Molecular systems and supramolecular assemblies composed of many chromophores are common in chemistry, biochemistry, and material science. When two or more chromophores are close together, their properties deviate from the properties of their constituent moieties. Excitation can delocalize over several chromophores, creating what are known as molecular excitons, which shape the optical and chiroptical properties of the assembly. New photophysical pathways arise as the result of interactions between chromophores in the excited state, such as excitation energy transfer and charge separation.
We develop new methods to describe multichromophoric systems from the first-principles quantum chemical properties of their constituents, and to study their optical properties. We combine multiscale quantum chemical calculations and theoretical models for the coupling of excitons to vibrations in order to describe spectroscopy and photophysics in these systems. We focus on biosystems such as light-harvesting complexes, nucleic acids, and proteins.
In light-harvesting complexes, protein-bound pigments are responsible for absorbing sunlight and transporting the excitation energy towards reaction centers where charge separation takes place. The flow of energy within between complexes is dictated by the multichromophoric properties of the aggregate and can be probed via ultrafast nonlinear spectroscopy. Our research is devoted to linking the structure of these complexes to their optical, photophysical, and energy transport properties. This work is done in collaboration with the groups of Carles Curutchet in Barcelona, Roberta Croce in Amsterdam, Nicoletta Liguori in Barcelona, and Giulio Cerullo in Milan.
Three selected publications
Probing the Effect of Mutations on Light Harvesting in CP29 by Transient Absorption and First-Principles Simulations
Saraceno, P.; Sardar, S.; Caferri, R.; Camargo, F.V.A.; Dall’Osto, L.; D’Andrea, C.; Bassi, R.; Cupellini, L.; Cerullo, G. & Mennucci, B.
J. Phys. Chem. Lett. 6398–6408 (2024)
The atomistic modeling of light-harvesting complexes from the physical models to the computational protocol
Cignoni, E.; Slama, V.; Cupellini, L. & Mennucci, B.
J. Chem. Phys. 156, 120901 (2022)
Quantum Chemical Modeling of the Photoinduced Activity of Multichromophoric Biosystems.
Segatta, F., Cupellini, L., Garavelli, M. & Mennucci, B.
Chem. Rev. , vol. 119 , p. 9361-9380 (2019)