U.S. Philips Corporation

Olivier O Kahn

Charlotte Jay

Jonas Krober

Renee Claude

Fran&ccedil;oise Groliere

Francedillaoise Groliere

Ren&eacute;e Claude

Epiphane Codjovi

Methods and devices having means for writing storing and erasing which comprise an active medium containing at least one spin-transition parent compound

A chemical composition is provided for the manufacture of devices for storing and/or displaying information, comprising a network having a molecule which is formed from a metallic element Fe.sub.(II) which is bonded to a 1-2-4 triazole ligand (H-Trz), which molecule further comprises one or more than one anions A selected from BF.sub.4.sup.-, ClO.sub.4.sup.-, CO.sub.3.sup.2-, Br.sup.-, Cl.sup.-, in accordance with the formulation:

Spin-transition parent compounds and devices having means for writing,

The invention relates to a spin-transition parent compound in powdered form, comprising a network having molecules which are each formed from a complex in which a metallic ion M having an electronic configuration in d5 or in d6 or in d7, is bonded to at least one aminotriazole ligand of the formula �L.sub.2 N-trz!, wherein L is an alkyl radical (C.sub.n H.sub.2n+1) and n is an integer which is equal to or greater than zero, each molecule also including a sulforganic anion comprising a sulfito radical (SO.sub.3.sup.-), and the network also including at least one water molecule (H.sub.2 O) per molecule of the metallic complex M, said water molecule(s) in the network only being bonded to the aminotriazole ligand by a hydrogen bond. In this compound, the anion may be, for example, a sulfito-aryl having a benzene radical or a sulfito-aryl derived from a benzene radical, or a sulfito-aryl having a saturated or unsaturated organic chain, an alkyl sulfito-halide or an aryl sulfito-halide.

Chemical substances are provided which exhibit thermally induced spin transitions between two stable spin states at ambient temperature, said transitions being associated with a hysteresis phenomenon and resulting in an abrupt variation of the color of the molecules for realizing a medium for storing, processing and/or displaying information by way of thermal writing, optical reading and thermal erasing, a particular embodiment of such a medium comprising at least a layer of chemical substances including a lattice with a molecule comprising a metallic element Fe.sub.(II), or Fe.sub.(III) or Co.sub.(II) associated with at least one ligand chosen from the substituted triazoles which are defined by the formula: ##STR1## in which R is H or an alkyl C.sub.n H.sub.2n+1 or R is an amine group NL.sub.2 where L is H and an alkyl radical, said molecule also comprising one or several anions chosen, for example, from BF.sub.4.sup.-, ClO.sub.4.sup.-, Br.sup.-, Cl.sup.-, and the lattice containing a defined quantity of non-ligand water, ensured by the presence of a hygroscopic substance.

Spin-transition compounds and their use for storing, processing and/or

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Bordeaux, France

Olivier O Kahn