Ferromagnetic crystalline compounds of copolymers of naphthylamine derivatives and aminoaromatic compounds

Crystalline compounds with ferromagnetic properties are described which are inclusion compounds comprising metal salts in copolymers in which the repeating unit includes one unit from a first group of aminoaromatic derivatives of 1-naphthylamine and corresponding oxidized forms, connected to one unit from a second group of substituted aminoaromatic compounds selected from substituted amines containing at least two condensed benzene nuclei, substituted polycyclic compounds containing at least one aniline moiety in their structure, and aniline derivatives carrying a substituent connected to the nucleus by an ethynylene or para-phenylene unit, and corresponding oxidized compounds. Methods for the preparation of these compounds are also described.

BACKGROUND OF THE INVENTION 
Field of the Invention 
The present invention concerns crystalline compounds with ferromagnetic 
properties which are inclusion compounds comprising metal salts in 
copolymers in which the repeating unit includes one unit from a first 
group of aminoaromatic derivatives of 1-naphthylamine and corresponding 
oxidized forms, connected to one unit from a second group of substituted 
aminoaromatic compounds selected from substituted amines containing at 
least two condensed benzene nuclei, substituted polycyclic compounds 
containing at least one aniline moiety in their structure, and aniline 
derivatives carrying a substituent connected to the nucleus by an 
ethynylene or para-phenylene unit, and corresponding oxidized compounds. 
These copolymers form the subject matter of US patent application Ser. No. 
08/313,440 filed 27 Sep. 1994. They exhibit magnetic properties, in some 
cases ferromagnetic properties. 
The provision of other polymer based compounds which also have 
ferromagnetic properties would be desirable. 
The present invention thus relates to crystalline compounds with 
ferromagnetic properties formed by the inclusion of metal salts in the 
copolymers described above. 
SUMMARY OF THE INVENTION 
The invention consists in crystalline compounds with ferromagnetic 
properties that are organic in origin but that are formed by the inclusion 
of metal salts in copolymers with a repeating unit composed of one unit 
from a first group of aminoaromatic derivatives of 1-naphthylamine and 
corresponding oxidized forms, and one unit from a second group of 
substituted aminoaromatic compounds selected from substituted amines 
containing at least two condensed benzene nuclei, substituted polycyclic 
compounds containing at least one aniline moiety in their structure, and 
aniline derivatives carrying a substituent connected to the nucleus by an 
ethynylene or para-phenylene unit, and corresponding oxidized compounds. 
The crystalline structure of these compounds corresponds to ordered cross 
linking of the copolymer, the metal salt being incorporated in a 
three-dimensional structure. 
The structure of the reduced form of the compounds in the first group and 
those of the second group with a naphthalene nucleus includes a radical: 
##STR1## 
and that of the oxidized form, a radical: 
##STR2## 
The structure of the reduced form of the compounds of the second group 
without a naphthalene nucleus include a radical: 
##STR3## 
and that of the oxidized form, a radical: 
##STR4## 
Many metal salts are suitable for producing the inclusion compounds, in 
particular alkaline or alkaline-earth metal salts, metals from the iron 
and platinum groups, rare-earth metals, and metals from classes 1B and 2B, 
5A and 6A of the periodic classification of the elements. Chlorides, 
bromides, iodides and sulfates of copper, iron, zinc, magnesium, silver, 
manganese, cobalt, chromium and nickel are of particular interest because 
of their ferromagnetism. 
The production process for these inclusion compounds is characterized in 
that one of the above copolymers is rendered soluble and is then complexed 
and precipitated by addition of a solution of the metal salt. 
Advantageously, precipitation is carried out in the presence of a magnetic 
field. 
If the starting copolymer used is the copolymer obtained from aniline and 
beta Cleve acid (5-amino-2-naphthalene sulfonic acid) by reacting the 
monomers in the presence of an oxidizing agent in solution in a weak acid, 
the copolymer is preferably re-dispersed in acetone, then decanted, the 
liquid phase being brought into contact with ether to precipitate a blue 
product. This is then separated and purified then taken up again into 
solution and a metal salt solution is added. The blue product obtained 
during this preparation, whose structure has not yet been precisely 
determined, already has a ferromagnetic character which is enhanced by the 
inclusion of a metal salt.

DETAILED DESCRIPTION OF THE INVENTION 
There follows a description, given by way of example only and with 
reference to the accompanying single figure, of the preparation of 
inclusion compounds in accordance with the invention, and of the 
ferromagnetic properties of these compounds. 
EXAMPLE 1 
a) preparation of a 1:1 copolymer of aniline and beta Cleve acid 
(5-amino-2-naphthalene sulfonic acid) 
5 g of unrefined Cleve acid was dissolved in 25 cm.sup.3 of aniline with 
agitation. After 15 minutes, 20 cm.sup.3 of acetic acid was added and left 
in contact for 5 minutes. 
A solution containing 5 cm.sup.3 of anhydrous acetic acid and 4 cm.sup.3 of 
50 vol. hydrogen peroxide was then added continuously. When all of the 
oxidizing solution had been introduced, centrifuging was carried out and 
agitation was continued for 48 hours. 
b) Treatment of centrifuged concentrate 
The centrifuged concentrate was redispersed in acetone, and then the 
dispersion was centrifuged until the supernatant liquid was almost 
completely translucent. About 2 mg of product was obtained which had 
ferromagnetic characteristics. 
c) Treatment of supernatant liquid 
This liquid was poured into an agitated beaker containing ether. A blue 
precipitate formed. The blue product, whose composition has not yet been 
determined, was then separated by centrifuging and washed with acetone 
until as much as possible of the azo derivatives had been eliminated. It 
was then washed with ether and dried in argon at room temperature. The 
mass of the recovered product corresponded to 36% of the unrefined Cleve 
acid used. 
This blue product was very soluble in methanol, soluble in ammonia, water, 
hydrochloric acid and acetic acid, and insoluble in toluene. Its 
saturation magnetization was 4.10.sup.- 3 emu/g. 
d) Formation of inclusion complexes from the blue product 
The blue product was re-dissolved in one of these solvents. A precipitate 
was then formed by adding a metal salt solution and separating the product 
obtained. The saturation magnetization of the latter was measured. 
It can be assumed, without limiting the scope of the invention, that the 
metal salt causes ordered three-dimensional cross linking by lodging 
within the lattice formed. 
Respective addition of aqueous solutions of copper (II) bromide, iron (II) 
sulfate and zinc chloride produced compounds with saturation 
magnetizations of 10.sup.-1 emu/g, 4.5.10.sup.-2 emu/g and 4.2.10.sup.-2 
emu/g, in yields of several percent following precipitation and washing. 
The figure shows a hysteresis curve for a sample obtained from an inclusion 
compound of a 1:1 aniline and beta Cleve acid copolymer and a copper (II) 
salt. The field H (in oersteds) is shown as the abscissa, with the 
magnetization M (in electromagnetic units) as the ordinate. The saturation 
magnetization of the inclusion compound was about 0.1 emu/g, its remanent 
magnetization was 0.08 emu/g and the coercive field was 487 oersteds. 
EXAMPLE 2 
The method of Example 1 was repeated up to the formation of the precipitate 
by addition of a metal salt solution and the separation of the product 
obtained. This product, which was strictly diamagnetic, was dissolved in a 
mixture of water and acetone to which was added a stoichiometric quantity 
of silver nitrate, with respect to the sulfonic radical of the copolymer. 
A very thin film of silver thus formed by the partial reduction of 
Ag.sup.+ ions. The solution was filtered, then left for three days to 
evaporate slowly at room temperature. Crystals were obtained. The 
saturation magnetization of some of these crystals was measured as 0.1 
emu/g.