39905-45-8Relevant articles and documents
[1,2,3]-triazole derivatives: Mesomorphic property dependence on the molecular shape
Benallou, Souria,Saidi-Besbes, Salima,Grelet, Eric,Bentaleb, Ahmed
, p. 290 - 298 (2017)
Nowadays, heterocyclic units have been extensively studied for the preparation of thermotropic liquid crystals due to their ability to impart lateral and/or longitudinal dipoles and induce changes in molecular shape. Key parameters to accede to stable mesophases are the position of the heterocycle and the nature of terminal and linking functions. We present in this paper, an overview of several series of 1,2,3-triazole liquid crystalline derivatives that we designed and characterized. We highlight the effect of different connecting functions and the geometry of mesogenic core on the mesomorphic behavior of these derivatives.
New long-chain donor-acceptor-donor pyromellitic diimide (PMDI) derivatives. A combined theoretical and experimental study
Dal-Bó, Alexandre Gon?alves,da Costa Duarte, Rodrigo,Cercená, Rodrigo,Peterson, Michael,Rafique, Jamal,Saba, Sumbal,Zapp, Eduardo,Gil, Eduarda Sangiogo,Bruno Gon?alves, Paulo Fernando,Rodembusch, Fabiano Severo,Frizon, Tiago Elias Allievi
, p. 143 - 150 (2018)
This study involves the electrochemical, thermal and photophysical profiling of new pyromellitic diimide (PMDI) derivatives containing alkyl chains of different sizes. The photophysical investigation shows that all compounds exhibited absorption in the UV-B region (~290 nm). The band-gaps were calculated by onset peak values of around 4.03 eV. The compounds are photoactive in the UV-A region (312–328 nm) with a small solvatochromic effect in the excited state (Δλem = 16 nm). The electrochemical studies revealed that the reduction of the bisimide moiety showed two waves due to the formation of both the radical anion and a dianion. On the other hand, oxidation showed two waves due to the formation of radical cations and dications. The thermal properties were measured by differential thermal analysis (DTA) and thermogravimetric analysis (TGA), and the materials showed high thermal stability (Td > 300 °C). Theoretical calculations were also performed to study the geometry and charge distribution of these compounds in their ground and excited electronic states. No significant changes in the absorption and emission maxima were found by changing the solvent or substituents attached to the PMDI structure.
Chiral polymorphism in new imine based rod-like liquid crystals
?a?lar, Fatma P?nar,Akda?-K?l??, Huriye,Eran, Belk?z Bilgin,Ocak, Hale
, (2020/07/06)
New imine based rod-like compounds, composed of three-benzene-ring molecular core linked with azomethine as well as ester groups and terminated with (S)-3,7-dimethyloctyloxy chiral unit at one side have been synthesized. The other terminal position has been varied by using n-octyloxy/decyloxy/dodecyloxy groups to reveal chain length effect on mesophase behavior. The liquid crystalline properties of the new compounds have been investigated by polarizing optical microscopy, differential scanning calorimetry and electro-optic studies. The novel chiral calamitics derived from Schiff base or salicylaldimine-core show a chiral polymorphism comprising of blue phase and chiral nematic as well as smectics such as chiral tilted smectic and unidentified smectic mesophase.
Thermotropic Liquid-Crystalline and Light-Emitting Properties of Bis(4-aalkoxyphenyl) Viologen Bis(triflimide) Salts
Agra-Kooijman, De?a M.,Al-Karawi, Muhammed Kareem M.,Bhowmik, Pradip K.,Chang, Anthony,Chen, Si L.,Cortez, Raymond G.,Dizon, Erenz J.,Fisch, Michael R.,Gutierrez, Bryan,Han, Haesook,Ho, Andy,Killarney, Shane T.,Kim, Jongin,Kumar, Satyendra,Mandal, Hari D.,Mendez, Klarissa,Principe, Ronald Carlo G.,Sharpnack, Lewis
, (2020/05/29)
A series of bis(4-alkoxyphenyl) viologen bis(triflimide) salts with alkoxy chains of different lengths were synthesized by the metathesis reaction of respective bis(4-alkoxyphenyl) viologen dichloride salts, which were in turn prepared from the reaction of Zincke salt with the corresponding 4-n-alkoxyanilines, with lithium triflimide in methanol. Their chemical structures were characterized by 1H and 13C nuclear magnetic resonance spectra and elemental analysis. Their thermotropic liquid-crystalline (LC) properties were examined by differential scanning calorimetry, polarizing optical microscopy, and variable temperature X-ray diffraction. Salts with short length alkoxy chains had crystal-to-liquid transitions. Salts of intermediate length alkoxy chains showed both crystal-to-smectic A (SmA) transitions, Tms, and SmA-to-isotropic transitions, Tis. Those with longer length of alkoxy chains had relatively low Tms at which they formed the SmA phases that persisted up to the decomposition at high temperatures. As expected, all of them had excellent thermal stabilities in the temperature range of 330-370 ?C. Their light-emitting properties in methanol were also included.