摘要:

AbstractAbsorption and fluorescence properties of a magnesium containing porphyrin pigment are described which generally resemble those of the cholorophylls.In organic solvents the absorption bands are appreciably sharper than those of the naturally occurring magnesium porphyrins, while the fluorescence yield is approximately equal. Dilution of alcoholic or other water miscible solvents with buffer or water results in the formation of non‐fluorescing “colloidal” pigment forms. Two are forms are evident which differ spectroscopically and photochemically. Addition of detergent prevents formation of such forms or may restore the “in solution” p

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1967.tb08754.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

AbstractAbsorption and fluorescence properties of MgTBP were studied resulting from chemical oxidation and phtooxidation. The absorption spectra of the oxidised product in methanol and acetone are markedly different from those in aqueous solvents.

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1967.tb08755.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

AbstractThis paper reports studies of the reaction between methyl chloride and methylene produced by the photolysis of ketene in the two spectral regions Λ˜ 2600 Å to 3200 Å and Λ˜ 3220 Å. The course of reactin is best described by an abstraction processCH2+ CH2CI—Ch2CI + CH3followed by recombination of the CH3and CH2Cl radicals to yield C2H5, C2H5Cl, C2H4Cl2. The recombination processes are highly exothermic, and excitation of the product molecules occurs, which in the case of C2H5Cl and C2H4Cl2leads to some unimolecular decomposition. It is shown that the rate constant for the decomposition of ethyl chloride depends upon the wavelength of the radiation used to photolyse the ketene, and it is suggested that the excess energy with which the methylene is born is handed on to the alkyl radicals. A simplified kinetic analysis of the system is given, and it is shown that the relative reactivity of methylene towards ketene and methyl chloride increases with an increase in the energy of the methylene. The rates of product formation predicted on the basis of the kinetic scheme agree satisfactorily with the measured values.“Insertion” of methylene into C‐H and C‐CI bonds has been postulated by other workers. The present results are inconsisistent with an insertion mechanism, since such a mechanism does not account for all the observed products. The effect of wavelength of photolysis and of total pressure predicted on the basis of an insertion process is the reverse of that observe

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1967.tb08756.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

AbstractA series of fluorescent converter solutions is described, increasing the radiation intensity of flash lamps in the region 4000–6000 Å with a factor RΛ1.5˜3. The converter solutions are composed for use at an optical path of 1 cm, are easy to prepare, and are stable under high intensity irradiation with u. v. and visible l

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1967.tb08757.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

AbstractAqueous solutions of ethylene glycol and hydroxylamine in a 10:1 weight ratio were irradiated with an immersion‐type mercury‐vapour lamp, under static and dynamic conditions. The photochemical products obtained were fractionated by means of ion‐exchange resins, gel filtration on Sephadex G 10, paper chromatography, and thin‐layer chromatography.Biuret reaction was carried out on the various fractions, and different nitrogen forms as well as amino acids, before and after hydrolysis, were determined. Irradiation was found to bring about the formation of a number of organic compounds, including peptides. The yields of these compounds were determined in relation to the concentration and the flow rate of the solutions. The yields increased with increase in the two variables.The fractions richest in peptide compounds, coming from gel‐filtration and thin‐layer chromatography, were studied by the technique of DNP‐derivatives. The constituent amino acids were found to be glycine, β‐alanine, α‐alanine, glutamic acid and leucine. The average length of the chains cont

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1967.tb08758.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

AbstractOxygen evolution and fluorescence have been studied with isolated chloroplasts illuminated, in the absence of Hill reagents, by flashes or continuous light. As in whole cells, at least two substances are involved in the primary process leading to the oxygen evolution. The first, calledE,probably is the photochemical “complex” of System II. After a long period of darkness,Eis not active. It is activated in two steps. Step one is a photochemical reaction, induced by a quantum of light absorbed by pigment‐system II, which results in the production ofEin a reduced state. Step two is a dark oxidation of the reducedEby the second substance,A.The oxidizedEcan then enter the normal photochemical cycle of system II. ReducedEmight alternatively be oxidized by oxygen, this reaction being responsible for a very rapid and brief light‐induced oxygen uptake. SubstanceAis measured by the oxygen burst and is present in the chloroplasts at the approximate ratio of 1 molecule for 70 molecules of total chlorophyll whileEis at the ratio of about 1/2800. This gives aEoverAvalue of 1/35 which is much smaller than the one found in whoe cells (ca.1/10). This independent behavior ofEandAsuggests that chloroplast extraction destroys some photochemical centers without having a direct impact onA, which might diffuse from one center to another. Besides the brief light‐induced oxygen uptake above mentioned, there is another one which is related to System I functioning.The kinetics of the oxygen evolution and of the fluorescence have been compared. During the activation process of the oxygen evolving ability, rate of oxygen evolution and fluorescence yield increase in a parallel way. After the maximum velocity of the oxygen burst is reached (i.e. after activation), the fluorescence yield keeps growing up until the steady‐state is attained (with an intermediary plateau), whereas the rate of oxygen emission slows down. The time‐course curves of fluorescence obtained with inactivated or activated chloroplasts are essentially different in that the initial yield is higher in th

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1967.tb08759.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

AbstractPhotolysis of benzyl and benzhydryl thiocyanates and of benzyl, benzhydryl and trityl isothiocyanates and disulfides has been studied in rigid glasses at liquid nitrogen temperature. Most intermediate and final products of photolysis have been identified by absorption and fluorescence spectroscopy. Evidence has been obtained for benzyl, diphenylmethyl and triphenylmethyl trapped radicals. A number of new luminescence bands of benzyl radical, in the 550–610 nm region, and the hitherto unknown lowest energy luminescence spectrum (doublet‐doublet) of diphenylmethyl radical, are repor

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1967.tb08760.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

AbstractThe carotenoids β‐carotene, lutein, lutein epoxide and violaxanthin are fluorescent compounds. Upon excitation around 280 mμ, at wavelengths close to those of their ultraviolet absorption maxima, these carotenoids fluoresce within the range 300–400 mμ, with maximal fluorescence at approximately 320

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1967.tb08761.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1967.tb08762.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1967.tb08763.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY