Photophysics and photoinduced-electron-transfer reactions of zinc and free-base octaethylporphycenes

Journal Article · Thu Apr 02 04:00:00 EST 1992 · Journal of Physical Chemistry

DOI:https://doi.org/10.1021/j100186a048· OSTI ID:263821

Berman, A; Michaeli, A; Feitelson, J ^[1]

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1. Hebrew Univ. of Jerusalem (Israel); and other

The photoexcited triplet states of free-base and zinc octaethylporphycenes (h{sub 2}OEPC and ZnOEPC, respectively) were investigated by laser photolysis in the liquid phase and by time-resolved CW-EPR spectroscopy in partially oriented liquid crystal matrices. The triplet and fluorescence yields of H{sub 2}OEPC are temperature dependent, and at room temperature they are lower by an order in magnitude than those of ZnOEPC. This temperature dependence is interpreted in terms of a thermally activated excited state in the singlet manifold, {approx} 2.5 kcal mol{sup -1} above S{sub 1}. Frozen solutions of both porphycenes exhibit strong triplet EPR spectra, from which the magnetic and spin dynamics could be extracted. electron transfer from the triplet state of H{sub 2}OEPC{sup T} and ZnOEPC{sup T} to duroquinone (DQ) was studied by the Fourier transform EPR method. The two triplet porphycenes transfer an electron to produce a spin-polarized anion radical DQ with a dominating radical-pair mechanism and a negligible contribution of triplet mechanism, due to mixing of in-plane and out-of-plane active spin states. 36 refs., 8 figs., 3 tabs.

• Sponsoring Organization: USDOE
• OSTI ID: 263821
• Journal Information: Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 7 Vol. 96; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
40 CHEMISTRY
ELECTRON SPIN RESONANCE
ELECTRON TRANSFER
PHOTOCHEMISTRY
PHOTOLYSIS
PORPHYRINS
RADICALS
TIME RESOLUTION
ZINC COMPLEXES