Towards the synthesis of alkoxy-substituted [2.2]para-cyclophenes and [2.2]para-cyclophane-1-enes : tailored monomers for the preparation of well-defined, functionalised PPV
This thesis describes a route towards the synthesis of alkoxy-functionalised [2.2] para-cyclophenes and [2.2]-para-cyclophane-1-enes as possible monomers for the preparation of functionalised PPVs via ROMP, using their corresponding alkoxy-functionalised stilbenes as precursors to furnish the desired cyclophenes through a ring-closing reaction. Chapter 1 is divided into three sections, A, B and C. Section A introduces the concept of conducting and electroluminescent polymers, with particular emphasis upon polyacetylene and PPV. Section B discusses stilbenes in detail, while section C examines the structure, preparation and reactivity of cyclophanes and cyclophenes, specifically [2.2] para-cyclophane and [2.2] para-cyclophene. Chapter 2 explains the synthesis of a series of alkoxy-substituted benzaldehydes, designed as easily accessible, readily functionalised precursors to alkoxy-substituted stilbenes, while Chapter 3 shows how these alkoxy-substituted benzaldehydes can be transformed into stilbenes, through the application of either the McMurry, Wittig, or Horner-Wittig reactions. Chapter 4 describes further transformations of alkoxy-substituted stilbenes, with emphasis placed upon achieving ring-closing to furnish the desired [2.2] para-cyclophenes and [2.2] para-cyclophene-1-enes. Preparation of an oligomeric form of PPV from the same stilbene precursors is also discussed, and the photophysics of both this oligomer and its related stilbenes is investigated. Chapter 5 outlines an alternative route towards alkoxy-functionalised [2.2] para-cyclophenes, via a Ramberg-Backlund rearrangement of functionalised cyclic dithioethers, and Chapter 6 gives overall conclusions for this thesis, briefly introducing possible further studies to be undertaken on this topic. Chapter 7 contains experimental details and characterisation data for all compounds prepared during the course of this work.