Despite their potential to overcome critical limitations of conventional organic dyes, metal complex luminophores have yet to be truly accepted as probes for cellular imaging and phototherapy. Longlived and reactive luminophore excited states grant a sensitivity not currently achievable by organic probes and offer the ability to efficiently photosensitise cellular toxicity. A barrier to their exploitation to date has been their relatively poor uptake and unpredictable localisation, especially to important theranostic targets like DNA. However, signal peptides are a powerful strategy towards achieving precision-targeting of key organelles and were previously successfully implemented to deliver metal complexes to the nucleus and mitochondria - two locales where cellular DNA resides. The overarching aim of this thesis was therefore: to explore the candidacy of peptide targeted Ru(II) luminophores for imaging and photo-destruction of DNA in live cells. Two prominent Ru(II) complexes were established as candidate complexes to derivatise under the scope of this work. The first was [Ru(bpy)2(dppz)]2+ - a molecular light switch for DNA that is nonluminescent in water but switches on upon intercalating DNA. The second was [Ru(tap)2(bpy)]2+ - a complex which possesses an excited state reduction potential sufficiently positive to photo-oxidise and damage DNA. Chapter 3 explored efficient synthesis routes to conjugatable derivatives of Ru(II) luminophores with a highlight being the development of a novel protocol to prepare tris-heteroleptic Ru(II) complexes in unprecedented yield. Chapter 4 investigated the interaction of Ru-dppz conjugates with DNA in vitro and in live cells, where remarkably, both nuclear and mitochondrial DNA were successfully targeted permitting high resolution imaging of structure and cellular phase. Phototoxicity was induced at higher irradiation intensities leading to cellular apoptosis. Chapter 5 investigated the photo-reactivity of a nuclear-targeted Ru-tap conjugate in live cells where singlet oxygen independent photo-oxidation of DNA led to photosensitised destruction of HeLa cells with spatiotemporal control. Finally, Chapter 6 explored additional imaging and biophysical applications of Ru(II) luminophores.