نتایج جستجو برای: expanded porphyrins

تعداد نتایج: 64232  

2004
Kathryn E. Splan Charlotte L. Stern Joseph T. Hupp

The synthesis of a pair of electron-deficient porphyrin building blocks and their resulting coordinatively linked supramolecular assemblies are described. The perfluorophenyl substituted porphyrins feature pendant pyridines which, upon reaction with Re(CO)5Cl assemble into discrete dimers and tetramers, as dictated by the geometry of the porphyrin monomer. The resulting supramolecular complexes...

Journal: :Clinical chemistry 1983
S Schwartz J Dahl M Ellefson D Ahlquist

We describe a new, specific, quantitative method for fecal blood, based on conversion of nonfluorescing heme to fluorescing porphyrins, that obviates serious deficiencies inherent in currently used tests. A two-reagent system is used to determine the two hemoglobin-related fractions that are found in feces. The hot citric acid extract includes only the variable fraction of porphyrins that have ...

Journal: :Clinical chemistry 1982
M A Alleman J H Wilson J W van den Berg A Edixhoven-Bosdijk L M van Gastel-Quist

Porphyria cutanea tarda is thought to result from an inherited deficiency of uroporphyrinogen decarboxylase (EC 4.1.1.37) in some patients. Present methods for determining uroporphyrinogen decarboxylase activity are time consuming, so we examined the pattern of porphyrins formed from porphobilinogen by hemolysates as a possible marker for hereditary porphyria cutanea tarda. After the hemolysate...

Journal: :Clinical chemistry 1971
S R Heller R F Labbe J Nutter

Recent investigations concerning the significance of porphyrins in erythrocytes indicate a need for a rapid quantitative assay, easily adaptable to routine clinical use. To till this need, we have developed a simplified procedure for the measurement of porphyrins (essentially protoporphyrin) in whole blood. Blood is stirred with acetone-ethyl acetate and the porphyrins are extracted with formic...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2015
John R Swierk Dalvin D Méndez-Hernández Nicholas S McCool Paul Liddell Yuichi Terazono Ian Pahk John J Tomlin Nolan V Oster Thomas A Moore Ana L Moore Devens Gust Thomas E Mallouk

Solar fuel generation requires the efficient capture and conversion of visible light. In both natural and artificial systems, molecular sensitizers can be tuned to capture, convert, and transfer visible light energy. We demonstrate that a series of metal-free porphyrins can drive photoelectrochemical water splitting under broadband and red light (λ > 590 nm) illumination in a dye-sensitized TiO...

2012
Abedien Zabardasti

The aromatic character of porphyrins can also be seen by NMR spectroscopy. Studies performed in the last decades demonstrated that 1H NMR spectra are very informative and adequately reflect the structural features of porphyrins.[1] The presence of the extended delocalized -electron system of the porphyrin macrocycle gives rise to a strong ring current in the molecules placed in the magnetic fi...

Journal: :Journal of clinical chemistry and clinical biochemistry. Zeitschrift fur klinische Chemie und klinische Biochemie 1982
P Martásek M Jirsa V Kordac

Porphyrinogens were determined in very fresh, diluted morning urine in two types of hepatic porphyria, using a simple and very quick spectrophotometric method. It was shown that acidification by itself is insufficient for the complete conversion of colourless porphyrinogens into porphyrins in photometric determination of porphyrins in diluted urine. A correlation was shown between percentual co...

Journal: :Journal of clinical pathology 1971
O Gutniak M Kopéc J Nieczaj

The ability of erythrocytes to synthesize porphyrins from delta-aminolaevulic acid was compared in healthy people, patients with true iron-deficiency anaemia, and anaemic patients with rheumatoid arthritis. Porphyrin synthesis was found to be impaired in true iron deficiency but not in rheumatoid arthritis cases showing a similar degree of anaemia. The delta-aminolaevulic acid dehydratase activ...

Journal: :The Journal of biological chemistry 1951
T C CHU SISTER A A GREEN E J CHU

A micromethod for detecting and determining various porphyrins extracted from biological materials, especially nervous tissues (I), is needed. The technique of filter paper chromatography by Consden, Gordon, and Martin (a), with modification by Williams and Kirby’s capillary ascent (3), has been applied to the problem in this study. The recent paper by Nicholas and Rimington (4) on partition ch...

Journal: :journal of physical & theoretical chemistry 2005
m. keshavarz k. zare m. akbarzadeh m.r khoshchehreh a.f.b mahdavi

in the present work, the interaction of three water soluble porphyrins, tetra (p-trimethyle) ammoniumphenyl porphyrin iodide (tapp) as a cationic porphyrin, tetra sodium meso-tetrakis (p-sulphonatophenyle) porphyrin (tspp) as an anionic porphyrin and manganese tetrakis (p-sulphonato phenyl)porphinato acetate (mntspp) as a metal porphyrin, with dna have been studied by isothermaltitration microc...

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