THE RELATIONSHIP BETWEEN MOLECULAR-STRUCTURE AND MESOMORPHIC PROPERTIES OF 2,2'-DIFLUOROTERPHENYLS AND 3,2'-DIFLUOROTERPHENYLS SYNTHESIZED BY PALLADIUM-CATALYZED CROSS-COUPLINGS

Several homologues of two structurally different types of mesogenic difluoroterphenyls have been prepared. One set of compounds contains two inner-core fluoro-substituents and the other set possesses both an inner-core and an outer-core fluoro-substituent. The use of various types of palladium-catalysed cross-coupling reactions was invaluable in the synthesis (for example, selective couplings, and couplings to trifluoromethanesulphonate derivatives). Additionally, a novel selective lithiation is reported. The mesogenic materials are all low melting and the types of mesophase generated are considerably structure dependent. However, most of the materials support the tilted S(C) phase which is required of ferroelectric host materials. The mesomorphic behaviour of these novel materials is discussed in terms of the molecular structure and the structure/property relationships are compared with those for difluoroterphenyls with different arrangements of lateral fluoro-substitution.