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Series of laterally multifluorinated heterocyclic compounds, 2-(2ʹ,3-difluoro-4ʹ-alkoxy-1,1ʹ-biphenyl-4-yl)-benzoxazole derivatives (nPF(2)PF(3)Bx), are prepared and characterised. They mainly display enantiotropic nematic mesophases with wider mesophase ranges of 12–107°C (heating process) and 22–134°C (cooling process) than the corresponding analogues. The enhanced nematic mesophase stability is achieved via slightly increasing inter-ring twist angle with inter-ring lateral fluorine substitute in biphenyl unit, as well as through improving the molecular polarity with multifluorine substitutes. Meanwhile, two inter-ring lateral fluorine atoms lead to a decrease in melting/clearing points and a wide nematic mesophase range, which makes it possible for heterocyclic mesogens nPF(2)PF(3)Bx to use in nematic liquid crystal display mixtures. [ABSTRACT FROM PUBLISHER]

Series of laterally monofluorinated compounds, 2-(4ʹ-alkoxy-3-fluorobiphenyl-4-yl)-1H-benzimidazole derivatives (nPPF(3)Mx) bearing different substituents (H, CH3, NO2, coded as nPPF(3)MH, nPPF(3)MM and nPPF(3)MN, respectively) at 5-position, were prepared and their structures were characterised. According to the results from differential scanning calorimetry and polarising optical microscopy, the present compounds nPPF(3)Mx exhibit enantiotropic smectic mesophases, for which the mesophase ranges are 13–67 and 47–111°C on heating and cooling for nPPF(3)MH, 84–112 and 126–154°C for nPPF(3)MM, and 23–102 and 49–117°C for nPPF(3)MN, respectively. Compared to non-fluorinated analogues, monofluorinated nPPF(3)Mx have low melting/clearing points and display enhanced mesophase range both in heating and cooling, which are attributed to the disruption of the side-to-side intermolecular packing caused by theortholateral fluoro substituents and the increased dipole–dipole interaction between the polar fluoro-substituted molecules, respectively. It is noted that nPPF(3)MM and nPPF(3)MN show a much wider mesophase range than nPPF(3)MH, which suggest that the substituent at benzimidazole moiety can improve the mesophase stability. [ABSTRACT FROM PUBLISHER]