2 Porphyrins and their effects
Porphyrins are macrocyclic pigments and cofactors that occur commonly in nature and are often referred to as the ”pigments of life”(Battersby 2000). The word porphyrin actually comes from the Greek word ”porphyra”, because porphyrins are usually bright purple or red in color(Senge et al. 2021). The backbone of porphyrins is porphine (Fig. 1), an aromatic compound that contains up to 26 π-electrons, 18 of which form a continuous plane. Its role in plants and animals as a metal-binding cofactor to form biomolecules is crucial in many metabolic pathways, especially in facilitating oxygen transport in cellular respiration and energy capture in photosynthesis(Pan et al. 2021). The insertion of metal atoms into porphyrins affects the degree of electron delocalization of the conjugated system, making their properties more diverse and further broadening the idea of the development of porphyrin-based photosensitizers(Gupta et al. 2006; Takechi et al. 2006).
Fig. 1 Structure of porphine.