Near‐room‐temperature π‐conjugated nematic liquid crystals in molecules with a flexible seven‐membered ring structure
Abstract Nematic liquid crystals (NLCs), that is, fluids with optical anisotropy as well as electric‐ and magnetic‐field responsiveness, have been widely used in commercial liquid crystal displays. Recent advancements have extended the scope of NLC molecules to large calamitic π‐conjugated systems,...
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Wiley
2025-01-01
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| Online Access: | https://doi.org/10.1002/agt2.660 |
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| author | Riki Iwai Hiroyuki Yoshida Yuki Arakawa Shunsuke Sasaki Yuuto Iida Kazunobu Igawa Tsuneaki Sakurai Satoshi Suzuki Masatoshi Tokita Junji Watanabe Gen‐ichi Konishi |
| author_facet | Riki Iwai Hiroyuki Yoshida Yuki Arakawa Shunsuke Sasaki Yuuto Iida Kazunobu Igawa Tsuneaki Sakurai Satoshi Suzuki Masatoshi Tokita Junji Watanabe Gen‐ichi Konishi |
| author_sort | Riki Iwai |
| collection | DOAJ |
| description | Abstract Nematic liquid crystals (NLCs), that is, fluids with optical anisotropy as well as electric‐ and magnetic‐field responsiveness, have been widely used in commercial liquid crystal displays. Recent advancements have extended the scope of NLC molecules to large calamitic π‐conjugated systems, which heralds prospects for novel applications that exploit their superior electronic or optical functionalities in, for example, electric field controlled fluorescence switch devices. However, NLC phases of such extended π‐systems usually flow only at high temperatures, which hampers device applications that operate around room temperature. Here, we show near‐room‐temperature NLCs of a π‐conjugated fluorophore by introducing a flexible cyclic structure into the mesogenic core. 3,8‐Bis(4‐propylphenyl)‐6,7‐dihydro‐5H‐benzo[7]annulene (DPB[7]‐C3) has a nematic phase in a significantly lower temperature range (52.6–160.4°C) than the DPB[7]‐C3 analog without flexible alkylene bridges, (E)‐4‐propyl‐4′‐(4‐propylstyryl)‐1,1′‐biphenyl (248–262°C). We attribute this large decrease in the phase transition temperature to large intramolecular conformational entropies that arise from the geometric change of the cyclic structure, which involves rotational motion of single biaryl‐bonds and bending motions along the long molecular axis in the thermal equilibrium state. The practical utility of these NLC molecules is demonstrated by preparing an electric‐field‐responsive large‐area fluorescent switch device with a sub‐millisecond response time from a mixture of 3,8‐bis(4‐alkylphenyl)‐6,7‐dihydro‐5H‐benzo[7]annulenes (DPB[7]‐Cns). |
| format | Article |
| id | doaj-art-7d3cb3c8959945eeadfd4d0f8bfdda30 |
| institution | Kabale University |
| issn | 2692-4560 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Wiley |
| record_format | Article |
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| spelling | doaj-art-7d3cb3c8959945eeadfd4d0f8bfdda302025-01-21T08:57:07ZengWileyAggregate2692-45602025-01-0161n/an/a10.1002/agt2.660Near‐room‐temperature π‐conjugated nematic liquid crystals in molecules with a flexible seven‐membered ring structureRiki Iwai0Hiroyuki Yoshida1Yuki Arakawa2Shunsuke Sasaki3Yuuto Iida4Kazunobu Igawa5Tsuneaki Sakurai6Satoshi Suzuki7Masatoshi Tokita8Junji Watanabe9Gen‐ichi Konishi10Department of Chemical Science and Engineering Tokyo Institute of Technology Meguro JapanSchool of Engineering Kwansei Gakuin University Sanda JapanDepartment of Applied Chemistry and Life Science Toyohashi University of Technology Toyohashi JapanInstitut des Matériaux de Nantes Jean Rouxel IMN Nantes Université CNRS Nantes FranceDepartment of Chemical Science and Engineering Tokyo Institute of Technology Meguro JapanDepartment of Chemistry Kumamoto University Kumamoto JapanFaculty of Molecular Chemistry and Engineering Kyoto Institute of Technology Kyoto JapanDepartment of Chemistry Kyushu University Fukuoka JapanDepartment of Chemical Science and Engineering Tokyo Institute of Technology Meguro JapanDepartment of Chemical Science and Engineering Tokyo Institute of Technology Meguro JapanDepartment of Chemical Science and Engineering Tokyo Institute of Technology Meguro JapanAbstract Nematic liquid crystals (NLCs), that is, fluids with optical anisotropy as well as electric‐ and magnetic‐field responsiveness, have been widely used in commercial liquid crystal displays. Recent advancements have extended the scope of NLC molecules to large calamitic π‐conjugated systems, which heralds prospects for novel applications that exploit their superior electronic or optical functionalities in, for example, electric field controlled fluorescence switch devices. However, NLC phases of such extended π‐systems usually flow only at high temperatures, which hampers device applications that operate around room temperature. Here, we show near‐room‐temperature NLCs of a π‐conjugated fluorophore by introducing a flexible cyclic structure into the mesogenic core. 3,8‐Bis(4‐propylphenyl)‐6,7‐dihydro‐5H‐benzo[7]annulene (DPB[7]‐C3) has a nematic phase in a significantly lower temperature range (52.6–160.4°C) than the DPB[7]‐C3 analog without flexible alkylene bridges, (E)‐4‐propyl‐4′‐(4‐propylstyryl)‐1,1′‐biphenyl (248–262°C). We attribute this large decrease in the phase transition temperature to large intramolecular conformational entropies that arise from the geometric change of the cyclic structure, which involves rotational motion of single biaryl‐bonds and bending motions along the long molecular axis in the thermal equilibrium state. The practical utility of these NLC molecules is demonstrated by preparing an electric‐field‐responsive large‐area fluorescent switch device with a sub‐millisecond response time from a mixture of 3,8‐bis(4‐alkylphenyl)‐6,7‐dihydro‐5H‐benzo[7]annulenes (DPB[7]‐Cns).https://doi.org/10.1002/agt2.660aggregation‐induced emissionfluorescenceliquid crystalstimuli‐responsive materialsπ‐conjugated molecules |
| spellingShingle | Riki Iwai Hiroyuki Yoshida Yuki Arakawa Shunsuke Sasaki Yuuto Iida Kazunobu Igawa Tsuneaki Sakurai Satoshi Suzuki Masatoshi Tokita Junji Watanabe Gen‐ichi Konishi Near‐room‐temperature π‐conjugated nematic liquid crystals in molecules with a flexible seven‐membered ring structure Aggregate aggregation‐induced emission fluorescence liquid crystal stimuli‐responsive materials π‐conjugated molecules |
| title | Near‐room‐temperature π‐conjugated nematic liquid crystals in molecules with a flexible seven‐membered ring structure |
| title_full | Near‐room‐temperature π‐conjugated nematic liquid crystals in molecules with a flexible seven‐membered ring structure |
| title_fullStr | Near‐room‐temperature π‐conjugated nematic liquid crystals in molecules with a flexible seven‐membered ring structure |
| title_full_unstemmed | Near‐room‐temperature π‐conjugated nematic liquid crystals in molecules with a flexible seven‐membered ring structure |
| title_short | Near‐room‐temperature π‐conjugated nematic liquid crystals in molecules with a flexible seven‐membered ring structure |
| title_sort | near room temperature π conjugated nematic liquid crystals in molecules with a flexible seven membered ring structure |
| topic | aggregation‐induced emission fluorescence liquid crystal stimuli‐responsive materials π‐conjugated molecules |
| url | https://doi.org/10.1002/agt2.660 |
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