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Proc Natl Acad Sci U S A. 2005 Aug 2;102(31):10801-6. Epub 2005 Jul 25.

Self-assembled graphitic nanotubes with one-handed helical arrays of a chiral amphiphilic molecular graphene.

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  • 1Aida Nanospace Project, Exploratory Research for Advanced Technology, Japan Science and Technology Agency, National Museum of Emerging Science and Innovation, 2-41 Aomi, Koto-ku, Tokyo 135-0064, Japan.

Abstract

Self-assembly of a Gemini-shaped, chiral amphiphilic hexa-peri-hexabenzocoronene having two chiral oxyalkylene side chains, along with two lipophilic side chains, yields graphitic nanotubes with one-handed helical chirality. The nanotubes are characterized by an extremely high aspect ratio of >1,000 and have a uniform diameter of 20 nm and a wall thickness of 3 nm. The nanotubes with right- and left-handed helical senses were obtained from the (S)- and (R)-enantiomers of the amphiphile, respectively, due to an efficient translation of point chirality into supramolecular helical chirality. The (S)- and (R)-enantiomers coassemble at varying mole ratios to give nanotubes, whose circular dichroism profiles are almost unchanged over a wide range of the enantiomeric excess of the amphiphile (100-20%). The high level of chirality amplification thus observed indicates a long-range cooperativity in the self-assembling process. In sharp contrast, a hexabenzocoronene amphiphile with chiral lipophilic side chains did not form nanotubular assemblies. The present work demonstrates the majority rule in noncovalent systems and also may provide a synthetic strategy toward realization of molecular solenoids.

PMID:
16043721
[PubMed]
PMCID:
PMC1182409
Free PMC Article
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