Synthesis and Thermotropic Properties of Dimesogenic Homologous Series Containing Disiloxyl Spacer, DI-4- (P-Substituted Phenoxycarbonyl) Phenoxymethyl Tetramethyl Disiloxanes

Abstract

A new series of thermotropic conpounds having two terminal, aromatic dyad ester-type mesogenic units and a disiloxyl spacer were prepared and their liquid crystalline properties were studied. The mesogenic units of these compounds were p-substituted phenyl-p-oxybenzoates with different substituents such as H, CH₃, OCH₃, C₆H₅, Cl, CN and NO₂. β-Naphthyl-p-oxybenzoyl containing compound also was included in this series. All of the conpounds were found to be smectic. The nature of the smectic mesophase depends on the structure of the p-substituent. The mesophase temperature range was fairly narrow between 10 to 30[ddot]C. The compounds’ heats of melting were very low compared with other dimesogenic conpound, e.g. those having polymethylene spacers.