PREDICTING THE MAXIMUM OXIDATION POTENTIAL SHIFT IN REDOX-ACTIVE PH-RESPONSIVE MOLECULES IN THEIR ELECTROSTATIC INTERACTION WITH SUBSTRATES

Potentiometric and electrochemical studies have been carried out in TH F-H2O (60:40 v/v) and H2O on several ferrocene-containing pH-responsiv e molecules and the acidity constants of the reduced species (K-m), th e 'oxidised' species (K-m(n)) and the maximum oxidation potential shif t due to the binding process of L with protons (Delta E) have been det ermined. From these values, and Delta E data in MeCN, MeCN-H2O (80:20 v/v), THF-H2O (80:20 v/v) and H2O, an empirical equation based on a Co ulomb charge model, is obtained which accounts for the maximum oxidati on potential shift as a function of the charge of the oxidised electro active framework, the charge of the substrate, the number of electrons involved in the electrochemical process, the number of redox-active u nits, the distance between the redox-active groups and the substrate a nd the macroscopic relative permittivity of the medium.