Twisted Carotenoids Do Not Support Efficient Intramolecular Singlet Fission in the Orange Carotenoid Protein.
J Phys Chem Lett
; 14(26): 6135-6142, 2023 Jul 06.
Article
em En
| MEDLINE
| ID: mdl-37364284
ABSTRACT
Singlet exciton fission is the spin-allowed generation of two triplet electronic excited states from a singlet state. Intramolecular singlet fission has been suggested to occur on individual carotenoid molecules within protein complexes provided that the conjugated backbone is twisted out of plane. However, this hypothesis has been forwarded only in protein complexes containing multiple carotenoids and bacteriochlorophylls in close contact. To test the hypothesis on twisted carotenoids in a "minimal" one-carotenoid system, we study the orange carotenoid protein (OCP). OCP exists in two forms in its orange form (OCPo), the single bound carotenoid is twisted, whereas in its red form (OCPr), the carotenoid is planar. To enable room-temperature spectroscopy on canthaxanthin-binding OCPo and OCPr without laser-induced photoconversion, we trap them in a trehalose glass. Using transient absorption spectroscopy, we show that there is no evidence of long-lived triplet generation through intramolecular singlet fission despite the canthaxanthin twist in OCPo.
Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Carotenoides
/
Cantaxantina
Idioma:
En
Revista:
J Phys Chem Lett
Ano de publicação:
2023
Tipo de documento:
Article
País de afiliação:
Reino Unido