title: Tetraalkoxyphenanthrene-fused dehydroannulenes: synthesis, self-assembly, and electronic, optical, and electrochemical properties.
abstract: Novel tetraalkoxyphenanthrene-fused dehydro[12]-, [18]-, and [24]annulenes 1-3 were synthesized by using Cu-mediated or Pd-catalyzed oxidative macrocyclization reactions as key steps, and their electronic, optical, and electrochemical properties have been investigated in detail. X-ray crystallographic analysis of a single crystal of 1 a demonstrated that the molecules were arranged longitudinally in a slipped π-stacked fashion to form a 1D column. (1)H NMR and UV/Vis spectroscopic and cyclic voltammetric analysis in conjugation with nucleus-independent chemical shift (NICS) calculations for 1-3 support that the annulation at the 9,10-positions of phenanthrene to the dehydroannulene ring enhances the tropicity and decreases the HOMO-LUMO gaps of the molecules relative to the benzannulation and that 1 possesses an antiaromatic character. Self-association behavior due to π-π stacking in CDCl3 was observed for 1 and 2 and was quantified by concentration-dependent (1)H NMR spectroscopic measurements. The self-assembly of 1 and 2 into well-defined 1D superstructures with high aspect ratios were obtained, and the morphology and crystallinity of these compounds were investigated by means of SEM and wide-angle X-ray diffraction (WAXD) measurements. Furthermore, it was shown that 1 b and 2 b display liquid-crystalline phases by means of differential scanning calorimetry, polarizing optical microscopy, and variable-temperature WAXD measurements.
authors.affiliation: Division of Molecular Science, Faculty of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515 (Japan), Fax: (+81) 277-30-1314.
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Kato
authors.forename: Nobutaka
authors.initials: N
authors.lastname: Takahashi
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Tanaka
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kobayashi
authors.forename: Toshitada
authors.initials: T
authors.lastname: Yoshihara
authors.forename: Seiji
authors.initials: S
authors.lastname: Tobita
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yamanobe
authors.forename: Hiroki
authors.initials: H
authors.lastname: Uehara
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Nakamura
keywords: alkynes; annulenes; antiaromaticity; liquid crystals; phenanthrenes; self‐assembly