Document Detail


Stereochemistry Dependent, Mechanoresponsive Supramolecular Host Assemblies for Fullerenes: A Guest Induced Enhancement of Thixotropy.
MedLine Citation:
PMID:  22206456     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Self-assembly behaviors of a series of systems (G1, G2, and G3) possessing same organic building blocks based on a substituted anthracene have been investigated in decalin. G2 and G3 are dominated by head-to-tail (ht) and head-to-head (hh) type dimers of G1, respectively. G1 gives a thermoresponsive gel which behaves ideally showing the frequency independent elastic and viscous moduli. Interestingly, G2 produces a thixotropic gel which shows the signature of structural relaxation signifying the dynamic nature of the system. In contrast, G3 remains fluid-like. As investigated by SEM, in the assembling process of G2, first disk-like nano-aggregates are formed and in the second step these aggregates interact to construct the densely packed secondary assembly. A transition from secondary assembly to primary assembly under the shear initiates the mechanoresponsive destruction of the gel. In the self-assembling process, G1 propagates in a one-dimensional fashion, whereas G2 and G3 can propagate in a two-dimensionional fashion. Same side orientation of the substituents in G3 facilitates the formation of a compact closed-shell type structure which results in the generation of isolated nanocrystals. The long-ranged weak interaction together with the capability of propagating in two dimensions is found to be essential for the construction of such a mechanoresponsive assembly. C60 and C70 could be incorporated successfully in G2 assembly to develop the mechanoresponsive fullerene assemblies. Presence of fullerenes not only enhances the elastic property of G2 but also intensifies the thixotropy. C70 is appeared to be a superior guest in terms of property enhancement due to its better size fitting with the concave-shaped host.
Authors:
Arnab Dawn; Tomohiro Shiraki; Hiroshi Ichikawa; Akihiko Takada; Yoshiaki Takahashi; Youichi Tsuchiya; Le Thi Ngoc Lien; Seiji Shinkai
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-12-28
Journal Detail:
Title:  Journal of the American Chemical Society     Volume:  -     ISSN:  1520-5126     ISO Abbreviation:  -     Publication Date:  2011 Dec 
Date Detail:
Created Date:  2011-12-30     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7503056     Medline TA:  J Am Chem Soc     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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