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Abstract
Twelve compounds based on lateral fluorinated bistolane moieties with cyano or trifluoromethyl terminal groups were synthesised with Hagihara–Sonogashira cross-coupling reaction. The molecular structures of the compounds were confirmed by Fourier transform infrared, 1H-nuclear magnetic resonance and mass spectrometry. The transition temperatures, optical textures and optical anisotropies were determined by differential scanning calorimetry, polarizing optical microscopy and ultraviolet microscopy. The effects of the terminal substituents and lateral fluorosubstituent group on their physical properties were investigated and discussed. The compounds with lateral double fluorosubstituent and cyano terminal group exhibited nematogenic texture, while other compounds showed smectic phase. All the compounds exhibited wide liquid crystal temperature ranges and high clearing points. Interestingly, the compounds have the high birefringence in the range of between 0.480 and 0.633.
Acknowledgements
This work was supported by the National Natural Science Fund for Distinguished Young Scholar (grant number 51025313), the National Natural Science Foundation (grant numbers 51103010, 50973010, 51173003), Fundamental Research Funds for the Central Universities (grant number FRF-TP-12-043A) and the Specialised Research Fund For Doctoral Program of Higher Education of China (grant number 20110006120002).