✍ Scribed by Miguel Clemente-León; Eugenio Coronado; Carlos J. Gómez-García; Christophe Mingotaud; Serge Ravaine; Gemma Romualdo-Torres; Pierre Delhaès
No coin nor oath required. For personal study only.
Langmuir and Langmuir–Blodgett (LB) films of a variety of polyoxometalates of different shapes, sizes, and charges were prepared by taking advantage of the adsorption properties of these polyanions on a positively charged monolayer of an organic surfactant spread on water. Three different aspects were investigated. 1) The electrochemical and electrochromic properties of LB films containing the easily reducible polyoxoanion [P~2~Mo~18~O~62~]^6−^. Absorbance changes of these LB films deposited onto an ITO substrate have been induced by repeated switching of the applied potential. These changes are due to the formation of the colored reduced forms of the polyanion. Coloration and bleaching of the LB film occur very quickly and are reversible. 2) The preparation of LB films based on magnetic polyoxometalates, such as the Keggin anions, [CoW~12~O~40~]^6−^ and [SiMn(OH~2~)W~11~O~39~]^6−^, or containing magnetic clusters of increasing nuclearities such as [Co~4~(H~2~O)~2~(PW~9~O~34~)~2~]^10−^ and [Co~4~(H~2~O)~2~(P~2~W~15~O~62~)~2~]^16−^ based on a Co~4~O~16~ ferromagnetic cluster, and the polyoxometalates [Co~9~(OH)~3~(H~2~O)~6~(HPO~4~)~2~(PW~9~O~34~)~3~]^16−^ and [Ni~9~(OH)~3~(H~2~O)~6~(HPO~4~)~2~(PW~9~O~34~)~3~]^16−^ based on a nonanuclear M~9~O~36~ cluster. 3) The preparation of LB films of the giant heteropolyoxomolybdate, [Na~3~(NH~4~)~12~][Mo~57~Fe~6~(NO)~6~O~174~(OH)~3~(H~2~O)~24~]⋅76 H~2~O.
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