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