A polymer library consisting of a series of three fluorescing monomers (i.e., blue, yellow and red-emitting) based on 4-hydroxy-1,3-thiazole chromophores as well as an Os(II) metal complex containing monomer was synthesized. These materials were characterized using ¹H NMR spectroscopy, size-exclusion chromatography (SEC) as well as TGA and DSC measurements. The optical properties were investigated utilizing UV-vis absorption and emission measurements. The tailor-made optical properties of the monomer units facilitate energy transfer from the blue over the yellow and red chromophores to the photoactive Os(II) polypyridyl moiety. For this purpose, the energy transfer was monitored using excitation–emission correlation spectroscopy.