Fluorinated liquid crystal systems

Abstract

Chapter 1. An introduction to the principles of two different types of LC cell and the design of new fluorinated materials for modem LCD applications is presented here. Discussion includes reasons why fluorinated molecules have become the compounds of choice for display devices, and a history of organo-fluorine chemistry from early discovery of the element, through nucleophilic substitution and debromolithiation reactions of bromoperfluorobenzenes, to very recent developments in synthesis.Chapter 2. This chapter presents a brief overview of some of our early ideas as to how new fluorinated LCs might be made synthetically, exploiting advances in the field of organo-fluorine chemistry, utilising perfluorobenzene and bromoperfluorobenzene "scaffolds."Chapter 3. A discussion of how new "model" fluorinated LC materials were obtained via nucleophilic aromatic substitution in bromoperfluorobenzenes is presented in this chapter. The flexibility of the methodology is demonstrated through use of different substrate isomers to afford different aromatic fluorination patterns, and of different nucleophiles to create "families" of homologous materials.Chapter 4. The versatility of bromoperfluorobenzenes as substrates is exemplified in this chapter, whereby a number of isomers of these "scaffold" molecules were built upon via debromolithiation followed by reaction with electrophiles. This methodology was also applied to functionalised bromofluorobenzenes from chapter 3, and a small library of related compounds was synthesised as in the previous chapter.Chapter 5. Recent advances in metal C-F bond activation have assisted with ourdevelopment of a new synthetic route to fluorobiphenyl moieties, based on Suzuki- Miyaura chemistry and presented in this chapter.Chapter 6. Many of the novel fluorinated materials synthesised in chapters 3 to 4 were sent to SONY MSL, Stuttgart, and their properties determined by tests including electro- optical, DSC, and VHR analysis. The results are discussed and compared, and their potential for application in current LC display devices assessed