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Formation of Columnar Liquid Crystals on the Basis of Unconventional Triazine‐Based Dendrimers by the C 3 ‐Symmetric Approach
Author(s) -
Lai LongLi,
Hsu ShunJu,
Hsu HuiChu,
Wang ShengWei,
Cheng KungLung,
Chen ChunJung,
Wang TsaiHui,
Hsu HsiuFu
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201103423
Subject(s) - dendrimer , differential scanning calorimetry , triazine , crystallography , materials science , symmetry (geometry) , supramolecular chemistry , chemistry , chemical physics , polymer chemistry , crystal structure , thermodynamics , physics , geometry , mathematics
Two series of unconventional triazine‐based dendrimers with C 2 symmetry and C 3 symmetry were prepared. The newly prepared C 3 ‐symmetrical dendrimers were characterized by 1 H and 13 C NMR spectroscopy, mass spectrometry, and elemental analysis. Differential scanning calorimetry, polarizing microscopy, and powder XRD showed that the C 3 ‐symmetrical dendrimers display columnar liquid‐crystalline phases during thermal treatment, but the C 2 ‐symmetrical dendrimers were not observed to behave correspondingly. The molecular conformations of C 3 ‐ and C 2 ‐symmetrical dendrimers were obtained by computer simulation with the MM2 model of the CaChe program in the gas phase. The simulation results reasonably explain the different mesogenicities of C 3 ‐ and C 2 ‐symmetric dendrimers. This new strategy should be applicable to other types of unconventional dendrimers with rigid frameworks for displaying columnar liquid‐crystalline behavior.