With the aim of developing new oligothiophene-based liquid crystals involving hydrogen bonding, new terthiophene derivatives containing an alkylamide group, N,iV'-dialkyl-5,5"-dibromo-2,2':5',2"-terthiophene-4, 4"-dicarboxamide (DNCnDBr3T, n = 5, 8, 16, 18), were designed and synthesized, and their thermal behaviors were examined. While DNCnDBr3T compounds with n = 8, 16, 18 were found to form smectic A phase, DNC5DBr3T did not form liquid crystal phase. In addition to liquid crystal behavior, crystal polymorphism was also observed for DNCigDBr3T. It is shown that the alkyl chain length greatly affects liquid crystal phase formation. The absence of liquid crystallinity in the corresponding ester derivatives suggests that intermolecular hydrogen bonding plays a role in the formation of liquid crystal phase in the DNCnDBr3T system.

Key words: THIOPHENE P, POLYMER, LIQUID CRYSTAL, HYDROGEN BONDS, IR, DSC, AMIDES