Rational design of perylene diimide macrocycles with diverse electron transfer properties in complexes with fullerene

Abstract

Perylene diimide (PDI)-based macrocycles offer a versatile platform for creating host–guest complexes with fullerenes. About 100 bay- and ortho-substituted PDIs, as well as their π-extended derivatives have been tested to select the best electron donor and electron acceptor systems. This work presents a computational study of macrocycles consisting of two PDI units linked by flexible spacers as hosts for C₆₀ fullerene. The results provide insight into their ground and excited state electronic properties and help to rationally design complexes with tailored photoinduced electron transfer behavior, thereby advancing the development of artificial photosystems. The results revealed that in the ground state, there is almost no electronic communication between macrocycle and fullerene. However, upon photoexcitation, the electron transfer from macrocycle to fullerene or vice versa was predicted, demonstrating a tunable directionality unprecedented in similar systems. The direction of electron transfer is determined by the electronic nature of the macrocycle. For electron-donating macrocycles, the electron is transferred from the macrocycle to fullerene, whereas for electron-accepting hosts, it occurs in the opposite direction. The electron transfer occurs within the normal Marcus region, with optimal electron transfer rates observed in specific complexes, making them interesting functional materials for organic solar cells. Based on the structure-electronic properties relationship, design principles for novel PDI-based macrocycles were formulated to guide chemists in developing advanced organic materials for photovoltaic applications.