initiators 1 and 2 show comparable efficiencies as do 4 and 5. In multilamellar vesicles (liposomes) of dipalmitoylphosphatidylcholine (DPPC) at 60.00 °C with a pH 7 buffer, 1.0 mM EDTA, under atmospheric oxygen, all of our initiators show a pronounced decrease in efficiency from the value obtained in chlorobenzene.This result is in contrast to the efficiencies obtained1 2345 6with 5 in liposomes at 50 °C (e = 0.25). We suggest that the high escape efficiency exhibited by 5 in bilayers may be attributed to its localization in a region of low microviscosity, e.g., near the terminal methyl groups of the acyl chains.11 The same reasoning would account for the slightly higher efficiency of 2 in bilayers compared to 1 since the diazene linkage for 2 would be in a region of lower microviscosity than that of 1.Of the initiators 1-3, 3 has the highest escape efficiency. We speculate that the hydrophobic effect12 provides a driving force for realignment of the lipid radicals once the diazene linkage is broken. This realignment of radicals would shear apart the radical centers and thus retard coupling of radicals during the initial encounter11 (see Figure 1).
The potassium cryptate salts of the title anions (I) and (II) are prepared by reaction of tetraphenylporphinato manganese(II) in THF with Cl‐ and O2‐, respectively (no yields given).
Offenbar können nicht nur ‐ wie bekannt ‐ Porphyrin‐Komplexe des Fe, Cr oder Mn eine Oxidation organischer Moleküle durch Sauerstoff‐Donatoren wie Iodosylbenzol, Peroxysäuren, Amin‐oxide oder das Hypochlorit‐Ion bewirken, sondern auch einfache lösliche Metallsalze scheinen dazu befähigt.
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