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 TTP@Y in Et₄NClO₄/MeCN and LiClO₄/MeCN electrolytes. In contact with aqueous electrolytes, TTP@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 TTP@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.