title: Formation of columnar liquid crystals on the basis of unconventional triazine-based dendrimers by the C3-symmetric approach.
abstract: 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.
authors.affiliation: Department of Applied Chemistry, National Chi Nan University, No.1 University Rd., Puli, Nantou, Taiwan. lilai@ncnu.edu.tw
authors.forename: Long-Li
authors.initials: LL
authors.lastname: Lai
authors.forename: Shun-Ju
authors.initials: SJ
authors.lastname: Hsu
authors.forename: Hui-Chu
authors.initials: HC
authors.lastname: Hsu
authors.forename: Sheng-Wei
authors.initials: SW
authors.lastname: Wang
authors.forename: Kung-Lung
authors.initials: KL
authors.lastname: Cheng
authors.forename: Chun-Jung
authors.initials: CJ
authors.lastname: Chen
authors.forename: Tsai-Hui
authors.initials: TH
authors.lastname: Wang
authors.forename: Hsiu-Fu
authors.initials: HF
authors.lastname: Hsu