Synthesis and Photophysical Properties of Fullerene–Phthalocyanine–Porphyrin Triads and Pentads

The synthesis and photophysical properties of several fullerene–phthalocyanine–porphyrin triads ( 1 – 3 ) and pentads ( 4 – 6 ) are described. The three photoactive moieties were covalently connected in an one‐step synthesis through 1,3‐dipolar cycloaddition to C 60 of the corresponding azomethine ylides generated in situ by condensation reaction of a substituted N ‐porphyrinylmethylglycine derivative and an appropriated formyl phthalocyanine or a diformyl phthalocyanine derivative, respectively. ZnP‐C 60 ‐ZnPc ( 3 ), (ZnP) 2 ‐ZnPc‐(C 60 ) 2 ( 6 ), and (H 2 P) 2 ‐ZnPc‐(C 60 ) 2 ( 5 ) give rise upon excitation of their ZnP or H 2 P components to a sequence of energy and charge‐transfer reactions with, however, fundamentally different outcomes. With (ZnP) 2 ‐ZnPc‐(C 60 ) 2 ( 6 ) the major pathway is an highly exothermic charge transfer to afford (ZnP)(ZnP .+ )‐ZnPc‐(C 60 .− )(C 60 ). The lower singlet excited state energy of H 2 P (i.e., ca. 0.2 eV) and likewise its more anodic oxidation (i.e., ca. 0.2 V) renders the direct charge transfer in (H 2 P) 2 ‐ZnPc‐(C 60 ) 2 ( 5 ) not competitive. Instead, a transduction of singlet excited state energy prevails to form the ZnPc singlet excited state. This triggers then an intramolecular charge transfer reaction to form exclusively (H 2 P) 2 ‐ZnPc .+ ‐(C 60 .− )(C 60 ). A similar sequence is found for ZnP‐C 60 ‐ZnPc ( 3 ).