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    Molecular Electrocatalysis for Oxygen Reduction by Cobalt Porphyrins Adsorbed at Liquid/Liquid Interfaces
    (AMER CHEMICAL SOC, 2010) Su, Bin; Hatay, İmren; Trojanek, Antonin; Samec, Zdenek; Khoury, Tony; Gros, Claude P.; Barbe, Jean-Michel; Daina, Antoine; Carrupt, Pierre-Alain; Girault, Hubert H.
    Molecular electrocatalysis for oxygen reduction at a polarized water/1,2-dichloroethane (DCE) interface was studied, involving aqueous protons, ferrocene (Fc) in DCE and amphiphilic cobalt porphyrin catalysts adsorbed at the interface. The catalyst, (2,8,13,17-tetraethyl-3,7,12,18-tetramethyl-5-p-aminophenylporphyrin) cobalt(II) (CoAP), functions like conventional cobalt porphyrins, activating 02 via coordination by the formation of a superoxide structure. Furthermore, due to the hydrophilic nature of the aminophenyl group, CoAP has a strong affinity for the water/DCE interface as evidenced by lipophilicity mapping calculations and surface tension measurements, facilitating the protonation of the CoAP-O(2) complex and its reduction by ferrocene. The reaction is electrocatalytic as its rate depends on the applied Galvani potential difference between the two phases.
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    Oxygen and Proton Reduction by Decamethylferrocene in Non-Aqueous Acidic Media
    (Royal Soc Chemistry, 2010) Su, Bin; Hatay, İmren; Ge, Pei Yu; Mendez, Manuel; Corminboeuf, Clemence; Samec, Zdenek; Ersöz, Mustafa; Girault, Hubert H.
    Experimental studies and density functional theory (DFT) computations suggest that oxygen and proton reduction by decamethylferrocene (DMFc) in 1,2-dichloroethane involves protonated DMFc, DMFcH(+), as an active intermediate species, producing hydrogen peroxide and hydrogen in aerobic and anaerobic conditions, respectively.
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    Oxygen Reduction by Decamethylferrocene at Liquid/Liquid Interfaces Catalyzed by Dodecylaniline
    (Elsevier Science Sa, 2010) Su, Bin; Hatay, İmren; Li, Fei; Partovi-Nia, Raheleh; Mendez, Manuel A.; Samec, Zdenek; Ersöz, Mustafa; Girault, Hubert H.
    Molecular oxygen (O-2) reduction by decamethylferrocene (DMFc) was investigated at a polarized water/1,2-dichloroethane (DCE) interface. Electrochemical results point to a mechanism similar to the EC type reaction at the conventional electrode/solution interface, in which an assisted proton transfer (APT) by DMFc across the water/DCE interface via the formation of DMFcH(+) corresponds to the electrochemical step and O-2 reduction to hydrogen peroxide (H2O2) represents the chemical step. The proton transfer step can also be driven using lipophilic bases such as 4-dodecylaniline. Finally, voltammetric data shows that lipophilic DMFc can also be extracted to the aqueous acidic phase to react homogeneously with oxygen.
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    Oxygen Reduction Catalyzed by a Fluorinated Tetraphenylporphyrin Free Base at Liquid/Liquid Interfaces
    (Amer Chemical Soc, 2010) Hatay, İmren; Su, Bin; Mendez, Manuel A.; Corminboeuf, Clemence; Khoury, Tony; Gros, Claude P.; Bourdillon, Melanie; Meyer, Michel; Barbe, Jean-Michel; Ersöz, Mustafa; Zális, Stanislav; Samec, Zdenek; Girault, Hubert H.
    The diprotonated form of a fluorinated free base porphyrin, namely 5-(p-aminophenyl)-10,15,20-tris(pentafluorophenyl)porphyrin (H(2)FAP), can catalyze the reduction of oxygen by a weak electron donor, namely ferrocene (Fc). At a water/1,2-dichloroethane interface, the interfacial formation of H(4)FAP(2+) is observed by UV-vis spectroscopy and ion-transfer voltammetry, due to the double protonation of H(2)FAP at the imino nitrogen atoms in the tetrapyrrole ring. H(4)FAP(2+) is shown to bind oxygen, and the complex in the organic phase can easily be reduced by Fc to produce hydrogen peroxide as studied by two-phase reactions with the Galvani potential difference between the two phases being controlled by the partition of a common ion. Spectrophotometric measurements performed in 1,2-dichloroethane solutions clearly evidence that reduction of oxygen by Fc catalyzed by H(4)FAP(2+) only occurs in the presence of the tetrakis(pentafluorophenyl)borate (TB(-)) counteranion in the organic phase. Finally, ab initio computations support the catalytic activation of H(4)FAP(2+) on oxygen.