The mechanism of the interaction of Cu+-a,a'-dipyridyl complex (Cu+Lz) with 0 2 in both neutral and acid media was studied by the stopped-flow method. The dependence of the mechanism on the acidity of the medium was established. In an acid medium H+ participated in a direct 0 2 reduction to HOn by interaction with an oxygen adduct L&u+O2 formed without displacement of ligand molecules. In a neutral medium the reaction rate was limited by inner sphere charge transfer from Cu+ to 0 2 to form an oxygen "charge transfer" complex L2CuOt. The latter interacted either with the second ion Cu+L2 or with the free ligand, or else it dissociated, reversibly or irreversibly, to form a radical anion 0;. The bimolecular rate constants of the oxygen "adduct" and "charge transfer" complex formation appeared to be kbi = (1.0 f 0.1) X lo5 and (1.5 f 0.2) X 104M-'-sec-', respectively. The effective termolecular rate constants of 0 2 reduction to H02 in an acid medium (with contribution from H+) and to 0; in a neutral medium (with contribution from a,a'-dipyridyl) were k,,, = 2.7 X lo8 and 107M-2.sec-1. The rate constants of the elementary steps were estimated. The auto-oxidation mechanism of the aquoion and complexes of Cu+ is discussed in terms of the results obtained.

Pectin conjugated magnetic nanocomposites were prepared by chemical coprecipitation method in situ. The FTIR, acoustic, Mössbauer spectrometry, XRD measurements confirmed the nanoscaled structure of Fe 3 O 4 -pectin composite. The synthesized magnetite nanoparticles were uniform with an mean size of $14-17 nm for low pectin concentration as 10 wt.%.

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