e). A mixture of 4-phenoxybenzaldehyde (1.50 g, 7.57 mmol) and potassium cyanate (150 mg, 2.27 mmol) in 70% aqueous ethanol solution (30 mL) was heated at the refluxing temperature for 24 h under an argon atmosphere. After the reaction mixture was cooled to room temperature, it was poured into saturated aqueous sodium hydrogencarbonate solution (50 mL) and extracted with dichloromethane (50 mL × 3). The organic layer was washed with brine (50 mL), dried over anhydrous magnesium sulfate, and evaporated in vacuo to dryness. A mixture of the obtained residue (1.65 g), bismuth nitrate pentahydrate (674 mg, 1.39 mmol), and copper diacetate (252 mg, 1.39 mmol) in 80% aqueous acetic acid solution (50 mL) was heated to refluxing temperature for 48 h under an argon atmosphere. After the reaction mixture was cooled to room temperature, it was poured into water and extracted with dichloromethane (30 mL × 5). The organic layer was washed with brine (50 mL), dried over anhydrous magnesium sulfate, and evaporated in vacuo to dryness. After the residue was washed with ether (30 mL), it was purified by GPC (JAIGEL-1H and 2H) eluting with chloroform to give 2e in 8% yield (120 mg, 0.304 mmol) as yellow powder: mp 114-116 °C; IR (KBr) 1665 (νCdO), 1601, 1582, 1488, 1419, 1308, 1246, 1198, 1162, 1119, 1022, 889; 1H NMR (CDCl ) δ 7.02 (d, J ) 8.5 Hz, 4 H, ArH), 7.08 (d, J ) 3 8.0 Hz, 4 H, ArH), 7.22 (t, J ) 8.0 Hz, 2 H, ArH), 7.41 (t, J ) 8.0 Hz, 4 H, ArH), 7.94 (d, J ) 8.5 Hz, 4 H, ArH); FAB-MS (NBA, positive) 395 [(M + H)+]. Anal. Calcd for C26H18O4: C, 79.14; H, 4.60. Found: C, 78.82; H, 4.61. General Procedure for Preparation of 2,3,6,7,10,11Hexakis(4′-diphenylaminobiphenyl-4-yl)-1,4,5,8,9,12hexaazatriphenylene (3a). A mixture of hexaaminobenzene trihydrochloride (1) (83 mg, 0.30 mmol) and 2a (626 mg, 0.90 mmol) in acetic acid (100 mL) was heated to refluxing temperature for 24 h under an argon atmosphere. After the reaction mixture was cooled to room temperature, it was poured into water and extracted with dichloromethane (50 mL × 3). The organic layer was washed with saturated aqueous sodium hydrogencarbonate (27) Gampp, H.; Haspra, D.; Spieler, W.; Zuberbu¨hler, A. D. Helv. Chim. Acta 1984, 67, 1019-1025.

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solution (200 mL) and with brine (100 mL), dried over anhydrous magnesium sulfate, and evaporated in vacuo to dryness. The residue was separated by silica gel chromatography (KANTO 60N) eluting with dichloromethane/n-hexane (1:1, v/v) and by GPC (JAIGEL-1H and 2H) eluting with chloroform. The main fraction was evaporated in vacuo to dryness, and the residue was purified by recrystallization from dichloromethane/n-hexane (1:1, v/v) to give 3a in 28% yield (180 mg, 0.0837 mmol) as yellow powder: IR (KBr) 1592, 1492, 1365, 1329, 1280, 821; 1H NMR (CDCl3) δ 7.05 (t, J ) 7.3 Hz, 12 H, ArH), 7.13-7.17 (m, 36 H, ArH), 7.22-7.33 (m, 24 H, ArH), 7.57 (d, J ) 8.9 Hz, 12 H, ArH), 7.57 (d, J ) 8.2 Hz, 12 H, ArH), 7.99 (d, J ) 8.2 Hz, 12 H, ArH); FAB-MS (NBA, positive) 2149 [(M + H)+]. Anal. Calcd for C156H108N12: C, 87.12; H, 5.06, N, 7.82. Found: C, 87.04; H, 5.07; N, 7.77. 2,3,6,7,10,11-Hexakis{4′-[N-(2-naphthyl)-N-phenylamino]biphenyl-4-yl}-1,4,5,8,9,12-hexaazatriphenylene (3b). According to a method similar to the preparation of 3a, 3b was obtained in 42% yield from 1 and 2b. The crude product was purified by silica gel column chromatography (Wakogel C-300) eluting with dichloromethane/n-hexane (9:1, v/v) and by GPC (JAIGEL-1H and 2H) eluting with chloroform: yellow powder (dichloromethane/n-hexane, 1:1 (v/v)); mp 271-273 °C; IR (KBr, cm-1) 1594, 1494, 1467, 1362, 1279, 1234, 1194, 1137, 1005, 812; 1H NMR (CDCl ) δ 7.08 (t, J ) 7.5 Hz, 6 H, ArH), 7.18-7.21 (m, 3 24 H, ArH), 7.28-7.42 (m, 30 H, ArH), 7.49 (s, 6 H, ArH), 7.59 (d, J ) 8.9 Hz, 12 H, ArH), 7.62 (d, J ) 8.7 Hz, 6 H, ArH), 7.69 (d, J ) 8.2 Hz, 12 H, ArH), 7.75 (d, J ) 8.9 Hz, 6 H, ArH), 7.77 (d, J ) 8.9 Hz, 6 H, ArH), 8.01 (d, J ) 8.2 Hz, 12 H, ArH); FABMS (NBA, positive) 2449 [(M + H)+]. Anal. Calcd for C180H120N12: C, 88.21; H, 4.93, N, 6.86. Found: C, 88.11; H, 5.11; N, 6.72. 2,3,6,7,10,11-Hexakis(4′-phenoxylbiphenyl-4-yl)-1,4,5, 8,9,12-hexaazatriphenylene (3c). According to a method similar to the preparation of 3a, 3c was obtained in 31% yield from 1 and 2c. The crude product was purified by silica gel column chromatography (Wakogel C-300) eluting with dichloromethane: yellow needles (dichloromethane/n-hexane, 1:1 (v/v)); IR (KBr) 1589, 1523, 1488, 1365, 1241, 1203, 1168, 1138, 1004, 870, 829; 1H NMR (CDCl3) δ 7.06-7.14 (m, 30 H, ArH), 7.37 (t, J ) 7.6 Hz, 12 H, ArH), 7.65 (d, J ) 8.6 Hz, 12 H, ArH), 7.68 (d, J ) 7.6 Hz, 12 H, ArH), 8.02 (d, J ) 8.6 Hz, 12 H, ArH); FAB-MS (NBA, positive) 1699 [(M + H)+]. Anal. Calcd for C120H78N6O6: C, 84.78; H, 4.62, N, 4.94. Found: C, 84.69; H, 4.57; N, 4.84. 2,3,6,7,10,11-Hexakis(4-phenoxyphenyl)-1,4,5,8,9,12hexaazatriphenylene (3e). According to a method similar to the preparation of 3a, 3e was obtained in 36% yield from 1 and 2e. The crude product was purified by silica gel column chromatography (Wakogel C-300) eluting with dichloromethane: yellow needles (dichloromethane/n-hexane, 1:1 (v/v)); mp 289-291 °C; IR (KBr) 1587, 1505, 1488, 1364, 1242, 1198, 1168, 1137, 870, 844; 1H NMR (CDCl3) δ 7.05 (d, J ) 8.7 Hz, 12 H, ArH), 7.08 (d, J ) 8.5 Hz, 12 H, ArH), 7.16 (t, J ) 7.5 Hz, 6 H, ArH), 7.38 (dd, J ) 7.5, 8.5 Hz, 12 H, ArH),7.86 (d, J ) 8.7 Hz, 12 H, ArH); FAB-MS (NBA, positive) 1243 [(M + H)+]. Anal. Calcd for C84H54N6O6: C, 81.14; H, 4.38; N, 6.76. Found: C, 81.51; H, 4.29; N, 6.56. 2,3,6,7,10,11-Hexakis(biphenyl-4-yl)-1,4,5,8,9,12-hexaazatriphenylene (3f). According to a method similar to the preparation of 3a, 3f was obtained in 44% yield from 1 and 2f. The crude product was purified by silica gel column chroma-

Ishi-i et al. tography (Wakogel C-300) eluting with dichloromethane/nhexane (2:1, v/v) and by GPC (JAIGEL-1H and 2H) eluting with chloroform. Pale yellow needles (dichloromethane/n-hexane, 1:1 (v/v)); mp 485-486 °C; IR (KBr) 1603, 1486, 1362, 1230, 1194, 1136, 1007, 932, 843; 1H NMR (CDCl3) δ 7.36-7.50 (m, 18 H, ArH), 7.67-7.72 (m, 24 H, ArH), 8.01-8.05 (m, 12 H, ArH); FABMS (NBA, positive) 1147 [(M + H)+]. Anal. Calcd for C84H54N6: C, 87.93; H, 4.74; N, 7.32. Found: C, 87.64; H, 4.75; N, 7.25. 2,3,6,7,10,11-Hexaphenyl-1,4,5,8,9,12-hexaazatriphenylene (3g). According to a method similar to the preparation of 3a, 3g was obtained in 44% yield from 1 and 2g. The crude product was purified by silica gel column chromatography (Wakogel C-300) eluting with chloroform. Colorless needles (chloroform/n-hexane, 1:1 (v/v)); mp 355-356 °C (lit.28 358 °C); IR (KBr) 3056, 1543, 1364, 1267, 1229, 1196, 1136; 1H NMR (CDCl3) δ 7.41-7.42 (m, 18 H, ArH), 7.83-7.85 (m, 12 H, ArH); FAB-MS (NBA, positive) 691 [(M + H)+]. Anal. Calcd for C48H30N6: C, 83.46; H, 4.38; N, 12.17. Found: C, 83.29; H, 4.42; N, 12.16. 2,3,6,7,10,11-Hexakis(4-bromophenyl)-1,4,5,8,9,12hexaazatriphenylene (3h). According to a method similar to the preparation of 3a, 3h was obtained in 20% yield from 1 and 2h. The crude product was purified by silica gel column chromatography (Wakogel C-300) eluting with dichloromethane: pale yellow needles (dichloromethane/n-hexane, 1:1 (v/v)); mp 454-457 °C; IR (KBr) 1588, 1487, 1392, 1362, 1229, 1182, 1135, 1073, 1011, 929, 830; 1H NMR (CDCl3) δ 7.59 (d, J ) 8.5 Hz, 12 H, ArH), 7.69 (d, J ) 8.5 Hz, 12 H, ArH); FAB-MS (NBA, positive) 1165 [(M + H)+]. Anal. Calcd for C48H24N6Br6: C, 49.52; H, 2.08; N, 7.22. Found: C, 49.94; H, 2.08; N, 7.26. 2,3,6,7,10,11-Hexakis[4-(diphenylamino)phenyl]-1,4,5, 8,9,12-hexaazatriphenylene (3d). A mixture of 3h (90 mg, 0.077 mmol), diphenylamine (262 mg, 1.55 mmol), tris (dibenzylideneacetone)dipalladium (141 mg, 0.16 mmol), 0.5 M tris(tert-butyl)phosphine toluene solution (0.31 mL, 0.16 mmol), sodium tert-butoxide (444 mg, 4.65 mmol) in toluene (60 mL) was stirred at the room temperature for 5 h under an argon atmosphere. After the reaction mixture was poured into water (50 mL), it was extracted with dichloromethane (50 mL × 5). The organic layer was washed with brine (50 mL), dried over anhydrous magnesium sulfate, and evaporated in vacuo to dryness. The residue was separated by silica gel column chromatography (KANTO 60N) eluting with dichloromethane/ n-hexane (9:1, v/v) and by GPC (JAIGEL-1H and 2H) eluting with chloroform to give 3d in 24% yield (32 mg, 0.019 mmol) as orange powder: mp 393-396 °C; IR (KBr) 1591, 1491, 1363, 1328, 1280, 840; 1H NMR (CDCl3) δ 7.07 (d, J ) 8.7 Hz, 12 H, ArH), 7.08 (t, J ) 7.3 Hz, 12 H, ArH), 7.15 (d, J ) 7.5 Hz, 24 H, ArH), 7.28 (dd, J ) 7.3, 7.5 Hz, 24 H, ArH), 7.80 (d, J ) 8.7 Hz, 12 H, ArH); FAB-MS (NBA, positive) 1693 [(M + H)+]. Anal. Calcd for C120H84N12: C, 85.08; H, 5.00; N, 9.92. Found: C, 84.82; H, 5.05; N, 9.75.

Supporting Information Available: Optical texture of 3a (Figure S1), 1H NMR spectra of 3a (Figure S2), and UV-vis and CD spectra of 3f (Figure S3). This material is available free of charge via the Internet at http://pubs.acs.org. LA047874+ (28) Kohne, B.; Praefcke, K. Liebigs Ann. Chem. 1985, 522-528.