ABSTRACT
The chlorophylls (Chl) and bacteriochlorophylls (BChl) comprise a group of more than 50 tetrapyrrolic pigments with common structural elements and functions.
Chemically, they are defined as Mg-complexes of cyclic tetrapyrroles of the porphyrin (Figure 117.1b), chlorin (Figure 117.1a), or bacteriochlorin (Figure 117.1b) oxidation state, all bearing a fifth, isocyclic ring, and most of them esterified at C-17
by the diterpenoid alcohol, phytol (Phy) (Figure 117.1a). However, an increasing number of structural variations have become obvious that do not strictly follow this definition (Section 117.2).
