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.
Polarization effect in luminescent mesogenic BF2 complexes derived from heterocyclic benzothiazoles
Hsu, Yuan?Chun,Wang, Chun?Yang,Hsiao, Pei?Chi,Cai, Yi-Hong,Lee, Gene?Hsiang,Lai, Chung K.
, (2019/12/09)
Two series of benzo(thia)xazoles 1–2 and one series of boron difluoride complexes 2-BF2 derived from benzothiazoles 2 were reported, and their mesomorphic and optical properties were investigated. The crystal and molecular structures of compound 2 and 2-BF2 (all n = 8) were determined by means of X?ray structural analysis, and both crystallize in the triclinic P-1 and monoclinic P21/c. The geometry at boron center is perfectly tetrahedral, and the overall molecular shapes are considered as rod?shape. Both benzo(thia)xazoles 1 and 2 exhibited N or/and SmC phase, and boron complexes 2-BF2 formed N or/and SmC phase. Benzothiazoles 2 showed a much wider temperature range of mesophase than those of benzoxazoles 1, which were attributed to the better polarization by sulfur atom incorporated. Boron complexes 2-BF2 (n = 10, 12) emitted a yellow?to?green emission at λmax = 569–571 nm in CH2Cl2. This is the first mesogenic BF2 complexes derived from benzothiazoles.
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.
