Control Over Diffusion of Ionic Ferrocene Species in Aqueous Solution Using Surfactant Based Organized Media

Abstract

The study of diffusion of chemical species is a fascinating domain of current research. In this work, diffusion of ionic ferrocene derivatives, ferrocenecarboxylic acid (FCA) and (ferrocenylmethyl)-trimethylammonium bromide (FMTAB) has been studied in the aqueous solution of a cationic surfactant, cetyltrimethylammonium bromide, an anionic surfactant, sodium dodecyl sulfate and a non-ionic surfactant, polyethyleneglycolp-(1,1,3,3-tetramethylbutyl)-phenylether by cyclic voltammetric measurements. The voltammetric peak currents of FCA and FMTAB have been used to determine the apparent diffusion coefficients (Dapp) in the supramolecular surfactant systems. The presence of surfactant slowed the diffusion of FCA and FMTAB. The Dapp is fairly dependent on the concentration and type of surfactants. The lowest Dapp of FCA is obtained in cationic micellar system, whereas, FMTAB demonstrated lowest Dapp in anionic micellar solution. Both FCA and FMTAB maintained a moderate value of Dapp in presence of nonionic micellar system. It has been observed that both hydrophobic and electrostatic interactions of ferrocene species with surfactant systems determine the relative binding affinity and incorporation, which eventually controls the diffusivity. Electrochemical parameters, current and potential as well as UV-visible spectroscopic results have been used to comprehend the influence of the surfactant system on the solvated state of ionic solutes.