Magnetic-field-induced molecular alignment in an achiral liquid crystal spin-labeled by a nitroxyl group in the mesogen core

Ferronematics Based on Paramagnetic Nitroxide Radical Liquid Crystal

“…These ferronematics showed the same order of magnitude of the magnetic responsivity compared to the classical ferronematics. It is because Δχpara hardly affects the magnetic responsivity because Δχ dia ≫ Δχ para (Δχ dia = 6.5 × 10 −5 emu· mol −1 and Δχ para = −1.7 × 10 −6 emu· mol −1 at 300 K [3]). The free energy density for the ferronematics with respect to the elastic deformation is written as [19,20]:…”

“…This is because most LC materials have a small anisotropy of magnetic susceptibility (Δχ~10 −7 ) [2]. However, the magnetic-field-induced molecular reorientation should be suitable for devices consisting of LC materials like ionic LC materials, to which the electric-field-induced molecular reorientation is not applicable [3]. In actual use, the responsivity of LC materials to a magnetic field needs to be improved in some way.…”

“…In contrast, the latter all-organic radical LC materials with the small magnetic anisotropy do not show such high viscosity. As one of the most stable all-organic radical PLC materials, a nitroxide radical LC compound 1 with an enantiotropic nematic phase has been reported to exhibit the magnetic-field-induced molecular reorientation in the nematic phase at below 1 T of magnetic field [3,13]. If the magnetic responsivity is improved by doping magnetic particles, the all-organic radical LC materials would be more suitable for the hosts of ferronematics.…”

Magnetic and Electric Properties of Organic Nitroxide Radical Liquid Crystals and Ionic Liquids

“…In contrast, LC compounds 12 with low viscosity, low phase transition temperature, and known principal gvalues of the NR moiety are considered to be a good spin-labeled candidate for the studies on the -controlled molecular orientation by weak magnetic fields. Therefore, to confirm that the magnetic-field-induced molecular alignment in the LC phases of 12 is dia-controlled, the para and dia values of 12 and the approximate magnitude of Hc for each LC phase of 12 were evaluated by EPR spectroscopy and SQUID magnetization measurement and by POM observation under variable magnetic fields, respectively (Uchida et al, 2009b).…”

Magnetic property of a spin-5/2 trigonal prismatic as a model for a molecule-based compound Cs4Na7[Fe6(OH)3(A-α-GeW9O34(OH)3)2]・30H2O

“…As two interesting topics in condensed state physics, ferromagnetic and anti-ferromagnetic spin systems have been attracting much more attention from both experimental [1][2][3][4][5][6][7][8][9][10][11][12] and theoretical points of view [13][14][15][16][17][18][19][20][21][22][23][24] , due to the notable progress in synthesizing bulk samples of identical molecular-size units. The relatively small number of paramagnetic ions (''spins''), mutually interacting via Heisenberg exchange interactions through organic bridge, are contained in the great majority of cases.…”