title: Metal-Ion-Induced Switch of Liquid-Crystalline Orientation of Metallomacrocycles.
abstract: A new series of shape-persistent imine-bridged macrocycles were synthesized based on dynamic covalent chemistry. The macrocycles had an alternating sequence of dibenzothiophene and N,N'-bis(salicylidene)-ethylenediamine (salen) tethering branched alkyl chains. The macrocycles and tetranuclear metallomacrocycles bearing long and branched alkyl chains exhibited thermotropic columnar liquid-crystalline phases over a wide temperature range and the metallomacrocycles greatly depended on the characteristics of the coordinated metal ions. The metal-free macrocycle showed a liquid-crystalline phase with a lamellar structure and poor birefringence. In sharp contrast, the macrocyclic Ni complex showed a columnar oblique liquid-crystalline phase, whereas the Pd and Cu complexes showed columnar liquid-crystalline phases with a lamellar structure. The macroscopic organization and thermal properties of the corresponding liquid-crystalline metallomacrocycles were significantly dependent on the subtle structural differences among the planar macrocycles, which were revealed by single-crystal X-ray crystallographic analysis of the macrocycles with shorter alkyl chains.
authors.affiliation: Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan.
authors.forename: Shin-Ichiro
authors.initials: SI
authors.lastname: Kawano
authors.affiliation: Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Hamazaki
authors.affiliation: Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Suzuki
authors.affiliation: Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan.
authors.forename: Kenshin
authors.initials: K
authors.lastname: Kurahashi
authors.affiliation: Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan. kentaro@chem.nagoya-u.ac.jp.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Tanaka
keywords: dynamic covalent chemistry; liquid crystals; macrocycles; metallomesogens; nanospace