Abstract

Synthesis and mesophase-transition behaviors of six 1,6-disubstituted pyrene-based hexacatenar liquid crystals 1n (n=8–18) are reported here. They were synthesized by the Sonogashira coupling between 1,6-diethynylpyrene and 2-bromothiophene bearing a trialkoxybenzoyl group. The phase-transition behavior was studied by differential scanning calorimetry and polarized optical microscopy; a few mesophase progressions, I–Col/I–X–Col and Col–Sm, were observed, where X was an optically isotropic but unidentified phase. The structures of Colr, Colh, and Sm phases were analyzed by the X-ray crystallography, and the effect of the terminal alkoxy chain length on the mesomorphism was evaluated.

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