Dissecting terminal fluorinated regulator of liquid crystals for fine-tuning intermolecular interaction and molecular configuration

Abstract

Intermolecular interaction and molecular configuration are of great importance to the formation of liquid crystals (LCs). In this study, we have designed a fluorinated regulator at the end of LC molecules to investigate mesomorphic properties. Dissecting the terminal fluorinated regulator shows 4-fluoro substituent with a polar effect could promote dipole-dipole interaction, 2,6-difluoro substituent with a twist effect could facilitate steric molecular configuration, while 3,5-difluoro substituent with twist & polar effects could regulate not only molecular configuration and π-π interaction but also dipole-dipole interaction. From the independent and joint effects of the three regulating positions, it is concluded that intermolecular interactions (i.e., dipole-dipole interaction, π-π interaction and perfluoroarene-arene interaction) and molecular configuration can be effectively fine-tuned by the degree and pattern of fluorination. In addition, their thermal stabilities are evaluated systematically. These results will provide a further insight into LC molecule design.