Chapter 3. Chlorophylls

Chlorophylls have several functions in photosynthesis: (1) in the light-harvesting antennas they efficiently absorb light and (2) transfer the excitation energy with minimum losses to the reaction centers, where (3) they act as primary electron donors and acceptors in light-induced charge separation across the photosynthetic membrane. In both types of complexes, they (4) contribute to the stabilization of the photosynthetic apparatus. Chlorophylls have also been found in other protein complexes, where less is known of their function. Pigment structures, biosynthetic pathways and spectroscopic properties are reviewed. Examples are given for strategies to study excitation energy transfer by the selective introduction of specifically modified chromophores. IUPAC numbering [1,2] is used throughout (Figure 1B).