Sensitization metal-porphyrin

Fe(edta) is sensitive to O2 but is a useful gentle reductant which, for example, unlike many reductants, does not attack the porphyrin ring in metal-porphyrin complexes. For the reactions of Co(tpps) and Co(tap) + with (excess) Fe(edta) , predict the rate vs [Fe(edta) ] profile, and the effect of ionic strength on any second-order rate constants for the two reactions. 

The investigation of porphyrins with Ru" and Os" is probably of greater interest for comparison with Fe" porphyrins. These show enhanced metal (d )-porphyrin(rr ) backbonding that is manifested in additional features of their electronic spectra. Similarly the resonance Raman spectra of bis(pyridine) adducts of Fe", Ru" and Os" octaethylporphyrin are sensitive to the nature of the metal, and probably reflect changes in metal-porphyrin porphyrin core size and charge on the metal. A substantial correlation is available for the effect of axial ligation on the electronic spectra of metalloporphyrins. ... 

The [Ru(bpy)3] complexes are not the only sensitizers that can be used for cyclic water photodecomposition, indeed metal porphyrins, metal phthalo-cyanines, proflavin, and other compounds have been investigated as possible sensitizers. 

Meyerhoff et al have reported the use of a non-metallated porphyrin film as an ion-selective electrode. They have shown that the electropolymerized films offer significant selectivity for the detection of iodide over a wide range of anions. The lifetime of these electrodes was estimated by analyzing some of their characteristics such as sensitivity and detection limits. The effect of pH on the detection of iodide by the film-supported electrodes was also established. For pH values from 3 to 8, there is relatively little effect of the pH on the electrochemical response of the electrodes. At pH values higher than 8, the electrode response is affected by the interference by hydroxide ions. 

Carboxylic acid terminated poly(aryl ether) dendrimers acted as good-microreactors for the photooxidation of ( )-stilbene and E,E)-1,4-diphenyl-1,3-butadiene sensitized by 9,10-dicyanoanthracene. The photooxidation of ( )-stilbene led to benzaldehyde, while ( , )-1,4-diphenyl-1,3-butadiene afforded the peroxide (190) in quantitative yield. In photodynamic tumor therapy, the oxidation by metalloporphyrines as visible-light-sensitizers is very important. Some non-metallated porphyrine and tetraphenylchlorins have been reported to act as visible-light-sensitizers for the oxidation of alkenes. ... 

The sensitivity is very good for nickel and vanadium but for these metals for which distribution data would be of great value, the chromatographic process is the lirniting factor, heavy molecules are not eluted from the column with the exception of some porphyrins. This detector can be used to supply H/C and S/C profiles for hydrocarbon cuts with the chromatograph operating in the simulated distillation mode. 

As a result of strong electronic interactions between the two metalloporphyrin units, there is a substantial uncertainty in assigning oxidation states in mixed-valence group 2 complexes of redox-active metals, such as Co. Thus, although reduced neutral C02 derivatives can be reasonably well described as those of Co the location (metal versus porphyrin) of the electron hole(s) in the singly and doubly oxidized derivatives is not known definitively, and may be very sensitive to the medium [LeMest et al., 1996, 1997]. For example, in benzonitrile, the UV-vis spectmm of [(FTF4)Co2]" ... 

Most clinically used PDT sensitizers are metal-free porphyrins and porphyrin derivatives such as 56. Hematoporphyrin and its deriva-... 

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