EP0403367A2 - Verfahren zur Herstellung von Radikal-Kation-Salzen und deren Verwendung in einem elektronischen paramagnetischen Resonanzmagnetometer - Google Patents

Verfahren zur Herstellung von Radikal-Kation-Salzen und deren Verwendung in einem elektronischen paramagnetischen Resonanzmagnetometer Download PDF

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Publication number
EP0403367A2
EP0403367A2 EP90401621A EP90401621A EP0403367A2 EP 0403367 A2 EP0403367 A2 EP 0403367A2 EP 90401621 A EP90401621 A EP 90401621A EP 90401621 A EP90401621 A EP 90401621A EP 0403367 A2 EP0403367 A2 EP 0403367A2
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EP
European Patent Office
Prior art keywords
salt
probe
substance
magnetic moment
electronic
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP90401621A
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English (en)
French (fr)
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EP0403367A3 (de
EP0403367B1 (de
Inventor
Mehdi Moussavi
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Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
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Commissariat a lEnergie Atomique CEA
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B3/00—Electrolytic production of organic compounds
    • C25B3/20—Processes
    • C25B3/23—Oxidation
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B3/00—Electrolytic production of organic compounds
    • C25B3/01—Products
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B3/00—Electrolytic production of organic compounds
    • C25B3/01—Products
    • C25B3/11—Halogen containing compounds
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
    • C25B9/19—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms

Definitions

  • the subject of the present invention is a process for the preparation of a radical cation salt which can be used in magnetometry by electronic paramagnetic resonance (EPR).
  • EPR electronic paramagnetic resonance
  • Ar can represent in particular naphthalene, fluoranthene, perylene, pyrene or triphenylene.
  • Salts of radical cations of this type for example fluoranthene hexafluorophosphate, have been recently developed as a material for magnetometry because they have interesting RPE characteristics as described by E. Dormann et al in Appl. Phys. A30, 227-231, 1983.
  • radical cation salts can be prepared by electrochemical reaction between a solution of the aromatic hydrocarbon Ar in an appropriate organic solvent with a quaternary ammonium salt comprising the anion X ⁇ as described by Kröhnke et al in Angew. Chem. Int. Ed. Engl. 19, 1980 No. 11, 912-913.
  • the present invention specifically relates to a process for the preparation of a radical cation salt of this type which leads to better stability, as well as a probe for an RPE magnetometer containing such a salt which makes it possible to overcome the drawbacks described above. .
  • the alkyl radical of the formate used as solvent preferably has from 1 to 2 carbon atoms.
  • alkyl formates mention may be made of methyl formate and ethyl formate.
  • the alkyl formate is purified in order to remove the traces of acid, water and alcohol which it contains, before being used for the implementation of the process of the invention.
  • This purification can be carried out by stirring the solvent on Na2CO3 or K2CO3 and by distillation in the presence of P2O5.
  • P2O5 In the case of ethyl formate, it can also be brought into contact with CaH2, then distill it in the presence of CaH2.
  • electrocrystallization of the salt of radical cation is carried out in the absence of water, thanks to the choice of the solvent used, which makes it possible to obtain a salt practically free of water and to improve its stability.
  • this salt can be used for an extended period in an RPE magnetometer, it is necessary to modify the probes containing this salt, used in RPE magnetometry, to further increase the period of stability of the salt of radical cation.
  • the present invention also relates to a probe for an electronic paramagnetic resonance magnetometer (EPR) which comprises a tube containing a substance having an electronic magnetic moment, sensitive to water, such as a salt of radical cation, and a material capable of absorbing water that does not give a parasitic RPE signal.
  • EPR electronic paramagnetic resonance magnetometer
  • the radical cation salt is in particular the salt of formula (Ar) 2 . + X ⁇ described above, and preferably used in the probe of the invention a salt of this type obtained by the method of the invention.
  • the material capable of absorbing the water used in the probe can in particular be a zeolitic molecular sieve.
  • the zeolitic molecular sieves are crystalline, absorbent substances, which contain pores which can be filled with molecules of corresponding dimensions. In the probe of the invention, this property of molecular sieves is used to trap the traces of water, solvent or hydrofluoric acid which could come from the salt of radical cation. In this way, the decomposition reaction described above is prevented from taking place, thereby increasing the stability of the radical cation salt.
  • the tube contains at at least one layer of a substance having an electronic magnetic moment, each layer of substance having an electronic magnetic moment being arranged between two layers of material capable of absorbing water.
  • each layer of substance having an electronic magnetic moment is in direct contact with the wall of the tube and with the two layers of material capable of absorbing the water which l surround
  • the layers of material capable of absorbing water additionally comprise basic alumina powder.
  • the material capable of absorbing water consists of particles of molecular sieves
  • the alumina is basic, it can fix the traces of phosphoric and hydrofluoric acid that may have formed.
  • an aluminosilicate or a mixture of aluminosilicates having pores of about 0.4 to 1 nm is used as the molecular sieve.
  • a molecular sieve of type 4A which is sodium aluminosilicate having a pore size of 0.4 nm
  • a molecular sieve of type 5A which is a calcium aluminosilicate having a pore size of 0.5nm
  • a 13X type molecular sieve which is a crystalline sodium aluminosilicate having a pore size of about 1nm.
  • the alumina powder used can be, for example, basic Al2O3 activity I (without water).
  • the probe of the invention which contains a substance exhibiting an electronic magnetic moment constituted for example by a salt of radical cation can be used in an EPR magnetometer conventionally comprising a probe constituted by a tube containing a substance exhibiting an electronic magnetic moment , a first winding (E1) wound around this tube and capable of producing a voltage due to a variation in magnetic flux resulting from the precession of the electronic magnetic moment around an ambient magnetic field (HO), this voltage having a so-called frequency of Larmor equal to ⁇ HO / 2 ⁇ where ⁇ is the gyromagnetic ratio proper to the substance used, a second winding (E2) capable of creating a rotating magnetic field (H1) at this Larmor frequency to maintain the precession, and suitable electronic means on the one hand, to measure the frequency of the signal sampled at the terminals of the first winding, which gives the module of the ambient magnetic field (HO) and, on the other hand, to deliver the maintenance field (H1).
  • This cell consists of a U-shaped tube (1) separated into two compartments (1a) and (1b) by a sintered glass membrane (3).
  • a pipe (5) makes it possible to connect the upper ends of the two compartments (1a) and (1b) in order to balance the pressures in the two compartments.
  • the compartment (1a) comprises a platinum electrode (7) connected to the positive pole of an electric current generator, which is partially covered with a polytetrafluoroethylene sheath (8) except at its lower end (7a) to allow free electrode length from 1 to 2mm.
  • the compartment (1b) is provided with an electrode (9) also made of platinum which is connected to the negative pole of an electric current generator.
  • the two compartments are hermetically sealed by plugs (11) and (13).
  • the methyl formate is purified to remove the traces of water, acid and alcohol which it contains, by washing it with a concentrated aqueous solution of Na2CO3, then drying it over sodium Na2CO3 and distilling it in the presence of P2O5.
  • a solution of fluoranthene and tetrabutylammonium hexafluorophosphate is then prepared by dissolving 0.9 g of fluoranthene and 1.2 g of tetrabutylammonium hexafluorophosphate in 150 ml of the methyl formate thus purified.
  • This solution is introduced into the electrocrystallization cell (1) and a constant current of 30 ⁇ A is applied to the terminals of the platinum electrodes (7) and (9) which are immersed in the solution, keeping the assembly at -30 °. vs.
  • Fluoranthene hexafluorophosphate crystals are thus formed in the form of black needles from 0.5 to 1.5 cm, with purple reflections.
  • the tubes can be made of glass or another material, for example plastic, gas-tight and not giving a parasitic RPE signal. They can be of different shapes depending on the magnetometer used, for example of cylindrical or toric shape.
  • Probes for RPE magnetometers are then produced in this glove box in order to maintain the degree of purity of the radical cation salt and to obtain the desired stability.
  • FIG 2 there is shown a cylindrical type probe for RPE magnetometer, according to the invention.
  • the probe comprises a cylindrical glass tube (21) having the quality required for the RPE, inside which are successively disposed a first layer C1 of the water-absorbing material (23) which in this example is associated with alumina powder (25), a second layer C2 of a substance having an electronic magnetic moment (27) such as a salt of radical cation, and a third layer C3 of the water-absorbing material (23) associated with alumina powder 25.
  • the tube is closed at its upper part by a plug (29), a layer of hydrophobic grease (30) being interposed between the plug (29) and the layer C3.
  • This probe is carried out by introducing successively in the tube (21) the mixture of particles of the molecular sieves of 0.4, 0.5 and 1nm (23) and the alumina powder (25) to form the first layer C1 then the radical cation salt obtained previously or fluoranthene hexafluorophosphate (27), and again the mixture of molecular sieves (23) associated with alumina powder (25).
  • the tube is then closed with the plug (29) after adding the layer of Apiezon L hydrophobic grease (30).
  • the diameter of the tube is 10mm and the three layers C1, C2 and C3 each have a height of 15mm.
  • the vacuum tube can be sealed as shown in FIG. 3.
  • the tube (21) is surmounted by an opening in ground glassware (33) which can be connected to a vacuum ramp, then it is vacuum sealed.
  • the hydrophobic fat layer (30) can be removed.
  • the alumina powder (25) makes it possible to increase the compactness of the layers C1 and C3 of molecular sieves (23) thereby avoiding the dispersion of the salt of radical cation (27) between the particles molecular sieves (23) of layers C1 and C3.
  • alumina being basic, it makes it possible to fix the traces of hydrofluoric acid and of phosphoric acid possibly formed.
  • the layered arrangement as shown in FIG. 2 is important because it makes it possible to obtain a good RPE signal, by giving the best filling coefficient of the tube in salt of radical cation without interposition of another material between the wall of the tube and the salt, while having the largest possible contact surface between the molecular sieves and the salt of radical cation. Indeed, we would obtain a much lower sensitivity if we had the molecular sieve layers of radical material in the radial direction instead of the longitudinal direction because the detection coils which are generally located around the tube would not allow to extract the maximum of RPE signal coming from the radical cation salt. It would be the same, if we included separation membranes between the layers C1, C2 and C3 in the arrangement of FIG. 2.
  • the probe described in FIGS. 2 and 3 can be used in an RPE magnetometer with a cylindrical probe such as that shown in FIG. 4.
  • the magnetometer comprises a probe (41) constituted by a cylindrical tube containing a substance having an electronic magnetic moment, for example by the probe represented in FIG. 2.
  • the probe is surrounded by a first wound E1 winding around the tube and capable of producing a voltage due to a variation in magnetic flux resulting from the precession of the electronic magnetic moment around an ambient magnetic field HO.
  • It is associated with two windings E2 and E′2 constituted by Helmholtz coils which make it possible to create a rotating magnetic field H1 at the Larmor frequency to maintain the precession.
  • the magnetometer further comprises electronic means not shown in the drawing capable, on the one hand, of measuring the frequency of the signal picked up across the winding E1 and, on the other hand, to deliver the rotating magnetic field H1.
  • the probe of the invention can also be toroidal in shape as described in French patent FR-A-2 603 384.
  • FIG 5 there is shown schematically an RPE magnetometer comprising such a probe (51).
  • the winding E1 is wound around the torus (51) and two coils E2 and E′2 are associated with the probe (51) on either side of the median plane of this probe; they are coaxial with the probe (51) but supplied in such a way that the magnetic fields which they create are in opposition. This results in field lines forming in the median plane of the probe (51) a field H1 of radial distribution.
  • connections 53, 55 and 53 ′, 55 ′ make it possible to bring the current into the coils E2 and E′2 while the connections (57, 59) make it possible to take the signal leaving the winding E1.
  • the toric probe (51) can be produced as shown in FIG. 6 by successively filling a glass toric tube (61) with alternating layers of salt of radical cation (27), and of mixture of molecular sieves (23) and alumina (25).
  • a glass toric tube (61) with alternating layers of salt of radical cation (27), and of mixture of molecular sieves (23) and alumina (25).
  • the arrangement of the cation salt radical and molecular sieves must be non-symmetrical to preserve the isotropy of the probe and to have the best compromise between the longevity of the probe and the sensitivity of the magnetometer.
  • the probe obtained according to the invention was used in the structure represented in FIG. 2 to measure a significant characteristic of the RPE signal of the probe and this measurement was carried out as a function of time over a period of 24 weeks, using the spectrometer.
  • RPE described in Synthétic Metals, 27 (1988) B175-B180.
  • curve I represents the evolution (in%) of this RPE characteristic as a function of time (in weeks). It is noted that this characteristic is practically preserved for 24 weeks.
  • curve II also shows the evolution of the same characteristic as a function of time for an RPE probe produced in accordance with the prior art.
  • the two probes were stored at room temperature 20 to 25 ° C.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Measuring Magnetic Variables (AREA)
  • Medicines Containing Antibodies Or Antigens For Use As Internal Diagnostic Agents (AREA)
EP90401621A 1989-06-14 1990-06-12 Verfahren zur Herstellung von Radikal-Kation-Salzen und deren Verwendung in einem elektronischen paramagnetischen Resonanzmagnetometer Expired - Lifetime EP0403367B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8907877A FR2648457B1 (fr) 1989-06-14 1989-06-14 Procede de preparation d'un sel de cation radicalaire et son utilisation dans un magnetometre a resonance paramagnetique electronique (rpe)
FR8907877 1989-06-14

Publications (3)

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EP0403367A2 true EP0403367A2 (de) 1990-12-19
EP0403367A3 EP0403367A3 (de) 1991-06-12
EP0403367B1 EP0403367B1 (de) 1994-08-24

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EP90401621A Expired - Lifetime EP0403367B1 (de) 1989-06-14 1990-06-12 Verfahren zur Herstellung von Radikal-Kation-Salzen und deren Verwendung in einem elektronischen paramagnetischen Resonanzmagnetometer

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US (1) US5159269A (de)
EP (1) EP0403367B1 (de)
DE (1) DE69011761T2 (de)
FR (1) FR2648457B1 (de)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2688594B1 (fr) * 1992-03-13 1994-04-29 Commissariat Energie Atomique Materiau organique utilisable dans un magnetometre et sonde pour magnetometre a resonance paramagnetique electronique (rpe) utilisant ce materiau.
FR2696008B1 (fr) * 1992-09-21 1994-11-04 Commissariat Energie Atomique Sonde pour la détection et le dosage d'oxygène moléculaire par spectrométrie de résonance paramagnétique électronique.

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL301518A (de) * 1962-12-11
BE756934R (fr) * 1969-10-15 1971-03-16 Commissariat Energie Atomique Nouveau procede de polarisation dynamique des noyaux atomiques d'un solvant, notamment d'un solvant hydrogene, et magnetometres pourla mesure de l'intensite des champs magnetiques faibles notamment du champ magnetique terrestre, mettant en oeuvre ce procede
FR2603384B1 (fr) * 1986-09-01 1988-10-28 Commissariat Energie Atomique Magnetometre a rpe omnidirectionnel
FR2631958B1 (fr) * 1988-05-31 1990-08-10 Thomson Csf Materiau organique a tres faible largeur de raie rpe et sonde de gaussmetre ou de magnetometre utilisant ce materiau
FR2634484B1 (fr) * 1988-07-20 1992-04-17 Commissariat Energie Atomique Phtalocyanines de lithium octasubstituees, leur procede de preparation et leur utilisation en magnetometrie rpe
JP2566000B2 (ja) * 1989-01-23 1996-12-18 日本電子株式会社 マンガンマーカーを使ったｇ値決定法

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US5159269A (en) 1992-10-27
FR2648457A1 (fr) 1990-12-21
EP0403367A3 (de) 1991-06-12
DE69011761T2 (de) 1995-03-16
FR2648457B1 (fr) 1991-09-20
EP0403367B1 (de) 1994-08-24
DE69011761D1 (de) 1994-09-29

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