Light-harvesting composites of directly connected porphyrin–phthalocyanine dyads and their coordination dimers

Directly linked porphyrin (Por)–phthalocyanine (Pc) heterodyads (H2Por–H2Pc and H2Por–ZnPc) with an imidazolyl group at porphyrin’s meso-position were synthesized. Introduction of a zinc ion into the porphyrin afforded stable complementary dimers of the heterodyads. The heterodyads and their dimers gave extensive and strong absorption bands owing to the porphyrin and phthalocyanine components and induced an efficient energy transfer from porphyrin to phthalocyanine. Strong fluorescence from phthalocyanine was observed in the case of H2Por–H2Pc.