J. Am. Chem. Soc. 2001, 123, 11817-11818
Molecular Assembly and Gelating Behavior of
11817
Didodecanoylamides of r,ω-Alkylidenediamines
Kiyoshi Tomioka,* Takaaki Sumiyoshi, Shinobu Narui,
Yasuo Nagaoka, Akira Iida, Yoshihisa Miwa, Tooru Taga,
Minoru Nakano, and Tetsuro Handa
Graduate School of Pharmaceutical Sciences
Kyoto UniVersity, Sakyo-ku, Kyoto 606-8501, Japan
ReceiVed August 24, 2001
Figure 1. Parallel and antiparallel structures of diamides 1 and 2. For
clarification, diamides of n ) 4 and 3 are presented.
We describe herein that didodecanoylamides of R,ω-alkylidene-
diamines self-complementarily assemble into microscopic struc-
tures through specific hydrogen bonding and van der Waals
interactions, which are assignable to origins for the gelation of
It seems reasonable to gain information on the relationships
between the spacial arrangement of two amide groups in a
molecule and their effects on microscopic structures. A series of
10 didodecanoylamides 1 and 2 of diamines bridged by a straight
1
organic liquids. Gelation by small quantities of a compound,
carbon chain varying in length from 0 to 9 carbons were examined
as possible gelator molecules. These diamides are classified into
two categories with regard to the length of the carbon chain: one
is diamide 1 bearing a bridging carbon chain of 0 or an even
number, and the other is 2, bearing a carbon chain of an odd
number. The zigzag arrangement of the carbon chain of even
number 1 directs the two amide carbonyl groups antiparallel (the
opposite direction), while the carbon chain of the odd number 2
is parallel (the same direction) (Figure 1). Consequently, a diamide
molecule of an even-numbered carbon chain 1 is able to form
two pairs of hydrogen bonds with two other molecules in a plane.
On the other hand, a diamide of an odd-numbered carbon chain
usually a polymer,2 has been known for several centuries.3
Although the most important factors, self-complementary gelator
aggregates, have been proposed from detailed spectroscopic and
4
diffraction studies, an understanding of the microscopic factors
responsible for the gelation of organic liquids has not yet been
thoroughly surveyed. Some attempts have been made to correlate
the properties of the gels and the chemical structures of the
5
gelators. Hydrogen bonding and van der Waals interactions are
representative fundamentals that determine the structures of
organic molecules. The recent discovery and development of low
molecular weight gelators have renewed interest in the determin-
6
ing factors for self-complementary assembly. In particular,
2
forms four independent hydrogen bonds with four other
7
8
Hanabusa and Feringa have succeeded in the construction of
gelators for organic liquids using a cyclic bisurea as donor and
molecules not in a plane. Furthermore, the dodecanoyl moieties
of diamides 1 and 2 favorably interact with each other within
van der Waals contact. These analyses boldly predict the shape
of self-complementary assembled structures of even- and odd-
numbered diamides 1 and 2 to be ribbon and woven, respectively.
These diamides 1 and 2 of varying length from 0 and 2 to 9
methylene bridges were synthesized in high yields by the
Schotten-Bauman acylation of the corresponding R,ω-diamines
with dodecanoyl chloride in ether-water in the presence of
sodium bicarbonate. The diamide of diamine (n ) 1) was prepared
by treatment with acid chloride in pyridine-THF. These diamides
were recrystallizable to afford thin leaflets. As a reference,
monoamide 3 was prepared by the acylation of dodecylamine with
dodecanoyl choloride.
9
acceptor functionalities for hydrogen-bonding interactions. More
precise and deeper understandings of these interactions are
necessary for the design of more efficient gelators and the
application into sophisticated materials.10 Here we describe
systematic studies toward an appropriate arrangement of two
amide groups for a self-complementary assembly.
(
1) Recent reviews on low molecular weight gelators. (a) Terech, P.; Weiss,
R. G. Chem. ReV. 1997, 97, 3133. (b) Esch, J. H.; Feringa, B. L. Angew.
Chem., Int. Ed. 2000, 39, 2263.
(
2) Guenet, G.-M. ThermoreVersible Gelation of Polymers and Biopoly-
mers; Academic Press: London, 1992.
3) (a) Flory, P. J. Discuss. Faraday Soc. 1974, 57, 7. (b) Tanaka, T. Sci.
Am. 1981, 244, 14.
4) Fuhrhop, J. H.; Koening, J. Membranes and Molecular Assemblies:
the synkinetic approach; Royal Society of Chemistry: Cambridge, 1994.
5) Recent impressive references: (a) Murata, K.; Aoki, M.; Suzuki, T.;
(
(
(
Harada, T.; Kawabata, H.; Komori, T.; Ohseto, F.; Ueda, K.; Shinkai, S. J.
Am. Chem. Soc. 1994, 116, 6664. (b) Tata, M.; John, V. T.; Waguespack, Y.
Y.; McPherson, G. L. J. Am. Chem. Soc. 1994, 116, 9464. (c) Placin, F.;
Colomes, M.; Desvergne, J.-P. Tetrahedron Lett. 1997, 38, 2665. (d) Terech,
P.; Allegraud, J. J.; Garner, C. M. Langmuir 1998, 14, 3991. (e) Garner, C.
M.; Terech, P.; Allegraud, J.-J.; Mistrot, B.; Nguyen, P.; de Geyer, A.; Rivera,
D. J. Chem. Soc., Faraday Trans. 1998, 94, 2173.
Gel formation of these diamides with organic liquids was
determined by the method “stable to inversion of the container”.
11
(6) (a) de Vries, E. J.; Kellogg, R. M. J. Chem. Soc., Chem. Commun.
A mixture of a crystalline diamide in an organic liquid in a
container was heated to a solution and was then cooled back to
room temperature. Benzene, toluene, mesitylene, and pyridine
were suitable organic liquids in forming opaque gels. Hexane,
diethyl ether, 1,4-dioxane, tetrahydrofuran, chloroform, ethyl
acetate, acetone, acetonitrile, dimethylformamide, ethanol, and
methanol were liquids that did not afford a gel and resulted in
the crystallization of diamides. The gel was very stable and was
converted to sol by heating, but upon cooling to room temperature,
it reverted again to gel repeatedly, being reversible. The minimum
concentration (MC) of diamides for gelation of mesitylene ranged
from 1 to over 50 mg/mL (Table 1). The gelation power of
diamides is not linearly correlated with the length of the carbon
chain. Rather than the carbon chain length, the even and odd
1
993, 238. (b) Snijder, C. S.; de Jong, J. C.; Meetsma, A.; van Bolhuis, F.;
Feringa, B. L. Chem. Eur. J. 1995, 1, 594. (c) Keller, U.; Muellen, K.; De
Feyter, S.; De Schryver, F. C. AdV. Mater. 1996, 8, 490.
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Ed. Engl. 1996, 35, 1949.
8) de Loos, M.; van Esch, J.; Stokroos, I.; Kellogg, R. M.; Feringa, B. L.
J. Am. Chem. Soc. 1997, 119, 12675.
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Soc. 1993, 115, 5991.
10) (a) Reetz, M. T.; Zonta, A.; Simpelkamp, J. Angew. Chem., Int. Ed.
(
(
(
Engl. 1995, 34, 301. (b) Yasuda, Y.; Takebe, Y.; Fukumoto, M.; Inada, H.;
Shirota, Y. AdV. Mater. 1996, 8, 740. (c) Gu, W.; Lu, L.; Chapman, G. B.;
Weiss, R. G. Chem. Commun. 1997, 543. (d) Hafkamp, R. J. H.; Kokke, B.
P. A.; Danke, I. M.; Geurts, H. P. M.; Rowan, A. E.; Feiters, M. C.; Nolte,
R. J. M. Chem. Commun. 1997, 545. (e) Yoshida, R.; Takahashi, T.;
Yamaguchi, T.; Ichijo, H. J. Am. Chem. Soc. 1996, 118, 5134. (f) Shi, C.;
Huang, Z.; Kilic, S.; Xu, J.; Enick, R. M.; Beckman, E. J.; Carr, A. J.;
Melendez, R. E.; Hamilton, A. D. Science, 1999, 286, 1540. (g) Maitra, U.;
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Asymmetry 2000, 12, 477.
(11) Menger, F. M.; Caran, K. L. J. Am. Chem. Soc. 2000, 122, 11679.
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0.1021/ja0169318 CCC: $20.00 © 2001 American Chemical Society
Published on Web 10/31/2001