Discs, dumbbells and superdiscs: molecular and supermolecular architecture dependent magnetic behavior of mesogenic Blatter radical derivatives
| Autor: | Damian Pociecha, Marcin Jasiński, Piotr Kaszynski, Jacek Szczytko, Szymon Kapuściński |
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| Rok vydání: | 2021 |
| Předmět: |
Materials science
010405 organic chemistry Mesogen Intermolecular force Exchange interaction 010402 general chemistry 01 natural sciences 0104 chemical sciences law.invention SQUID Crystallography Ferromagnetism law Phase (matter) Materials Chemistry General Materials Science Dumbbell Electron paramagnetic resonance |
| Zdroj: | Materials Chemistry Frontiers. 5:6512-6521 |
| ISSN: | 2052-1537 |
| DOI: | 10.1039/d1qm00391g |
| Popis: | A series of isomeric supermolecular bi-and tri-radicals, in which “half disc” mesogens are connected 1,4- and 1,3,5-through benzene, respectively, are investigated for liquid crystalline (optical, thermal and powder XRD methods) and magnetic properties (SQUID and VT-EPR methods). The results demonstrate diverse phase structures of the bi- and tri-radicals, which self-organize into Colr, Colh, and Colh(3D) phases. Magnetic data revealed intermolecular ferromagnetic interactions in the solid-state only in bi- and tri-radicals with the connection at the C(3) position, for which the Weiss constant θ (7.8 and 5.2 K, respectively; from Curie–Weiss analysis) and J/kB exchange interaction energy (2.74 and 3.14 K, respectively; from Baker thermal expansion analysis) were obtained. Variable temperature EPR data demonstrated an increase of signal intensity in most liquid crystalline phases and continuous increase above the mesophase-isotropic liquid transition in two biradicals. Overall results indicate that the dumbbell shape (biradicals) and connection through the C(3) position are most favorable for mesogenic and non-trivial magnetic properties in the series. |
| Databáze: | OpenAIRE |
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