MSGID: 1:317/3 6430edf4
PID: hpt/lnx 1.9.0-cur 2019-01-08
TID: hpt/lnx 1.9.0-cur 2019-01-08
 Toward tunable molecular switches from organic compounds 

  Date:
      April 7, 2023
  Source:
      Hokkaido University
  Summary:
      Newly synthesized organic molecules can be tuned to emit different
      colors depending on their molecular structures in crystal form.


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FULL STORY
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Newly synthesized organic molecules can be tuned to emit different colors
depending on their molecular structures in crystal form.


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Molecular switches are chemicals with molecular structures that can
be shifted between two or more stable configurations in response
to changes in their environment. They are of great interest in the
development of molecular computers, molecular machines and drug delivery
systems. Compounds with conformational isomers -- identical molecular
formulas but different molecular structures -- can make very effective
molecular switches.

Researchers at Hokkaido University and Kyushu University have
developed a technique to synthesize potential molecular switches
from anthraquinodimethanes (AQDs), a group of overcrowded organic
molecules. The study, led by Associate Professor Yusuke Ishigaki at
Hokkaido University and Associate Professor Toshikazu Ono at Kyushu
University, was published in the journal Materials Chemistry Frontiers.

"AQDs are a type of overcrowded ethylene, molecules with carbon-carbon
double bonds surrounded by large chemical groups," explains Ono. "They
have two common isomers, the folded and twisted forms. They are especially
interesting as molecular switches, as their sterically hindered double
bond can provide isomers absorbing and emitting different wavelengths
of light."  AQDs generally adopt the most stable folded or twisted form,
making it difficult to isolate pure samples of any other isomer to study
its properties.

The researchers surmounted this obstacle by designing flexible AQD
derivatives that can more easily and stably form different isomers.

The synthesized derivatives were not only able to stably form twisted
and folded isomers, but also other isomeric forms, when recrystallized
in different solvents. The researchers performed detailed analysis of
the derivatives to fully understand their properties.

In a crystalline state, each of these isomers absorbs and emits distinct
frequencies of light, which is due to the differences in the distribution
of electrons in the isomer molecules. Interestingly, the light absorption
and emission changed when the crystals were ground into amorphous solid,
and following treatment with appropriate solvents can produce original
or other crystals with a variety of colors.

"This work is the first report on the isolation of multiple isomeric
forms of AQD," Ishigaki concluded. "Their absorption and emission
of different light frequencies, and more importantly, the ability to
modulate the absorption and emission by external stimuli, make these
compounds excellent candidates for the development of molecular switches."
    * RELATED_TOPICS
          o Matter_&_Energy
                # Chemistry # Organic_Chemistry # Materials_Science
                # Optics # Biochemistry # Nanotechnology #
                Inorganic_Chemistry # Engineering_and_Construction
    * RELATED_TERMS
          o Polymer o Chemistry o Nanowire o Amino_acid o Macromolecule
          o Supercooling o Crystal_structure o Organic_chemistry

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Story Source: Materials provided by Hokkaido_University. Note: Content
may be edited for style and length.


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Journal Reference:
   1. Kazuma Sugawara, Toshikazu Ono, Yoshio Yano, Takanori Suzuki, Yusuke
      Ishigaki. Exceptionally flexible quinodimethanes with multiple
      conformations: polymorph-dependent colour tone and emission of
      crystals.

      Materials Chemistry Frontiers, 2023; DOI: 10.1039/D2QM01199A
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Link to news story:
https://www.sciencedaily.com/releases/2023/04/230407094255.htm

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