Formation of Columnar Liquid Crystals on the Basis of Unconventional Triazine‐Based Dendrimers by the C3‐Symmetric Approach |
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| Authors: | Prof. Dr. Long‐Li Lai Shun‐Ju Hsu Hui‐Chu Hsu Sheng‐Wei Wang Dr. Kung‐Lung Cheng Chun‐Jung Chen Tsai‐Hui Wang Prof. Dr. Hsiu‐Fu Hsu |
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| Affiliation: | 1. Department of Applied Chemistry, National Chi Nan University, No.1 University Rd., Puli, Nantou (Taiwan), Fax: (+886)?49‐2917956;2. Material and Chemical Research Laboratories, Industrial Research Institute, Hsinchu (Taiwan);3. Department of Chemistry, National Central University, Jhongli (Taiwan);4. Department of Chemistry, Tamkang University, Tamsui (Taiwan) |
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| Abstract: | Two series of unconventional triazine‐based dendrimers with C2 symmetry and C3 symmetry were prepared. The newly prepared C3‐symmetrical dendrimers were characterized by 1H and 13C NMR spectroscopy, mass spectrometry, and elemental analysis. Differential scanning calorimetry, polarizing microscopy, and powder XRD showed that the C3‐symmetrical dendrimers display columnar liquid‐crystalline phases during thermal treatment, but the C2‐symmetrical dendrimers were not observed to behave correspondingly. The molecular conformations of C3‐ and C2‐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 C3‐ and C2‐symmetric dendrimers. This new strategy should be applicable to other types of unconventional dendrimers with rigid frameworks for displaying columnar liquid‐crystalline behavior. |
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| Keywords: | dendrimers liquid crystals molecular mechanics calculations nitrogen heterocycles |
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