Electrochemical studies and self diffusion coefficients in cyclic ammonium based ionic liquids with allyl substituents

Several cyclic ammonium-based ionic liquids (ILs) with allyl substituent are synthesized, these ally! substituent ILs have high ionic conductivity (up to 4.72 mS cm(-1) at 30 degrees C) and wide electrochemical window of 5V. The electrochemical behaviors of two organometallic redox couples Fc/Fc(+) (ferrocene/ferrocenium) and Cc/Cc(+) (cobaltocene/cobaltocenium) have been studied in these ILs, the calculated Stokes-Einstein product (D eta T-1) of ferrocene in ILs is larger than that of cobaltocenium in ILs. The self-diffusion coefficients of cation and anion in these ILs are studied using pulsed gradient spin-echo NMR technique. There are very few reports where electrochemically derived diffusion coefficients and self diffusion coefficients are available for comparison, so a new key concept in electrochemistry could be developed in this paper. (C) 2011 Elsevier Ltd. All rights reserved.