Voltammetric, Spectroscopic, and Microscopic Investigation of the Oxidation of Solid and Solution Phases of Tetrathiafulvalene (TTF) to (TTF)2MO4 (M=Mo, W)

Abstract

The diffusion-controlled solid−solid-state transformation of TTF to (TTF)2MoO4 and (TTF)2WO4 is reported at TTF-modified glassy carbon, indium tin oxide (ITO), Au, and Pt electrodes in contact with aqueous MoO42− or WO42− electrolytes. Electrocrystallization of (TTF)2MoO4 and (TTF)2WO4 onto the electrode surface also was achieved by oxidation of TTF to TTF+ in the presence of Na2MoO4 and Na2WO4 in the mixed CH3CN/H2O (90 : 10 v/v) solvent containing 0.1 M Bu4NPF6 as the supporting electrolyte. Mechanistic aspects of the solid−solid state interconversion reactions and electrocrystallization have been probed by using cyclic voltammetry, chronoamperometry, electrochemical quartz crystal microbalance (EQCM), and electrochemical surface plasmon resonance (ESPR), whereas the morphology of the electrocrystallized materials was established by using scanning electron microscopy (SEM). Vibrational (IR, Raman) and UV/Vis spectroscopic methods, as well as other techniques, were used to establish that the products of electrooxidation are (TTF)2MoO4 and (TTF)2WO4.