A02 Tomohiro Seki

Tomohiro Seki

Participating A02


Faculty of Engineering, Hokkaido University


Assistant professor



Research Project

Design of Versatile Stimuli-Responsive Materials and Luminescent Mechanochromism of Asymmetric Crystals


Hajime Ito (Professor, Faculty of Engineering, Hokkaido University)


Our group has studied luminescent mechanochromism of a series of gold isocyanide complexes. Luminescent mechanochromism is referred to as photoluminescence color changes of the solid/liquid crystal samples by mechanical stimulation such as grinding and pressing. These emission color changes are generally caused by molecular arrangement changes. In my study in the Asymmetry Coordination, I focus on the development of stimuli-responsive materials with novel chiral properties by using luminescent mechanochromic gold isocyanide complexes. Recently, we found that several gold isocyanide complexes exhibited luminescent mechanochromism involving the phase transition from viscous oil (an amorphous phase) to a chiral crystal (P212121), and then to an achiral crystal (P-1). We also found that this mechanochromism accompanied with on-off switching of circular dichroism spectral activity. In this research, we tried to further develop a novel chiral mechanochromic material.

Research Areas

Functional Material Chemistry, Photochemistry, Organic Chemistry


Luminescent mechanochromism; Phase transition; Photoluminescence; Chiral optical property


[30] Thermosalience in Macrocycle-Based Soft Crystals via Anisotropic Deformation of Disilanyl Architecture,
Kenichiro Omoto; Toyotaka Nakae; Masaki Nishio; Yoshinori Yamanoi; Hidetaka Kasai; Eiji Nishibori; Takaki Mashimo; Tomohiro Seki; Hajime Ito; Kazuki Nakamura; Norihisa Kobayashi; Naofumi Nakayama; Hitoshi Goto; Hiroshi Nishihara, J. Am. Chem. Soc., 142, 12651 - 12657, 2020
DOI: 10.1021/jacs.0c03643.
[29] Hydrogen Bond-Directed Supramolecular Polymorphism Leading to Soft and Hard Molecular Ordering,
Takumi Aizawa; Keisuke Aratsu; Sougata Datta; Takaki Mashimo; Tomohiro Seki; Takashi Kajitani; Fabien Silly; Shiki Yagai, Chem. Commun., 56, 4280 - 4283, 2020
DOI: 10.1039/D0CC01636E.
[28] Photoluminescent Ferroelastic Molecular Crystals,
Tomohiro Seki; Chi Feng; Kentaro Kashiyama; Shunichi Sakamoto; Yuichi Takasaki; Toshiyuki Sasaki; Satoshi Takamizawa; Hajime Ito, Angew. Chem. Int. Ed., 59, 23, 8839 - 8843, 2020
DOI: 10.1002/anie.201914610.
[27] Synthesis and Tunable Optical Properties of C,N‐Chelated Borate Luminophores Derived from Potassium Acyltrifluoroborates,
Jumpei Taguchi ; Satsuki Matsuura; Tomohiro Seki; Hajime Ito, Chem. Eur. J., 26, 2450 - 2455, 2020
DOI: 10.1002/chem.201904983.
[26] Mixed Crystal Formation of Two Gold Isocyanide Complexes with Various Ratios for Continuous Tuning of Photophysical Properties,
Tomohiro Seki; Naoki Toyoshima; Hajime Ito, Dalton Trans., 49, 2073 - 2076, 2020
DOI: 10.1039/D0DT00195C.
[25] Crystal Jumping of Simple Hydrocarbons: Cooling-Induced Salient Effect of Bis-, Tri-, and Tetraphenylethene through Anisotropic Lattice Dimension Changes without Thermal Phase Transitions,
Tomohiro Seki; Takaki Mashimo; Hajime Ito, Chem. Lett., 49, 174 - 177, 2020
DOI: 10.1246/cl.190768.
[24] Aurophilicity-Mediated Construction of Emissive Porous Molecular Crystals as Versatile Hosts for Liquid and Solid Guests,
Tomohiro Seki; Kentaro Ida; Hiroyasu Sato; Shinji Aono; Shigeyoshi Sakaki; Hajime Ito, Chem. Eur. J., 13, 735 - 744, 2020
DOI: 10.1002/chem.201904597.


[23] Anisotropic Thermal Expansion as the Source of Macroscopic and Molecular Scale Motion in Phosphorescent Amphidynamic Crystals,
Mingoo Jin; Sho Yamamoto; Tomohiro Seki; Hajime Ito; Miguel A. Garcia‐Garibay, Angew. Chem. Int. Ed., 58, 18003 - 18010, 2019
DOI: 10.1002/anie.201909048.
[22] The Direct Dimesitylborylation of Benzofuran Derivatives via an Iridium-Catalyzed C–H Activation with Silyldimesitylborane,
Ryosuke shishido; Ikuo Sasaki; Tomohiro Seki; Tatsuo Ishiyama; Hajime Ito, Chem. Eur. J., 25, 12924 - 12928, 2019
DOI: 10.1002/chem.201903776.
[21] Luminescent Mechanochromism of Gold N-Heterocyclic Carbene Complexes with Hypso- and Bathochromic Spectral Shifts,
Tomohiro Seki; Kentaro Kashiyama; Hajime Ito, Dalton Trans., 48, 7105 - 7109, 2019
DOI: 10.1039/C9DT00566H.
[20] Anisotropic Strain Release in a Thermosalient Crystal: Correlation between the Microscopic Orientation of Molecular Rearrangements and the Macroscopic Mechanical Motion,
Tomohiro Seki; Takaki Mashimo; Hajime Ito, Chem. Sci., 10, 4185 - 4191, 2019
DOI: 10.1039/C8SC05563G.
[19] Dependence of Absorption and Emission Spectra on Polymorphs of Gold(I) Isocyanide Complexes: Theoretical Study with QM/MM Approach,
Shinji Aono; Tomohiro Seki; Hajime Ito; Shigeyoshi Sakaki, J. Phys. Chem. C, 123, 4773 - 4794, 2019
DOI: 10.1021/acs.jpcc.8b10602.


[18] Synthesis and Evaluation of 1,3a,6a-Triazapentalene (TAP)-Bonded System,
Masami Ito; Akane Mera; Takaki Mashimo; Tomohiro Seki; Sangita Karanjit; Eisaku Ohashi; Atsushi Nakayama; Kei Kitamura; Toshiyuki Hamura; Hajime Ito; Kosuke Namba, Chem. Eur. J., 24, 17727 - 17733, 2018
DOI: 10.1002/chem.201804733.
[17] Structural Modulation of Luminescent Lanthanide Coordination Polymers by Side-Group Alternation,
Yuichi Hirai; Pedro Paulo Ferreira da Rosa; Takayuki Nakanishi; Yuichi Kitagawa; Koji Fushimi; Tomohiro Seki; Hajime Ito; Yasuchika Hasegawa, Inorg. Chem., 57, 14653 - 14659, 2018
DOI: 10.1021/acs.inorgchem.8b02367.
[16] A Gold Isocyanide Complex with a Pendant Carboxy Group: Orthogonal Molecular Arrangements and Hypsochromically Shifted Luminescent Mechanochromism,
Tomohiro Seki; Koh Kobayashi; Takaki Mashimo; Hajime Ito, Chem. Commun., 54, 11136 - 11139, 2018
DOI: 10.1039/C8CC06490C.
[15] Spiral Eu(III) Coordination Polymers with Circularly Polarized Luminescence,
Yasuchika Hasegawa; Yui Miura; Yuichi Kitagawa; Satoshi Wada; Takayuki Nakanishi; Koji Fushimi; Tomohiro Seki; Hajime Ito; Takeshi Iwasa; Tetsuya Taketsugu; Masayuki Gon; Yoshiki Chujo; Shingo Hattori; Masanobu Karasawa; Kazuyuki Ishii, Chem. Commun., 54, 10695 - 10697, 2018
DOI: 10.1039/C8CC05147J.
[14] Light-Regulated Crystal Growth of π-Conjugated Luminophores in an Azobenzene Matrix,
Takuji Kobayashi; Yuichi Kitamoto; Yu Hirai; Takashi Kajitani; Tomohiro Seki; Shiki Yagai, Commun. Chem., 1, 58, 2018
DOI: 10.1038/s42004-018-0061-8.
[13] A meta-Diisocyanide Benzene-Based Aryl Gold Isocyanide Complex Exhibiting Multiple Solid-State Molecular Arrangements and Luminescent Mechanochromism,
Tomohiro Seki; Kentaro Ida; Hajime Ito, Mater. Chem. Front., 2, 1195 - 1200, 2018
DOI: 10.1039/C8QM00074C.
[12] Thermo‐sensitive luminophores using seven‐coordinate TbIII complexes based on LLCT transition,
Pedro Paulo Ferreira da Rosa; Takayuki Nakanishi; Yuichi Kitagawa; Tomohiro Seki; Hajime Ito; Koji Fushimi; Yasuchika Hasegawa, Eur. J. Inog. Chem., 2031 - 2037, 2018
DOI: 10.1002/ejic.201800281.
[11] Mechanical-Stimulation-Triggered and Solvent-Vapor-Induced Reverse Single-Crystal-to-Single-Crystal Phase Transitions with Alterations of the Luminescence Color,
Mingoo Jin; Toshiki Sumitani; Hiroyasu Sato; Tomohiro Seki; Hajime Ito, J. Am. Chem. Soc., 140, 8, 2875 - 2879, 2018
DOI: 10.1021/jacs.7b12455.
[10] A Luminescent Dinuclear EuIII/TbIII Complex with LMCT Band for Single-Molecular Thermosensor,
Kei Yanagisawa; Yuichi Kitagawa; Takayuki Nakanishi; Tomohiro Seki; Koji Fushimi; Hajime Ito; Yasuchika Hasegawa, Chem. Eur. J., 24, 1956 - 1961, 2018
DOI: 10.1002/chem.201705021.
[9] Origin of Concentration Quenching in Ytterbium Coordination Polymers: Phonon-Assisted Energy Transfer,
Shun Omagari; Takashi Nakanishi; Yuichi Hirai; Yuichi Kitagawa; Tomohiro Seki; Koji Fushimi; Hajime Ito; Yasuchika Hasegawa, Eur. J. Inog. Chem., 561 - 567, 2018
DOI: 10.1002/ejic.201701040.


[8] Phosphorescence Control Mediated by Molecular Rotation and Aurophilic Interactions in Amphidynamic Crystals of 1,4-bis[tri-(p-fluorophenyl)phosphane-gold(I)-ethynyl]benzene,
Mingoo Jin; Tim S Chung; Tomohiro Seki; Hajime Ito; Miguel A. Garcia-Garibay, J. Am. Chem. Soc., 139, 18115 - 18121, 2017
DOI: 10.1021/jacs.7b11316.
[7] Synthesis and Photophysical Properties of Eu(III) Complexes with Phosphine Oxide ligands Including Metal Ions,
Masanori Yamamoto; Takayuki Nakanishi; Yuichi Kitagawa; Tomohiro Seki; Hajime Ito; Koji Fushimi; Yasuchika Hasegawa, Bull. Chem. Soc. Jpn., 91, 6 - 11, 2017
DOI: 10.1246/bcsj.20170241.
[6] Tuning the Lifetime of Transient Phases of Mechanochromic Gold Isocyanide Complexes through Functionalization of the Terminal Moieties of Flexible Side Chains,
Tomohiro Seki; Kentaro Kashiyama; Shiki Yagai; Hajime Ito, Chem. Lett., 46, 1415 - 1418, 2017
DOI: 10.1246/cl.170482.
[5] Enhanced Luminescence of Asymmetrical Seven-Coordinate EuNaIII Complexes Including LMCT Perturbation,
Kei Yanagisawa; Yuichi Kitagawa; Takayuki Nakanishi; Tomoko Akama; Masato Kobayashi; Tomohiro Seki; Koji Hushimi; Hajime Ito; Tetsuya Taketsugu; Yasuchika Hasegawa, Eur. J. Inog. Chem., 2017, 3843 - 3848, 2017
DOI: 10.1002/ejic.201700815.
[4] Low-Temperature-Selective Luminescent Mechanochromism of a Thienyl Gold Isocyanide Complex,
Tomohiro Seki; Koh Kobayashi; Hajime Ito, Chem. Commun., 53, 6700 - 6703, 2017
DOI: 10.1039/c7cc03190d.
[3] Triboluminescence of Lanthanide Coordination Polymers with Face-to-Face Arranged Substituents,
Yuichi Hirai; Takayuki Nakanishi; Yuichi Kitagawa; Koji Fushimi; Tomohiro Seki; Hajime Ito; Yasuchika Hasegawa, Angew. Chem. Int. Ed., 56, 40, 7171 - 7175, 2017
DOI: 10.1002/anie.201703638.
[2] Mechano-Responsive Luminescence via Crystal-to-Crystal Phase Transitions between Chiral and Non-Chiral Space Groups,
Mingoo Jin; Tomohiro Seki; Hajime Ito, J. Am. Chem. Soc., 139, 19, 7452 - 7455, 2017
DOI: 10.1021/jacs.7b04073.
[1] Luminescent Mechanochromic 9‑Anthryl Gold(I) Isocyanide Complex with an Emission Maximum at 900 nm after Mechanical Stimulation,
Tomohiro Seki; Noriaki Tokodai; Shun Omagari; Takayuki Nakanishi; Yasuchika Hasegawa; Takeshi Iwasa; Tetsuya Taketsugu; Hajime Ito , J. Am. Chem. Soc., 139, 19, 6514 - 6517, 2017
DOI: 10.1021/jacs.7b00587.