Tailoring Liquid Crystalline Self‐Assembly in Dialkoxybenzimidazoles: The Role of Charge and Shape

Liquid crystalline self‐assembly in neutral and ionic dialkoxybenzimidazoles can be precisely tuned or suppressed by controlling molecular symmetry and charge, revealing key structure–property relationships for mesophase design. To elucidate these effects, a series of neutral ( L‐Bi(n) , U‐Bi(n) ) and ionic ( L‐Me ₂ Bi(n)I , U‐Me ₂ Bi(n)I ) derivatives differing in the substitution pattern of the side chains ( n  = chain length) at the benzimidazole was synthesized and characterized by POM, DSC, and X‐ray diffraction. Nonionic systems exhibit mesomorphism only for rod‐like linear homologues ( n  = 9–14), forming nematic phases, whereas the neutral bent U‐shaped derivatives remain non‐mesomorphic. In contrast, ionic U‐shaped derivatives form smectic phases, including a cubic phase for n  = 12, while linear derivatives do not form mesophases. The solid‐state structures demonstrate that both the capacity for hydrogen bonding in the neutral derivatives and the presence of π‐stacking interactions in the ionic derivatives significantly influence the molecular packing. Furthermore, distinct differences in the packing arrangements are observed depending on the specific substitution patterns.