Semi-flexible star-shaped molecules : conformational analysis of nano-segregated mesogens forming columnar liquid-crystal phases

Abstract The structural prerequasites are investigated, which make star-shaped molecules suitable precursors for the formation of columnar liquid-crystalline phases. Electronic structure calculations on smaller mesogens show that not all conformers exhibit the atomistic structure, the stability against distortion, and additional dipole moments, which favour columnar stacking. For the presentlq studied compounds with short terminating alkyl chains, the calculations indicate that the sterac factor becomes dominant with increasing star size. Thus, the optimised geometric structures were employed to generate a simplified mathematical model of the structures, which accounts only for the sterac interaction in the larger stars. With the help of these diagrams, the most common conformers of star-shaped molecules can be derived in a systematic fashion.