Synthesis and mesomorphic properties of four-ring fluorinated liquid crystals with trifluoromethyl group

ABSTRACT

The discovery of nematic phase in 3-fluoro-4-trifluoromethyl-4ʹ-(4ʹ-alkyl [trans, trans-1,1ʹ-bicyclohexyl]-4-yl) 1,1ʹ-biphenyls (n = 2, 3, 4, 5) is an accidental affair. A convenient method was used for the synthesis of these target compounds. After the preparation of the intermediate with trifluomethyl group, the target compounds were synthesised by Suzuki cross-coupling reaction. Then, these phase transition temperatures were measured by polarising textural observation, which confirmed the existence of single nematic phase. These temperatures were also measured by differential scanning calorimetry, which showed that the clearing point of compound (n = 3) is 267℃. The possible mechanism of occurrence of unique nematic phase was discussed on the basis of the principles of fluorine chemistry.

Graphical Abstract

KEYWORDS:

• Fluorinated liquid crystal
• clearing point
• nematic phase
• fluorophilic
• trifluoromethyl

Acknowledgement

The authors are very grateful to engineer Jixiang Li for his help in measurement.