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 longchains 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 200mV for the alkylammonium-polyoxometalate hybrids, and four redox couples between 400 and 520mV for the alkylviologen-polyoxometalate bifunctional hybrid.