Redox potential poly

A similar polymer, composed of osmium complexed with bis-dichlorobipyridine, chloride, and PVI in a PVI—poly(acrylamide) copolymer (Table 2, compound 3), demonstrated a lower redox potential, 0.57 V vs SHE, at 37.5 °C in a nitrogen-saturated buffer, pH 5 109,156 adduct of this polymer with bilirubin oxidase, an oxygen-reducing enzyme, was immobilized on a carbon paper RDE and generated a current density exceeding 9 mA/cm at 4000 rpm in an O2-saturated PBS buffer, pH 7, 37.5 °C. Current decayed at a rate of 10% per day for 6 days on an RDE at 300 rpm. The performance characteristics of electrodes made with this polymer are compared to other reported results in Table 2. 

As shown by their redox potentials oxoruthenium(IV) species containing polypyridyl ligands are strong oxidants and they oxidize a variety of substrates. The complex [Ru(0)(bpy)2(py)] has also been used electrocatalytically for the oxidation of alcohols, aldehydes, alkenes, and aromatics." Electrocatalytic oxidation has also been performed on this complex that has been incorporated into poly-4-vinylpyridine. ... 

FIGURE 6.1 Illustration of the effects of mammalian metabolism and microbial metabolism on the redox potential of (poly)phenols found in plasma compared with their precursors in the diet and the aglycones commonly used in studies in vitro. (Reprinted from Clifford, M.N., Planta Med., 12, 1103, 2004. With permission.)... 

Scheme 3 Terminal i (CO) frequencies (squares) versus redox potential for [Pt24(CO)3o]" the circles show the corresponding response of i>(CO) on poly crystalline platinum (from Ref 37 with permission).

In conclusion, the order of reduction of metal ions is controlled by their redox potential. This is also true in other pairs of precious metals such as Pd/Pt, Au/Pd, etc. (53). In addition, poly(jV-vinyl-2-pyrrolidone) (PVP) plays an important role for the formation of the core/shell structure. In the case of the Au/Pt system, the aggregation starts from Au but not Pt. This is probably due to the coordinating ability of metals to PVP. The Pt atoms or microclusters coordinating to PVP are more stable than the Au atoms or microclusters, since Au cannot coordinate to PVP. Thus, Au atoms or microcluster aggregate at first after the reduction, and then Pt atoms or microclusters deposit on the Au nuclei. In summary, the core/shell structure is controlled by (1) the redox potential of metal ions, and (2) the coordination ability of metals to PVP, stabilizing polymer. 

Dimethylphenol is oxidatively polymerized to poly(2,6-dimethyl-1,4-phenyl-ene ether) with a copper-amine complex by a laccaselike reaction. The activated phenols are coupled to form a dimer. The dimer is activated by a mechanism similar to that by which the polymerization proceeds. The effects of the amine ligands are to improve the solubility and the stability of the copper complex as well as the phenol-coordinated complex and to control the redox potential of the copper complex. 

Cyclic Voltammetric Behavior of the PPy-GOD Film. Figure 1 shows the cyclic voltammetric curves of a PPy-GOD film (4000 A) in phosphate buffer solution with pH 7.4 at different scan rates. Both anodic and cathodic peaks should correspond to the redox reactions of PPy chains. The peak potentials, which were recorded at the scan rate of 200 mV/s, were -380 mV and -200 mV for cathodic and anodic peaks, respectively. This is similar to the potential shifts of the PPy film doped with large anions (27) such as poly(p-styrenesulfonate). Enzyme protein molecules are composed of amino acid and have large molecular size, which can not move out freely from the PPy-GOD film by the application of the reduction potential. In order to balance the charge of the Pfy-GOD film, cations must move into the film, and redox potentials move toward a more negative potential. This behavior is different from the one observed for the PPy-GOD film, which was prepared in the solution of GOD... 

Sim et al. (1996) described electron mobilities of copolymers of poly(4-vinylbenzyl-9-dicyanomethylenefluorene-4-caiboxylate) and butyl acrylate or butyl methacrylate. The copolymers showed two reversible redox potentials between -0.59 and -0.61 and -1.15 to -1.12 V. The field dependencies of the mobilities were described as log// At fields of 5.0 x HP V/cm, the... 

The control of the Eu redox stability is certainly a key issue for an eventual MRI contrast agent application. With the exception of cryptate complexes of Eu such as Eu (2.2.2) + and Eu (2.2.1) +, the complexation with poly(amino carboxylates) diminishes the redox stability of the Eu state, as compared to the aqua ion (some representative redox potentials are -0.63 V (Eu(H20) ) -0.21 V (Eu(2.2.2)2+) -0.82 V (EuODDA) -1.00 V (EuTETA -) -1.18 V (EuDO-TA ) -1.35 V (EuDTPA )) [111, 112]. Macrocyclic ligands that match in size with the larger Eu ion have a stabilizing effect of the reduced state, whereas carboxylate coordinating groups seem to be unfavorable in this respect. 

By subsequent deposition of crosslinked hole conductors with increasing redox potential, so-called electronic stairs can easily be fabricated. Those electronic stairs , introduced underneath HTLs between the anode and an endcapped poly-fluorene derivative lead to an increase in efficiency by a factor of three [40]. 

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