Daisy chain necklace: Tri[2]rotaxane containing cyclodextrins [21]

Full text of DOI:10.1021/ja0018264

9876
J. Am. Chem. Soc. 2000, 122, 9876-9877
Daisy Chain Necklace: Tri[2]rotaxane Containing
Cyclodextrins
Scheme 1
Taiki Hoshino, Masahiko Miyauchi, Yoshinori Kawaguchi,
Hiroyasu Yamaguchi, and Akira Harada*
Department of Macromolecular Science
Graduate School of Science, Osaka UniVersity
Toyonaka, Osaka 560-0043, Japan
ReceiVed May 25, 2000
ReVised Manuscript ReceiVed August 9, 2000
Recently, much attention has been focused on design and
synthesis of interlocked molecules, such as rotaxanes and cat-
1
enanes, because of their unique structures and properties. Host-
guest interactions are used for efficient preparation of such
interlocked molecules. When a guest group is covalently attached
to a cyclic host, the molecule may form an intramolecular
2
3
complex or intermolecular complexes to give supramolecular
polymers. When supramolecular polymers are treated with bulky
stopper groups, they may form poly[2]rotaxanes, daisy chains.4
Now we found that a cyclodextrin derivative which has a
cinnamoyl group as a guest part on the 6-position of cyclodextrin
forms an oligomeric supramolecular structure in aqueous solutions
and that the supramolecular structure could be stabilized by
attaching bulky stoppers to give the cyclic trimer of [2]rotaxane,
daisy chain necklace.
We chose cyclodextrin (CD) as a cyclic host and a phenyl group
as a guest moiety because a phenyl group is suitable for fitting
in a cyclodextrin cavity. However, benzoyl CD did not form
5
6
supramolecular polymers. This result suggests that some spacer
and ethyl cinnamate, in which â-CDs form a layer structure. In
1
groups are required for efficient formation of intermolecular
complexes. Therefore, we tested a hydrocinnamoyl group as a
guest moiety. However, 6-hydrocinnamoyl â-CD (6-HyCi-â-CD)
formed an intramolecular complex and 6-HyCiO-R-CD gave only
weak intermolecular complexes. So we have decided to use
cinnamoyl derivatives as a guest because cinnamoyl derivatives
have a rigid carbon-carbon double bond. The synthetic route is
shown in Scheme 1.
contrast, 6-CiO-R-CD is soluble in water. The H NMR spectra
2
of 6-CiO-R-CD in D O are similar to those of methyl cinnamate
(a model compound) in the presence of R-CD, indicating that a
1
cinnamoyl group is included in the R-CD cavity. The H NMR
spectra are dependent on the concentration, although those in
DMSO-d
of 6-CiO-R-CD in D
the inner protons of CD. These results indicate that 6-CiO-R-CD
forms intermolecular complexes in D O solutions.
6
are independent of concentration. The ROESY spectra
2
O showed NOE between phenyl signals and
6
-Cynnamoyl â-CD (6-CiO-â-CD) is sparingly soluble in
water, although most of 6-substituted â-CDs are soluble. However,
-CiO-â-CD is solubilized in water on the addition of p-
2
Therefore, we measured the molecular weight of 6-CiO-R-CD
using vapor pressure osmometry (VPO) at various concentrations.
Figure 1 shows the results of the VPO measurements of the CD
and their derivatives at various concentrations at 40 °C in D O.
Although R-CD showed no concentration dependency of the
6
iodoaniline or p-iodophenol which can be included in a â-CD
cavity. These results suggest that 6-CiO-â-CD forms supramo-
lecular polymers in the solid state. The X-ray powder pattern of
2
6-CiO-â-CD is very similar to that of the complex between â-CD
molecular weight, 6-CiO-R-CD showed concentration dependence.
The molecular weight increased with increase in the concentra-
tions and the molecular weight reached saturation at about 3000.
This result suggests that 6-CiO-R-CD forms a trimer. 6-4-
AminoCiO-R-CD (6-4AmCiO-R-CD) showed a similar result,
(
1) (a) Amabilino, D. B.; Stoddart, J. F. Chem. ReV. 1995, 95, 2725. (b)
Harada, A. AdV. Polym. Sci. 1997, 133, 141. (c) Molecular Catenanes,
Rotaxanes and Knots; Sauvage, J.-P., Dietrich-Buchecker, C., Eds.; Wiley-
VCH: Weinheim, 1999.
(2) (a) Hamasaki, K.; Ikeda, H.; Nakamura, A.; Ueno, A.; Toda, F.; Suzuki,
1
although the molecular weight observed by VPO and the H NMR
I.; Osa, T. J. Am. Chem. Soc. 1993, 115, 5035. (b) Ueno, A.; Minato, S.;
Suzuki, I.; Fukushima, M.; Ohkubo, M.; Osa, T.; Hamada, F.; Murai, K. Chem.
Lett. 1990, 605. (c) Corradini, R.; Dossena, A.; Marchelli, R.; Panagia, A.;
Sartor, G.; Saviano, M.; Lombardi, A.; Pavone, V. Chem. Eur. J. 1996, 2,
spectra of the starting tosyl R-CD are independent of the
concentrations. At higher temperature (at 70 °C) the molecular
weight observed is lower than that observed at lower temperature
(at 40 °C). Supramolecular polymeric structures have been
reported in the solid states of â-CD having a guest moiety by
3
73. (d) Corradini, R.; Dossena, A.; Galaverna, G.; Marchelli, R.; Panagia,
A.; Sartor, G. J. Org. Chem. 1997, 62, 6283. (e) Wang, Y.; Ikeda, T.; Ikeda,
H.; Ueno, A.; Toda, F. Bull. Chem. Soc. Jpn. 1994, 67, 1598.
(3) (a) Zanotti-Gerosa, A.; Solari, E.; Giannini, L.; Chiesi-Villa, A.; Rizzoli,
7
X-ray studies. To the best of our knowledge, there have been
C. Chem. Commun. 1996, 119. (b) Yamaguchi, N.; Nagvekar, D. S.; Gibson,
H. W. Angew. Chem., Int. Ed. 1998, 37, 2361. (c) Bulger, J.; Sommerdik, N.
A. J. M.; Visser, A. J. W. G.; van Hoek, A.; Nolte, R. J. M.; Engbersen, J. F.
J.; Reinhoudt, D. N. J. Am. Chem. Soc. 1999, 121, 28.
no reports on the formation of supramolecular polymers of CD
derivatives in aqueous solutions, although there have been a few
reports in which dimeric complexes have been suggested in
aqueous solutions.8
(
4) (a) Ashton, P. R.; Baxter, I.; Cantrill, S.; Fyfe, M. C. T.; Glink, P. T.;
Stoddart, J. F.; White, A. J. P.; Williams, D. J. Angew. Chem., Int. Ed. 1998,
7, 1294. (b) Ashton, P. R.; Parsons, I. W.; Raymo, F. M.; Stoddart, J. F.;
White, A. J. P.; Williams, D. J.; Wolf, R. Angew. Chem., Int. Ed. 1998, 37,
913. (c) Rowan, S. J.; Cantrill, S. J.; Stoddart, J. F.; White A. J. P.; Williams,
D. J. Org. Lett. 2000, 2, 759.
5) Tong, L.-H.; Hou, Z.-J.; Inoue, Y.; Tai, A. J. Chem. Soc., Perkin Trans.
, 1992, 1253
3
(6) Hursthouse, M. B.; Smith, C. Z.; Thornton-Pett, M.; Utley, J. H. P. J.
Chem. Soc., Chem. Commun. 1982, 881.
(7) (a) Hirotsu, K.; Higuchi, T.; Fujita, K.; Ueda, T.; Shinoda, A.; Imoto,
T.; Tabushi, I. J. Org. Chem. 1982, 47, 1143. (b) Mentzafos, D.; Terzis, A.;
Coleman, A. W.; de Rango, C. Carbohydr. Res. 1996, 282, 125.
1
(
2
1
0.1021/ja0018264 CCC: $19.00 © 2000 American Chemical Society
Published on Web 09/21/2000

Communications to the Editor
J. Am. Chem. Soc., Vol. 122, No. 40, 2000 9877
Figure 1. Effects of the concentrations on the molecular weight of R-CD
(a, b) and 6-CiO-R-CD (b, 9) observed by VPO in water at 40 °C.
Scheme 2
Figure 2. 1H NMR spectra of 4TNBAmCiOMe (a), 6-4TNBAmCiO-
R-CD monomer (b), and 6-4TNBAmCiO-R-CD cyclic trimer (c) in D
2
O
at 30 °C.
or higher aggregates. This result clearly showed that the product
is a cyclic trimer. When the reaction was carried out in the
presence of 3 M excess of p-iodophenol, the product is only the
monomer, 6-4-TNBAmCiO-R-CD (Scheme 2). These results
indicate that p-iodophenol inhibited the formation of self-
assembling supramolecular structures. The ROESY spectrum of
the cyclic trimer shows cross-peaks between phenyl protons close
to an amino group and secondary hydroxyl groups (O(2)H),
indicating that a trinitrophenyl group is located at the secondary
hydroxyl group side. A proposed structure of cyclic trimer (a daisy
chain necklace) isolated is shown in Scheme 2.
When 6-4AmCiO-R-CD (40 mM) was treated with 2 M excess
2
,4,6-trinitrobenzenesulfonic acid sodium salt (TNBS) as bulky
stoppers in aqueous solutions (Scheme 2), the solution became
1
turbid and the product was obtained as a precipitate. The H NMR
Detailed structures and their dynamic aspects are now being
investigated and the results will be published later.
and TOF mass spectra showed that the crude product is mainly
a cyclic trimer with a small amount of cyclic dimer and monomer.
The product was purified by column chromatography on DIAION
HP20 followed by chromatography on TOYOPEARL HW-40.
The product was characterized by UV-visible absorption, FT IR,
Supporting Information Available: Experimental details (PDF). This
material is available free of charge via the Internet at http://pubs.acs.org.
JA0018264
1
13
H NMR, C NMR, 2D ROESY spectra, and MALDI TOF mass
9
1
(9) Cyclic trimer: cyclo-tri[mono-6-O-{4-(N-2,4,6-trinitrobenzamino)cin-
spectra. The H NMR spectra showed that the product does not
have a nonincluded cinnamoyl group and that each peak is
broadened (Figure 2). These results indicate that the product is a
polymer or a cyclic compound. Therefore, we measured the
MALDI TOF mass spectra and found a signal with the mass of
1
namoyl}-R-CD] (cyclo[6-4TNBAmCiO-R-CD]3). Yield: 38%. H NMR
(
6
DMSO-d , 270 MHz): δ 10.26 (s, 1H, Ph-NH-Ph), 8.99 (s, 2H, H of
trinitrophenyl), 7.85-7.78 (3H, Ph-CHd, and 2-H of phenyl), 7.25 (d, J )
7
.6 Hz, 2H, 3-H of phenyl), 6.20 (d, J ) 15.8 Hz, 1H, dCH-CO-), 5.54-
.12 (m, 12H, O(2)H and O(3)H of R-CD), 5.00-4.26 (m, 13H, C(1)H, O(6)H,
5
and C(6′)H of R-CD), 4.01-3.25 (m, overlaps with HOD, C(2-6)H of R-CD);
+
-1
the cyclic trimer, 4009 (trimer + Na ), and no peaks due to dimers
IR (KBr, cm ): 3394 (vs, νOH), 2932 (vs, νCH), 1715 (s, νCdO), 1338 (s,
ν
(CdO)-O), 1151, 1076, 1029 (vs, νC-O). MALDI-TOF-MS 4009 [cyclic trimer
+
(
8) (a) Mirzoian, A.; Kaifer, A. E. Chem. Commun. 1999, 1603. (b)
+ Na] ; Anal. Calcd for (C51
H N
68 4
O )
37 3
2
‚17H O: C, 42.80; H, 5.59; N, 3.91.
McAipine, S. R.; Garcia Garibay, M. A. J. Am. Chem. Soc. 1998, 120, 4269.
Found: C, 42.44; H, 5.09; N, 3.89.