Synthesis and properties of (E)-1,2-difluoroethylene derivatives: improvement of the ultraviolet light stability

Abstract

The synthesis and properties of (E)-α,β-difluorostilbene derivatives were studied. In particular, we investigated three suppression methods of (E)–(Z) isomerisation by shortening the molecular conjugation length, which included the introduction of a fluorine atom into the ortho or para position of the benzene ring or the replacement of the benzene ring with a cyclohexane ring. The relationship between the molecular structure of liquid crystals and the level of isomerisation by ultraviolet (UV) light was discussed.

Keywords:

• (E)-α,β-difluorostilbene derivatives
• isomerisation
• UV photostability
• molecular conjugation length

Acknowledgements

We thank Mr. K. Kitajima, Mr. T. Koike and Ms. K. Isono and Ms. T. Watanabe from AGC Seimi Chemical for the physical evaluation of the new LC compounds.