Modification of Glassy Carbon Electrodes with Complexes of Manganese(II) with Some Phenanthroline Derivatives Immobilized in Nafion Layer.

Manganese(II) complexes with phenanthroline derivatives modified with different substituents were synthesized and incorporated into Nafion layers covering the surfaces of glassy carbon electrodes and were studied electrochemically. Formal potentials and apparent diffusion coefficients were calculated and discussed. The suitability for electrocatalytic oxidation of ascorbic acid and glycolic acid was examined. The surfaces of modified electrodes were characterized using atomic force microscopy.

The Influence of Electrolyte Type on Kinetics of Redox Processes in the Polymer Films of Ni(II) Salen-Type Complexes.

Electrodes modified with polymers derived from the complexes [Ni(salcn)], [Ni(salcn(Me))] and [Ni(salcn(Bu))] were obtained in order to study the kinetics of electrode processes occurring in polymer films, depending on the thickness of the films, the type of electrolyte and the solvent. FTIR and EQCM methods were used to determine the type of mass transported into polymer films during anode processes and the number of moles of ions and solvent. The rate of charge transport through films was determined by the cyclic voltammetry method, by the quantity cD1/2. It was shown that the charge transport was determined by the transport of anions. The kinetics were most efficient for poly[Ni(salcn(Bu))] modified electrodes, obtained from TBAPF6 and working in TBAClO4 and TBABF4. It was also shown that a solvent with a higher DN value and lower viscosity (MeCN) facilitated the transport of the charge through polymer films.

Electrocatalytic Properties of Ni(II) Schiff Base Complex Polymer Films.

Platinum electrodes were modified with polymers of the (±)-trans-N,N'-bis(salicylidene)-1,2-cyclohexanediaminenickel(II) ([Ni(salcn)]) and (±)-trans-N,N'-bis(3,3'-tert-Bu-salicylidene)-1,2-cyclohexanediaminenickel(II) ([Ni(salcn(Bu))]) complexes to study their electrocatalytic and electroanalytical properties. Poly[Ni(salcn)] and poly[Ni(salcn(Bu))]) modified electrodes catalyze the oxidation of catechol, aspartic acid and NO2-. In the case of poly[Ni(salcn)] modified electrodes, the electrocatalysis process depends on the electroactive surface coverage. The films with low electroactive surface coverage are only a barrier in the path of the reducer to the electrode surface. The films with more electroactive surface coverage ensure both electrocatalysis inside the film and oxidation of the reducer directly on the electrode surface. In the films with the most electroactive surface coverage, electrocatalysis occurs only at the polymer-solution interface. The analysis was based on cyclic voltammetry, EQCM (electrochemical quartz crystal microbalance) and rotating disc electrode method.

The Determination of Protonation Constants of Peptidomimetic Cyclophanes in Binary Methanol-Water Mixtures.

The protonation constants of new group of peptidomimetic cyclophanes with valine or phenylalanine moieties incorporated into the macrocyclic skeleton as well as their linear analogues were determined by potentiometric measurements in solutions of methanol-water mixtures at 25°C and constant ionic strength. The influence of cavity size, location of protonation sites, and attached substituents of the macrocyclic ligands on the protonation constants were discussed on the basis of potentiometric measurement as well as H(1)-NMR results.