Crystal-smectic E mesophases in a series of 2-(4-n-alkylphenyl)indenes.

A series of 2-(4-n-alkylphenyl)indenes (3) with different alkyl substituents (CH3 to C10H21) were synthesized and systematically characterized using differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction compared with 2-phenylindene (3a). Depending on the alkyl chain length, highly ordered crystal-smectic E mesophases were observed and confirmed by X-ray diffraction for the derivatives 3h-3k with heptyl to decyl chains (n = 6-9). For 3f with a pentyl side chain (n = 4), an X-ray crystal structure analysis was carried out. [ABSTRACT FROM AUTHOR]