Exciplex mediated photoinduced electron transfer reactions of phthalocyanine-fullerene dyads

Marja Niemi*, Nikolai V. Tkachenko, Alexander Efimov, Heli Lehtivuori, Kei Ohkubo, Shunichi Fukuzumi, Helge Lemmetyinen

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


Evidences of an intramolecular exciplex intermediate in a photoinduced electron transfer (ET) reaction of double-linked free-base and zinc phthalocyanine-C-60 dyads were found. This was the first time for a dyad with phthalocyanine donor. Excitation of the phthalocyanine moiety of the dyads results in rapid ET from phthalocyanine to fullerene via an exciplex state in both polar and nonpolar solvents. Relaxation of the charge-separated (CS) state Pc center dot+-C-60(center dot-) in a polar solvent occurs directly to the ground state in 30-70 ps. In a nonpolar solvent, roughly 20% of the molecules undergo transition from the CS state to phthalocyanine triplet state Pc-3*-C-60 before relaxation to the ground state. Formation of the CS state was confirmed with electron spin resonance measurements at low temperature in both polar and nonpolar solvent. Reaction schemes for the photoinduced ET reactions of the dyads were completed with rate constants obtained from the time-resolved absorption and emission measurements and with state energies obtained from the fluorescence, phosphorescence, and voltammetric measurements.
Original languageEnglish
Pages (from-to)6884-6892
Number of pages9
JournalJournal of Physical Chemistry A
Issue number30
Publication statusPublished - 31 Jul 2008


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