Collective modes, relaxations, de Vries behavior and field influence in SmA and SmC*deVr phases of chiral liquid crystal dimer C-10Bms with siloxy spacer.

Investigations in chiral liquid crystal dimer with trisiloxy unit on spacer unit, viz. C-10Bms, are reported with respect to its resolved dipole moment. Occurrence of SmA and SmC*deVr LC phases was characterized by POM and DSC. Relatively enhanced thermal range of LC phases in dimer configuration was detailed. Tilt angle, hysteresis, polarization, collective modes and other low-frequency relaxations were investigated. Primary order parameter revealed validity of critical field model. Moderate tilt for viewing angle and electro-clinic response for switch speed in dimer were addressed. Hysteresis in SmC*deVr ensued storage capability for memories. Slightly higher activation energy Ea was attributed to siloxy chain on spacer. Goldstone and Soft modes were identified in SmC*deVr phase. Field influence on Goldstone mode was analyzed. Equivalence of thermal/Arrhenius and field activation energies was observed. Curie-Weiss law for SM revealed strong collective ferroelectric response. Temperature and field trends of dielectric relaxation parameters were addressed in terms of chiral center-based out-of-phase dipole moment. Figure of merit parameters in SmC*deVr estimated by dielectric loss revealed its relative performance far below the SmA-SmC*deVr phase transition.

N,N-dimethyl-5-methoxymethyl-2'-deoxycytidine.

In the title compound, C13H21N3O5, the pyrimidine ring adopts the antiperiplanar (-ap) conformation [chi = 193.54 (19) degrees]. The deoxyribose sugar ring has the C2'-exo-C3'-endo (2T3) twist conformation. The pseudo-rotational parameters of the deoxyribose sugar ring are P = 6.83 (2) degrees and Tm = 38.27 (2) degrees. The exocyclic side chain at C5' has the g+ conformation [gamma = 47.7 (3) degrees]. The 5-methoxymethyl group is distal to the deoxyribose sugar ring, with a C6-C5-C52-O52 torsion angle of -91.9 (3) degrees.