Related Porphyrin Research Articles

Magnetic and spectroscopic probes for FeOFe linkages in hemin systems

Magnetic and spectroscopic properties of μ-oxo- bis-hemins from natural and structurally related porphyrins were investigated as probes for ascertaining the presence or absence of Fe III-O-Fe III linkages between hemin moieties of hemeproteins. Magnetic susceptibilities of solids from 2.2 to 293 °K were investigated. The data fit the temperature variations expected for a pair of antiferromagnetically coupled S= 5 2 , iron(III) porphyrins with J values of

Pyrroles and related compounds. XX. Syntheses of coproporphyrins.

Coproporphyrin-I has been synthesised by modifications of Fischer's original methods; Coproporphyrin-II has been synthesised by three methods including a variant of the MacDonald method, involving self-condensation of a 5-formylpyrromethane-5′-carboxylic acid. Coproporphyrins-III and -IV and a related porphyrin tricarboxylic acid have been synthesised by application of the a-oxobilane route. The products in each case were single isomerically pure species as shown by spectroscopic, chromatographic, X-ray, and m.p. comparisons with each other and with authentic samples prepared by other workers.

The proton magnetic resonance spectra of porphyrins. Part V. Syntheses and spectra of some meso-methylated porphyrins

A number of new meso-methyl- and related meso-unsubstituted porphyrins have been synthesised including 2,3-dithyl-γ-meso,1,4,5,8-pentamethylporphin. Comparison of the proton magnetic resonance spectra of the two series confirms our earlier suggestion that the meso-methyl group exerts a pronounced steric effect if the two neighbouring β-positions are occupied, and that there is also an overall decrease in ring current (ca. 3%). These and other new results show that the precise position and multiplicity of the meso and NH-proton resonances of meso-unsubstituted porphyrins in trifluoroacetic acid are not dependent only on the nature of the two neighbouring β-substituents, but are also affected to a lesser extent by the other substituents.

Relative oöporphyrin content and porphyrin forming capacity of wild-type and white-egg Japanese quail uterine tissue.

SummarySpectrophotometric analysis of wild-type and mutant quail uterine extracts has shown there is much less ooporphyrin in the mutant uterus than in the wild-type uterus, both before and after the expected time of superficial pigment deposition. The data also show that after the time of expected superficial pigment deposition there is significantly less ooporphyrin in the mutant uterus than there was before. In vitro incubation of wild-type and mutant quail uterine homogenates with delta-aminolevulinic acid (ALA) produced data indicating that mutant homogenates have less capacity for ooporphyrin synthesis than do wild-type homogenates. The evidence suggests that some factor other than ALA availability prevents mutant homogenates from synthesizing as much ooporphyrin as wild-type homogenates.

Prof. J. B. Conant, For.Mem.R.S

PROF. JAMES BRYANT CONANT held the position of professor of chemistry and head of the Chemical Faculty at Harvard up to 1933, when he was elected to the high office of president of the University. In relinquishing his post in the Department of Chemistry, although the University as a whole gained, American science lost to a large extent one of its most distinguished investigators. Nevertheless, Prof. Conant never abandoned chemical research, and has published original work continuously up to the present time. His researches cover an impressive range of subjects, and are especially noteworthy by the novelty of the physical chemical approach and the skill with which this has been employed in the field of organic chemistry. Although it is impossible adequately to indicate the scope of his work in % short summary, some idea of his versatility can be gained by mention of some of the major themes. These include: (a) A comprehensive study of the addition of phosphorus halides to organic compounds in the course of which entirely novel reactions were brought to light; (6) Numerous publications dealing with the study of oxidation-reduction potentials of organic compounds, including haemin and related substances; (c) Investigations of free radicals and the kinetics of their formation; (d) The application of physical methods to structural problems of organic chemistry; (e) The study of reaction mechanism as applied both to substitution displacements and keto-enol tautomerism; (/) Researches on the constitution of chlorophyll and the related porphyrin groups; (g) Biological-chemical applications of induced radioactive indicators.