A Panchromatic Supramolecular Fullerene-Based Donor-Acceptor Assembly Derived from a Peripherally Substituted Bodipy-Zinc Phthalocyanine Dyad

A panchromatic 4,4-difluoro4-bora-3a,4a-diaza-s-indacene -zinc phthalocyanine conjugate (Bodipy-ZnPc) 1 was synthesized starting from phthalocyanine aldehyde 4, via dipyrromethane 3 and dipyrromethane 2. Conjugate I represents the first example in which it Bodipy unit is tethered to the peripheral position of it phthalocyanine core. Electrochemical and optical measurements provided evidence for strong electronic interactions between the Bodipy and ZnPc constituents in the ground state of 1. When conjugate 1 is Subjected to photoexcitation in the spectral region corresponding to the Bodipy absorption. the strong fluorescence characteristic of the latter subunit is effectively quenched (i.e., >= 97%). Excitation spectral analysis confirmed that the photoexcited Bodipy and the tethered ZnPc subunits interact and that intraconjugate singlet energy transfer Occurs with all efficiency of ca. 25%. Treatment Of conjugate 1 with N-pyridylfulleropyrrolidine (8). an electron-acceptor system containing it nitrogen ligand, gives rise to the novel electron donor-acceptor hybrid 1 <-> 8 through ligation to the ZnPc center. irradiation Of the resulting supramolecular ensemble within the visible range leads to it charge-separated Bodipy-ZnPc center dot+-C-60(center dot-) radical-ion-pair state, through it sequence of excited-state and charge transfers. characterized by it remarkably long lifetime of 39.9 ns in toluene.