Study of redox processes in zeolite Y-associated 2,4,6-triphenylthiopyrylium ion by square wave voltammetry

The electrochemical responses of 2.4.6-triphenylthiopyrylium ion (TTP) in solution and attached to zeolite Y (TTP@Y) are described using cyclic and square wave voltammetries upon immersion of zeolite-modified polymer film electrodes in MeCN (LiClO4, Et4NClO4, and BuN4PF6 electrolytes) and aqueous (LiNO3, NaNO3, and KNO3 electrolytes) media. The electrochemistry of TTP@Y in contact with Bu4NPF6/MeCN is identical to that of TTP(BF4) in solution, with reduction processes at -0.25, -0.74. and -1.36 V vs SCE, and oxidation steps at +0.85 and +1.11 V. This response differs from those obtained for TTPa@Y in Et4NClO4/MeCN and LiClO4/MeCN electrolytes. In contact with aqueous electrolytes, TTPa@Y displays a reversible one-electron transfer at -0.25 V in contrast with the adsorptive behavior observed for solid TTP(BF4) attached to (graphite, platinum, and gold electrodes. For TTPa@Y, two different thick-layer and thin-layer responses are obtained which can be attributed to different topological redox isomers associated to different sites in the zeolite boundary. Thermochemical data for such processes are obtained from the temperature dependence of electrode potentials.