ISSN:
1042-7147
Keywords:
catalysis
;
multi-electron transfer
;
multi-photon excitation
;
photochemistry
;
photoelectrochemistry
;
phthalocyanines
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
At different phthalocyanines and related macrocycles it is shown that one-step, multi-electron transfer and one-step, multi-change of oxidation states occur. At first, the catalytic oxidations of thiols and sulfide in the presence of different Co(II)phthalocyanines are discussed. Thiolates are oxidized to disulfides via a two-electron transfer whereas the reduction of O2 occurs via a two- or four-electron transfer to H2O2 or H2O. Zn(II) and Al(III)phthalocyanines are efficient sensitizers for the conversion of triplet to singlet dioxygen under illumination with visible light. In the presence of thiolates or sulfides an efficient photo-oxidation to sulfonic acids or sulfate is observed. The oxidation state of sulfur changes from -2 to +4 or +6, respectively. This process of singlet oxygen reactions finds application in the photodynamic therapy of cancer. The unsubstituted zinc(II)-phthalocyanine as p-type molecular semiconductor can efficienfly reduce O2 in photoelectrochemical experiments whereas zinc(II)phthalocyanines with electronwithdrawing groups as n-type conductors are active in the photoelectrochemical oxidation of thiols. All processes include multi-electron transfer. The electrocatalytic reduction of CO2 is investigated at electrodes modified with Co(II)phthalocyanine. In particular, the phthalocyanine in a polyvinylpyridine membrane is active, so the CO2 is reduced to CO by multi-electron transfer. In addition, two photon excitations of a Mg(II)phthalocyanine are presented and some examples are reviewed.
Additional Material:
15 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pat.1995.220060305
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