A terminal-group and fluorination matrix for designing polar nematic liquid crystals

Overview & Synopsis

Lateral fluorination has emerged as a powerful design variable in the design of polar liquid crystals, but its interplay with terminal-group identity remains poorly understood. Here we report a 40-member matrix of biphenyl-ester-phenyl mesogens that independently varies lateral core fluorination and terminal-group identity. Increasing lateral fluorination generally suppresses apolar mesophases and clearing points, however this same change can enable polar nematic phase behaviour in conjunction with suitable terminal units. Graph Fourier analysis of conformer averaged atomic charges shows polar materials occupy a high-frequency region of charge-spectral space, consistent with a bond-scale electrostatic motif. Different terminal units can bias this towards higher or lower frequencies, and in doing so can enable polar order to emerge.