TY - JOUR
T1 - Structural Monitoring of the Onset of Excited-State Aromaticity in a Liquid Crystal Phase
AU - Hada, Masaki
AU - Saito, Shohei
AU - Tanaka, Sei'Ichi
AU - Sato, Ryuma
AU - Yoshimura, Masahiko
AU - Mouri, Kazuhiro
AU - Matsuo, Kyohei
AU - Yamaguchi, Shigehiro
AU - Hara, Mitsuo
AU - Hayashi, Yasuhiko
AU - Röhricht, Fynn
AU - Herges, Rainer
AU - Shigeta, Yasuteru
AU - Onda, Ken
AU - Miller, R. J.Dwayne
N1 - Funding Information:
We thank Prof. Takashi Kato at the University of Tokyo, Prof. Yoshiaki Uchida at Osaka University, Prof. Shin-ya Koshihara at Tokyo Institute of Technology for valuable discussions, Dr. Sercan Keskin at the University of Hamburg for the measurement of static electron diffraction, and Dr. Yumi Nakaike for the measurement of DSC. This work was funded by Japan Science Technology Agency (JST), PRESTO, Grant numbers: JPMJPR13KD, JPMJPR12K5, JPMJPR16P6. JSPS KAKENHI, Grant Numbers: JP15H02103, JP17K17893, JP15H05482, JP17H05258, JP26107004. JP17H06375.
Publisher Copyright:
© 2017 American Chemical Society.
PY - 2017/11/8
Y1 - 2017/11/8
N2 - Aromaticity of photoexcited molecules is an important concept in organic chemistry. Its theory, Baird's rule for triplet aromaticity since 1972 gives the rationale of photoinduced conformational changes and photochemical reactivities of cyclic π-conjugated systems. However, it is still challenging to monitor the dynamic structural change induced by the excited-state aromaticity, particularly in condensed materials. Here we report direct structural observation of a molecular motion and a subsequent packing deformation accompanied by the excited-state aromaticity. Photoactive liquid crystal (LC) molecules featuring a π-expanded cyclooctatetraene core unit are orientationally ordered but loosely packed in a columnar LC phase, and therefore a photoinduced conformational planarization by the excited-state aromaticity has been successfully observed by time-resolved electron diffractometry and vibrational spectroscopy. The structural change took place in the vicinity of excited molecules, producing a twisted stacking structure. A nanoscale torque driven by the excited-state aromaticity can be used as the working mechanism of new photoresponsive materials.
AB - Aromaticity of photoexcited molecules is an important concept in organic chemistry. Its theory, Baird's rule for triplet aromaticity since 1972 gives the rationale of photoinduced conformational changes and photochemical reactivities of cyclic π-conjugated systems. However, it is still challenging to monitor the dynamic structural change induced by the excited-state aromaticity, particularly in condensed materials. Here we report direct structural observation of a molecular motion and a subsequent packing deformation accompanied by the excited-state aromaticity. Photoactive liquid crystal (LC) molecules featuring a π-expanded cyclooctatetraene core unit are orientationally ordered but loosely packed in a columnar LC phase, and therefore a photoinduced conformational planarization by the excited-state aromaticity has been successfully observed by time-resolved electron diffractometry and vibrational spectroscopy. The structural change took place in the vicinity of excited molecules, producing a twisted stacking structure. A nanoscale torque driven by the excited-state aromaticity can be used as the working mechanism of new photoresponsive materials.
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U2 - 10.1021/jacs.7b08021
DO - 10.1021/jacs.7b08021
M3 - Article
C2 - 29037042
AN - SCOPUS:85033214299
SN - 0002-7863
VL - 139
SP - 15792
EP - 15800
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 44
ER -