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Science 8 April 1994:
Vol. 264. no. 5156, pp. 249 - 251
DOI: 10.1126/science.264.5156.249
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Articles

Molecular Nanotube Aggregates of beta- and ggr-Cyclodextrins Linked by Diphenylhexatrienes

Guang Li 1 and Linda B. McGown 1

1 Department of Chemistry, P. M. Gross Chemical Laboratory, Duke University, Box 90346, Durham, NC 27708, USA.

Linked by strings of diphenylhexatriene (DPH) molecules, beta- and ggr-cyclodextrins (CDs) can form nanotube aggregates that contain as many as sim20 betaCDs (20 nanometers long) or sim20 to 35 ggrCDs (20 to 35 nanometers long). Nanotube formation was indicated in solution, by fluorescence anisotropy and light scattering results, and on graphite surfaces, by scanning tunneling microscopy. Tubes were not observed for the smaller agrCDs. Molecular modeling shows that CD cavity size and the rodlike DPH structure are key factors in nanotube formation. Spectra generated by proton nuclear magnetic resonance indicate the inclusion of DPH in the interior of the CDs and formation of nanotubes in betaCDs and ggrCDs only. The photophysical properties of DPH are affected by its arrangement into a one-dimensional array within the CD nanotube, possibly because of exciton formation.

Submitted on November 19, 1993
Accepted on February 9, 1994

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Science. ISSN 0036-8075 (print), 1095-9203 (online)