Preparation and electrochemical properties of organic-inorganic hybrids with the use of alkylammonium or alkylviologen cations and polyoxometalate anions

We report preparation of organic-inorganic hybrids by using Langmuir monolayers of several alkylammonium derivatives and a viologen cation as templates at the air-water interface. Surface pressure area isotherms indicated that, although the alkylammonium with four long-chains is able to form stable monolayer on the pure water surface, it is difficult to form on the 0.1 mmol/L polyoxometalate (H₃PMo₁₂O₄₀) subphase surface; reversely, although the alkylammonium and the viologen with one long-chain unable to form stable monolayer on the pure water surface, it becomes stable on the 0.1 mmol/L H₃PMo₁₂O₄₀ subphase surface. The hybrids were transferred onto solid supports by Langmuir-Blodgett (LB) method and characterized by X-ray photoelectron spectroscopy. Electrochemical measurements of the transferred LB films showed reversible three redox couples between 400 and -200 mV for the alkylammonium-polyoxometalate hybrids, and four redox couples between 400 and -520 mV for the alkylviologen-polyoxometalate bifunctional hybrid.