Electrochemistry of Tris(1,10-phenanthroline)iron(II) inside a polymeric hydrogel. Coupled chemical reactions and migration effects

MARIA VICTORIA MARTINEZ; RUSBEL CONEO RODRÍGUEZ; BAENA MONCADA, A. M.; BRUNO M.; BARBERO C. A.

JOURNAL OF SOLID STATE ELECTROCHEMISTRY (PRINT)

SPRINGER

Lugar: Berlin; Año: 2016

1432-8488

The retention, release, and detection of metalliccomplexes in polymeric hydrogels are of interest in drug delivery,analytical chemistry, and water remediation. The electrochemistryof the redox complexes inside the hydrogel couldbe affected by the viscoelastic properties of the gel, local ionicforce and pH, and interactions (e.g., hydrophobic) between thecomplex and the polymer chains. In this work, it is shown thata simple setup, consisting of a disk electrode pressed on thehydrogel, allows to perform electrochemistry of a redox couple:Tris(1,10-phenanthroline)iron(II) (Fe(phen)32+) inside ahydrogel matrix. The behavior is compared with the samecouple in solution, and it is found that the electrochemicalproperties of the redox couple are strongly affected by thepresence of the hydrogel matrix. The cyclic voltammogramof the hydrogel loaded with complex shows a response, whichsuggests electrochemical-chemical mechanism. The chemicalstep is likely linked to a catalytic oxidation of free hydratedFe2+ ions present inside the hydrogel together with the redoxcomplex. Since Fe2+ ions have small charge transfer constantson the glassy carbon electrodes, only the catalytic current isobserved. Indeed, when excess ligand (phenanthroline) isabsorbed inside the hydrogel, the measured cyclic voltammogramsshow a single reversible oxidation/reduction step