Browsing by Author "Land, Edward J."

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    Absorption Spectra of Radical Ions of Polyenes of Biological Interest
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (03), 1977) Land, Edward J.; Lafferty, Joseph; Sinclair, Roy S.; Truscott, T. George
    The radical cations and anions of a number of carbonyl containing polyenes of biological importance have been generated, and their absorptions characterised using pulse radiolysis techniques. The wavelength maxima of the absorption bands are linearly dependent on the number of conjugated double bonds. The radical cation and the radical anion derived from the same parent molecule absorb at very similar wavelengths. There is a large hypsochromic shift in the radical anion absorption on changing from hexane to methanol solutions. The radical anions decay rapidly, in methanol, to form a species which is probably the protonated anion.
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    Bipyridylium Quaternary Salts and Related Compounds: Part 6.—Pulse Radiolysis Studies of the Reaction of Paraquat Radical Analogues with Oxygen
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (3), 1978) Farrington, John A.; Ebert, Michael; Land, Edward J.
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    Luminescence Excitation and De-excitation Involving One-electron Transfer Aqueous Solutions of l-Aminonaphthalene-4-(Na)sulphonate
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (08), 1978) Prütz, Walter A.; Land, Edward J.
    The radiation-induced chemiluminescence (RCL) in aqueous solutions of 1-aminonaphthalene-4-(Na)sulphonate (AnsH) predominantly involves: AnsH·++ eaq→ AnsH*. This conclusion is due to quantitative correlations found between the transient absorption, assigned to AnsH·+, and the RCL emission under various conditions modifying the AnsH·+ formation. Phosphates act on AnsH·+via the reaction: AnsH·++ HPO2–4⇌ Ans·+ H2PO–4. Azide radicals (·OH + N–3→ OH–+ N˙3) are about 7.5 times more efficient than ·OH in generating AnsH·+, at the expense of Ans· and AnsH·OH. Analogous phosphate and azide effects were found for a number of other efficient RCL compounds. Direct electron impact excitation of AnsH appears to occur 75 % by charge recombination. Halide type compounds are capable of perturbing this recombinational excitation process. Fluorescence quenching, on the other hand, is particularly efficient with electron-affinic compounds (A). A fairly good correlation was found between the fluorescence quenching rates k(AnsH*+ A) and the corresponding reaction rate constants k(e–aq+ A), suggesting that AnsH* de-excitation occurs by electron transfer to A. For ionic acceptors k(AnsH*+ A) depends upon the ionic strength of the solution.