The synthesis and liquid crystal properties of certain 5,5''-disubstituted 2,2':5',2''-terthiophenes

The synthesis and liquid crystal properties of eight members of an homologous series of 5-n-alkanoyl-5 ''-n-alkyl-2,2':5',2 ''-terthienyls and the corresponding eight 5,5 ''-di-n-alkyl-2,2':5',2 ''-terthienyls are reported. The disposition of the three thiophene rings is sufficiently linear that suitably substituted compounds are mesomorphic, and the liquid crystal transition temperatures of related members of the two series are compared. Corresponding 5,5'-disubstituted 2,2'-bithienyls are not liquid crystalline.