209673-74-5Relevant articles and documents
New pyridine based liquid crystalline esters with different terminal chains
Karanl?k, Gürkan,Ocak, Hale,Bilgin Eran, Belk?z
, (2019)
The synthesis, structural and mesomorphic characterization of new pyridine-based methyl esters carrying a n-alkoxy chain or 3,7-Dimethyloctyloxy branched group at terminal have been presented. The liquid crystalline properties of the new pyridine-based calamitic molecules have been investigated by polarized optical microscopy and differential scanning calorimetry. New compounds exhibit enantiotropic smectic A mesophase at a variable mesomorphic range depending on alkoxy chain length and branching at terminal. The presence of a branched terminal group in chiral or racemic form gives rise to a sharply increase in mesomorphic range as well as decrease in crystallization points by preserving mesophase type.
Tuning the optical and electronic properties of 4,8-disubstituted benzobisoxazoles via alkyne substitution
Tlach, Brian C.,Tomlinson, Aimee L.,Bhuwalka, Achala,Jeffries-El, Malika
experimental part, p. 8670 - 8681 (2011/12/22)
In an effort to design new electron-deficient building blocks for the synthesis of conjugated materials, a series of new trans-benzobisoxazoles bearing halogen or alkynyl substituents at the 4,8-positions was synthesized. Additionally, the impact of these modifications on the optical and electronic properties was investigated. Theoretical calculations predicted that the incorporation of various alkynes can be used to tune the energy levels and band gaps of these small molecules. The targeted 4,8-disubstituted benzobisoxazoles were easily prepared in good yields using a two-step reaction sequence: Lewis acid catalyzed orthoester cyclization followed by Sonogashira cross-coupling. The experimentally determined HOMO values for these 4,8-disubstituted benzobisoxazoles ranged from -4.97 to -6.20 eV and showed reasonable correlation to the theoretically predicted values, with a percent deviation that ranged from 2.4-12.8%. However, the deviation between actual and predicted HOMO values was reduced to less than 3.5% when the theoretical values were extrapolated to the long-chain limit and compared to copolymers containing the 4,8-disubstituted benzobisoxazoles. Collectively, these results indicate that these 4,8-disubstituted trans-benzobisoxazoles can be used for the synthesis of new conjugated materials with electronic properties that are variable and predictable.
Room-temperature discotic nematic liquid crystals
Kumar, Sandeep,Varshney, Sanjay Kumar,Chauhan, Diwakar
, p. 241 - 250 (2007/10/03)
The use of discotic nematic liquid crystals instead of calamitic nematic liquid crystals to improve the viewing angle of a liquid crystal display device has recently been reported. Compared to the large number of calamitic molecules showing nematic phase at room temperature, the number of disk-shaped molecules showing subambient discotic nematic phase ND are rare. In this paper we present the design, synthesis, mesomorphic behaviour and structureproperty relationship of discotic nematic liquid crystals based on benzene multiyne core.
