Excitonic Nature of Carotenoid-Phthalocyanine Dyads and Its Role in Transient Absorption Spectra.

ABSTRACT: Artificial carotenoid-tetrapyrrole dyads have been extensively used as model systems to understand the quenching mechanisms that occur in light-harvesting complexes during nonphotochemical quenching. In particular, dyads containing a carotenoid covalently linked to a zinc phthalocyanine have been studied by transient absorption spectroscopy, and the observed signals have been interpreted in terms of an excitonically coupled state involving the lowest excited states of the two fragments. If present, such excitonic delocalization would have significant implications on the mechanism of nonphotochemical quenching. Here, we use quantum chemical calculations to show that this delocalization is not needed to reproduce the transient absorption spectra. On the contrary, the observed signals can be

SUBMITTER: Slama V 

PROVIDER: S-EPMC9136948 | biostudies-literature | 2022 May

REPOSITORIES: biostudies-literature