TY - JOUR

T1 - Unique Superparamagnetic-like Behavior Observed in Non-π-delocalized Nitroxide Diradical Compounds Showing Discotic Liquid Crystalline Phase

AU - Takemoto, Yusa

AU - Zaytseva, Elena

AU - Suzuki, Katsuaki

AU - Yoshioka, Naoki

AU - Takanishi, Yoichi

AU - Funahashi, Masahiro

AU - Uchida, Yoshiaki

AU - Akita, Takuya

AU - Park, Jayeong

AU - Sato, Shuichi

AU - Clevers, Simon

AU - Coquerel, Gérard

AU - Mazhukin, Dmitrii G.

AU - Shimono, Satoshi

AU - Sugiyama, Masahito

AU - Takahashi, Hiroki

AU - Yamauchi, Jun

AU - Tamura, Rui

N1 - Publisher Copyright: © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

PY - 2018/11/22

Y1 - 2018/11/22

N2 - A unique superparamagnetic-like behavior and a large “positive magneto-LC effect” were observed in the solid phases and the hexagonal columnar (Colh) liquid crystalline (LC) phase, respectively, of novel achiral non-π-delocalized nitroxide diradical compounds (R,S)-1, which showed polymorphism in the solid phases (solids I and II). The SQUID magnetization measurement revealed that (1) (R,S)-1 containing a small amount of racemic diastereomers (R*,R*)-1 possessed an unusual and large temperature-independent magnetic susceptibility (χTIM>0) component in the original nanocrystalline solid I that was responsible for the observed superparamagnetic-like behavior under low magnetic fields and did not arise from the contamination by extrinsic magnetic metal or metal ion impurities, besides ordinary temperature-dependent paramagnetic susceptibility (χpara>0) and temperature-independent diamagnetic susceptibility (χdia<0) components, (2) a large increase in molar magnetic susceptibility (χM) (positive magneto-LC effect) that occurred at the solid I-to-liquid crystal transition upon heating was preserved as an additional χTIM increase in the resulting polymorphic nanocrystalline solid II by cooling, and (3) such unique magnetic phenomena were induced by thermal processing for (R,S)-1 or by adding a small amount of (R*,R*)-1 to (R,S)-1 as the impurity.

AB - A unique superparamagnetic-like behavior and a large “positive magneto-LC effect” were observed in the solid phases and the hexagonal columnar (Colh) liquid crystalline (LC) phase, respectively, of novel achiral non-π-delocalized nitroxide diradical compounds (R,S)-1, which showed polymorphism in the solid phases (solids I and II). The SQUID magnetization measurement revealed that (1) (R,S)-1 containing a small amount of racemic diastereomers (R*,R*)-1 possessed an unusual and large temperature-independent magnetic susceptibility (χTIM>0) component in the original nanocrystalline solid I that was responsible for the observed superparamagnetic-like behavior under low magnetic fields and did not arise from the contamination by extrinsic magnetic metal or metal ion impurities, besides ordinary temperature-dependent paramagnetic susceptibility (χpara>0) and temperature-independent diamagnetic susceptibility (χdia<0) components, (2) a large increase in molar magnetic susceptibility (χM) (positive magneto-LC effect) that occurred at the solid I-to-liquid crystal transition upon heating was preserved as an additional χTIM increase in the resulting polymorphic nanocrystalline solid II by cooling, and (3) such unique magnetic phenomena were induced by thermal processing for (R,S)-1 or by adding a small amount of (R*,R*)-1 to (R,S)-1 as the impurity.

KW - liquid crystals

KW - magnetic properties

KW - magneto-LC effect

KW - nitroxide diradicals

KW - phase transitions

KW - RESONANCE

KW - ANTIOXIDANT

KW - RADICALS

KW - WEIGHT

KW - DERIVATIVES

UR - http://www.scopus.com/inward/record.url?scp=85055941530&partnerID=8YFLogxK

U2 - 10.1002/chem.201803534

DO - 10.1002/chem.201803534

M3 - Article

C2 - 30378204

AN - SCOPUS:85055941530

VL - 24

SP - 17293

EP - 17302

JO - Chemistry - A European Journal

JF - Chemistry - A European Journal

SN - 0947-6539

IS - 65

ER -