Synthesis and properties of fluorinated terphenyl liquid crystals utilizing 5,6-dihydro-4H-cyclopenta[b]thiophene as core unit

•Incorporating 5,6-dihydro-4H-cyclopenta[b]thiophene into fluorinated terphenyl and six novel liquid crystals obtained.•Expanding the mesophase ranges.•Increasing both the birefringence and dielectric anisotropy values of mesogens.•Relationship between microscopic molecular structures and macroscopic physical properties. 5,6-dihydro-4H-cyclopenta[b]thiophene was incorporated to fluorinated terphenyl and six novel liquid crystals were designed and synthesized by Suzuki coupling reactions in high yields. These mesogens possessed wide smectic A or nematic phase ranges, which proved the usefulness of this core in the formation of liquid crystal phase as 1,4-disubstituted phenylene-based reference compound have no mesomorphic phase. Besides, the birefringence and dielectric anisotropy values of liquid crystals were also increased, making this core a practical candidate for the modification of terphenyl-typed mesogens. The density functional theory calculations were then used and whose reliability was ensured by comparison of the experimental and calculated absorption spectrum. The calculated length/width ratios of mesogens were improved after the introduction of this core unit, which might promote the formation of mesomorphic phases. The orders of calculated polarizability and dipole moment of two representative mesogens and their references were in agreement with the sequences of their birefringence and dielectric anisotropy values, respectively, providing some relationship information between microscopic molecular structures and macroscopic physical properties. [Display omitted]