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Arakawa, Y., Ishida, Y., Sasaki, Y., Sasaki, S., Tokita, M. & Tsuji, H. (2022) Alkylthio-based asymmetric liquid crystals: unravelling the substituent effects and intercalated cybotactic nematic and smectic phases. Mater. Adv. 
Added by: Richard Baschera (2022-03-25 10:58:41)   Last edited by: Richard Baschera (2022-03-25 11:00:50)
Type de référence: Article
DOI: 10.1039/D2MA00050D
Numéro d'identification (ISBN etc.): 2633-5409
Clé BibTeX: Arakawa2022a
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Créateurs: Arakawa, Ishida, Sasaki, Sasaki, Tokita, Tsuji
Collection: Mater. Adv.
Consultations : 17/291
Indice de consultation : 6%
Indice de popularité : 1.5%
Liens URLs     https://pubs.rsc.o ... 2022/ma/d2ma00050d
To reveal not only the effects of alkylthio groups but also an unknown layered smectic (Sm) phase formed by short-chain-based liquid crystals (LCs), a novel series of asymmetric 1,4-phenylene bis(benzoate)s possessing 4,4 '-alkylthio and alkoxy groups with various chain lengths (SOn, n = 1-8) was established. All members formed well-defined enantiotropic LC phases. The SOn homologs with n = 2-7 exhibited only a nematic (N) phase, and the longest SO8 showed an inclined smectic C (SmC) phase in addition to the N phase. Notably, the shortest SO1 formed an enantiotropic orthogonal smectic A (SmA) phase as well as the N phase. The primary effects of the alkylthio and alkoxy groups were identified for each phase transition over varied chain lengths and through comparison with those of their symmetric alkoxy- and alkylthio-based counterparts (OOn and SSn, respectively). In addition, X-ray diffractometry unraveled surprising results, wherein the N and SmA phases of SO1 were found to possess a layer period that was half of the molecular length, thereby suggesting half-intercalation of the intermolecular cores. These phases are distinct from the conventional N and Sm phases without such core intercalation. The remarkable formation of half-intercalated LC phase was discussed based on plausible intermolecular interactions (e.g., multiple hydrogen bonds due to the presence of esters) implied by single-crystal structural analyses. Furthermore, the birefringence increased when replacing the alkoxy group with the more polarizable alkylthio group.
Publisher: RSC
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