3 years ago

Structural Monitoring of the Onset of Excited-State Aromaticity in a Liquid Crystal Phase

Structural Monitoring of the Onset of Excited-State Aromaticity in a Liquid Crystal Phase
Ken Onda, Masahiko Yoshimura, Yasuhiko Hayashi, Shigehiro Yamaguchi, Kazuhiro Mouri, Shohei Saito, R. J. Dwayne Miller, Mitsuo Hara, Yasuteru Shigeta, Sei’ichi Tanaka, Kyohei Matsuo, Ryuma Sato, Fynn Röhricht, Rainer Herges, Masaki Hada
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.

Publisher URL: http://dx.doi.org/10.1021/jacs.7b08021

DOI: 10.1021/jacs.7b08021

You might also like
Never Miss Important Research

Researcher is an app designed by academics, for academics. Create a personalised feed in two minutes.
Choose from over 15,000 academics journals covering ten research areas then let Researcher deliver you papers tailored to your interests each day.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.