Organic/Inorganic Langmuir−Blodgett Films Based on Metal Phosphonates. 5. A Magnetic Manganese Phosphonate Film Including a Tetrathiafulvalene Amphiphile1

Abstract

Mixed organic/inorganic Langmuir−Blodgett (LB) films have been prepared in which the polar network is a manganese phosphonate continuous lattice and the organic network contains a substituted tetrathiafulvalene amphiphile. The bis(phosphonic acid) amphiphile, 2,3-bis[(4‘-phosphonobutyl)thio]-6,7-bis(tetradecylthio)tetrathiafulvalene, 1, has been synthesized and deposited from an aqueous Mn2+ subphase to form Y-type LB films with stoichiometry Mn2(1)(H2O)2. Since the amphiphile is a bis(phosphonate), the inorganic network forms the Mn(O3PR)H2O structure known in other manganese phosphonate LB films and layered solids. The film becomes magnetic near 11.5 K when the manganese phosphonate network orders as a canted antiferromagnet. Attempts to subsequently oxidize the tetrathiafulvalene (TTF) network did not result in stable phases. Structural characterization was aided by the synthesis of a solid-state manganese bis(phosphonate) model compound, Mn2(2)(H2O)2, where 2 is the ligand 2,3-bis[(2‘-phosphonoethyl)thio]-6,7-bis(methylthio)tetrathiafulvalene.