In combination with the "bent cylinder binding site" model for the molecular origins of the ferroelectric polarization P in ferroelectric liquid crystals (FLCs), the observed sign and magnitude of P in mixtures of nonracemic guests with a low-polarization host is used to establish absolute and relative configuration of the guests. The assignments are fully confirmed by conventional methods. It is shown that fluorination with (diethylamido)sulfur trifluoride (DAST) of the benzylic epoxy alcohol 4'-(«-decyloxy)phenyl 4-[(5,S)-2,3-epoxy-(S)-l-hydroxynonyl(benzoate (3) proceeds with predominant retention of configuration, while DAST fluorination of the benzylic alcohol 4'-(decyloxy)phenyl 4-[(S)-1 -hydroxynonyl]benzoate (6) proceeds
The speed of electrooptic switching in the surface stabilized ferroelectric liquid crystal (SSFLC) cell is dependent on the polarization density and orientational viscosity of the FLC material. These properties are, of course, related to the chemical structure of the FLC components. In an effort to design new high-performance FLC materials in a directed way, we have developed a stereochemical model for the molecular origins of the polarization based on the concept that the polarization is a manifestation of a novel form of molecular recognition occurring in the FLC phase.1 Recent results of work aimed at testing this model are described. Specifically, a novel series of chiral fluorinated FLC components have been prepared and characterized with respect to polarization, viscosity, and electrooptic response. Comparison of the properties of diastereomeric materials provides experimental evidence for the details of orientation of organic functional groups occurring in the FLC Phase.
ChemInform Abstract The basic correctness of the "bent cylinder binding site" model for packing in the smectic C* phase and its usefulness for stereochemical assignments are demonstrated. This recently proposed model for the molecular origins of the ferroelectric polarization P observed in chiral, layered, tilted liquid crystal phases such as smectic C* phase states that doping of a chiral compound (the guest) into a achiral (or low-polarization) C phase (the host) will afford orientation of the guest molecules such that measurement of P of the fluid mixture can establish the absolute configuration of the guest independently of any optical activity or crystallography measurements, a completely unique method for configurational assignments. Mixtures of host (IV) with 10% by weight of each guest (IIIa) and (IIIb) have P values of +2.8 and -17 nC/cm2, resp., thus demonstrating the absolute configuration of both (obtained from (I) in a 2:1 ratio at 0 rc C) on the one hand and predominant retention in the fluorination on the other. In contrast, fluorination of (V) proceeds with redominant inversion as is shown by the same method. The assignments are fully confirmed by conventional methods.
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