ISMSC 2007 - Università degli Studi di Pavia

PSB 25
A Minimalist Design for Self-Assembled Rosette Nanotubes based on
Mascal’s Motif
Martins Oderinde, Grigory Tikhomirov and Hicham Fenniri*
National Institute for Nanotechnology (NINT-NRC), Department of Chemistry,
University of Alberta, 11421 Saskatchewan Dr, Edmonton, Alberta T6G 2M9, Canada
H
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Rosette of 1
G/C base 1, based on Mascal’s motif, was synthesized and its ability to self-assemble into
rosette nanotubes in water was investigated. This presentation will focus on the synthesis and
characterization of compound 1 by SEM, TEM, AFM and UV-VIS. Consistent with the calculated
diameter of 2.2 nm, the TEM-measured diameter of a single tube was 2.2 0.2 nm. This value
is also consistent with height profiles obtained from TM-AFM images, which give slightly
compressed diameter of 2.0 0.2 nm.
[1] (a) Fenniri, H.; Mathiavanan, P.; Vidale, K. L.; Sherman, D. M.; Hallenga, K.; Wood, K. V.;
Stowell, J. G. J. Am. Chem. Soc. 2001, 123, 3854-3855. (b) Fenniri, H.; Deng, B. L.; Ribbe, A.
E. J Am. Chem. Soc. 2002, 124, 11064-11072. (c) Fenniri, H.; Deng, B. L.; Ribbe, A. E.;
Hallenga, K.; Jacob, J.; Thiyagarajan, P. Proc. Natl. Acad. Sci. U.S.A. 2002, 99, 6487-6492.
[2] (a) Mascal, M.; Hext, N.; Warmuth, R.; Moore, M. H.; Turkenburg, J. P. Angew. Chem. 1996,
35, 2204-2206. (b) Mascal, M.; Farmer, S. C.; Arnall-Culliford, J. R. J. Org. Chem. 2006, 71,
8146-8150
PSB 26
Chemically-Responsive Sol-Gel Transition of Supramolecular Single-Walled
Carbon Nanotubes (SWNTs) Hydrogel Made by SWNTs-Cyclodextrins
Hybrids
Tomoki Ogoshi a , Tada-aki Yamagishi a , Yoshiaki Nakamoto a , and Akira Harada b
a
Department of Chemistry and Chemical Engineering, Graduate School of Natural Science and
Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan and
b
Department of Macromolecular Science, Graduate School of Science, Osaka University,
Toyonaka, Osaka 560-0043, Japan
Single-walled carbon nanotubes (SWNTs) have received a great deal of interests because of
their unique structural, electrical, and mechanical properties. However, their applications have
been extremely limited due to their low solubility in solvents. Therefore, solubilization of SWNTs
has been one of hot topics for the past few years. Soluble SWNTs in aqueous media are
obtained using interaction between pyrene having ionic groups and SWNTs. Herein, we
report novel chemically-responsive supramolecular SWNT hydrogel by using soluble SWNTs
functionalized cyclodextrin (CD) moieties on SWNT surface. Since CD shows high solubility in
water, water-soluble SWNTs carrying CDs are obtained by using interaction between
pyrene modified -CDs and SWNTs (Py--CD/SWNT hybrids) [1].
By utilizing host-guest interactions between poly(acrylic acid) carrying dodecyl groups (PAA2)
and -CDs of Py--CD/SWNT hybrids, nanocomposites of polymer and SWNTs were prepared.
By mixing Py--CD/SWNT hybrids and PAA2 in aqueous media (Scheme 1a), a homogeneous
SWNT hydrogel formed, indicating that host-guest complexes between -CD moieties
immobilized on the SWNT surface and dodecyl groups in PAA2 act as cross-links to form
network structures which showed gel-like behavior. Furthermore, SWNT hydrogels composed of
Py--CD/SWNT hybrids and PAA2 changed to sol by adding competitive guests or host
compounds. When sodium adamantane carboxylate (AdCNa, 100 eq. to dodecyl moieties of
PAA2) was added to the hydrogel as a competitive guest, gel to sol transition was observed
(Scheme 1b). This result indicates dissociation of the host-guest complexes between -CDs of
Py--CD/SWNT hybrids and dodecyl groups of PAA2 because AdCNa strongly interacts with -
CD compared with dodecyl group. Upon addition of -CD (100 eq. to dodecyl groups of PAA2)
as a competitive host, the gel also changed to sol (Scheme 1c). It is because dodecyl moieties
form complexes with -CD more favorably than with -CD.
(b) (a)
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gel
sol
Supramolecular SWNT Hydrogel
Scheme 1. Supramolecular SWNT Hydrogel Prepared from Py--CD/SWNT Hybrids and
Guest Modified Polymer (PAA2).
[1] Ogoshi, T. et al. J. Am. Chem. Soc. 2007, in press.
PAA2
Py--CD