The invention is directed to a color-tunable emitter material comprising a crystal containing complexes of luminescent biomolecule-based ligands and metal ions and to a method for preparing the color-tunable emitter material. Furthermore, the invention relates to a color-tuned material comprising the abovementioned material and a liquid. Ultimately, a LED-based device comprising either or both of the color-tunable material and the color-tuned materials is part of the present invention.