title: A π-stacked porphyrin-fullerene electron donor-acceptor conjugate that features a surprising frozen geometry.
abstract: A "frozen" electron donor-acceptor array that bears porphyrin and fullerene units covalently linked through the ortho position of a phenyl ring and the nitrogen of a pyrrolidine ring, respectively, is reported. Electrochemical and photophysical features suggest that the chosen linkage supports both through-space and through-bond interactions. In particular, it has been found that the porphyrin singlet excited state decays within a few picoseconds by means of a photoinduced electron transfer to give the rapid formation of a long-lived charge-separated state. Density functional theory (DFT) calculations show HOMO and LUMO to be localized on the electron-donating porphyrin and the electron-accepting fullerene moiety, respectively, at this level of theory. More specifically, semiempirical molecular orbital (MO) configuration interaction (CI) and unrestricted natural orbital (UNO)-CI methods shed light on the nature of the charge-transfer states and emphasize the importance of the close proximity of donor and acceptor for effective electron transfer.
authors.affiliation: Dipartimento di Scienze e Tecnologie Chimiche, University of Rome-Tor Vergata, Italy.
authors.forename: Alina
authors.initials: A
authors.lastname: Ciammaichella
authors.forename: Pavlo O
authors.initials: PO
authors.lastname: Dral
authors.forename: Timothy
authors.initials: T
authors.lastname: Clark
authors.forename: Pietro
authors.initials: P
authors.lastname: Tagliatesta
authors.forename: Michael
authors.initials: M
authors.lastname: Sekita
authors.forename: Dirk M
authors.initials: DM
authors.lastname: Guldi