Modelling excitation energy transfer in covalently linked molecular dyads containing a BODIPY unit and a macrocycle

With the help of time-dependent density functional theory coupled to an implicit solvation scheme (the polarisable continuum model), we have investigated the singlet-singlet Excitation Energy Transfer (EET) process in a panel of large BODIPY-macrocycle dyads. We have first considered different strategies to compute the electronic coupling in a representative BODIPY-zinc porphyrin assembly and, next evaluated the performances of the chosen computational protocol on several BODIPY-porphyrinoid molecular architectures for which the EET rate constants have been experimentally measured. This step showed the robustness of our approach, which is able to reproduce the magnitude of the measured rate constants in most cases. We have finally applied the validated methodology on newly designed dyads combining a BODIPY unit and an azacalixphyrin macrocycle, a recently synthesised porphyrin analogue that displays exceptional optical properties. This work allowed us to propose new molecular architectures presenting improved properties and also to highlight the interest of using azacalixphyrin as a building block in molecular light-harvesting antennas.