Coloured compounds are an essential attribute of the developed forms of life. Indeed, the most visual sign of life on earth is due to the chlorophylls, that give the plants their green colour and that belong to the class of the porphinoid pigments. The natural porphinoids, called the "pigments of life", comprise metal free tetrapyrroles and metal complexes, such as the iron complex heme, the magnesium complex chlorophyll, the nickel complex coenzyme F430 and the corrinoid cobalt complex coenzyme B12. The natural porphinoids play central roles in all spheres of life, e.g. as cofactors for transport of oxygen, nitric oxide and electrons, for collecting and transforming solar energy, and as catalysts in biosynthesis.
How did the porphinoid structures develop in nature ? How do their unique properties arise from the interactions between the metal centers and the tetrapyrrolic ligands ? To which particular chemical reactivities and modes of action do the porphinoid compounds owe their specific biological functions ? These questions may pave the way to insights into how life developed on earth. They also may open the prospect, that the properties of the porphinoid pigments might not only be beneficial for the living nature, but could be exploited profitably otherwise, e.g. by the use of porphinoids as catalysts for laboratory synthesis, for the storage and conversion of energy and for medical purposes.