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Biomedical subjects

A Gold

Publications and source records attributed to A Gold.

113 records · Page 7Linked to original sources
PubMedDate not supplied

N-porphyrinylamino and -amido compounds by addition of an amino or amido nitrogen to a porphyrin meso position.

This report describes the synthesis and characterization of a series of octaethylporphyrin derivatives in which the porphyrin pi-network is connected to phenyl, 3-fluoranthenyl, or 1-pyrenyl aromatic systems through a meso amino or amido nitrogen. Metal-free bases and zinc(II) and iron(III) complexes have been obtained. These compounds represent the first examples of linkages between porphyrins and extended pi-networks through a nitrogen atom directly attached to a porphyrin meso position. 1H NMR studies of the metal-free bases and zinc complexes showed that in the amido-linked adducts, the plane containing the aryl substituent was oriented perpendicular to the plane of the porphyrin. Linkage through the secondary amino nitrogen, however, allowed the aryl plane to rotate toward coplanarity with the porphyrin plane, resulting in conjugation of the highest occupied aryl and porphyrin molecular orbitals through the nitrogen lone pair. In developing routes to the amino-linked compounds, the facile formation of fused azaaryl chlorins via an oxidative intramolecular cycloaddition was observed. An aryl carbon ortho to the meso linkage attacked the beta-carbon of an adjacent pyrrole ring, accompanied by 1,2-migration of a pyrrole beta-ethyl substituent and a two-electron oxidation of the initially formed macrocycle. The resulting structures are analogous to benzochlorins. The electronic spectra of the metal-free bases are characterized by intense, long-wavelength bands in the visible region. Molecular structures of the chloroferric complexes of the azabenzofluorantheno- and azabenzpyrenoporphyrin macrocycles (derived from fusion of the fluoranthenyl and pyrenyl substituents, respectively) were obtained by X-ray diffraction. The porphyrin moiety in the azabenzofluoranthenoporphyrin adopted a gable structure, with a 22 degrees fold along a diagonal including the pyrrole-ring C4 and C16 alpha-carbons. By contrast, the azabenzpyrenoporphyrin was virtually planar.

Hemoglobins↗
PubMedDate not supplied

Synthesis of [4,5,6,8-(13)C4]guanine, a reagent for the production of internal standards of guanyl DNA adducts.

Using readily available labeled compounds, [4,5,6,8-(13)C4]guanine was synthesized in high overall yield. Intermediates as well as the final product were characterized by 1H NMR, 13C NMR, and high resolution mass spectrometry. The labeled guanine was used to generate [13C4]-labeled analogs of the guanine adducts, N2,3-ethenoguanine and 7-(2-hydroxyethyl)guanine. The application of such adducts in isotope dilution mass spectrometry was illustrated with DNA samples from rats exposed to two different mutagenic compounds, vinyl chloride and ethylene oxide.

Animals↗