Semi-fluorinated p-terphenyl liquid crystals
| Autor: | Dámaso Navarro-Rodríguez, Moisés Alberto Valdés-Pech, Isaura Felix-Serrano, Nayely Trejo-Carbajal, Leticia Larios-López, Rosa Julia Rodríguez-González |
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| Rok vydání: | 2019 |
| Předmět: |
Diffraction
010405 organic chemistry Organic Chemistry chemistry.chemical_element Electroluminescence 010402 general chemistry Ring (chemistry) 01 natural sciences Biochemistry 0104 chemical sciences Inorganic Chemistry Crystallography symbols.namesake chemistry.chemical_compound chemistry Liquid crystal Stokes shift Terphenyl Phase (matter) symbols Fluorine Environmental Chemistry Physical and Theoretical Chemistry |
| Zdroj: | Journal of Fluorine Chemistry. 218:42-50 |
| ISSN: | 0022-1139 |
| Popis: | p-Terphenyls carrying two or four fluorine atoms in the central ring were synthesized via Suzuki-Miyaura cross-coupling reaction using phenylboronic acids and fluorinated dibromobenzenes. By calorimetric and X-ray diffraction analyses it was found that the p-terphenyls carrying two fluorine atoms develop nematic and/or smectic (A and C) phases. On the contrary, the p-terphenyls substituted with four fluorine atoms are not liquid crystals. Differences found in the thermal behavior are explained in terms π – πF interactions arising from the electron withdrawing ability of the fluorine atom. Such π – πF interactions let the p-terphenyls stack in a staggered configuration that explains the stability of the smectic C phase. On the other hand, the semi-fluorinated p-terphenyls absorb and emit in the blue region of the electromagnetic spectrum; a measured large Stokes shift indicates that these compounds are nearly transparent to their own emitted light. This optical characteristic, combined with liquid crystals properties of low order, makes these new p-terphenyls potential candidates for linearly polarized blue-emitting layers in electroluminescent devices. |
| Databáze: | OpenAIRE |
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