(SEMINAR) Davide Accomasso, PhD Faculty of Chemistry, University of Warsaw

event date: 26 April 2024

The Centre of New Technologies, University of Warsaw invites to a seminar by

Davide Accomasso, PhD

Faculty of Chemistry, University of Warsaw

Excited-state dynamics of carotenoids in photoresponsive and light-harvesting proteins

Date: 26th April 2024, Friday

Time: 12:00 pm (Central European Time)

Host: Professor Bartosz Trzaskowski

The seminar will be in the CeNT aula hall (00.142) on the main floor.


Carotenoids are natural polyenic pigments synthesized by photosynthetic organisms, such as plants, bacteria and algae. In these organisms, carotenoids can act both as light-harvesting pigments and photoprotective compounds. These natural functions of carotenoids are directly linked to the electronic states of such pigments, featuring a dark (non-fluorescent) first singlet excited state S1, a bright S2 state, and a number of additional states whose nature is still under debate [1]. Among them, a dark SX state was proposed to act as an intermediate in the S2 → S1 decay which follows the photo-excitation [2,3]. Moreover, spectroscopic investigations suggested that an additional singlet excited state, called S*, is formed before the relaxation to the ground state [4]. While SX appears to be involved in light harvesting, S* plays a role in photoprotection.

In this talk, I will show how simulations of the nonadiabatic excited-state dynamics, based on a semiempirical QM/MM technique and the surface hopping method [5], can uncover the nature of the aforementioned SX and S* states of carotenoids and their roles in photoresponsive and light-harvesting proteins. In particular, in the first part of the talk, I will show the results of excited-state dynamics simulations of lutein (one of the most abundant carotenoids in nature) in two different light-harvesting complexes of plants, namely LHCII [6] and CP29 [7]. Next, I will present nonadiabatic dynamics simulations of the keto-carotenoid canthaxanthin in the Orange Carotenoid Protein (OCP) [8], a photoresponsive protein employed by cyanobacteria for photoprotection.

[1] T. Polívka and V. Sundström. Chem. Phys. Lett., 477 1 (2009)
[2] G. Cerullo, D. Polli, G. Lanzani, S. De Silvestri, H. Hashimoto, and R. J. Cogdell. Science, 298 2395 (2002)
[3] D. Accomasso, S. Arslancan, L. Cupellini, G. Granucci, and B. Mennucci. J. Phys. Chem. Lett., 13 6762 (2022)
[4] V. Mascoli, N. Liguori, P. Xu, L. M. Roy, I. H.M. van Stokkum, and R. Croce. Chem, 5 2900 (2019)
[5] G. Granucci, M. Persico, and A. Toniolo. J. Chem. Phys., 114 10608 (2001)
[6] L. M. Pedraza González, D. Accomasso, L. Cupellini, G. Granucci, and B. Mennucci. Photochem. Photobiol. Sci., 23 303 (2024)
[7] D. Accomasso, G. Londi, L. Cupellini and B. Mennucci. Nat. Commun., 15 847 (2024)
[8] A. Arcidiacono, D. Accomasso, L. Cupellini, and B. Mennucci. Chem. Sci., 14 11158 (2023)