Metal ligand complex syntheses for imaging applications

This thesis describes an investigation into the roles and effects of nitrogen-donor chelating ligands and complexes containing metal centres as tools for molecular imaging. Chapter 1 gives a brief introduction to Positron Emission Tomography (PET) imaging,the radionuclides and metal centres currently available for therapeutic use, and a discussion and comparison between metal and organic-based contrast agents. Chapter 1 also contains an introduction to macrocycles and their role as ligands, with particular focus on azamacrocycles and their applications. Finally, a brief introduction to luminescence spectroscopy and optical imaging is made. Chapter 2 reports the synthetic procedures used, and gives characterisation data for the compounds synthesised and discussed in subsequent chapters. Chapter 3 investigates the role of the triazine core of the azamacrocycles, showing some compounds of biological interest and the synthesis of new ligands and complexes based on a tetraazamacrocycle (DO3A) moiety with a triazine core. One example has been successfully used to study the coordination chemistry and structure of different metal centres, while another has shown promise with a potential application in mimicking dipyridamole compounds. Moreover it has been conducted a study to determinate the empirical formula and the nature of the complexes in solution. Chapter 4 contains an introduction to the benzothiazole group, which has relevance in the study of Alzheimer's disease as it is a biological marker for metal-dependant formation of Aβ plaques. The synthesis of new ligands derived from several macrocycles (including those reported earlier, and those containing an acyclic moiety with a benzothiazole core) are reported, including procedures to produce complexes of lanthanides and PET-active metal centres including copper, vanadium and gallium. Benzothiazole ligands and complexes have been characterised by fluorimetry, allowing discussion of the role of the ligand