The red solution was heated at 35 1C under nitrogen for 18 h.
All the solvent was removed and diethyl ether (100 mL) was
added. The ethereal solution was washed with water (3 ꢀ 50 mL),
dried over Na2SO4, and concentrated to give the crude product.
Purification by flash column chromatography using CH2Cl2 and
hexane (1 : 1, v/v) as the eluent afforded AVM 2 as a white solid
(109 mg, 64%).
1 (a) W. Zhang and J. S. Moore, Angew. Chem., Int. Ed., 2006, 45,
4416; (b) S. Hoger, Angew. Chem., Int. Ed., 2005, 44, 3806;
¨
(c) S. Hoger, Chem.–Eur. J., 2004, 10, 1320; (d) D. Zhao and
¨
J. S. Moore, Chem. Commun., 2003, 807; (e) Y. Yamaguchi
and Z. Yoshida, Chem.–Eur. J., 2003, 9, 5430; (f) C. Grave and
Fig. 5 The most favored conformer of AVM 20: top view (top left),
side view (bottom left), and AVM 40: top view (top right), side view
(bottom right). Methyl group was used in calculation instead of decyl
for simplification. Energy minimization was performed with Spartan
04 at semi-empirical PM3 level.
A. D. Schluter, Eur. J. Org. Chem., 2002, 3075; (g) F. Diederich,
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Chem. Commun., 2001, 219; (h) U. H. F. Bunz, Y. Rubin and
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(b) J.-M. Lehn, Chem.–Eur. J., 1999, 5, 2455.
The most favored conformer of methyl substituted analogue
AVM 20 has a planar carbon backbone, and the molecule is
highly symmetrical, which is fully consistent with the NMR
characterization data (Fig. 5). The favored conformer of AVM
40 is not perfectly planar, and has a saddle-like conformation
with alternating carbazole moieties tilted up and down.
However, the distorted non-planar conformation seems not
to impede the self-aggregation of AVM 4, as evidenced by
successful nanofibril fabrication, which is probably due to the
conformational flexibility provided by the vinylene linkage.
In summary, we successfully developed a one-step synthetic
approach to shape-persistent AVMs from simple aromatic
dienes. The highly efficient ADMAC method is generally
applicable, and AVMs with different shape and geometry
can be prepared. The AVMs showed a strong self-aggregation
behavior, and can be fabricated into nanofibrils. Considering
the great importance and growing interest in 1D self-assembly
of planar aromatic molecules into well-defined nanowires or
nanotubes,12 the AVMs reported herein open many new
possibilities for novel tubular nanomaterial fabrication. The
substrate scope of such an ADMAC approach, the AVM
self-association behaviors, as well as the structure–function
relationship of the aggregation-induced nanofibrils are being
investigated in our lab and will be reported in due course.
We thank Dr Kuthanapillil Jyothish for helpful discussions,
and Dr Richard K. Shoemaker for NMR assistance. W. Z.
thanks the CRCW Junior Faculty Development Award and
the University of Colorado for funding support through the
innovative seed grant program.
3 (a) J. Jiang and G. N. Tew, Org. Lett., 2008, 10, 4393;
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¨
6 A. K. Chatterjee, T.-L. Choi, D. P. Sanders and R. H. Grubbs,
J. Am. Chem. Soc., 2003, 125, 11360.
7 Presumably the presence of cis double bonds results in high angle
strain in the macrocycles, so the unfavored cyclic products were
converted into the most stable cyclohexamer 1 under the reversible,
thermodynamically-controlled condition.
8 (a) S. H. Seo, T. V. Jones, H. Seyler, J. O. Peters, T. H. Kim,
J. Y. Chang and G. N. Tew, J. Am. Chem. Soc., 2006, 128, 9264;
(b) S. Hoger, K. Bonrad, A. Mourran, U. Beginn and M. Moller,
¨
¨
J. Am. Chem. Soc., 2001, 123, 5651; (c) S. Lahiri, J. L. Thompson
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(d) A. S. Shetty, J. Zhang and J. S. Moore, J. Am. Chem. Soc.,
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1992, 114, 9701.
9 Linear decyl group was installed to enhance the solubilityof AVM
2 and oligomeric reaction intermediates. For the effect of side chain
substituents on the self assembly process, see K. Balakrishnan,
A. Datar, T. Naddo, J. Huang, R. Oitker, M. Yen, J. Zhao and
L. Zang, J. Am. Chem. Soc., 2006, 128, 7390.
10 Y. Che, X. Yang and L. Zang, Chem. Commun., 2008, 1413.
11 Previously the preparation of nanofibrils from carbazole-based
AEMs has been reported, and the fibril formation is primarily
due to the columnar stacking of the macrocycles, see
K. Balakrishnan, A. Datar, W. Zhang, X. Yang, T. Naddo,
J. Huang, J. Zuo, M. Yen, J. S. Moore and L. Zang, J. Am. Chem.
Soc., 2006, 128, 6576.
Notes and references
z Procedure for the synthesis of AVM 2: To a Schlenk tube were added
1,3-divinyl-5-decyloxy-benzene (1, 217 mg, 0.76 mmol) and a solution
of Grubbs’ 2nd generation catalyst (48 mg, 0.076 mmol) in 1,2,4-
trichlorobenzene (14 mL). The reaction apparatus was evacuated
and refilled with nitrogen, and this process was repeated three times.
12 (a) L. Zang, Y. Che and J. S. Moore, Acc. Chem. Res., 2008, 41,
1596; (b) J. Wu, W. Pisula and K. Mullen, Chem. Rev., 2007, 107,
¨
718; A. P. H. J. Schenning and E. W. Meijer, Chem. Commun.,
2005, 3245.
c
8260 Chem. Commun., 2010, 46, 8258–8260
This journal is The Royal Society of Chemistry 2010