In Search of Smectic C Phases at Mesogens with a Phenyl Ring Containing Lateral Branch

Abstract

Generally, substituepts laterally attached at calamitic molecules prevent the existence of tilted smectic phases. However, mesogens with a bulky phenyl ring containing lateral branch are subjected to other relationships. The following constitutional parameters should be realized to prepare liquid crystals exhibiting smectic C* phases: the lateral aromatic ring is linked by an odd-numbered spacer to a four-ring basic molecule bearing the chiral group. The lateral phenyl ring should be substituted in 4-position with substituents having a suitable shape and defined electron-withdrawing properties. Biphenyl units within the basic mesogen are of advantage. Measurements of the spontaneous polarization were performed. Therefore, by the existence of one chloro or nitro substituent in ortho-position to the chiral 1-methylheptyloxy group the values of Ps are increased. However, the bulky lateral segment is of few influence on the spontaneous polarization.