Excitation Relaxation Dynamics of Carotenoids in Solutions and in Photosynthetic Pigment Protein Complexes.

Abstract

Excited state dynamics of carotenoids were investigated to access relationship among molecular structures, dynamics, and energy transfer to chlorophylls in photosynthetic pigment protein complexes. The relaxation kinetics are strongly affected by conjugation systems, such as conjugation length and an additional conjugation with a keto-carbonyl group. Energy transfer pathways also depend on the conjugation systems; the energy transfer to chlorophyll occurred via the S2 state of carotenoids for polyene-type carotenoids, whereas the S2 transfer was not recognized for the carotenoids which have a keto-carbonyl group in their conjugations.