Polymer-modified electrodes with pendant [RhIII(C5Me5)(L)Cl]+-complexes formed by γ-irradiation cross-linking

Höfer, Eva; Steckhan, Eberhard; Ramos, Brigitte L.; Heineman, William R.

doi:10.1016/0022-0728(95)04243-1

Cited by 23 publications

(13 citation statements)

References 32 publications

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“…As demonstrated in Heineman's paper, the use of spacers between polymer backbones and redox centers can achieve higher catalytic efficiencies because suitable spacers are able to generate a distance between electrodes which, in turn, makes redox centers more accessible to substrates. 28 Thus, a spacer was also incorporated into the synthesis route.…”

Section: Resultsmentioning

confidence: 99%

“…The use of a polymer network to immobilize rhodium catalysts hinders mass transfer of cofactor through polymer layers and can limit the rate of electron transfer of rhodium complex near the electrode surface. [28][29][30][31] In these circumstances, a porous polymer is preferred and the thickness of the polymer layer should be carefully controlled.Besides polymers, carbonaceous materials such as graphene 32,33 and carbon nanotubes [34][35][36] are also catalyst supports and are widely used in various fields. The π-π stacking effect is an effective strategy to immobilize catalysts whereby aromatic moieties are attached to the catalysts, which can then strongly adsorb onto carbon nanotubes.…”

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confidence: 99%

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confidence: 99%

“…Heineman and coworkers reported the immobilization of a rhodium complex onto hydrophilic N-vinylpyrrolidone. 28 The resulting redox polymer, which was equipped with spacers between the rhodium redox center and the polymer backbone, demonstrated higher electrochemical activity toward the regeneration of NADH compared to the one without spacers. Lütz and coworkers also reported the use of polyethylene glycol polymerized with 2,2 -bipyridine-4,4 -dialdehyde to form a polymer backbone for rhodium complex coordination.…”

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confidence: 99%

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Regeneration of the NADH Cofactor by a Rhodium Complex Immobilized on Multi-Walled Carbon Nanotubes

Tan

Hickey

Milton

et al. 2014

J. Electrochem. Soc.

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The regeneration of the enzymatic cofactor nicotinamide adenine dinucleotide (NADH) by rhodium-based catalysts such as [Rh(Cp * )(bpy)Cl] + (Cp * = pentamethylcyclopentadienyl, bpy = 2,2 -bipyridine) and derivatives have previously been studied extensively in solution. In this work, we report a synthetic route of a rhodium complex with a pyrene-substituted phenanthroline ligand (pyr-Rh). The immobilization of the pyr-Rh complex was accomplished on multi-walled carbon nanotubes (MWCNTs) via π-π stacking to obtain effective and durable indirect electrochemical regeneration of NADH. Cyclic voltammetry and amperometry were used to demonstrate the electrochemical activity of the surface-confined pyr-Rh complex. The loading quantity of the pyr-Rh complex was found to be 47 ± 2 nmol/mg of MWCNTs. The reusability of the electrodes modified with the pyr-Rh complex was investigated and an average turnover frequency of 3.6 ± 0.1 s −1 over ten cycles in the presence of 2 mM nicotinamide adenine dinucleotide (NAD + ) was observed. Lastly, malate dehydrogenase (MDH), a NADH-dependent enzyme, was evaluated in the presence of the immobilized pyr-Rh complex to confirm the catalyst's capability to regenerate biologically active NADH for biocatalysis. In biological systems, the cofactor nicotinamide adenine dinucleotide (NAD + ) and its reduced form (NADH) are of significance in assisting oxidoreductase enzymes to catalyze redox reactions.1 The efficient in situ regeneration of NADH from NAD + is valuable in biocatalysis due to the stoichiometric amount required for NADHdependent enzymes along with its relatively high cost.1 It was reported that the combination of three NAD + -dependent dehydrogenases (formate dehydrogenase, formaldehyde dehydrogenase and alcohol dehydrogenase) is capable of generating methanol from CO 2 by reversing the original enzymatic reaction direction. [2][3][4][5] In this enzyme cascade, one molecule of methanol is produced at the cost of three equivalents of NADH. It is environmentally beneficial to convert CO 2 into useful biofuel by enzymatic reactions, but the high cost of stoichiometric NADH consumption makes this process impractical. Therefore, a regeneration system is necessary. Galarneau and coworkers also investigated the application of this three NADH-dependent dehydrogenases cascade and the use of the enzymatic regeneration of NADH by phosphite dehydrogenase (PTDH). 6 In comparison to enzyme systems which do not incorporate a NADH regeneration system, their polyenzymatic system had a higher activity in generating methanol from carbon dioxide.6 Practical cofactor regeneration is necessary for maintaining stable concentrations of NAD + /NADH, which provides a driving force for the desired enzymatic reactions. The reduced NADH cofactor can be regenerated enzymatically, 7-9 chemically, 10 photochemically 11-13 and electrochemically. 14,15 Two methods are commonly used when electrochemically converting NAD + to NADH: direct and indirect regeneration. In the direct regeneration of NADH, the cofactor N...

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Regeneration of the NADH Cofactor by a Rhodium Complex Immobilized on Multi-Walled Carbon Nanotubes

Tan

Hickey

Milton

et al. 2014

J. Electrochem. Soc.

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“…The importance of the redox chemistry of rhodium complexes has led to the modification of various electrode surfaces with rhodium complexes for the use in electrocatalytic hydrogen generation and in electroenzymatic syntheses [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical reduction of at Hg/phosphate electrolyte interface

Mandić

Gašparović

Weitner³

2006

Journal of Electroanalytical Chemistry

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Graphite Electrodes Coated with Poly(dimethyldiallylammonium)chloride Network Films Cross-Linked by Gamma-Irradiation

Maizels¹,

Heineman²,

Seliskar³

2000

Electroanalysis

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Properties of graphite electrodes coated with poly(dimethyldiallylammonium) chloride (PDMDAAC) are described. Gamma‐irradiation was used to immobilize the polymer on the graphite surface by cross‐linking the water‐soluble polymer into an insoluble network. Immobilization of the network is aided by the high porosity of the graphite electrodes. Potassium ferricyanide was used as a model analyte to demonstrate electrochemical properties of the polymer modified electrode. Cyclic voltammograms of Fe(CN)63– at the PDMDAAC modified electrodes exhibit partitioning of the analyte into the polymer film. Chronocoulometry was used to determine the quantities of Fe(CN)63– trapped in the polymer network. The results of ion‐exchange reactions of Fe(CN)63– with the PDMDAAC film were used to determine distribution coefficients (Kd) between the polymer film and the bulk solution of the analyte. Kd is 4000 for 0.01 M Fe(CN)63– in 0.2 M KCl. Analytical calibration plots of cyclic voltammetric peak currents for Fe(CN)63– at gamma‐irradiated PDMDAAC/graphite electrodes were linear from 0.01 mM to 0.4 mM. Substantial enhancement of current signal was observed at the PDMDAAC modified graphite vs. bare electrodes. Variation in radiation dosage from 0.48 to 5.5 Mrad does not change the cross‐link density of PDMDAAC on the graphite surface as evidenced by almost identical cyclic voltammograms of Fe(CN)63– at electrodes exposed to dosages over this range.

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Polymer-modified electrodes with pendant [RhIII(C5Me5)(L)Cl]+-complexes formed by γ-irradiation cross-linking

Cited by 23 publications

References 32 publications

Regeneration of the NADH Cofactor by a Rhodium Complex Immobilized on Multi-Walled Carbon Nanotubes

Regeneration of the NADH Cofactor by a Rhodium Complex Immobilized on Multi-Walled Carbon Nanotubes

Electrochemical reduction of at Hg/phosphate electrolyte interface

Graphite Electrodes Coated with Poly(dimethyldiallylammonium)chloride Network Films Cross-Linked by Gamma-Irradiation

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