Theoretical Study on Charge-Transfer Excitations of Buckycatcher-Fullerene Complexes

In particular, p/p stacking compounds have become of interest in new materials for photocatalysis, solar energy and phosphorescent organic light-emitting diodes. We investigate theoretically the photo-induced charge transfer in supramolecular chemistry. Buckycatcher (BC) molecules, bowl-shaped polycyclic hydrocarbons, have attracted attention as a new type of π conjugated compound. BC molecules with two corannulene or two sumanane subunits can form a complex (BC/C₆₀) with C₆₀ because of the π-π interaction between the convex surface of the C₆₀ and the concave faces of corannulene subunits of the BC. We have performed DFT and TD-DFT calculations on the structures and excitation spectrum of BC molecules and BC/C₆₀ complexes. The most stable structures are BC/C₆₀ in which the p–p stacking of the two corannulene subunits of BC and C₆₀ takes a concave–convex arrangement; therefore, the van der Waals contact is maximized. It is found that the charge-transfer-type excitations from BC to C₆₀ start at the ultraviolet light region. The BC/C₆₀ complexes and their derivatives are potential candidates as key elements for photovoltaic devices and other molecular electronic devices.