Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Reexamination Certificate
1999-08-19
2001-07-17
Barts, Samuel (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
C564S248000
Reexamination Certificate
active
06262306
ABSTRACT:
The present invention relates to materials with ferromagnetic properties containing organic molecules with magnetic properties and methods for manufacturing these.
The molecules making up the materials proposed by the invention have what are referred to as magnetic properties since they have a permanent magnetic moment which specifically enables them to align themselves in a magnetic field. The materials proposed by the invention containing such molecules are what are known as ferromagnetic because they exhibit spontaneous magnetisation in the absence of an external field, the permanent magnetic moments of the molecules with magnetic properties which they contain tending to be aligned parallel with one another within an organisation in the solid phase.
Certain organic materials are known to possess ferromagnetic properties. Such materials are described in the patent documents fled under references EP-A-0 512 926, FR-A-2 710 648 and FR-A-2 684 677. These are zwitterionic copolymers such as the polymer below, for example, made from aniline and naphthylamine sulphonic acid:
The ferromagnetism of this copolymer appears in the solid state only, when there is repeated twisting, stabilised by an acid-base interaction involving the sulphonate groups, along the length of the polymer chain and along a stack of aromatic rings.
Turning to the prior art cited above, one problem which the invention is intended to overcome is that of providing a material whose ferromagnetic properties, due to the presence of organic molecules with magnetic properties within said material, are not attributable to twisting in a polymer or oligomer chain stabilised by acid-base interactions.
The preliminary objective of the solution proposed by the invention is to provide a solid material with ferromagnetic properties, characterised in that it contains organic molecules with magnetic properties which satisfy the following general formula:
A═N—B
in which
A═N— is a cyclic imine with a substituted conjugated structure in the &agr; position, N being the nitrogen atom; and
B— is a substituted cyclic radical in the &agr; position.
A second objective of the invention is to propose a method of making a solid material with ferromagnetic properties such as defined above, characterised in that it includes a step whereby a B—NH
2
amine derivative of B— is mixed in a solvent with an O═A═B quinionic derivative of A═. By preference, the solvent is DMSO and the mixture contains a Lewis acid of the BF
3
type in stoichiometric quantities, mixing being effected at a temperature ranging between 80 and 200° C. and crystallisation taking place in a magnetic field.
The A═N—B molecule is not macro-molecular and does not constitute a polymer. It has, intrinsically, magnetic properties as well as organisation and correlation properties and, as a result, will lead to the production of a ferromagnetic material. This molecule is not stabilised by acid-base bonds involving positive and negative charges, particularly of the sulphonate groups.
A═ is preferably a hydrocarbonic monocyclic or polycyclic unsaturated radical, possibly poly-substituted, each cycle comprising 3 to 15 carbon atoms and possibly being interrupted by one or more heteroatoms N, S or O.
More preferably, A═ is a quinone, aminoquinone or cyclopentadienyl ring, substituted at the &agr;, &agr;′ positions at least by substituents Y
1
and Y
2
and complying with the following formulas respectively:
Clearly, if A═ is a polycylic radical such as a naphtho-anthraquinone or fluorenyl radical, Y
1
and/or Y
2
will then correspond to a ring portion. This being the case, substituents satisfying the definition of Y
1
and/or Y
2
will then, advantageously, be present in the peri-positions of the polycyclic radical, for example, at the 1 and 7 positions in a naphthoquinone radical where the nitrogen atom is in position 8; or in positions 1 and 8 in an anthraquinone radical where the nitrogen atom is in position 9.
B— is preferably an unsaturated, hydrocarbonic, mono- or polycyclic, mono- or poly-substituted radical with a conjugated, possibly polysubstituted structure, each ring having 3 to 15 carbon atoms and possibly being interrupted by one or more heteroatoms N, S or O.
More preferably, B— is a benzene ring, substituted at least at positions &agr;, &agr;′ by substituents X
1
and X
2
and complying with the following formula:
Clearly, if B— is a polycyclic radical such as a naphtho or anthracene radical, X
1
and/or X
2
will then correspond to a ring portion. This being the case, the substituents satisfying the definition of X
1
and/or X
2
will then, advantageously, be present at the peri-positions of the polycyclic radical as illustrated below:
In the molecules defined above for A═N— and B—, the substituents R
i
may be electron donors or acceptors and in particular will be substituents selected from among the radicals defined below for X
1
, X
2
, Y
1
or Y
2
.
The molecules of the invention exhibit a more marked magnetic nature if the substituents of the cyclic radical of the imine are electron acceptors and if the substituents of the cyclic radical of B— are electron donors, i.e. if said substituents induce an electronic displacement of the cyclic radical B— towards the cyclic imine A═N— with a conjugated structure.
Consequently, in the molecules proposed by the invention, the substituents of positions &agr;, &agr;′ of the cyclic radical B—, i.e. X
1
and X
2
in the above-mentioned formulas, are advantageously electron donors such as —NH
2
, —NRH, —NRR, —OH, —OR, —R where —R is an alkyl, cycloalkyl, aryl, cycloalkylalkyl, arylalkyl radical and possibly includes one or more heteroatoms. In particular, X
1
and/or X
2
are selected from among the following radicals: —NH
2
, —NMe
2
, —OH, —OMe, and —iPr.
In addition, in said molecules, the substituents at positions &agr;, &agr;′ of the A═ ring conjugated with imine, i.e. Y
1
and/or Y
2
in the formulas given above, are, advantageously, electron acceptors such as —NO
2
, —COR, —CO
2
R, —COOR, —SO
3
R, —SO
2
R where R is an alkyl, cycloalkyl, aryl, cycloalkylalkyl, arylalkyl radical and possibly includes one or more heteroatoms. In particular, Y
1
, and/or Y
2
are selected from among the following radicals: —NO
2
, —SO
3H
, —SO
2
Me, —SO
3
Me, —CO
2
H, —CO
2
Me and —COMe.
In the ground state, each molecule A═N—B is subject to constraints which are mainly steric in nature, imposed on them by the substituents which they carry at the &agr; and &agr;′ positions of their cyclic radicals A═ and B—. These substituents take up position on said molecule A═N—B at the level of the nitrogen atom and therefore cause orthogonalisation of the orbitals carrying the radical electrons, breaking the double bond A═N leads to the formation of a bi-radical A.—B. so that the electrons are then trapped on the rings and said molecules can then exhibit a spin correlation characteristic of the triplet state. Consequently, in the ground state, the molecules of the invention are generally in the triplet state, which is the source of the ferromagnetic properties of the materials proposed by the invention. Clearly, orthogonalisation is improved if the cyclic radicals are di-substituted at the &agr; and &agr;′ positions, which increases the steric occupation at the level of the nitrogen atom. However, it should be pointed out that the A═N—B molecules which, in the ground state, are in the singlet state but whose energy needed for the changeover to the nearest triplet state is low, in the order of several kCal/mole, can easily change from the singlet state to the triplet state after a slight excitation, which may be magnetic, chemical, electrochemical or electric, for example, and will then be able bring about a crystallisation based on materials with ferromagnetic properties.
In a material such as proposed by the invention, n molecules are structured in the solid state in such a way that the said material exhibits ferromagnetic pro
Le Mehaute Alain
Leriche Christian
Barts Samuel
Gemplus
Plottel Roland
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