Electron and Mass Transport in Hybrid Redox Polyether Melts Contacted with Carbon Dioxide

Hutchison, John C.; Leone, Anthony; DeSimone, Joseph M.; Murray, Royce W.

doi:10.1021/ja026209p

Cited by 25 publications

(52 citation statements)

References 72 publications

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“…Ultimately, the results extend our understanding of these materials in regard to possible use in molecular electronic environments that incorporate nucleic acid sequence programming. The present results are consistent with recent results 10 on CO 2 -plasticized Co complex melts, and with the notion that immobilization of counterions can produce a large impediment to electron transfer. 11…”

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confidence: 93%

Ion Atmosphere Relaxation and Percolative Electron Transfer in Co Bipyridine DNA Molten Salts

et al. 2003

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Polypyridyl complexes of Co decorated with 350-Da polyether chains (Co(350)(2+)) form molten phases of nucleic acids when paired with DNA counterions (Co(350)DNA) or 25-mer oligonucleotides. Analysis of voltammetry and chronoamperometry of mixtures of these phases with complexes having ClO(4)(-) counterions (Co(350)(ClO(4))(2)) and no other diluent provides charge transport rates from the oxidation and reduction currents for the complexes. As the mole fraction of the Co(350)(ClO(4))(2) complex in the mixture is varied from ca. 0.25 to 1, the physical diffusion constants derived from the Co(III/II) wave increase from 1 x 10(-11) cm(2)/s to 5 x 10(-10) cm(2)/s, and apparent diffusion constants dominated by the Co(II/I) electron self-exchange increase from 1 x 10(-10) cm(2)/s to 2 x 10(-8) cm(2)/s. Pure Co(350)DNA melts, containing no Co(350)(ClO(4))(2) complex, do not exhibit recognizable voltammetric waves; DNA suppresses the Co(II/I) electron transfer reactions of Co complexes for which it is the counterion. There are therefore two microscopically distinct kinds of Co(350) complexes, those with DNA and those with ClO(4)(-) counterions, with respect to their Co(II/I) electron-transfer dynamics, leading to percolative behavior in their mixtures. The electron-transfer rates of the Co(II/I) couple are controlled by the diffusive relaxation of the ionic atmosphere around the reaction pair, and the inactivity of the bound Co complexes can be attributed to the very low mobility of the anionic phosphate groups in the DNA counterion. Substitution of sulfonated polystyrene for DNA produced similar results, suggesting that this phenomenon is general to other polymer counterions of low mobility. We conclude that the measured Co(II/I) charge transport and electron-transfer rate constants reflect more the diffusive mobility of the perchlorate counterion than the intrinsic Co(II/I) electron hopping rate.

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confidence: 93%

Ion Atmosphere Relaxation and Percolative Electron Transfer in Co Bipyridine DNA Molten Salts

et al. 2003

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“…It is additionally possible that ionic atmosphere relaxation phenomena influence the DNA electron hopping rate. We have shown that ionic atmosphere relaxation can dominate electron-transfer rates in semisolid media; ,, such control in the present case would mean that the k EX results above are lower limits of the intrinsic electron-transfer rate. Measurements given below show, however, that the physical diffusion of dilute, nontailed metal complexes in a 1:3 (mole ratio) Ni 350 DNA + Ni 350 (ClO 4 ) 2 melt at 67 °C is about 10 -8 cm 2 /s.…”

Section: Resultsmentioning

confidence: 56%

Electrocatalysis in Nucleic Acid Molten Salts

et al. 2004

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This paper describes redox chemistry in semisolid molten salts ionic liquids of DNA in which the counterions of the phosphates are redox-active metal complexes with bipyridine ligands labeled with MW 350 poly-(ethylene glycol) (PEG) "tails", e.g., M(bpy 350 ) 3 DNA (where M ) Co, Ni, and bpy 350 ) 4,4′-(CH 3 (OCH 2 -CH 2 ) 7 OCO) 2 -2,2′-bipyridine). Other redox-active metal complexes are added to the M(bpy 350 ) 3 DNA melt: (a) the PEG-tailed metal bipyridine complexes Fe(bpy 350 ) 3 (ClO 4 ) 2 and Ru(bpy 350 ) 3 (ClO 4 ) 2 and (b) the nontailed complexes Os(bpy) 3 Cl 2 (bpy ) 2,2′-bipyridine) and Os(bpy) 2 dppzCl 2 (dppz ) dipyridophenazine). In example a, electrogeneration of the powerful oxidizers [Fe(bpy 350 ) 3 ] 3+ and [Ru(bpy 350 ) 3 ] 3+ gives microelectrode voltammetry indicative of electrocatalytic oxidation of DNA base sites. Since physical diffusion of the metal complexes is slow in the viscous semisolids (and that of DNA is nil), the rate of electron hopping between the base sites of the DNA becomes a significant contributor to the overall charge transport rate, as deduced from analysis of the voltammetry. DNA base site self-exchange rate constants of 1.1 × 10 6 and 1.8 × 10 6 s -1 are estimated from measurements using Fe(bpy 350 ) 3 3+ and Ru(bpy 350 ) 3 3+ oxidants, respectively. In example b, a complex known to be a DNA intercalator in aqueous solutions is found to not be an intercalator in the DNA molten salt environment, as deduced from measurements showing the physical diffusion coefficients of aqueous nonintercalator Os(bpy) 3 Cl 2 and aqueous intercalator Os(bpy) 2 dppzCl 2 to be indistinguishable in the M(bpy 350 ) 3 DNA melt.

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“…[49][50][51][52] In this work, we will demonstrate how the PFIL-modified electrode assembly can be used in flow injection analysis (FIA) in supporting electrolyte-free solutions. [37][38][39][40][41][42][43] The structure of a detection cell for the flow system was shown in Scheme 2(B). Fig.…”

Section: Application In Amperometric Flow Analysismentioning

confidence: 99%

“…Similar results have been obtained with some other ionexchange membranes employed in electrochemical flow systems any added supporting electrolyte. [37][38][39][40][41][42][43] The advantage of our approach is that we do not need any internal electrolyte in the flow cell construction. Another advantage in our system is that the PFIL film has good dissolving properties for many analytes.…”

Section: Application In Amperometric Flow Analysismentioning

confidence: 99%

“…In these applications, the detection is done with ultramicroelectrodes (UMEs) or their modifications with moist ion-exchange membranes such as Nafion. 19,26,[37][38][39][40][41][42][43] Fuchigami and Tajima have developed another novel method to generate in situ the supporting electrolyte during the electro-organic synthesis. This procedure not only eliminates the use of expensive supporting electrolytes in organic media, but also makes the product separation very simple.…”

Section: Introductionmentioning

confidence: 99%

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Polyelectrolyte-functionalized ionic liquid for electrochemistry in supporting electrolyte-free aqueous solutions and application in amperometric flow injection analysis

et al. 2007

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As a green process, electrochemistry in aqueous solution without a supporting electrolyte has been described based on a simple polyelectrolyte-functionalized ionic liquid (PFIL)-modified electrode. The studied PFIL material combines features of ionic liquids and traditional polyelectrolytes. The ionic liquid part provides a high ionic conductivity and affinity to many different compounds. The polyelectrolyte part has a good stability in aqueous solution and a capability of being immobilized on different substrates. The electrochemical properties of such a PFIL-modified electrode assembly in a supporting electrolyte-free solution have been investigated by using an electrically neutral electroactive species, hydroquinone (HQ) as the model compound. The partition coefficient and diffusion coefficient of HQ in the PFIL film were calculated to be 0.346 and 4.74 6 10 26 cm 2 s 21 , respectively. Electrochemistry in PFIL is similar to electrochemistry in a solution of traditional supporting electrolytes, except that the electrochemical reaction takes place in a thin film on the surface of the electrode. PFILs are easily immobilized on solid substrates, are inexpensive and electrochemically stable. A PFIL-modified electrode assembly is successfully used in the flow analysis of HQ by amperometric detection in solution without a supporting electrolyte. The results indicate a green electrochemical methodology in supporting electrolyte-free solution and a potential application in amperometric detection in a flow system without any supporting electrolyte in the solution, such as the high performance liquid chromatography electrochemical detection (HPLC-ECD) system.

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Electron and Mass Transport in Hybrid Redox Polyether Melts Contacted with Carbon Dioxide

Cited by 25 publications

References 72 publications

Ion Atmosphere Relaxation and Percolative Electron Transfer in Co Bipyridine DNA Molten Salts

Ion Atmosphere Relaxation and Percolative Electron Transfer in Co Bipyridine DNA Molten Salts

Electrocatalysis in Nucleic Acid Molten Salts

Polyelectrolyte-functionalized ionic liquid for electrochemistry in supporting electrolyte-free aqueous solutions and application in amperometric flow injection analysis

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