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ISMSC 2007 - Università degli Studi di Pavia

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PSB 25<br />

A Minimalist Design for Self-Assembled Rosette Nanotubes based on<br />

Mascal’s Motif<br />

Martins Oderinde, Grigory Tikhomirov and Hicham Fenniri*<br />

National Institute for Nanotechnology (NINT-NRC), Department of Chemistry,<br />

University of Alberta, 11421 Saskatchewan Dr, Edmonton, Alberta T6G 2M9, Canada<br />

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Rosette of 1<br />

G/C base 1, based on Mascal’s motif, was synthesized and its ability to self-assemble into<br />

rosette nanotubes in water was investigated. This presentation will focus on the synthesis and<br />

characterization of compound 1 by SEM, TEM, AFM and UV-VIS. Consistent with the calculated<br />

<strong>di</strong>ameter of 2.2 nm, the TEM-measured <strong>di</strong>ameter of a single tube was 2.2 0.2 nm. This value<br />

is also consistent with height profiles obtained from TM-AFM images, which give slightly<br />

compressed <strong>di</strong>ameter of 2.0 0.2 nm.<br />

[1] (a) Fenniri, H.; Mathiavanan, P.; Vidale, K. L.; Sherman, D. M.; Hallenga, K.; Wood, K. V.;<br />

Stowell, J. G. J. Am. Chem. Soc. 2001, 123, 3854-3855. (b) Fenniri, H.; Deng, B. L.; Ribbe, A.<br />

E. J Am. Chem. Soc. 2002, 124, 11064-11072. (c) Fenniri, H.; Deng, B. L.; Ribbe, A. E.;<br />

Hallenga, K.; Jacob, J.; Thiyagarajan, P. Proc. Natl. Acad. Sci. U.S.A. 2002, 99, 6487-6492.<br />

[2] (a) Mascal, M.; Hext, N.; Warmuth, R.; Moore, M. H.; Turkenburg, J. P. Angew. Chem. 1996,<br />

35, 2204-2206. (b) Mascal, M.; Farmer, S. C.; Arnall-Culliford, J. R. J. Org. Chem. 2006, 71,<br />

8146-8150<br />

PSB 26<br />

Chemically-Responsive Sol-Gel Transition of Supramolecular Single-Walled<br />

Carbon Nanotubes (SWNTs) Hydrogel Made by SWNTs-Cyclodextrins<br />

Hybrids<br />

Tomoki Ogoshi a , Tada-aki Yamagishi a , Yoshiaki Nakamoto a , and Akira Harada b<br />

a<br />

Department of Chemistry and Chemical Engineering, Graduate School of Natural Science and<br />

Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan and<br />

b<br />

Department of Macromolecular Science, Graduate School of Science, Osaka University,<br />

Toyonaka, Osaka 560-0043, Japan<br />

Single-walled carbon nanotubes (SWNTs) have received a great deal of interests because of<br />

their unique structural, electrical, and mechanical properties. However, their applications have<br />

been extremely limited due to their low solubility in solvents. Therefore, solubilization of SWNTs<br />

has been one of hot topics for the past few years. Soluble SWNTs in aqueous me<strong>di</strong>a are<br />

obtained using interaction between pyrene having ionic groups and SWNTs. Herein, we<br />

report novel chemically-responsive supramolecular SWNT hydrogel by using soluble SWNTs<br />

functionalized cyclodextrin (CD) moieties on SWNT surface. Since CD shows high solubility in<br />

water, water-soluble SWNTs carrying CDs are obtained by using interaction between<br />

pyrene mo<strong>di</strong>fied -CDs and SWNTs (Py--CD/SWNT hybrids) [1].<br />

By utilizing host-guest interactions between poly(acrylic acid) carrying dodecyl groups (PAA2)<br />

and -CDs of Py--CD/SWNT hybrids, nanocomposites of polymer and SWNTs were prepared.<br />

By mixing Py--CD/SWNT hybrids and PAA2 in aqueous me<strong>di</strong>a (Scheme 1a), a homogeneous<br />

SWNT hydrogel formed, in<strong>di</strong>cating that host-guest complexes between -CD moieties<br />

immobilized on the SWNT surface and dodecyl groups in PAA2 act as cross-links to form<br />

network structures which showed gel-like behavior. Furthermore, SWNT hydrogels composed of<br />

Py--CD/SWNT hybrids and PAA2 changed to sol by ad<strong>di</strong>ng competitive guests or host<br />

compounds. When so<strong>di</strong>um adamantane carboxylate (AdCNa, 100 eq. to dodecyl moieties of<br />

PAA2) was added to the hydrogel as a competitive guest, gel to sol transition was observed<br />

(Scheme 1b). This result in<strong>di</strong>cates <strong>di</strong>ssociation of the host-guest complexes between -CDs of<br />

Py--CD/SWNT hybrids and dodecyl groups of PAA2 because AdCNa strongly interacts with -<br />

CD compared with dodecyl group. Upon ad<strong>di</strong>tion of -CD (100 eq. to dodecyl groups of PAA2)<br />

as a competitive host, the gel also changed to sol (Scheme 1c). It is because dodecyl moieties<br />

form complexes with -CD more favorably than with -CD.<br />

(b) (a)<br />

(c)<br />

+<br />

+ -CD<br />

sol<br />

gel<br />

sol<br />

Supramolecular SWNT Hydrogel<br />

Scheme 1. Supramolecular SWNT Hydrogel Prepared from Py--CD/SWNT Hybrids and<br />

Guest Mo<strong>di</strong>fied Polymer (PAA2).<br />

[1] Ogoshi, T. et al. J. Am. Chem. Soc. <strong>2007</strong>, in press.<br />

PAA2<br />

Py--CD

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