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The first report regarding SOD activity of metallocorroles, investigated via the combination of the cytochrome C assay, pulse radiolysis, and electrochemistry, is used for identifying the main criteria needed for achieving good performance, as well as for elucidating mechanistic aspects of their action.

Silver and gold nanoparticles are very efficient catalysts for the dimerization of methyl-radicals in aqueous solutions. The rate constants for the reaction of methyl-radicals with the gold and silver nanoparticles were measured and found to be 3.7 x 10(8) M(-1) s(-1) and 1.4 x 10(9) M(-1) s(-1), respectively. The results thus suggest that alkyl-radicals, also not reducing ones, are scavenged by these nanoparticles. This might explain the role, if such a role exists, of these nanoparticles in medical applications.

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Conspectus CO 2 , HCO 3 – , and CO 3 2– are present in all aqueous media at pH > 4 if no major effort is made to remove them. Usually the presence of CO 2 /HCO 3 – /CO 3 2– is either forgotten or considered only as a buffer or proton transfer catalyst. Results obtained in the last decades point out that carbonates are key participants in a variety of oxidation processes. This was first attributed to the formation of carbonate anion radicals via the reaction OH • + CO 3 2– → CO 3 •– + OH – . However, recent studies point out that the involvement of carbonates in oxidation processes is more fundamental. Thus, the presence of HCO 3 – /CO 3 2– changes the mechanisms of Fenton and Fenton-like reactions to yield CO 3 •– directly even at very low HCO 3 – /CO 3 2– concentrations. CO 3 •– is a considerably weaker oxidizing agent than the hydroxyl radical and therefore a considerably more selective oxidizing agent. This requires reconsideration of the sources of oxidative stress in biological systems and might explain the selective damage induced during oxidative stress. The lower oxidation potential of CO 3 •– probably also explains why not all pollutants are eliminated in many advanced oxidation technologies and requires rethinking of the optimal choice of the technologies applied. The role of percarbonate in Fenton-like processes and in advanced oxidation processes is discussed and has to be re-evaluated. Carbonate as a ligand stabilizes transition metal complexes in uncommon high oxidation states. These high-valent complexes are intermediates in electrochemical water oxidation processes that are of importance in the development of new water splitting technologies. HCO 3 – and CO 3 2– are also very good hole scavengers in photochemical processes of semiconductors and may thus become key participants in the development of new processes for solar energy conversion. In this Account, an attempt to correlate these observations with the properties of carbonates is made. Clearly, further studies are essential to fully uncover the potential of HCO 3 – /CO 3 2– in desired oxidation processes.

The reactions (CuTL + 'R -LCun-R and the mechanism of decomposition of the transient complexes LCu11-R were studied using the pulse-radiolysis technique (L1 = H2O, L* 12 = 2,5,8,ll-tetramethyl-2,5,8,ll-tetraazadodecane; 'R = 'CH3, 'CH2COOH, 'CH(CH3)COOH, •-CH2CH2COOH.) The kinetics of formation of the transient complexes obey pseudo-firstorder rate laws. The rate constants measured for these reactions are in the range (2-4) x 109 M-1 s-1 for L1 and 6 x 106 7*-1 x 10s M-1 s-1 for L2. The mechanisms of decomposition of the transient complexes depend on the nature of R and L as follows: 1. For R = CH3 ethane is the final product. The kinetics of its formation obey second-order rate laws. Free methyl radicals are not intermediates in these processes. 2. For R = CH2CH2COOH the transient complexes decompose via an analogous mechanism to that of R = CH3 for L1 and via homolysis of the copper-carbon a bond for L2. 3. For R = CH2COOH and CH(CHs)-COOH the transient complexes decompose via heterolysis of the copper-carbon a bonds forming CunL. The effect of the nature of R and L on the kinetics of these reactions is discussed.