A fast electron transfer rate for the oxidation of ferrocene in acetonitrile or dichloromethane at platinum disk ultramicroelectrodes

Bond, Alan M.; Henderson, T. L.; Mann, D. R.; Mann, Terence F.; Thormann, Wolfgang; Zoski, Cynthia G.

doi:10.1021/ac00169a008

Cited by 158 publications

(108 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…10b, bottom). The irreversible electrochemical oxidation of Fc and its derivatives is well-known, but this effect is highly dependent on the experimental conditions such as electrode dimensions, the nature of the support electrolyte, the concentration of Fc functionalities together with the degree of ferrocene modification [29][30][31][32][33][34][35][36]. In a previous study [6], ethynyl Fc, Lip Fc and Fc-PVC in membranes that were plasticized by the ionic liquid, 1- exerts a similar influence on the reaction product formed from an aqueous electrolyte of 10 mM NaCl, which is due partially to severe suppression of the permeation of NaCl with water nanodroplets/ion exchange of Cl -from the aqueous electrolyte into these membranes containing very high concentrations of organic cations and anions in the IL plasticized membranes.…”

mentioning

confidence: 99%

Electrochemical Mechanism of Ferrocene-Based Redox Molecules in Thin Film Membrane Electrodes

Cuartero

Acres

Bradley

et al. 2017

Electrochimica Acta

View full text Add to dashboard Cite

2 GRAPHICAL ABSTRACTCartoon illustrating NaCl permeation through water nanodroplets and Cl -exchange at the membrane/sample interface, both of which create an environment to enable the formation of FeCln 3-n complexes, leading to a non-reversibility in the redox chemistry of the membrane. RESEARCH HIGHLIGHTS electrochemistry of ferrocene derivatives in polymeric membranes  role of chloride on the irreversible oxidation of ferrocene in thin film membranes  synchrotron radiation study of chloride on the ferrocene reactivity in membranes  elimination of chloride induced irreversibility of the ferrocene reaction chemistry ABSTRACTCyclic voltammetry (CV) in chloride-based aqueous electrolytes of ferrocene molecule doped thin membranes (~200 nm in thickness) on glassy carbon (GC) substrate electrodes, both plasticized poly(vinyl chloride) (PVC) and unplasticized poly(methyl methacrylate)/poly(decyl methacrylate) (PMMA-PDMA) membranes, has shown that the electrochemical oxidation behavior is irreversible due most likely to 3 degradation of ferrocene at the buried interface (GC|membrane). Furthermore, CV of the ferrocene molecules at GC electrodes in organic solvents employing chloride-based and chloride-free organic electrolytes has demonstrated that the chloride anion is inextricably linked to this irreversible ferrocene oxidation electrochemistry. Accordingly, we have explored the electrochemical oxidation mechanism of ferrocenebased redox molecules in thin film plasticized and unplasticized polymeric membrane electrodes by coupling synchrotron radiation-X-ray photoelectron spectroscopy (SR-XPS) and near edge X-ray absorption fine structure (NEXAFS) with argon ion sputtering to depth profile the electrochemically oxidized thin membrane systems. With the PVC depth profiling studies, it was not possible to precisely study the influence of chloride on the ferrocene reactivity due to the high atomic ratio of chloride in the PVC membrane; however, the depth profiling results obtained with a chlorine-free polymer (PMMA-PDMA) provided irrefutable evidence for the formation of a chloride-based iron product at the GC|PMMA-PDMA interface. Finally, we have identified conditions that prevent the irreversible conversion of ferrocene by utilizing a high loading of redox active reagent and/or an ionic liquid (IL) membrane plasticizer with high ionicity that suppresses the mass transfer of chloride.

show abstract

mentioning

confidence: 99%

Electrochemical Mechanism of Ferrocene-Based Redox Molecules in Thin Film Membrane Electrodes

Cuartero

Acres

Bradley

et al. 2017

Electrochimica Acta

View full text Add to dashboard Cite

show abstract

“…Considering that the effects of uncompensated solution resistance are the highest at the largest surface area electrode, the close similarity in the peak separations in the voltammograms in Figure 2 indicates that the increasing ∆E pp values shown in Figure 1 at faster scan rates are mainly the result of relatively slow heterogeneous electron transfer rates (k s ), rather than the effects of uncompensated solution resistance. By comparing the ∆E pp values obtained for ferrocene under identical conditions (where it was assumed that the k s value was g1 cm s -1 ), 16 estimates on the solution resistance at varying temperatures were made and incorporated into the simulations. Figure 3 shows CVs obtained of (CH 3 )R-TOH at various temperatures, illustrating that the i p ox /i p red ratios and ∆E pp values remain close to constant as the temperature is changed.…”

Section: Resultsmentioning

confidence: 99%

“…A further interesting result from the electrostatic potential derived charges is that, for (CH 3 )R-TO + , the ether oxygen (Scheme 6, O 16 ) carries a high negative charge compared to the other phenoxonium cations (-0.46 compared to between -0.24 and -0.35) ( Table 3). The high negative charge on O 16 could provide a mechanism for electrostatic repulsion for incoming nucleophiles, thereby decreasing the solution phase reaction rate. The calculations predict that the negative charge on O 16 in (CH 3 )R-TO + is even higher than on the carbonyl oxygen (O 15 ), while for the other compounds the negative charge on O 16 < O 15 (except for (CH 3 )H 3 -TO + , where the charges on the oxygen atoms are equal).…”

Section: Theoretical Calculationsmentioning

confidence: 99%

Variable Scan Rate Cyclic Voltammetry and Theoretical Studies on Tocopherol (Vitamin E) Model Compounds

et al. 2008

View full text Add to dashboard Cite

Variable scan rate (0.1-500 V s -1 ) cyclic voltammetry experiments were performed on a series of model tocopherol (vitamin E) compounds with differing degrees of methyl substitution around the aromatic (phenolic) ring. R-Tocopherol, with a fully methylated aromatic ring, produced stable phenoxonium cations upon oxidation in CH 3 CN, and was modeled via an ECE mechanism (where "E" represents an electron transfer and "C" a chemical step). Compounds with less methyl substitution around the aromatic ring were more reactive following oxidation, and formed additional oxidation products (hemiketals and p-quinones), and were modeled according to a more complicated ECECC mechanism. The equilibrium and rate constants associated with the chemical steps were estimated by digital simulations of the variable scan rate data over a range of temperatures (T ) 253-313 K) in acetonitrile containing 0.5 M Bu 4 NPF 6 as the supporting electrolyte. The relative lifetimes of the phenoxonium cations of tocol and the tocopherols were compared with theoretical results obtained from molecular orbital calculations.

show abstract

“…The most popular technique for determining kinetic parameters using ultramicroelectrodes has been cyclic voltammetry using fast scan rates [42,49,50].…”

Section: New Developments In Experimental Methodsmentioning

confidence: 99%

The Kinetics of Heterogeneous Electron Transfer Reactions in Polar Solvents

Fawcett¹,

Opallo²

1994

View full text Add to dashboard Cite

A fast electron transfer rate for the oxidation of ferrocene in acetonitrile or dichloromethane at platinum disk ultramicroelectrodes

Cited by 158 publications

References 54 publications

Electrochemical Mechanism of Ferrocene-Based Redox Molecules in Thin Film Membrane Electrodes

Electrochemical Mechanism of Ferrocene-Based Redox Molecules in Thin Film Membrane Electrodes

Variable Scan Rate Cyclic Voltammetry and Theoretical Studies on Tocopherol (Vitamin E) Model Compounds

The Kinetics of Heterogeneous Electron Transfer Reactions in Polar Solvents

Contact Info

Product

Resources

About