Abstract

The synthesis and liquid crystalline properties of a new series of amides (series 2a-f, 3a-d and 4a-d) incorporating pyridine and 1,3,4-thiadiazole rings are reported. No homologues of the series 2 show mesomorphic properties. In the series 3 only the highest homologues (3d) displays an enantiotropic SmA mesophase; the compound 3c exhibits a monotropic SmA mesophase, and the homologues 3a,b display no liquid crystal properties. The amides 4b-d display an enantiotropic SmA phases and the first homologue (4a) exhibit only crystal-isotropic transition. These series are compared with previously reported Schiff's bases and amide analogues. A structural study by AMI semi-empirical calculation is also described.