Heterocyclic polycatenar liquid crystals

We report the synthesis of polycatenar liquid crystals incorporating 2,5-disubstituted 1 3 4-oxadiazole and 1 3 4-thiadiazole rings joined by a combination of carbon-carbon single and double bonds (-CH = CH-). The ratio of the aromatic core to the aliphatic chains was varied systematically by changing the number of the aliphatic chains, from two to six, and their length, from short to very long, i.e. from methoxy to hexadecyloxy. The shape anisotropy of the core was varied by exchanging the oxygen atom in the 1 3 4-oxadiazole for a sulfur atom to form the corresponding 1 3 4-thiadiazole ring with a smaller deviation from coaxiality of the bonds in the 2,5-positions. The shape anisotropy of the core was increased by the presence of an additional phenylenevinylene unit in a series of tetracatenar oxadiazoles. We report the synthesis, physical properties and polymerization of a polycatenar reactive mesogen in a columnar phase to form a polycatenar polymer network.