title: Tilt orientationally disordered hexagonal columnar phase of phthalocyanine discotic liquid crystals.
abstract: The structures of the discotic liquid crystalline (LC) phase of metal-free octa-substituted phthalocyanine (Pc) derivatives were investigated using molecular dynamics (MD) simulations. Special attention was paid to the LC phase structure of the non-peripheral octa-hexyl substituted Pc-derivatives that were recently found to show very high carrier mobilities for the discotic LCs. We obtained spontaneous transition to the columnar hexagonal (Col_{h}) LC phase in a melting simulation from the crystal structure obtained using an x-ray diffraction study. In this simulated Col_{h} structure, the Pc-core normal vectors were tilted 47{∘} from the column axis in parallel within each column, but the tilting directions are disordered between columns. We also found that the inter-core distance was not as large as previously suggested (0.4-0.5 nm) but similar to the common value (0.36 nm). This may resolve the contradiction between the high carrier mobility of the non-peripheral substituted Pcs, because larger inter-core separations degrade the mobilities.
authors.affiliation: National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba 305-8568, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Yoneya
authors.affiliation: National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba 305-8568, Japan.
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Makabe
authors.affiliation: National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba 305-8568, Japan.
authors.forename: Ayano
authors.initials: A
authors.lastname: Miyamoto
authors.affiliation: National Institute of Advanced Industrial Science and Technology, 1-8-31 Midorioka, Ikeda, 563-8577, Japan.
authors.forename: Yo
authors.initials: Y
authors.lastname: Shimizu
authors.affiliation: National Institute of Advanced Industrial Science and Technology, 1-8-31 Midorioka, Ikeda, 563-8577, Japan and Osaka University, 2-1 Yamada-oka, Suita, Osaka, 565-0871, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Miyake
authors.affiliation: Osaka University, 2-1 Yamada-oka, Suita, Osaka, 565-0871, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yoshida
authors.affiliation: Osaka University, 2-1 Yamada-oka, Suita, Osaka, 565-0871, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Fujii
authors.affiliation: Osaka University, 2-1 Yamada-oka, Suita, Osaka, 565-0871, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Ozaki
mesh_terms: D005615:Freezing; D007211:Indoles / Q000737:chemistry*; D054833:Isoindoles; D050866:Liquid Crystals / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D015394:Molecular Structure; D014961:X-Ray Diffraction
chemical_list: D007211:Indoles; D054833:Isoindoles; C013647:phthalocyanine