Stilbene Derivatives. A New Class of Room Temperature Nematic Liquids

Abstract

A series of planar, trans-stilbene derivatives of type A has been prepared. Although most of these substances exhibited nematic mesophases, all displayed melting points above 100°. In order to achieve nematic compounds with lower melting points, a series of related nonplanar stilbene derivatives (type B) was synthesized; the purpose of the methyl or chlorine group was to twist the benzene rings out of coplanarity in order to relieve steric crowding about the central double bond. As expected, these nonplanar stilbenes exhibited significantly lower melting points than their planar counterparts, although not at the expense of loss of liquid crystalline character. Ten nematic stilbenes of type B displayed melting points between 14 and 35°, and ar/-4-(2-methylhexyl)-4′-ethoxy-α-chloroforms-stilbene exhibited a thermodynamically stable nematic phase from 22 to 35°. In addition to being inherently interesting, these compounds show promise for utilization in physical chemical studies as well as in technology. © 1972, American Chemical Society. All rights reserved.