Three kinds of acryloxy-capping substituted benzoic acid compounds were synthesized and characterized; the corresponding symmetric hydrogen-bonded liquid crystals (H-boned LCs) based on 4
4'-bipyridine (BP) or 4-((E)-2-(pyridin-4-yl)vinyl)pyridine (DPE) were prepared. The structure of precursors as well as the H-bond structures were confirmed by the
1
H nuclear magnetic resonance (
1
H-NMR) and by Fourier transform infrared spectroscopy (FTIR). The mesogenic behavior of the H-bonded complexes was demonstrated by the polarizing optical microscopy (POM) and the differential scanning calorimetry (DSC). It was found that the fluoro substituent on the mesogenic core made the molecular width increased and thus the aspect ratio of the molecular decreased
therefore it could weaken the mesogenic behaviors of the H-bonded LCs such as decreasing the melting point as well as the clear point. Additionally
the introduction of terminal acryloxy group and the increase of induced rigid core could enhance the molecular length and regularity
resulting in the increase of phase transition temperatures of the complexes.
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