The first part of this thesis is concerned with the synthesis o f a series of mononuclear ruthenium(II) and rhenium(I) complexes incorporating 2,2';4,4";4",4'" -quaterpyridyl ligand. The electronic and spectroscopic behaviour of the complexes is discussed. These complexes possess extremely interesting photophysical and electrochemical properties in themselves which can be exploited for the construction of higher order arrays. In order to compare the DNA binding ability of the metallomacrocycles constructed from the mononuclear building blocks, the binding of these complexes with CT-DNA has been studied using a variety of techniques including viscometry, continuous variation analysis (Job plots), UV-Visible absorption and luminescence emission spectroscopy, ITC and luminescence lifetime. In all cases the complexes bind via intercalation, with an affinity around 105 M-1 to 106 M-1. In consequent chapters, a series of self-assembled metallomacrocycles that incorporate ruthenium(II) and rhenium® metal centres are reported. The electronic and spectroscopic behaviour of the complexes is again discussed and compared to the respective building blocks. These complexes also possess extremely interesting photophysical properties and concomitant studies with biomolecules such as adenine, ATP, GTP, cGMP and uridine revealed that these macrocycles are able to act as hosts for such molecules in water. Indeed, the macrocycles have demonstrated the capability of binding to oligonucleotides, such as CT-DNA with binding affinities comparable to other mononuclear DNA binding substrates. Strikingly, the binding affinity and binding mode can be modulated upon changing the ancillary ligands of the macrocycles.