A Simple Artificial Light Harvesting Dyad as a Mimic of Nonphotochemical Quenching in Green Plants

BERERA, RUDI; VAN STOKKUM, IVO H. M.; HERRERO, CHRISTIAN; VENGRIS, MIKAS; KODIS, GERDENIS; PALACIOS, RODRIGO E.; VAN AMERONGEN, HERBERT; VAN GRONDELLE, RIENK; GUST, DEVENS; MOORE, THOMAS A.; MOORE, ANA L.; KENNIS, JOHN T. M.

Femtochemistry VII: Fundamental Ultrafast Processes in Chemistry, Physics, and Biology

Elsevier B.V.

Lugar: Amsterdam, The Netherlands; Año: 2006; p. 387 - 390

Activation of the thermal dissipation of excess energy in plants PSII (nonphotochemical quenching) is linked to the conversion of a 9 double-bond carotenoid (violaxanthin) into an 11 double-bond carotenoid (zeaxanthin) [I]. It has been suggested that the increase in the conjugation length turns the carotenoid from a non-quencher into a quencher of chlorophyll excited states, but there is no unequivocal evidence for this. We present results from transient absorption spectroscopy on a model system made up of a phthalocyanine molecule (Pc) covalently linked to carotenoids with conjugation lengths of 9, 10, or 11. We show that a carotenoid can quench the Qy energy of Pc and the conjugation length is critical to the process. By using target analysis of the timeresolved data, we show that the quenching mechanism is energy transfer.