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Chemistry. 2012 Nov 26;18(48):15361-7. doi: 10.1002/chem.201200933. Epub 2012 Oct 2.

Induction of the columnar phase of unconventional dendrimers by breaking the C2 symmetry of molecules.

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  • 1Department of Applied Chemistry, National Chi Nan University, No. 1 University Rd., Puli, Nantou, Taiwan 545. lilai@ncnu.edu.tw

Abstract

Two triazine-based unconventional dendrimers were prepared and characterized by (1)H and (13)C NMR spectroscopy, mass spectrometry, and elemental analysis. Differential scanning calorimetry, polarizing microscopy, and powder XRD studies showed that these dendrimers display columnar liquid-crystalline phases during thermal treatment. This is ascribable to breaking of their C(2) symmetry. The molecular conformations of prepared dendrimers were obtained by computer simulation with the MM3 model of the CaChe program in the gas phase. The simulation showed that the conformations of the prepared dendrimers are rather flat and disfavor formation of the LC phase. However, due to C(2)-symmetry breaking, the prepared dendrimers have structural isomers in the solid state and thus show the desired columnar phases. This new strategy should be applicable to other types of unconventional dendrimers with rigid frameworks.

Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

PMID:
23032583
[PubMed]
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