In this work, we present a concise modular assembly strategy using one universal heteroleptic 2,6-di(quinolin-8-yl)pyridine-based ruthenium(II) complex as a starting building block. Extending the concept from established ligand modifications and subsequent complexation ( classical route ), the later appearing chemistry-on-the-complex methodology was used for late-stage syntheses, i.e. , assembling discrete building blocks to molecular architectures (here: dyad and triads). We focused on Suzuki–Miyaura and Sonogashira cross-couplings as two of the best-known C–C bond forming reactions. Both were performed on one building block complex bearing a bromine and TIPS-protected alkyne for functional group interconversion (bromine to TMS-protected alkyne, a benzyl azide, or a boronic acid pinacol ester moiety with ≥95% isolated yield and simple purification) as well as building block assemblies using both a triarylamine-based donor and a naphthalene diimide-based acceptor in up to 86% isolated yield. Additionally, the developed purification via automated flash chromatography is simple compared to tedious manual chromatography for ruthenium(II)-based substrates in the classical route . Based on the preliminary characterization by steady-state spectroscopy, the observed emission quenching in the triad (55%) serves as an entry to rationally optimize the modular units via chemistry-on-the-complex to elucidate energy and electron transfer. The present work shows the investigation of photosensitizer triad syntheses via chemistry-on-the-complex. The heteroleptic bis(di(quinoline-8-yl)pyridine) ruthenium(II)-based parental photosensitizer was transformed in terms of functional group interconversion from bromide (to azide, protected alkyne, boronic acid ester), and coupling chemistry to introduce both electron-rich and -deficient moieties with simple workup procedures after chemistry-on-the-complex throughout.