Multiple photosynthetic reaction centers composed of supramolecular assemblies of a zinc porphyrin dendrimer with pyridylnaphthalenediimide

Abstract

Multiple photosynthetic reaction centers have successfully been constructed using a supramolecular complex of zinc porphyrin dendrimer [D(ZnP) 16 ] with pyridylnaphthalenediimide (PyNIm) in benzonitrile. The apparent formation constant determined from the fluorescence quenching of the singlet excited state of porphyrin moieties by PyNIm is significantly larger than that determined from the UV-vis spectral change. This indicates that efficient energy migration occurs between the porphyrin units of the dendrimer prior to the electron transfer from the singlet excited state of zinc porphyrin to PyNIm. The charge-separated (CS) state has been successfully detected as the transient absorption spectrum in the laser flash photolysis. The CS lifetime of in the supramolecular complex of D(ZnP) 16 with PyNIm was determined to be 0.83 ms at 298 K.