Topological Redox Isomers: Surface Chemistry of Zeolite-Encapsulated Co(salen) and [Fe(bpy)3]2+ Complexes

Abstract

The electroactivity of zeolite-encapsulated redox-active transition metal complexes, {M(L)}Z, was explored for Co(salen) and [Fe(bpy)3]2+ formed in NaY zeolite (where salen = N,N‘-bis(salicylidene)ethylenediamine and bpy = 2,2‘-bipyridine). The zeolite boundary was characterized via X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry in nonaqueous electrolyte at either zeolite-modified electrodes (ZMEs) or a stirred microheterogeneous dispersion of the redox-modified zeolite. Voltammetric incongruities arising for {M(L)}Z studied as a ZME rather than as a dispersion are attributed to changes imposed on the redox-modified zeolite by the mechanical force used to prepare a ZME. An increase in the time in which a mixture of {[Fe(bpy)3]2+}NaY and carbon are either ground or pressed produces improved peak resolution and an initial but short-lived increase in the magnitude of the voltammetric peak currents. Cyclic voltammetry of a stirred dispersion of {M(L)}Z particles at a large surface area electrod...