Fixation of Multilayered Structures of Liquid-Crystalline 2:1 Complexes of Benzoic Acid Derivatives and Dipyridyl Compounds and the Effect of Nanopillars on Removal of the Dipyridyl Molecules from the Polymers

A polymerizable benzoic acid derivative, 3,5-bis(propenoyloxymethyl)-4- hexadecyloxybenzoic acid (1), was synthesized and complexed in a molar ratio of 2:1 with each of the dipyridyl compounds 4,4′-bipyridyl (2a), 1,2-dipyridylethane (2b), 1,2-dipyridylethene (2c), and 1,3-dipyridylpropane (2d). All of these 2:1 complexes exhibited a monotropic smectic A liquid crystal phase. Complex compound 12·2b (denoted 3b) in the liquid crystal phase was photopolymerized by UV irradiation. As the polymerization proceeded, the multilayered structure of 3b was maintained. In addition, the polymerizations of 3b containing the polymerizable rodlike compound PL at concentrations of 5 and 10 mol % also proceeded in the smectic A phases while maintaining their multilayered structures. By treatment with dilute hydrochloric acid for 216 h, all of the 2b molecules were removed from the polymer obtained from a mixture of 3b and PL in a molar ratio of 90:10, though only 50% of 2b could be removed from the polymer obtained from pure 3b. This suggested that PL molecules cross-linked each pair of polymer sheets and functioned as nanopillars between the two sheets

Room-Temperature Discotic Nematic Liquid Crystals over a Wide Temperature Range: Alkali-Metal-Ion-Induced Phase Transition from Discotic Nematic to Columnar Phases

Triphenylene derivatives possessing poly(ethylene oxide) (PEO) units exhibited discotic nematic (ND) phases at room temperature. Unique phase transition from a ND phase to a hexagonal columnar (Colh) phase was triggered by the addition of alkali metal salts. This phase transition was dependent on the type of the counterion of alkali metal salts added

Generation of Stable Calamitic Liquid-Crystal Phases with Lateral Intermolecular Hydrogen Bonding

Generation of Stable Calamitic Liquid-Crystal Phases with Lateral Intermolecular Hydrogen Bondin

Self-Assembly of <i>N,N</i><i>‘</i>-Bis(2-<i>tert</i>-Butylphenyl)pyromellitic Diimide and Phenols or Indoles into a Piled Sandwich Structure. Networks Constructed by Weak Host−Host and Strong Host−Guest Interaction in the Clathrate Compounds

A novel clathrate host, N,N‘-bis(2-tert-butylphenyl)pyromellitic diimide (1), was designed to create a sandwich structure without using cyclophanes nor the acyclic compounds. In the host−guest crystal, the host molecule is sandwiched between two aromatic guest molecules. The inclusion experiment was performed by recrystallization of 1 from chloroform in the presence of the guest at room temperature to give the clathrate compounds. Phenols (phenol, p-cresol, α-naphthol, β-naphthol, catechol) and indoles (indole, 3-methylindole, 4-methylindole, 5-methylindole) were included in the clathrate compounds, and the host/guest ratio 1:2 was observed in all cases. To explain the mechanism of the self-assembly to the piled sandwich structure, X-ray analysis of the single crystals was performed in all cases. Further, charge-transfer complexation, hydrogen bonding and dipole−dipole interaction were investigated using UV, IR, differential scanning calorimertry (DSC), and AM1 calculation. The order of the decomposition temperature related well with the order of the guest insertion. During the crystallization process, the packing of a guest with a small dipole moment smoothly proceeds and forms a stable clathrate compound. However, a guest which has a large dipole moment generates large electrostatic repulsion in the networks and forms an unstable clathrate compound

Liquid Crystal and Crystal Structure of Octahomotetraoxacalix[4]arenes

Octahomotetraoxacalix[4]arenes bearing long alkyl chains on their lower rim were prepared. Ester 4a existed in a 1,2-alternate conformation in its crystal structure, which was examined by single-crystal X-ray diffraction analysis. To prepare liquid crystalline materials possessing calixarene moieties by self-assembling, carboxylic acid derivatives 5 were synthesized. Among them, 5c, the octadecyloxy derivative, showed smectic liquid crystal phase. Homooxacalixarenes 5 also formed liquid crystal phases with longer layer distances when two equivalent moles of 1,2-ethylenediamine were added as a linker. These phases were investigated with X-ray diffraction, differential scanning calorimetry, and polarized optical microscopy

Generation of Square-Shaped Cyclic Dimers vs Zigzag Hydrogen-Bonding Networks and Pseudoconformational Polymorphism of Tethered Benzoic Acids

Two approaches to create hydrogen-bonding (H-bonding) cyclic dimers of tethered benzoic acids in a crystalline state were examined. The cyclic dimers of the methoxy derivative 1 were generated by inclusion of aromatic guest molecules: benzene or benzonitrile. Depending on the size of the guests, the conformation of the pentylene linker of 1 took either the all-trans or 1,2- and 4,5-gauche conformation to adjust the size of the cavity for the guest. The tethered benzoic acids 2 possessing benzyloxy groups as pendants generated a poly(pseudo)rotaxane-like structure in which pendants were included in the cavity of the cyclic dimer itself. In contrast, 1 afforded a zigzag H-bonding network by recrystallization from methanol or ethanol. Incorporation of methanol in the zigzag network was observed when 1 was recrystallized from methanol

Self-Assembly of <i>N,N</i><i>‘</i>-Bis(2-<i>tert</i>-Butylphenyl)pyromellitic Diimide and Phenols or Indoles into a Piled Sandwich Structure. Networks Constructed by Weak Host−Host and Strong Host−Guest Interaction in the Clathrate Compounds

A novel clathrate host, N,N‘-bis(2-tert-butylphenyl)pyromellitic diimide (1), was designed to create a sandwich structure without using cyclophanes nor the acyclic compounds. In the host−guest crystal, the host molecule is sandwiched between two aromatic guest molecules. The inclusion experiment was performed by recrystallization of 1 from chloroform in the presence of the guest at room temperature to give the clathrate compounds. Phenols (phenol, p-cresol, α-naphthol, β-naphthol, catechol) and indoles (indole, 3-methylindole, 4-methylindole, 5-methylindole) were included in the clathrate compounds, and the host/guest ratio 1:2 was observed in all cases. To explain the mechanism of the self-assembly to the piled sandwich structure, X-ray analysis of the single crystals was performed in all cases. Further, charge-transfer complexation, hydrogen bonding and dipole−dipole interaction were investigated using UV, IR, differential scanning calorimertry (DSC), and AM1 calculation. The order of the decomposition temperature related well with the order of the guest insertion. During the crystallization process, the packing of a guest with a small dipole moment smoothly proceeds and forms a stable clathrate compound. However, a guest which has a large dipole moment generates large electrostatic repulsion in the networks and forms an unstable clathrate compound

Self-Assembly of <i>N,N</i><i>‘</i>-Bis(2-<i>tert</i>-Butylphenyl)pyromellitic Diimide and Phenols or Indoles into a Piled Sandwich Structure. Networks Constructed by Weak Host−Host and Strong Host−Guest Interaction in the Clathrate Compounds

A novel clathrate host, N,N‘-bis(2-tert-butylphenyl)pyromellitic diimide (1), was designed to create a sandwich structure without using cyclophanes nor the acyclic compounds. In the host−guest crystal, the host molecule is sandwiched between two aromatic guest molecules. The inclusion experiment was performed by recrystallization of 1 from chloroform in the presence of the guest at room temperature to give the clathrate compounds. Phenols (phenol, p-cresol, α-naphthol, β-naphthol, catechol) and indoles (indole, 3-methylindole, 4-methylindole, 5-methylindole) were included in the clathrate compounds, and the host/guest ratio 1:2 was observed in all cases. To explain the mechanism of the self-assembly to the piled sandwich structure, X-ray analysis of the single crystals was performed in all cases. Further, charge-transfer complexation, hydrogen bonding and dipole−dipole interaction were investigated using UV, IR, differential scanning calorimertry (DSC), and AM1 calculation. The order of the decomposition temperature related well with the order of the guest insertion. During the crystallization process, the packing of a guest with a small dipole moment smoothly proceeds and forms a stable clathrate compound. However, a guest which has a large dipole moment generates large electrostatic repulsion in the networks and forms an unstable clathrate compound

Self-Assembly of <i>N,N</i><i>‘</i>-Bis(2-<i>tert</i>-Butylphenyl)pyromellitic Diimide and Phenols or Indoles into a Piled Sandwich Structure. Networks Constructed by Weak Host−Host and Strong Host−Guest Interaction in the Clathrate Compounds

A novel clathrate host, N,N‘-bis(2-tert-butylphenyl)pyromellitic diimide (1), was designed to create a sandwich structure without using cyclophanes nor the acyclic compounds. In the host−guest crystal, the host molecule is sandwiched between two aromatic guest molecules. The inclusion experiment was performed by recrystallization of 1 from chloroform in the presence of the guest at room temperature to give the clathrate compounds. Phenols (phenol, p-cresol, α-naphthol, β-naphthol, catechol) and indoles (indole, 3-methylindole, 4-methylindole, 5-methylindole) were included in the clathrate compounds, and the host/guest ratio 1:2 was observed in all cases. To explain the mechanism of the self-assembly to the piled sandwich structure, X-ray analysis of the single crystals was performed in all cases. Further, charge-transfer complexation, hydrogen bonding and dipole−dipole interaction were investigated using UV, IR, differential scanning calorimertry (DSC), and AM1 calculation. The order of the decomposition temperature related well with the order of the guest insertion. During the crystallization process, the packing of a guest with a small dipole moment smoothly proceeds and forms a stable clathrate compound. However, a guest which has a large dipole moment generates large electrostatic repulsion in the networks and forms an unstable clathrate compound

Liquid Crystal and Crystal Structure of Octahomotetraoxacalix[4]arenes

Octahomotetraoxacalix[4]arenes bearing long alkyl chains on their lower rim were prepared. Ester 4a existed in a 1,2-alternate conformation in its crystal structure, which was examined by single-crystal X-ray diffraction analysis. To prepare liquid crystalline materials possessing calixarene moieties by self-assembling, carboxylic acid derivatives 5 were synthesized. Among them, 5c, the octadecyloxy derivative, showed smectic liquid crystal phase. Homooxacalixarenes 5 also formed liquid crystal phases with longer layer distances when two equivalent moles of 1,2-ethylenediamine were added as a linker. These phases were investigated with X-ray diffraction, differential scanning calorimetry, and polarized optical microscopy