Polyoxometalates in Langmuir–Blodgett films: toward new magnetic materials

Abstract Polyoxometalates having various structures and properties can be organized by the Langmuir–Blodgett (LB) technique. The adsorption of such polyanions along a positively charged monolayer of DODA (dimethyldioctadecylammonium) induces large changes in the compression isotherm and enables the transfer of the Langmuir film onto solid substrate. X-ray diffraction and infrared dichroism experiments demonstrate that the polyoxometalates are organized in monolayers within the LB films. Furthermore, these magnetic multilayers were characterized by their paramagnetic susceptibility measured by a SQUID magnetometer.

First tetrathiafulvalene (TTF) cation-radical salt containing the inorganic polyoxometalate β-[Mo8O26]4⊖

First Magnetic Observation of a Spin Crossover in a Langmuir-Blodgett Film

Magnetic LB films based upon polyoxometalate clusters and single molecule nanomagnets

Abstract By using the adsorption properties of polyoxometalates such as the ferromagnetic cluster [Co 4 (H 2 O) 2 (PW 9 O 34 ] 10− ) along a positively charged monolayer, we have prepared well organized monolayers of the magnetic polyanions. A similar procedure allowed us to obtain Langmuir-Blodgett films (LB films) based on Mn 12 clusters which show a marked hysteresis

Magnetic transition metal complexes of tetrathiafulvalene (TTF) derivatives

We have prepared and characterized the transition metal complexes of two different TTF derivatives. We have oxidized the different complexes with electrooxidation and chemical oxidation techniques and the results are discussed. The magnetic properties of the complexes have been studied. TTF-carboxylate chelates are not stable enough, but thioether-TTF shows promising charge transfer salts.

Polyoxometalate Monolayers in Langmuir-Blodgett Films

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 [P2Mo18O62]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 f…