6-1) Novel Ion Conductive Materials Based on Ionic Bicontinuous Cubic Liquid Crystals

6-2) Development of Anisotropically Ion-Conductive Nanostructured Films

6-3) Development of Columnar Liquid-Crystalline π-Conjugated Molecules

6-4) Stimuli-Responsive Luminescent Liquid Crystals: Change of Photoluminescent Colors Triggered by a Shear-Induced Phase Transition

6-5) Development of Full-Color Tunable Photoluminescent Ionic Liquid Crystals

6-6) Construction of Aligned Opto- and Electroactive Self-Assembled Fibers

6-7) Development of Redox-Active Liquid Crystals

Wedge-shaped ammonium and phosphonium salts self-assemble into bicontinuous cubic liquid-crystalline structures having three-dimensionally interconnected ionic nanochannels. Synchrotron small-angle X-ray measurements have been performed to construct the electron density maps in the bicontinuous cubic phases. The location of anions in the bicontinuous cubic structures has been revealed by novel differential mapping technique.
(collaboration with Prof. H. Ohno in Tokyo University of Agriculture and Technology and Prof. G. Ungar in University of Sheffield)

Selected papers on this subject:

1. Induction of Thermotropic Bicontinuous Cubic Phases in Liquid-Crystalline Ammonium and Phosphonium Salts
   Takahiro Ichikawa, Masafumi Yoshio, Atsushi Hamasaki, Satomi Taguchi, Feng Liu, Xiang-bing Zeng, Goran Ungar, Hiroyuki Ohno, and Takashi Kato
   J. Am. Chem. Soc., 134, 2634 (2012)
2. Self-Organization of Room-Temperature Ionic Liquids Exhibiting Liquid-Crystalline Bicontinuous Cubic Phases: Formation of Nano-Ion Channel Networks
   Takahiro Ichikawa, Masafumi Yoshio, Atsushi Hamasaki, Tomohiro Mukai, Hiroyuki Ohno, and Takashi Kato
   J. Am. Chem. Soc., 129, 10662 (2007)

Selected papers on this subject:

1. Nano-Segregated Polymeric Film Exhibiting High Ionic Conductivities
   Kenji Kishimoto, Tomoyuki Suzawa, Tomoki Yokota, Tomohiro Mukai, Hiroyuki Ohno, and Takashi Kato
   J. Am. Chem. Soc., 127, 15618 (2005).
2. Nanostructured Anisotropic Ion-Conductive Films
   K. Kishimoto, M. Yoshio, T. Mukai, M. Yoshizawa, H. Ohno, and T. Kato
   J. Am. Chem. Soc., 125, 3196 (2003).

6-3) Development of Columnar Liquid-Crystalline π-Conjugated Molecules

We have succeeded in the preparation of liquid-crystalline oligothiophenes that self-assemble into one-dimensional columnar stacks.

Selected papers on this subject:

1. Columnar Liquid Crystalline π-Conjugated Oligothiophenes
   Takuma Yasuda, Kenji Kishimoto, and Takashi Kato
   Chem. Commun., 2006, 3399.
2. Oligothiophene-Based Liquid Crystals Exhibiting Smectic A Phases in Wider Temperature Ranges
   Masaomi Kimura, Takuma Yasuda, Kenji Kishimoto, Günther Götz, Peter Bäuerle, and Takashi Kato
   Chem. Lett., 35, 1150 (2006).

A stimuli-responsive liquid crystal showing the change of the photoluminescent color on the shear-induced liquid-crystalline phase transition has been developed. A pyrene derivative having amide groups and dendritic side chains shows a micellar cubic phase. In this cubic phase, the compound exhibits yellow photoluminescence arising from the excimer formation of luminescent cores. By mechanical shearing for the compound in the cubic phase, a shear-induced cubic-columnar liquid-crystalline phase transition occurs, leading to the change of the photoluminescent color from yellow to blue-green. Such stimuli-responsive liquid crystals are promising candidates for sensing devices or memories.

Selected papers on this subject:

1. Guanine-Oligothiophene Conjugates: Liquid-Crystalline Properties, Photoconductivities and Ion-Responsive Emission of Their Nanoscale Assemblies
   Kian Ping Gan, Masafumi Yoshio, Yuki Sugihara and Takashi Kato
   Chem. Sci., 9, 576-585 (2018)
2. Tuning of Luminescence Color of p-conjugated Liquid Crystals through Co-Assembly with Ionic Liquids
   Masato Mitani, Masafumi Yoshio and Takashi Kato
   J. Mater. Chem. C, 5, 9972-9978 (2017).
3. Brightly Tricolored Mechanochromic Luminescence from a Single-Luminophore Liquid Crystal: Reversible Writing and Erasing of Images
   Yoshimitsu Sagara and Takashi Kato
   Angew. Chem. Int. Ed., 50, 9128 (2011).
4. Mechanically Induced Luminescence Changes in Molecular Assemblies
   Yoshimitsu Sagara and Takashi Kato
   Nature Chemistry, 1, 605 (2009).
5. Stimuli-Responsive Luminescent Liquid Crystals: Change of Photoluminescent Colors Triggered by a Shear-Induced Phase Transition
   Yoshimitsu Sagara and Takashi Kato
   Angew. Chem. Int. Ed., 47, 5175 (2008).

We have prepared tripodal ionic liquid crystals by introducing electron-donating parts into electron-accepting cationic parts. These ionic liquid crystals exhibit photoluminescence, and the emission colors cover visible region simply by changing electron-donating and/or accepting characters.
(collaboration with Prof. M. Hasegawa, Dept. of Chemistry and Biological Science, Aoyama Gakuin Univ.)

Selected papers on this subject:

1. Full-Color Tunable Photoluminescent Ionic Liquid Crystals Based on Tripodal Pyridinium, Pyrimidinium, and Quinolinium Salts
   Kana Tanabe, Yuko Suzui, Miki Hasegawa, and Takashi Kato
   J. Am. Chem. Soc., 134, 5652-5661 (2012).
2. Luminescent Ionic Liquid Crystals Based on Tripodal Pyridinium Salts
   Kana Tanabe, Takuma Yasuda, and Takashi Kato
   Chem. Lett., 37, 1208 (2008).

Aligned electroactive fibers have been formed by anisotropic self-assembly of hydrogen-bonded amino acid derivatives having tetrathiafulvalene (TTF) moieties in liquid crystals. After iodine doping, the self-assembled fibers exhibit electronic conductivity.

(collaboration with Prof. K. Ito, Graduate School of Frontier Sciences, The Univ. Tokyo)

A series of amino acid derivatives having photoconductive carbazole moieties are synthesized. Aligned fibers are formed via anisotropic self-assembly of the hydrogen-bonded molecules in liquid crystals. These aligned fibers are expected to show anisotropic opto- and electronic functions.

Selected papers on this subject:

1. Electroactive Supramolecular Self-Assembled Fibers Comprised of Doped Tetrathiafulvalene-Based Gelators
   Tetsu Kitamura, Suguru Nakaso, Norihiro Mizoshita, Yusuke Tochigi, Takeshi Shimomura, Masaya Moriyama, Kohzo Ito, and Takashi Kato
   J. Am. Chem. Soc., 127, 14769 (2005).
2. Self-Assembly of Carbazole-Containing Gelators: Alignment of the Chromophore in Fibrous Aggregates
   Kazuhiro Yabuuchi, Yusuke Tochigi, Norihiro Mizoshita, Kenji Hanabusa, and Takashi Kato
   Tetrahedron, 63, 7358 (2007).
3. Liquid-Crystalline Physical Gels
   Takashi Kato, Yuki Hirai, Suguru Nakaso, and Masaya Moriyama
   Chem. Soc. Rev., 36, 1857 (2007).

6-7) Development of Redox-Active Liquid Crystals

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