48161-40-6Relevant articles and documents
Electrochemical studies of heterogeneous reduction of tetracyanoquinodimethane in poly(ethylene oxide) electrolytes using ac impedance and cyclic voltammetry at an ultramicroelectrode
Los,Zabinska,Kisza,Christie,Mount,Bruce
, p. 5449 - 5454 (2000)
Electrochemical studies of the TCNQ0/TCNQ- couple have been carried out using ac impedance spectroscopy and cyclic voltammetry at platinum ultramicroelectrodes (UME). Liquid poly(ethylene oxide) (PEO) CH3-O-(CH2-CH2-O4)-CH3 has been used as the solvent with different concentrations of the TCNQ0/TCNQ- couple and LiClO4 as the supporting electrolyte. On the basis of the ac impedance results at the UME it has been found that the double layer capacitance and standard heterogeneous rate constant are independent of the presence of electroactive species and supporting electrolyte concentrations, indicating that adsorption of electroactive species onto the electrode is not significant. The standard heterogeneous rate constant ks was found to be 0.109 ± 0.005 cm s-1. A similar value of k(s) = 0.094 cm s-1 was obtained for the second reduction step TCNQ-/TCNQ2-. Diffusion coefficients of both TCNQ and TCNQ- are equal, D = 1.0 x 10-6 cm2 s-1 for a 0.5 M LiClO4 solution. Higher diffusion coefficients are obtained in less concentrated supporting electrolyte. Comparison is made between these results and those reported previously for PEO-400 HO-(CH3CH2O)8-OH. The different end groups significantly influence the viscosity and hence k(s).
Effect of comproportionation on voltammograms for two-electron reactions with an irreversible second electron transfer
Lehmann, Mark W.
, p. 1947 - 1950 (2007/10/03)
Many organic and organometailic compounds are reduced or oxidized in two steps with the addition or removal of the second electron occurring with greater difficulty than the first In such EE reactions, a comproportionation reaction can occur in solution near the electrode by which the final product exchanges an electron with the reactant to form two molecules of the intermediate species. Normally, this comproportionation reaction has little or no effect in voltammetry. In this paper, a substantial effect of comproportionation is predicted for the case where the second electron-transfer reaction is irreversible. In steady-state voltammetry, the normally symmetric, sigmoid-shaped second wave is predicted to rise more sharply near its base than is observed in the absence of comproportionation and, in the limit of a very fast comproportionation reaction, an "onset potential" develops at which the current at the second wave increases abruptly from the limiting current of the first plateau. Experimental examples of these effects are presented for the reduction of tetracyanoquinodimethane in acetonitrile by steady-state microelectrode voltammetry, normal-pulse voltammetry, and cyclic voltammetry.
Spectroscopic studies of molecular interaction of 2-thiouracil and dithiouracil donors with 7,7,8,8-tetracyanoquinodimethane as an electron acceptor
Randhawa,Sirdhana,Jassal,Sekhon
, p. 68 - 71 (2007/10/03)
The electronic absorption and electron spin resonance studies on the interaction of thiouracil and dithiouracil as donors with 7,7,8,8-tetracyanoquinodimethane (TCNQ) as an acceptor reveal that the absorption bands in these systems are not due to the charge transfer complex but are due to the formation of products (free radical in nature). The equilibrium constants, K, for the D-A systems as determined from the Benesi Hildebrand model follow the direct trend of pKH of the donors and K(dithiouracil) > · K(thiouracil).
