title: Sequential charge separation in two axially linked phenothiazine-aluminum(III) porphyrin-fullerene triads.
abstract: New supramolecular triads (PTZpy→AlPor-C(60), TPTZpy→AlPor-C(60)), containing aluminum(III) porphyrin (AlPor), fullerene (C(60)), and phenothiazine (phenothiazine = PTZ, 2-methylthiophenothaizine = TPTZ) have been constructed. In these triads the fullerene and phenothiazine units are bound axially to opposite faces of the porphyrin plane via covalent and coordination bonds, respectively. The ground- and excited-state properties of the triads and reference dyads are studied using steady-state and time-resolved spectroscopic techniques. The time-resolved data show that photoexcitation results in charge separation from the excited singlet state of the porphyrin to the C(60) unit, generating (Donor)py→AlPor(•+)-C(60)(•-), Donor = PTZ and TPTZ. A subsequent hole shift from the porphyrin to phenothiazine generates the charge-separated state (Donor)(•+)py→AlPor-C(60)(•-). The lifetime of the charge separation exhibits a modest increase from 39 ns in the absence of the donor to 100 ns in PTZpy→AlPor-C(60) and 83 ns in TPTZpy→AlPor-C(60). These lifetimes are discussed in terms of the electronic coupling between phenothiazine, the porphyrin, and C(60).
authors.affiliation: Department of Chemistry, Brock University, St. Catharines, Ontario, Canada.
authors.forename: Prashanth K
authors.initials: PK
authors.lastname: Poddutoori
authors.forename: Atula S D
authors.initials: AS
authors.lastname: Sandanayaka
authors.forename: Niloofar
authors.initials: N
authors.lastname: Zarrabi
authors.forename: Taku
authors.initials: T
authors.lastname: Hasobe
authors.forename: Osamu
authors.initials: O
authors.lastname: Ito
authors.forename: Art
authors.initials: A
authors.lastname: van der Est