Nous avons développé la synthèse d'hétérocycles indoliziniques fonctionnalisés par un cation pyridinium et étudié leur interaction avec L'ADN. L'étape-clé pour accéder aux indolizines est la cycloaddition [3+2]-dipolaire des ylures dérivés des sels quaternaires de la 4,4'-bipyridine avec des dipolarophiles. La synthèse a été effectuée par la voie classique (chauffage en solvant) et par irradiation avec des micro-ondes (“chimie verte”). Nous avons étudié les propriétés acido-basiques des sels diquaternaires et leur activité biologique sur une série de microorganismes. Par ailleurs les propriétés électriques et optiques ainsi que la photoluminescence des indolizines se sont révélées prometteuses pour des applications comme les traceurs biomédicaux. L'interaction des indolizines avec l'ADN a aussi été étudiée. Finalement, nous avons évalué les propriétés antioxydantes des indolizines, qui ont montré une activité inhibitrice de la peroxydation des huiles végétales in vitro.

Six new crystal structures were determined using a Rigaku Mercurcy 375/MCCD(XtaLab mini) diffractometer. The structure of a molybdenum cofactor was solved resulting in an R1 (R1 = Σ ||Fo| - |Fc|| / Σ |Fo|) of 3.61% despite the presence of a disordered DMSO molecule. New Tetrakis(N-phenylacetamidato) Dirhodium(II) complexes were synthesized and characterized. Two 2,2-cis-[Rh2(NPhCOCH3)4]•(C3H4N2)x where x= 1 or 2 were successfully crystallized and solved with R1 values below 5%. Additional studies were conducted via NMR to observe formation of both products. Three potential catalysts were synthesized starting with 3,1-[Rh2(NPhCOCH3)4]. The resulting compounds were a mono adduct 3,1-[Rh2(NPhCOCH3)4]•(C3H4N2), and two dimer of dimers complexes with amine bridges 3,1-[Rh2(NPhCOCH3)4]2•(C8H6N2) and 3,1-[Rh2(NPhCOCH3)4]2•(C10H8N2). All three complexes were crystallized and solved with R1 values less than 10%. Additional NMR studies were conducted to elucidate solid and solution phase structures and to determine the possibility of additional amine bonds forming.

This thesis describes the synthesis and characterisation of metal complexes that contain chemically reduced bipyridyl ligands. The crystal structures of twenty-six novel complexes are reported alongside detailed discussions on the electronic and spectroscopic effects and trends associated with the different oxidation states within these species. Chapter One introduces the isomers of bipyridine and their redox chemistry, the concept of non-innocent ligands and the spectroscopic techniques that are currently used in determining ligand oxidation states. Subsequently, examples of main group, transition metal, lanthanide and actinide species that contain or may contain reduced forms of the ligand are discussed. Chapter Two details the synthesis and structural characterisation of alkali metal salts of singly and doubly reduced forms of the three commercially available bipyridine isomers. The effects of this reduction are investigated with the aim of developing diagnostic fingerprints for each of the ligand oxidation states. Chapter Three discusses the synthesis of an homologous series of compounds of the form [M(2,2'-bipy)(mes)₂]^n– where M = Cr, Mn, Fe, Co, Ni and n = 0, 1. Trends in magnetism, bonding and electronic structure are investigated with reference to theoretical calculations and the diagnostic fingerprints identified in the previous chapter. Chapter Four describes the synthesis and characterisation of three compounds containing the isostructural motif [Zn₂(4,4'-bipy)(mes)₄]^n– where n = 0, 1, 2. Structural and spectroscopic changes are discussed and com- pared to theoretical calculations. Chapter Five contains descriptions of the spectroscopic techniques employed in the above research and synthesis routes to all compounds featured in this thesis.