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- Title
Thermally Activated Paramagnets from Diamagnetic Polymers of Biphenyl-3,5-diyl Bis(tert-butyl Nitroxides) Carrying Methyl and Fluoro Groups at the 2'- and 5'-Positions.
- Authors
Toru Yoshitake; Hiroki Kudo; Takayuki Ishida
- Abstract
Three new biradicals--2',5'-dimethyl-, 2'-fluoro-5'-methyl-, and 5'-fluoro-2'-methylbiphenyl- 3,5-diyl bis(tert-butyl nitroxides)--were synthesized. The magnetic susceptibility measurements revealed their diamagnetism below and around room temperature. The nitroxide groups are located close to each other in an intermolecular fashion to form a weakly covalent head-to-tail (NO)2 ring. Biradical molecules are connected on both radical sites, constructing a diamagnetic chain. The dimethyl derivative underwent a structural phase transition at 83 °C, clarified via differential scanning calorimetry and powder X-ray diffraction, and a paramagnetic solid phase with S = 1 irreversibly appeared. The other analogues exhibited a similar irreversible upsurge of the magnetic susceptibility on heating, but the transition was characterized as the melting.
- Subjects
NITROXIDES; BIRADICALS; INTERMOLECULAR interactions
- Publication
Crystals (2073-4352), 2016, Vol 6, Issue 3, p30
- ISSN
2073-4352
- Publication type
Article
- DOI
10.3390/cryst6030030