Intermediate-paramagnetic phases with a half and a quarter spin entities in fluorinated biphenyl-3,5-diyl bis(tert-butyl nitroxides)
作者： Takuya Konno , Hiroki Kudo , Takayuki Ishida
DOI: 10.1039/C5TC00668F
关键词: Spin transition 、 Paramagnetism 、 Materials science 、 Stereochemistry 、 Phase (matter) 、 Spins 、 Intermolecular force 、 Nitroxide mediated radical polymerization 、 Crystallography 、 Biphenyl 、 Derivative (chemistry)
摘要: A new ground-triplet biradical, 2′,5′-difluorobiphenyl-3,5-diyl bis(tert-butyl nitroxide), showed spin-transition-like behaviour at TC↑ = 182 K and TC↓ 181 K. This compound had a quarter of the nominal amount paramagnetic spins in low-temperature phase half high-temperature phase. Another 3′-monofluoro derivative maintained as single solid phase, which is isomorphous to difluoro analogue. During spin transition, reversible bond formation–cleavage between nitrogen oxygen atoms takes place neighbouring nitroxide groups an intermolecular fashion. These intermediate states emerge during multi-step transition from unsymmetrical biradicals designed.
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