Two-electron oxidation of cobaltous octaethylporphyrin [Co(II)(Et)(8)P] yields a stable pi-cation radical [Co(III)(Et)(8)P](2+.), the optical spectrum of which exhibits spectral changes dependent upon the nature of the counterion. Comparison of these spectra with those of Compounds I of horseradish peroxidase and catalase leads us to propose that these Compounds I contain a pi-cation radical of the heme prosthetic group. This proposal explains the oxidation level, optical spectra, and stability of the primary compounds without recourse to properties such as stoichiometric mixtures of special porphyrins, stable Fe(V) porphyrins, or unique conformers of heme porphyrins. Explanations are advanced to account for the missing electron spin resonance signal of Compound I of horseradish peroxidase.

Catalase↗

PubMed1970

pi-Cation radicals and dications of metalloporphyrins.

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Electrolysis↗

PubMed1970

A convenient and economical preparation of L-methionine-methyl-d3.

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Deuterium↗

PubMed1970

The pi-Cation Radical of Chlorophyll a.

Chlorophyll a undergoes reversible one-electron oxidation in dichloromethane and butyronitrile. Removal of the electron by controlled potential electrolysis or by stoichiometric charge transfer to a known cation radical yields a radical (epr line width = 9 gauss, g = 2.0025 +/- 0.0001) whose optical spectrum is bleached relative to that of chlorophyll. Upon electrophoresis this bleached species behaves as a cation. By comparison with the known properties of pi-cation radicals of porphyrins and chlorins, the chlorophyll radical is also identified as a pi-cation. Further correlation of optical and epr properties with published studies on photosynthesis leads to the conclusion that oxidized P700, the first photochemical product of photosystem I in green plants, contains a pi-cation radical of the chlorin component of chlorophyll a. This radical is the likely source of the rapidly-decaying, narrow epr signal of photosynthesis.

Journal Article↗

PubMedDate not supplied

Durene-capped porphyrin complexes of iron(II). Binding of imidazoles, and spectroscopic trends within Fe(porp)B(L) species (B = imidazole base; L = RNC, CO, O2).

Solution equilibria are presented for in situ reactions of the type FeII(porp) + B----FeII(porp)B, where porp represents the dianion of some durene-capped porphyrins with variable length linking methylene straps, and B is 1-methyl, 1,2-dimethyl, or 1,5-dicyclohexylimidazole. Increasing distortion of the porphyrin skeleton has no effect on coordination of B at the unhindered side of the capped porphyrin. Increasing skeleton distortion gives rise to regular trends within the visible spectra of the free base porphyrins, the hemin (FeIII) chlorides, and six-coordinate FeII(porp)B(L) species (L = RNC, CO, O2), while the visible spectra of FeII(porp) and of FeII(porp)B species are independent of the nature of porp and B, which may be related to greater flexibility of the lower coordination number systems. v(CO) data for the FeII(porp)(CO)B species are discussed briefly.

Benzene Derivatives↗

PubMedDate not supplied

The multilingual videotape project: community involvement in a unique health education program.

The large number of Southeast Asian, Hispanic, and Portuguese immigrants in Rhode Island face formidable language and cultural barriers in gaining access to the health care that they need. As the funding for refugee-specific programs diminishes, the focus is on programs that encourage self-sufficiency, assist in gaining access to mainstream health care, and involve a collaboration among service agencies and the communities they serve. On behalf of a coalition of health care and community agencies, Women and Infants Hospital of Rhode Island received a private foundation grant to produce nine multilingual videotapes that would educate immigrants and refugees about health issues specific to them and help them access the health care system. The project was structured to maximize the involvement of the various communities and to "empower" community members in working with mainstream service agencies. Coalition and other community members provided input into topic selection, script content, and presentation methods for the videotapes that would be culturally appropriate. During the 2-year project, nine videotapes were produced with narration in seven languages. Copies of the videotapes were distributed free of charge to coalition members.

Asia, Southeastern↗