Abstract: A covalently linked porphyrin-phthalocyanine heterodimer was synthesied, the absorption spectra, fluorescence spectra, fluorescence lifetime and redox potantials were determined. There is a considerable overlap between the fluorescence spectrum of porphyrin and the ground state absorption spectrum of phthalocyanine, indicating that energy transfer should be extremly efficient. The efficiency and rate constant of intramolecular energy transfer (lEnT) from porphyrin moiety to phthalocyaneine in each model was measured in polar and non-polar solvent. Neither fluorescence quenching by dipole-dipole interaction, nor quenching by collision occurs in dilute mixture of monomers (1/1 mixture of TTP & PC). In contrast, selective excitation at 420nm of the heterodimer, a decrease of the porphyrin fluorescence, concomitant with a slight increase of phthalocyanine fluorescence occurs, indicating IEnT reaction takes place. The efficiency and rate constant of IEnT depends on heterodimer.Selective excitation of the phthalocyanine chromophore in heterodimer, intramolecular electron transfer (IET) takes place only. The efficiency of IET is rather high (38%). IEnT and IET process takes place in competition with different solvent. IEnT process is a very efficient in non-polar solvent, but IET process is a very efficient in polar solvent.

Key words: porphyrin, phthalocyanine, porphyrin-phthalocyanine heterodimer, intramolecular energy transfer, intramolecular electron transfer