| Abstract
| - A new sol−gel precursor, based on 1-methyl-3-[3-(trimethoxy-λ4-silyl)propyl]imidazolium iodide (MTMSPI+I-),was synthesized and investigated as a potential novel quasi-solid-state ionic liquid redox electrolyte for dye-sensitized photoelectrochemical (DSPEC) cells of the Graetzel type. MTMSPI+I- was hydrolyzed with acidifiedwater, and the reaction products of the sol−gel condensation reactions were assessed with the help of 29SiNMR and infrared spectroscopic techniques. Results of time-dependent analyses showed the formation of apositively charged polyhedral cubelike silsesquioxane species, which still contained a small amount of silanolend groups that were removed after heating at 200 °C. After cooling, the material formed was a tough, yellowish,and transparent solid, consisting mainly of ladderlike polysilsesquioxane species. The specific conductivity(σ) of the nonhydrolyzed MTMSPI+I- (no I2) was 0.23 mS/cm, while the activation energy (Ea), determinedfrom the Vogel−Tamman−Fulcher (VTF) relation, was 0.29 kJ/mol. After 56 days of aging the σ value ofthe hydrolyzed MTMSPI+I- dropped to 0.11 mS/cm but the viscosity had already increased to 7500 Pa·safter 17 days, demonstrating that a quasi solid state was attained. Apparent diffusion coefficients (Dapp) of I-and I3- obtained from the voltammetric measurements were ∼10-7 cm2/s and decreased to ∼10-8 cm2/s after15 days of sol aging. Time-dependent vibrational spectra, which served in assessing the hydrolysis andcondensation reactions of MTMSPI+I-, were measured with the help of the attenuated total reflectance (ATR)IR spectroscopic technique. The results revealed that, in the course of condensation of sols, the refractiveindex of the modes attributed to the polysilsesquioxane species exhibited strong dispersion, which led to ashift of the vibrational band position in the experimental ATR spectra. This effect accompanies the sol-to-geltransformations and has not yet been considered as a possible error in analysis of the ATR spectra of sols andgels. The calculation procedure for obtaining the corresponding transmission spectra is briefly outlined, andthe results are applied in this work.
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