This research focuses on the development of site-selective and sequence-specific Ru(II) polypyridyl probes to manipulate and relay structural information about the target biological macromolecules. Recent developments in microscopy have led to the demand for new imaging agents with improved photophysical and chemical properties, enhanced biocompatibility, photostability, and highly specific targeting. Here, three discrete classes of Ru(II)-phenanthrene complexes are reported and were examined as viable alternatives to the current suite of chromophores used for live cellular imaging, sensing and derivatising cellular function. Ru(II)phenanthrene complexes offer a set of unique photophysical, spectroscopic and reactive properties which can be tuned by altering the associated ligands. Such complexes bind DNA by a process of intercalation of the phenanthrene ligand between stacked base-pairs of duplex DNA. Additionally, these complexes can catalyse the generation of radical oxygen species when photoirradiated at a specific wavelength and can therefore be used as selective cytotoxins. In the pursuit of improving Ru(II)-phenanthrene complexes for medicinal applications, the first class of Ru(II) complexes was developed, employing copper(I)-catalysed azide-alkyne cycloaddition (CuAAC) click chemistry to incorporate a triphenylphosphine (TPP) moiety to exploit the selective mitochondrial delivery provided by the lipophilic cations, such as TPP, to localise complexes within the mitochondria of malignant cells. Thereafter, a new series of bis- and tris-heteroleptic Ru(II)-phenanthrene compounds were designed and examined for their ability to bind DNA duplexes, inhibit topoisomerase enzymes, discriminate specific DNA steps, and photocatalytically cleave plasmid DNA. This work then informed the design of sequence-specific targeting of Ru(II)-peptide nucleic acid (PNA) hybrids that were developed through strainpromoted azide-alkyne cycloaddition (SPAAC) click chemistry. PNAs are known for their strong binding with DNA and RNA sequences largely due to their neutral backbone and hence the absence of electrostatic phosphate repulsion. The Ru(II)-PNA probes produced here were developed to sequence-specifically bind and cleave a portion of exon 5 of the epidermal growth factor receptor (EGFR) oncogene which is overexpressed in several forms of human cancers.