New layered organic-inorganic magnets incorporating azo dyes

New hybrid organic/inorganic magnets have been synthesized by insertion of stilbazolium-carboxylate and/or -sulfonate dyes into cobalt and copper layered hydroxides. Co-2(OH)(3.57)(MR)(0.43)center dot 1.88 H2O (MR subset of Co (1)) (MRNa: Methyl Red sodium salt: sodium 2-[4-(Dimethylamino)phenylazo]benzoate), Co-2(OH)(3.27)(MO)(0.73)center dot 2.94 H2O (MO subset of Co (2)) (MONa: Methyl Orange sodium salt: sodium 4-[4-(Dimethylamino)phenylazo]benzenesulfonate), Co-2(OH)(3.45)(OrangeIV)(0.55)center dot 2.92 H2O (OrangeIV subset of Co (3)) (OrangeIVNa: OrangeIV sodium salt: sodium 4-[4-(Anilino)phenylazo]benzenesulfonate), and Co-2(OH)(3.46)(MY10)(0.27)center dot 2.34 H2O (MY10 subset of Co (4)) (MY10Na(2): Mordant Yellow 10 disodium salt: sodium 3-[4-(sodium sulfonate)phenylazo]-6-hydroxybenzoate) have been synthesized by anionic exchange in alkaline media starting from Co-2(OH)(3)(OAc)center dot H2O. Cu-2(OH)(3.23)(MR)(0.77)center dot 2.92 H2O (MR subset of Cu (5)), Cu-2(OH)(3.29)(MO)(0.71)center dot 2.31 H2O (MO subset of Cu (6)), and Cu-2(OH)(3.39)(OrangeIV)(0.61)center dot 1.80 H2O (OrangeIV subset of Cu (7)) were obtained starting from the pre-intercalated copper hydroxide Cu-2(OH)(3)(DS) (DS-: dodecylsulfate). This is the first time pre-intercalation is used for the insertion of molecules within the interlamellar space of simple layered hydroxides. The hybrid copper layered hydroxides show ferrimagnetic behaviour with ordering at very low temperature (below 1.8 K). The cobalt analogues are ferrimagnets with ordering temperatures ranging from 6.9 K to 18 K.