TRIPHENYLENE-BASED DISCOTIC-LIQUID-CRYSTALLINE POLYMERS - A UNIVERSAL, RATIONAL SYNTHESIS

A simple, regiospecific synthesis of main-chain, triphenylene-based discotic-liquid-crystalline polymers is described in which the key step is the assembly of the triphenylene nucleus through the oxidative coupling of phenyl and biphenyl residues. Hence, treatment of a mixture of 3,3'-bis(hexyloxy)-4,4'-dimethoxybiphenyl and 1,2-bis(hexyloxy)benzene with ferric chloride in dichloromethane followed by a reductive, methanol workup gives 2,7-dimethoxy-3,6,10,11-tetrakis(hexyloxy)tr 7. The 2,7-linked main-chain polymer 8 is produced by demethylation and condensation with 1,11-dibromoundecane, has average molecular weight 24 000, and D-h mesophase range of 98-118 degrees C. The 3,6- and 2,3-linked polymers were prepared in a similar manner.