Intramolecular charge-transfer state of carotenoids siphonaxanthin and siphonein: function of non-conjugated acyl-oxy group

0532625 - BC 2021 RIV NL eng J - Článek v odborném periodiku
Staleva-Musto, H. - Kuznetsova, V. - Bína, David - Litvín, Radek - Polívka, Tomáš
Intramolecular charge-transfer state of carotenoids siphonaxanthin and siphonein: function of non-conjugated acyl-oxy group.
Photosynthesis Research. Roč. 144, č. 2 (2020), s. 127-135. ISSN 0166-8595. E-ISSN 1573-5079
Grant CEP: GA ČR(CZ) GA16-10417S
Institucionální podpora: RVO:60077344
Klíčová slova: Carotenoid * Excited-state dynamics * Ultrafast spectroscopy * Charge-transfer state
Obor OECD: Biophysics
Impakt faktor: 3.573, rok: 2020
Způsob publikování: Open access
https://link.springer.com/article/10.1007/s11120-019-00694-x

We used ultrafast transient absorption spectroscopy to study excited-state dynamics of two keto-carotenoids, siphonaxanthin and siphonein. These two carotenoids differ in the presence of dodecanoyl-oxy group in siphonein, which is attached to the C19 carbon on the same side of the molecule as the conjugated keto group. We show that this dodecanoyl-oxy group, though not in conjugation, is still capable of modifying excited state properties. While spectroscopic properties of siphonein and siphonaxanthin are nearly identical in a non-polar solvent, they become markedly different in polar solvents. In a polar solvent, siphonein, having the dodecanoyl-oxy moiety, exhibits less pronounced vibrational bands in the absorption spectrum and has significantly enhanced characteristic features of an intramolecular charge-transfer (ICT) state in transient absorption spectra compared to siphonaxanthin. The presence of the dodecanoyl-oxy moiety also alters the lifetimes of the S-1/ICT state. For siphonaxanthin, the lifetimes are 60, 20, and 14 ps in n-hexane, acetonitrile, and methanol, whereas for siphonein these lifetimes yield 60, 11, and 10 ps. Thus, we show that even a non-conjugated functional group can affect the charge-transfer character of the S-1/ICT state. By comparison with fucoxanthin acyl-oxy derivatives, we show that position of the acyl-oxy group in respect to the conjugated keto group is the key feature determining whether the polarity-dependent behavior is enhanced or suppressed.
Trvalý link: http://hdl.handle.net/11104/0311061