Molecular Dynamics in a Chiral Smectic Liquid Crystal Studied by¹³C-Nuclear Magnetic Resonance Spin-Lattice Relaxation Time Observation

13C-NMR Studies on Fluctuation of Rod-Like Molecules in Solution: Molecular Dynamics in a Polar Solvent of CDCl3

“…In addition, the T 1 minimum occurs in the measurements of the 100 wt=v% and 200 wt=v% solutions, because the correlation time s c of the molecular motion should be about 10 À8 s here. We would like to point out that s c almost agrees with that of the molecular rotation around its long axis in a smectic phase of MHPOBC as reported in previous papers [14,15]. Namely, the rotational motion of MHPOBC molecule in solution seems to be slowing down to the molecular mobility in a smectic phase, when the rod-like molecules of MHPOBC leave solution and deposit as crystals in the lyotropic system.…”

Recent NMR Studies of Thermotropic Liquid Crystals

“…However, it is not straightforward to carry out these in reality. To list a few recent 13 C relaxation works, these include 10B1M7 [217], 4-(1-methylheptyloxycarbonyl)phenyl-4 0 -octyloxybiphenyl-4-carboxylate (MHPOBC) [218][219][220], 4-(2-methyloctanoyl)phenyl 4 0 -nonylbiphenyl-4-carboxylate (MONBIC) [216], 4-(1-methylhexyloxycarbonyl) phenyl 4 0 -octyloxybiphenyl-4-carboxylate (MH(6)POBC) [221]. In general, the 13 C T À1 1 rates of the aromatic carbons increase with decreasing temperature in a manner similar to the observed spectral densities for the aromatic deuterated sites (see for instant, ZLL 7/* [189]).…”

Molecular Dynamics in Smectic and Crystalline Phases Studied by13C-NMR Spin Lattice Relaxation Time Observation

“…As for its dynamical aspect, however, details of the hindered molecular rotation associated with the emergence of spontaneous polarization are still open for question, although several experimental approaches have been carried so far [1][2][3][4][5][6][7][8][9][10][11][12][13]. Although nuclear magnetic resonance (NMR) spectroscopy is a powerful method for investigating molecular dynamics in liquid-crystalline compounds, neither the slowing down nor the hindrance of molecular rotation has been confirmed even in recent studies [14][15][16][17][18][19][20][21][22][23][24][25].…”

“…In 2003, Seki et al investigated the correlation time τ c of the molecular motion detected in the spin-lattice relaxation time T 1 observation, which was carried out by solidstate 13 C-NMR spectroscopy at a Larmor frequency ω 0 of 100 MHz [21]. They reported that the correlation frequency due to τ c almost corresponded to the dielectric relaxation frequency of the molecular rotation around its long axis in chiral smectic phases of the prototype antiferroelectric liquid crystal S-MHPOBC [21,26].…”

“…They reported that the correlation frequency due to τ c almost corresponded to the dielectric relaxation frequency of the molecular rotation around its long axis in chiral smectic phases of the prototype antiferroelectric liquid crystal S-MHPOBC [21,26]. By continued study, here, we show changes in the molecular rotation during successive phase transitions in a chiral smectic liquid crystal (S)-(4-(1-methylhexyloxycarbonyl) phenyl 4 -octyloxybiphenyl-4-carboxylate (S-MH(6)POBC), which is a derivative of S-MHPOBC.…”