EP2145179A2 - Process for detecting gaseous halogenated compounds - Google Patents

Abstract

Process for detecting a gaseous compound of BX3, HX or X2 type within a gas using a composition containing a probe molecule, characterized in that the probe molecule is a molecule for which the reaction with one or more compounds of BX3, HX or X2 type leads to a variation of at least one of its physicochemical properties, this variation being measurable via a suitable analysis technique, and in that the following steps are carried out in this order: (a) measurement of said physicochemical property of the probe molecule, such as a spectral property, (b) bringing the gas into contact with the composition containing the probe molecule from step (a), (c) repeat measurement of said physicochemical property, (d) correlation of the variation of said spectral property between steps (a) and (c) in the presence of said gaseous compound of BX3, HX or X2 type, the measurement of the physicochemical property from step (a) possibly being a prior step, process for trapping gaseous compounds of BX3, HX or X2 type contained in a gas, material capable of reacting with at least one compound of BX3, HX or X2 type in gaseous form and sensor for compounds of BX3, HX or X2 type.

Description

 PROCESS FOR DETECTION OF HALOGENATED GAS COMPOUNDS

PRIOR ART

The present invention concerns the field of metrology halogenated boron compounds and halogenated and corresponding halogenated acids, for example, in contaminated environments, ^as well as to the pollution of said environments.

Halogenated boron derivatives today have an important place in ^the semiconductor industry. Indeed, boron, by its electronic configuration, is considered a particularly useful p-type dopant. Also, ^the F electronic industry, to provide specific properties to silicon substrates, is a major consumer of compounds such as BF ₃ or BCl _3. These gaseous compounds remain delicate to handle and their toxicity is particularly great since the damage they cause can be delayed, especially in the case of inhalation, and lead to fatal pulmonary edema. The decomposition of boron halides often leads to the formation of the corresponding hydrogen halides.

The properties of the corresponding halogens and acids, and their relative stability, have been exploited for longer than the boron derivatives. As diverse industries use ^today day these compounds in their activity. Chlorine is used in particular by the chemical industry for the preparation of polymers such as polyvinyl chloride (PVC) or for the preparation of solvents, herbicides or refrigerants. Although qu'aujourd ^'hui less used in the manufacture of pulp and paper, chlorine gas is still a widely used ingredient for bleaching. It is also used in metallurgy, in particular for the production of titanium oxide, and in the form of plasma in electronics for the manufacture of semiconductors. Its recognized biological toxicity is used for the purification of aqueous media. Fluoride is mainly used in particular in ^the nuclear industry for the synthesis ^of uranium hexafluoride by fluorination ^{of uranium} oxide. Bromine, less used, is particularly useful in the manufacture of specialty chemicals such as pesticides or herbicides. Halogen-derived acids are also used in various fields of activity. The production of chlorinated compounds and chlorinated specialty chemicals such as methyl chloride or benzyl chloride, metal chlorides (such as aluminum or silicon chlorides) requires ^the use of HCl. The ^hydrogen chloride is also used in hot-dip galvanizing process or separation of minerals; in electronics, it is not only used for the manufacture of semiconductors but also as a moisture trap. The ^hydrogen fluoride generally experiencing the same applications which must be added its use in uranium treatment processes. In addition to the direct consequences that their acidity may cause on materials and living organisms, both externally (skin and eye) and internally (especially at the pulmonary level), more specific effects may be caused. This is particularly the case of hydrofluoric acid, which, like fluorine, can cause in biological organisms of lethal disorders related to hypocalcemia. In addition, some of these gases are particularly flammable compounds and the products resulting from their combustion are often equally harmful.

Considering ^the high toxicity of all compounds mentioned, it is important to ^ensure users maximum security when handling such products. The high reactivity of these compounds imposes storage conditions that are particularly effective and safe. However, whatever the precautions used for handling gaseous compounds highly reactive, it must imperatively be framed by effective detection measures to prevent any leak in the system used.

For most of these compounds, the concentrations currently admitted in ^the work environment are generally between 0.1 and 10 ppm.

The methods for detecting halogenated compounds, and particularly halogenated boron complexes, known from the prior art are in the majority of cases based on a colorimetric detection from colored reagents in liquid solution or reagents impregnated on solid supports of the alumina type, silica gel, activated carbon, TiOa bentonite. clay, carbonate or zeolite.

A method of detecting BCI ₃ using curcumin has been developed as part of the purification of silicon metal for the semiconductor industry. It involves several steps including treating the chlorosilane sample to be analyzed with mannitol to form a nonvolatile compound with boron. The solution is then hydrolysed and then fluorinated before being extracted. The residual boron compound is then treated with curcumin in a nonaqueous acid medium and led, by reaction of curcumin with the boron cations, to the formation of a red complex (rosocyanine) which absorbs at 540 nm, which allows a quantitative analysis of the boron complex with a sensitivity of 50 ppb.

Boron-based impurities in chlorosilane can also be extracted by treatment with quinalizarin in sulfuric acid. This intense blue-violet solution which becomes red on addition of water regains its original color in the presence of boron compounds. The colorimetric analysis, at 630 nm, allows the quantitative measurement of boron compounds with a sensitivity of 5 ppb, according to US-A-4,529,707.

A spectrophotometric method based on the monitoring of the absorbance of a 275 nm BF3: EtOH complex was developed to study the solution formation of stable complexes between BF ₃ and an alcohol (MeOH, EtOH) or ethers, ( Et ₂ O or dioxane.

Among the reagents employed on a solid support, there may be mentioned curcumin, also used in the liquid phase, which makes it possible to detect BCI ₃ but also SiH ₂ Cl ₂ , HF, F ₂ , HBr, Cb or bromocresol green which makes it possible to detect SiHiCL. , HF, Cl ₂ , BCI ₃ , SiHC 2 and BF ₃ . Thus, in US Pat. No. 6,773,925, these two compounds, deposited on activated alumina, are used in colorimetric detectors whose sensitivity is between 0.5 and 5 ppm.

^The carminic acid may also be used for detection eolorimétrique BCI ₃ and in the presence of hydrochloric acid and ^sulfuric acid, as described in Japanese Patent Application No. 60-140209. It is also proposed in US-A-4,820,316 to utilize not the color variations of this compound. but for measuring mass variations ^of a particular material containing carminic or dianthramide acid and ^hydrochloric acid and sulfuric acid in order to detect the BCI _3.

The reaction between the β-diketones grafted in a porous matrix and the BF-. leading to the formation of benzoylmethanatobore difluoride highly absorbent and fluorescent, has been described in the French patent application No. 2,869,036 for the determination of BF ₃ gas.

For the detection of other halogenated compounds, there are dye-impregnated reaction tubes which change color in the presence of a halogen derivative. For example, for chlorine and / or bromine, it is ortho-toluidine or orthotolidine which take on an orange-brown color. For FIC1, the bromophenol blue becomes yellow.

Detection methods based on electrochemical measurements are also known. Among the work carried out so far, it appears that few processes can be used directly, rapidly and efficiently to detect and / or capture the halogenated compounds of boron, the corresponding acids as well as halogens.

Moreover, none of these methods makes it possible to simultaneously detect these different compounds. Considering the reactivity and toxicity of these compounds, it is essential to offer users a variety of safe and rapid means for detecting relatively low concentrations in the particular working atmospheres. Moreover, especially in the field of electronics where different compounds may be present simultaneously, it may be useful to monitor the presence of each ^of them. Moreover, to be able to measure these compounds would be advantageous.

The method of detection, dosing and trapping proposed by the present patent application alleviates this lack in a safe and effective manner.

DESCRIPTION

The present invention particularly relates to a method for detecting halogenated halides of boron, halogens and corresponding acids. The process is particularly intended to detect gaseous compounds of formulas BX _? , HX and X ₂ wherein X represents a halogen, ^using probe molecules.

This method also makes it possible to quantify the amount of compound that has been detected. The invention thus in particular relates to a method for detecting a type ^of gaseous compound BX _3, HX or X ₂ in ^a gas using ^a composition containing a probe molecule, characterized in that the probe molecule is a molecule whose reaction with one or more compounds of BX _3, HX or X ₂ causes a variation of at least one of its physicochemical properties, this variation being measured by a ^technique appropriate analysis, and in that the following steps are carried out in this order:

(a) measuring said physico-chemical property of the probe molecule, such as a spectral property,

(b) contacting the gas with the composition containing the probe molecule of ^step (a),

(c) new measurement of said physico-chemical property,

(d) correlating the variation of said spectral property between steps (a) and (c) with the presence of said gaseous compound of BX ₃ , HX or X _{2 type} .

Measuring the physico-chemical property of step (a) may be a preliminary step, carried out once and for all, so that the method of the ^invention, routine, no longer includes the step (a) .

The gaseous compound of BX ₃ , HX or X _{2 type} is, for example, HBr, HF, F _2, Br ₂ and especially HCl, Cl ₂ , BCl ₃ or BF _3.

It may be present in a gas such as ^that one particular encounter in production workshops or research various industries like those mentioned above, particularly in the semiconductor industry.

The contacting between the gaseous mixture and the composition can be carried out directly, and typically in the presence of a stream of the gaseous mixture, or under reduced pressure, or after dissolution of the gaseous compound by bubbling in a liquid solvent, the setting contact between the components of the gas mixture and the composition being in the liquid medium consisting of the solvent and the mixture of dissolved gas. Preferably the contacting is carried out directly without dissolution in a liquid solvent.

The physicochemical property of which it is a question may notably be a spectral property, such as absorbance, which may be measured by reflection or transmission, fluorescence, luminescence, or an electrical property, such as conductivity, dielectric constant, or other properties such as resistivity or mass.

The measurement can be a simple detection.

The physicochemical property variation is related to the reaction of the probe molecule with one or more compounds of the BX, HX or X _{2 type} , it is based on the structural differences existing between the probe molecule and the reaction product. of the probe molecule with the compound to be detected.

By "composition" is meant a compound or mixture of compounds, which will advantageously be in solid form and typically comprise a matrix and in particular a porous matrix.

The composition may in particular consist solely of the probe molecule, especially when the latter is a polymer.

It may also contain surfactants whose role is either to increase the solubility of the probe molecules in the composition, or to stucture the porous matrices by shaping cavities of precise size and shape.

By "probe molecule" is meant any molecule whose reaction with one or more compounds of BX _3, HX or X ₂ causes a variation of at least one of its physico-chemical properties detectable by a ^technique appropriate assay. Given the nature of the physicochemical property in question, ^the man of ^the art can easily determine what is the appropriate detection technique. Thus, a modification of the spectral properties may be detectable by spectrophotometry. As such, it is possible to speak of modification of the spectrophotometric properties. Several changes in detectable physicochemical properties may occur during the implementation of the process. One or more of these changes may be used. The change in physicochemical properties ^of a probe molecule is detectable from the composition which may contain it, when it comes to measuring physico-chemical properties for a probe molecule, before or after reaction with one of the gases, it should of course be understood that the measurement can be carried out on a composition containing the probe molecule, so it is possible by extension to speak of "measurement of the property of the composition" as well as "measuring the property of the probe molecule". In other words, the measurement can be made on the probe molecule or on the composition containing it. The structure of the probe molecule can be modified at ^the end of the reaction. Thus it is possible that the probe molecule as such initially has no remarkable property, but that its reaction product has a remarkable property, for example spectral. The variation observed at the end of the reaction makes it possible to detect the presence of the desired gaseous compound.

Thus, the probe molecule is characterized by spectral properties for example before and / or after reaction with a compound of BX ₃ , HX or Xi type. Absorption and / or fluorescence spectra, whose variation is measurable by an appropriate spectrophotometric method known to those skilled in the art, are particularly concerned. For example, the probe molecule can be a chromophore whose absorption and / or fluorescence spectra are modified by reaction with a compound of BX _3, HX and / or X _2. By "modification of the absorption and / or fluorescence spectrum" is meant in particular an effect such as a loss or a gain in the intensity of absorption or fluorescence at a given wavelength, a displacement in length ^wave absorption and / or fluorescence maxima, or ^the appearance of new bands. The measured property can also correspond to the interaction with Love waves, related to the dielectric constants, but also to a mass or viscoelasticity.

The probe molecules that can be used according to the invention are in particular alkali metal halides, quaternary ammonium halides, coumarin and its derivatives, porphyrazine and its derivatives, fluorescein and its derivatives and trlarylmethanes. Mention may also be made of rhodamines, cresyl violet, phenoxazine derivatives and oxazones. More particularly retains métauc alkali halides (NaI, KI, KBr, NaCl), halides ^of quaternary ammonium (methyl glycol chitosan iodide, trimethylammonium. Dibromide and decamethonium ^iodide 3-hydrox \ propyl trimethyl, coumarins 522, 500. 120. 102, 47, phthalocyanines of magnesium, silicon, dilithium and disodium. fluorescein. and the purple crystal.

The probe molecules can be used to detect all compounds of type BX ₃ , HX and X ₂ OR only certain ones. They can react differently according to the compound of type BX ₃ , HX and X ₂ and thus provide qualitative information on the nature of the detected compound or on its absence.

The preferred alkali metal halides are KL KBr, KCl, NaI, NaBr and NaCl. It is remarkable ^that an alkali halide may generally be used to detect a compound having the same halide. For such probe molecules the spectrophotometric measured property is in particular ^the absorbance. The wavelength observed corresponds to that of the halogen derivative which is formed, such as I ₃ ^" , Br ₃ ^" or Cl ₃ ^" , or of an interhalogen derivative, such as BrCl ₂ ^" , Br ₂ Cl ^" , and which has a specific absorption spectrum. for example, during ^exposure of KBr to Br _2, the variation in absorbance is related to the formation of Br ₃ ^"which has a specific absorption spectrum. These probe molecules are characteristic of compounds of BX ₃ and X _{2 type} . They do not react significantly with HX-type compounds.

From halide ^quaternary ammonium, it is advantageous to employ those of formula (I):

in which,

Ri, R ₂ . R ₃ independently corresponds to an H or a carbon chain containing from 1 to 22 carbon atoms,

R ₄ is chosen from carbon chains and polysaccharides, X is a halogen, preferably I, Br or Cl. A carbon chain may be optionally mono- or polysubstituted, linear, branched or cyclic, bridging or otherwise, saturated or unsaturated, C 1 -C ₂₂ , preferably C ₁ -C 10, the substituent or substituents which may contain one or more heteroatoms such as N, OF Cl, P, Si or S. Among such carbon chains the preferred alkyl radicals are methyl, ethyl, propyl. isopropyl, butyl. isobut> on. tert-butyl and pentyl. Mention may also be made, among the unsaturated alkyl radicals, of vinyls, allyls, isopropenyls, butenyls, isobutenyls, tert-butenyls, pentenyls and acetylenyls.

Aryl represents an aromatic or heteroaromatic carbon structure, mono- or polysubstituted, consisting ^of one or more aromatic or heteroaromatic rings each comprising from 3 to 8 carbon, rhétéroatome can be N, O, P, F, Cl, Si or Preferably, R 1, R 2, R 4 are aliphatic groups independently selected from H, CH _V C ₂ H ₅ C ₁ H ₇ . C ₄ H _9, CH ₂ (C ₆ Hs), CH ₂ (C ₆ H n), C ₆ H _n.

Preferably, R ₄ will be a C 1 -C ₂₂ carbon chain and more particularly a C 1 -C ₂₂ alkyl group and in particular of formula - (CH ₂ ) _H -CH ₃ with n = 1 to 21, and typically a group of Cn to C ₂₁ , advantageously comprising at least one ammonium, an aryl, a cyclohexyl, a cetyl, or a polysaccharide chosen especially from cellulose, chitosan or their derivatives.

A polysaccharide is a polymeric structure composed of a large number of monosaccharide units united by glycosidic bonds, the units may be independently substituted, the substituent (s) may contain one or more heteroatoms such as N, O, F. Cl, P , Si or S as well as alkyl or aryl radicals. The mass of the polymer has an impact on its viscosity, the use ^of a polysaccharide type of probe molecule is easier if the average degree of polymerization or the average number of monomers in the polymer (m), is between 2 and 100 000, particularly between 10 and 20,000, more particularly between 20 and 1,000.

In the case where R ₄ is a polysaccharide, it typically contains from 100 to 500 monomers. ^The monomeric unit bearing ^the ammonium is preferably of formula (V):

wherein R40 represents a hydrogen or a carbon chain typically Ci-Ci ₂ which advantageously comprises an ether-based oxide; it ^s' be a particularly CH ₃ OC ₂ H _4. X is a halogen, and preferably a Cl, Br or I, as previously defined. It is preferable that R |. R ₂ and R 3 are independently H or C ₁ -C ₄ alkyl, and preferably C 1.

When R4 is a polysaccharide consisting ^of monomer units presented above, it is of course possible that the number of ^nitrogen present as ^ammonium is variable. It can vary theoretically from 1 to m, it is recommended that the amount of monomeric unit containing an ammonium within the polymer is between 40 and 90% of the total amount of monomeric unit, typically it will be close to 70%. It is advantageous furthermore that ^the quaternary ammonium has surfactant properties, it is also advantageous that it is in the form of a cationic polymer.

Advantageously, the quaternary ammonium halide probe molecule will be cetyltrimethylammonium bromide (CTAB) or trimethylammonium iodide methylglycol chitosan (Kikuchi, Y., et al., Makromol Chem.

& 108. 2631 & 6776c (1987)), or ^iodide or tetrabutylammonium bromide.

For such probe molecules, the measured spectrophotometric property will preferably ^absorbance and the observed wavelength correspond preferably to that of the product formed as a function of the starting reactants. These probe molecules are characteristic of BX-type compounds _. and X ₂ , they do not react significantly with HX-type compounds. The probe molecules concerned by ^the invention also correspond to derivatives of coumarin. in particular derivatives whose carbon in position 7 carries a nitrogen, preferably not charged and sp3 type. and more particularly to the compounds of formula (II):

wherein, R ₅ and R _e are independently selected from H, alkyl or aryl radicals, preferably from H, alkyl radicals C ₁ -C _15, the cétoalkyies, esters, fluoroalkyl such as trifluoromethyl, benzimidazoles, benzothiazoles,

R ₇ and R ₈ are independently selected from H, C ₁₅ C ₁₅ alkyl radicals,

R9, Rio and Rn are independently selected from H, C ₁ -C ₁₅ alkyl radicals,

Typically, the probe molecule will thus be chosen from the following coumarin derivatives (designation and reference to the CAS number): coumarin 120 (CAS: 26093-31-2), coumarin 2 (CAS: 26078-25-1), coumarin 466 ( CAS: 20571-42-0), coumarin 47 (CAS: 99-44-1), coumarin 102 (CAS: 41267-76-9), coumarin 152A (CAS: 41934-47-8). coumarin 152 (CAS: 53518-14-2), coumarin 151 (CAS: 53518-13-3), coumarin 6H (CAS: 58336-35-9), coumarin 307 (CAS: 55804-66-5), coumarin 500 (CAS: 52840-38-7), coumarin 314 (CAS: 55804-66-5), coumarin 30 (CAS: 41044-12-6), coumarin 334 (CAS: 55804-67-6), coumarin 522 (CAS: : 55318-19-7), coumarin 7 (CAS: 27425-55-4), coumarin 6 (CAS: 38215-35-0) and coumarin 153 (CAS: 53518-18-6), coumarin 445 (CAS: 28821- 18-36). coumarin 460 (CAS: 91-44-1). coumarin 461 (CAS: 87-01-4), coumarin 503 (CAS: 55804-70-1), coumarin 510 (CAS: 87349-92-6), coumarin 519 (CAS: 55804-65-4), coumarin 52 IT (CAS: 1 14768-72-8). coumarin 522B (CAS: 53518-197). coumarin 523 (CAS: 55804-68-7). coumarin 525 (CAS: 87331-47-3), coumarin 540 (CAS: 38215-36-0), coumarin 545 (CAS: 85642-1 1 -1). The spectral properties of these compounds are based in particular on the existence of the conjugated ring system and the presence ^of a nitrogen donor moiety. Numerous compounds corresponding to formula (II) have already been synthesized and are commercially available, especially in the laser dye industry, and their spectral properties have already been determined.

For such probe molecules the measured spectrophotometric property may be absorbance or fluorescence. For absorbance measurements. the wavelength of interest will correspond to that of the lower energy absorption band, generally between 320 and 440 nm. As and extent of ^exposure, the intensity of this band decreases and a new band shifted toward the blue appears. The fluorescence of these probe molecules is between 400 and 580 nm. These probe molecules are characteristic of the compounds of the HX and BX _{3 type} , and do not react with the X ₂ type compounds.

Porphyrazine and its derivatives and in particular tetrabenzotetraazaporphyrins can also be used as probe molecules according to the invention. It is particularly the compounds of formula (III):

in which, Ra to Rh independently correspond to H, sulfur-containing or phosphorus-containing organic groups, such as acids, carbon chains which may optionally be mono- or polysubstituted, linear, branched or cyclic, bridging or not. saturated or unsaturated, in CpC ₂₂ , preferably in CpC m, the substituent or substituents which may contain one or more heteroatoms such as N. O, F, Cl. P. Si or S. Among the carbon chains are the alkyl radicals which are preferred are, in particular, methyl, ethyl, propyl, isopropyl and butyl radicals. isobutyl, tert-butyl and pentyl. Mention may also be made, among the unsaturated alkyl radicals, of vinyls, allyls, isopropenyls, butenyls, isobutenyls, tert-butenyls, pentenyls and acetylenyls. S may also ^act an aryl radical corresponding to an aromatic or heteroaromatic carbon structure, mono- or polysubstituted, comprising one or more aromatic or heteroaromatic rings each comprising 3 to 8 atoms, the heteroatom can be N , O, P, F, Cl, Si or

S. Since Ra and Rb, Rc and Rd, Re and Rf or Rg and Rh may correspond to bridging groups connected to each other, the molecule may thus comprise a cyclic structure contiguous to one or more of nitrogenous cycles at the heart of the structure.

Preferably, Ra and Rb, Rc and Rd, Re and Rf or Rg and Rh together form an aromatic ring or correspond to a hydrogen; the molecule will advantageously be tetrabenzoporphyrazine (phthalocyanine).

When Ra and Rb, Rc and Rd, Re and Rf or Rg and Rh together form an aromatic ring, the molecule may for example be synthesized by condensation of four identical phthalonitrile molecules. The porphyrazine and its derivatives can optionally complexing a cation or a group of cation M, and p is a number of 0 or 1 indicating the presence of this type ^of entity. It may be a metal, generally chosen from transition metals such as Fe, Co, Cu or Ni, whose oxidation state is typically 2 or 3. Advantageously this metal will be Mg (II) or Cu ( II). It is also possible that porphyrazine and its derivatives complex lighter elements such as Si (IV) or alkali metals. In this case we observe the eomplexation of two atoms such as Li (I) or Na (I).

The spectrophotometric properties that are recommended to observe for such molecules are fluorescence and absorbance. Absorption, one can simultaneously observe a gradual disappearance of lowest energy of the transition typically about 690 nm ^and correlated occurrence of a new transition, the absorption maximum is shifted to the red. This displacement increases when BX ₃ reacts successively with each of the 4 azotes of the aza bridges of the macrocycle. These spectral variations are accompanied by an isobestic point at about 560 nm. In fluorescence, by exciting the probe molecule at the isobestic point, wavelength for which the number of absorbed photons will be constant, at about 560 nm we can observe a fluorescence whose spectrum is centered around 700 nm, which undergoes a batochrome shift when the film is exposed to BF ₃ . Jl is also possible to excite the starting compound to other wavelengths as at its maximum ^absorption around 690 nm. The position of isosbestic points and ^absorption maxima and fluorescence molecules can be influenced by the nature of the environment, including the other constituents of the composition that contains them. On the other hand, the action of HX probably takes place on the central metal with ejection of it and protonation of the two nitrogens of the center. A doubling of the peaks is then observed. These molecules are particularly suitable for type BX ₃ and HX compounds. They do not react with compounds of type X ₂ .

Fluorescein and its derivatives, especially those used as dyes, can also be used as molecule probes according to the invention. It is more typically a fluorone derivative having an aryl group on the carbon not engaged in the bridging bonds of the central ring and more particularly compounds of formula (IVa) and (IVb):

(IVa) [IVb) in which.

Ri ₂ . R _13, R 14 and R ₁₅ correspond to H, independently, an alkyl group having 1 to 4 carbon atoms, a halogen, NO ₂ ^{^.}

Ri _6, Rn, R | g and R ₁ to 9 correspond independently H, alkyl C -C ₆ alkyl, aryl Cl-C _6. halogen, amine, hydroxyalkyl, -N = C = S.

Formulas (IVa) and (IVb) correspond to forms that can exist in chemical equilibrium.

Typically, the probe molecule will be chosen from the following fluorescein derivatives (designation and reference to the CAS number): fluorescein "Acid yellow 73" (CAS: 2321-07-5), 6-aminofluorescein (CAS: 51649-83 -3), 5-aminofluorescein (CAS: 3326-34-9), 6-carboxyfluorescein (CAS: 3301-79-9), fluoresceinethioisocyanate (CAS: 3326-32-7), fluorescein 27 (CAS: 76-54-0), dinitro fluorescein CAS 24545-86-6, tetrachloro fluorescein (CAS 6262-21-1), dibromofluorescein "solvent red 72" (CAS: 596-03-2), teosin B "acid red 91 "(CAS: 56360-46-4), eosin Y" acid red 87 "(CAS: 15086-94-9), eosin-5-thiosemicarbazide (CAS: 1 19881-42-4), erythrosine B "solvent red 1 14" (CAS: 15905-32-5), erythrosin B isothiocyanate (CAS: 72814-84-7), rose bengal lactone (CAS: 4159-77-7), phloxine B (CAS: 18472-87-2).

For such probe molecules, the spectrophotometric properties measured are in particular tabsorbance and fluorescence. These probe molecules are characteristic of compounds of BX ₃ and HX type. They do not react significantly with X ₂ compounds.

Among the usable probe molecules there are still the dyes of the family of triarylmethanes, and especially the dyes of the family of aminotriarylmethanes. especially di- and triaminotriarylmethanes. the. triarylmethanes bearing on two or three of the rings a nitrogen in the para position of the carbon connecting the three rings, more particularly the aminotriarylmethanes of formula (V):

in which,

R ₂₀ . R21, R22 and R25 independently correspond to an H, a carbon chain, and in particular an alkyl radical containing from 1 to 6 carbon atoms, and preferably methyl, propyl, butyl, an aryl radical,

R ₂₆ , R ₂₇ -R ₂₈ , R 29, R ₃₀ , R 31, R 32, R 33, R ₃₄ , R ₃₅ , R 36, and R ₃₇ independently represent an H, a carbon chain, and especially an alkyl radical containing from 1 to 6 carbon atoms, and preferably methyl, propyl, butyl, an aryl radical which may be bridging, an organic functional group having no carbon and typically SO 3 ^- ,

Z is H, an amine of the type -NR ₂₃ R ₂₄ , an ammonium of the type -N ⁺ R ₂₃ R24 R54, and with R ₂₃ , R24 and R ₅₄ independently selected from H, a carbon chain, and in particular a radical alkyl containing from 1 to 6 carbon atoms, and preferably methyl, propyl, butyl, an aryl radical,

X 'is a halogen and preferably F. Cl, Br or I or an organic anion such as Foxalate.

Preferably, the probe molecule is a hydrophobic compound. Crystal violet (or Paris violet, or gentian violet, or methyl violet) which is used mainly in microbiology to carry out gram-type stains. is a particularly preferred example of aminotriarylmethane. It may also be (name and reference to the CAS number) of the lactone resulting from crystal violet (CAS: 1552-42-7). malachite green G (CAS: 633-03-4), green cetyl (CAS: 71 14-03-6). methyl 2B (CAS: 8004-87-3), methyl 6B (CAS: 548-62-9), methyl 10 B, coomasia (CAS: 6104-58-1). fuchsin (CAS: 569-61-9), methyl blue (CAS: 28983-56-4). new fuchsin (CAS: 3248-91-7), pararosaniline (CAS: 569-61-9), Victoria blue BO (CAS: 2390-60-5). For such probe molecules, the measured spectrophotometric properties include absorbance and fluorescence. These probe molecules are characteristic of the BX- and HX compounds. They do not react significantly with X ₂ compounds.

Typically the spectral properties measured in steps (a) and (c) are the absorbance, or fluorescence.

It is possible to simultaneously use different probe molecules. In this case, it is preferable to use molecules whose variations in physico-chemical properties, such as the spectral properties, are different in the presence of the same compound. Thus, for example, a probe molecule reacting only with compounds of BX ₃ and X _{2 type} may be used simultaneously with a probe molecule reacting only with compounds of BX ₃ and HX type to simultaneously detect and measure the presence of the different types of compounds. The different probe molecules can be mixed in as they are inert to one another, preliminary tests can be performed by ^the skilled person by mixing it plans to use. It is also possible to separate them physically.

The composition may, as seen above, also contain one or more compounds other than the probe molecule.

According to a particular embodiment, the composition comprises a matrix, in which the probe molecule is incorporated. Typically, the matrix is an organic polymer that can be selected from polysaccharides such as chitosan. cellulose or their derivatives, porous materials based on inorganic polymers, or organic-inorganic hybrids, hydrogels or aerogels. This embodiment is recommended especially when the probe molecules alone can not be easily deposited directly and easily preserved on a support, such as those typically employed in the context of measurements. spectrophotometric such that ^a glass slide, for example when powdery or liquid.

The probe molecule may also be deposited directly on a support by evaporation of the solvent, in which case the preferred structure of the probe molecule is of polymeric type and typically corresponds to the formula (I) in which R ₄ corresponds to a polysaccharide.

In the case of matrices of porous materials based on inorganic polymers or organic-inorganic hybrids, the incorporation of the probe molecule into the matrix involves, in particular, the chemistry of sol-gel (polycondensation of metal oxide networks) and physicochemistry. -chemistry of the surfactant phases in solution (self-assembly of micelles in structures organized on a nanoscopic scale).

It is preferable ^to use porous matrices with small pore size (diameter <20A) in order to increase the specific surface adsorption of the pollutant-target and increase the probability of reactive collisions between the reactants.

The probe molecule may advantageously be incorporated into a nanoporous sol-gel matrix of metal oxides. The nanoporous sol-gel matrix of metal oxides can be prepared from at least one metal precursor of formula (VI):

in which :

M is a metal selected from silicon, aluminum, titanium, zirconium, niobium, vanadium, yttrium and cerium,

Y is a halogen, preferably chlorine.

R ₃₈ and R ₃ 9 correspond independently alkyl or aryl, i. and k are integers, such that their sum is equal to the magnitude of M and i + j is greater than or equal to 2. According to a preferred embodiment, the metal M is silicon or zirconium. According to a particularly preferred embodiment, the metal precursor is Si (OMe) ₄ or Si (OEt) ₄ .

Furthermore, it is known that the choice of the metal precursor affects the size of pores of the matrix and thus ^the accessibility to the probe molecule of the compounds to be detected. For example, in the case of silicon oxides, the pore size decreases with chain length of R ₃₈ and R ₃ 9, because the chains are entangled and the porosity decreases. The pore size can be increased by incorporating a surfactant which will serve as a mold and around which rigid walls of the inorganic polymer will form, the surfactant then being removed by washing. Thus, it is preferable to use matrices developed from metal oxides of the formula (VI) in which R ₃₈ and R ₃ 9 are alkyl or alkylamine having from 1 to 6 carbon atoms and preferably methyl radicals or ethyls to specifically detect molecules smaller than 6 Å, or propylamine to detect higher diameter molecules (12 Å). When it is said that the composition contains a probe molecule, it must of course be understood that the composition contains at least one probe molecule, and preferably an amount of probe molecule sufficient to allow the measurement of the physicochemical properties of interest in the conditions corresponding to the desired minimum detection threshold. The determination of the threshold is a function of the detection threshold of the technical means available to the user. Similarly, it should be understood that one proceeds to the measurement of at least one physicochemical property of the composition. Similarly, it should be understood that the presence and / or amount of one or more gaseous compounds can be detected and / or measured. The person skilled in the art knows from reading the description in which cases the term "one" means "at least one" or "one".

In order ^to perform the measurements of physicochemical properties of the composition it is generally desirable, in particular when ^it is ^a question of spectrophotometric or electrical properties, of depositing the composition on a suitable support to the means of metric properties. In the case of spectrophotometric properties it typically will be a solid support which does ^not interact with the composition and generally having a flat surface. In the case of electrical properties it ^s' will include conductive substrates as conductive polymers or nanowires or carbon nanotubes. The spectral properties of the support are variable but they will be chosen so that they do not interfere with the measurement of the spectrophotometric properties of the composition. The substrate is suitable for spectrophotometric technique that makes it possible ^to make measurements, there is typically a blade, often transparent to UV light and / or visible, typically made of glass, plastic or quartz when it ^s' act to measure the absorption by transmission variations. When ^{it s'} will measure changes in absorption or reflectance of luminescence, the support may be opaque and also have a curved surface which allows a better distribution of the optical beams for analysis.

The composition, initially in the form of a liquid solution, is typically deposited directly on the support by various techniques such as depositing a drop of solution and spreading on the substrate, (Langmuir-Blodgett, spray, spin coating). soaking-shrinkage at constant shrinkage rate (dip-coating) ...) or by evaporation under partial vacuum. The dipping method is particularly suitable in the presence of quaternary ammonium compounds which readily form micelles in particular when wearing long chains, typically Cl _O C _22. When the composition comprises a matrix which is a cationic polymer such as chitosan. this can be solubilized in a solvent and then deposited on a suitable substrate by spin-coating or dip-coating. The composition, initially in solid form, can also be deposited directly on the support by sublimation under partial vacuum.

The gas can be dissolved in a solvent to be contacted with the composition during step (b). Preferably, in ^step (b), the gas is contacted with the composition comprising the probe molecule in ^the form of a gas stream.

The second measure, performed in ^step (c), regarding the same property as in ^step (a), especially the ^absorbance. reflectance or luminescence. In all three cases. the variation is related to the change ⁱⁿ absorbance, reflectance, or luminescence from the probe molecule, or to the appearance of properties associated with the product resulting from the reaction of the probe molecule with the gas that has been detected. According to a particular embodiment, ^step (d) further comprises correlating the variation of said spectral property between steps (a) and (c) to the quantity of the gaseous compound type type BX _3, HX or X ₂ in the gas.

Steps (b) and (c) can be performed simultaneously. Thus the variation of the spectral property can be followed in time, and by correlation the amount of gaseous compound type BX type ₃ , HX or Xj can be determined.

According to another embodiment, different properties, and in particular spectrophotometric properties such as absorbance, reflectance or luminescence, are measured in steps (a) and (c). The means that can be used to carry out the measurements of the physicochemical properties of the composition are those usually employed in the field under consideration. Regarding the spectrophotometric properties, the means used are those that make it possible to make optical measurements and in particular absorbance, fluorescence or reflectance measurements. Generally photons can be collected and analyzed via a spectrophotometer, a diode array or directly by a photomultiplier. In the latter case, the use of narrowband or broadband interference optical filters will be necessary to distinguish variations in the properties of the probe molecule and / or the product resulting from its reaction with the pollutant. Depending on the property that is measured the apparatus will include means for exciting the probe molecule at a suitable wavelength.

According to a particular embodiment, it is possible ^to use surface plasmon to exalt the variations of the optical properties of the probe molecules. Indeed, excited probe molecules, by light irradiation, near a thin layer of metal can couple to the surface plasmons and lead to lower detection limits and thus allow the detection or dosing of smaller amounts of gas.

According to another embodiment, the measured property corresponds to ^the interaction with Lo \ e type waves. The structural modifications related to the reaction of the probe molecules with the gas notably cause a variation in mass, viscoelasticity, or a dielectric constant which affects the Love type waves. This embodiment is generally implemented in presence of a piezoelectric material which serves as a support or on which it is possible to detect and generate Love waves, typically ^using combs interdigitated electrodes according to a delay line or resonator configuration. The micro-scale devices taking advantage of the resonance frequency variation measurements of the quartz crystals on which the composition is deposited can also be used to quantify the target pollutants reacted with them.

One or more type of gaseous compounds BX _3, HX or X has been detected, the ^invention also allows to eliminate them.

The subject of the invention is therefore also a process for trapping gaseous compounds of BX ₃ , HX or X _{2 type} contained in a gas, characterized in that the gas is brought into contact with a composition as defined above.

It is preferable that the composition comprises a matrix or that the probe molecule is of polymeric nature.

The composition is typically installed in a cell which may in particular take the form of an enclosure of any shape, for example rectangular or cylindrical, provided or not with baffles to lengthen the contact, provided ^with an inlet for gas to be treated and a treated gas outlet. The composition may, as indicated above, be deposited on a support that can be arranged in particular in the baffles. The nature of the support, in the context of gas removal, is of little importance, it is of course desirable that it be chemically inert with respect to the composition. These include support glass, quartz or plastics.

For such treatment, the porous matrices may be in form of powders or granules enclosed in a cylindrical tube or in the form of porous thin films deposited on the walls ^of a cylinder, the deposition may be done through evaporation. Depending on the content of pollutant to be treated, it can modulate ^the thickness of the film or the quantity of powders or granules and the concentration of the probe molecule.

It is possible to treat several pollutants by incorporating several specific molecules-probes.

The amount of trapped gas corresponds at most to the amount of molecule (s) probe (s) present in the composition. So for example for a composition comprising a porous matrix kilogram with a molecule weight rate sensor 5 to 10%, it will be possible to treat, according to the probe molecule selected, 5000-1 1000 m ^{3 of} effluent gas containing 1 ppm of BX _3, HX or Xj- Depending on the gas content (> 1 ppm or <lppm) in the stream, lower or higher volumes may be processed.

A ^suction device of the gas is advantageously used for contacting significant amounts of gas to be treated with the probe molecules.

The cell will be particularly designed to handle a flow rate ^of at least 1 liter of gas per hour, especially at least 10 liters of gas per hour and preferably at least 100 liters of gas per hour. In general, a volume to be processed from 5,000 to 1,000 m ^J corresponds to one month of use. In terms of flow, we can of course consider higher flow rates, 100 liters of gas per minute to treat a few m ^J in 1 to 2 hours.

The cell may in particular be a tube. Depending on the gas flow rate to be treated, it is possible to modulate the diameter and the length of the tube.

With Ms 15, the reaction is reversible. The tube can be pumped under vacuum to regenerate Ms 15.

It is possible to control the saturation of the probe molecules by taking measurements of their physicochemical, and particularly spectrophotometric, properties, as indicated above.

For the implementation of the above methods, the inventors have also developed novel materials capable of reacting with a compound of BX ₃ , HX or X _{2 type} .

This is why the present invention also relates to a material capable of reacting with at least one type BX ₃ , HX or X ₂ compound in gaseous form comprising one or consisting of a porous matrix containing at least one probe molecule such that defined above. The porous matrix typically consists of a matrix of inorganic or hybrid organic-inorganic polymers developed according to the sol-gel process. The invention also relates to a process for the preparation of the above material comprising the following steps:

(a) preparing a porous, preferably sol-gel matrix, and

^(b) incorporating into said porous matrix ^of a molecule probe as defined above. to obtain the desired material.

The porous matrix according to ^the invention is preferably prepared using a sol-gel method. Under the generic name "sol-gel process", we group together techniques that make it possible, by simple polymerization of metal precursors, in particular metal oxides, to obtain inorganic or hybrid organic-inorganic matrices at temperatures close to room temperature. (20 to 35 ° C). Chemical reactions, The. ^hydrolysis and condensation, the basic sol-gel methods, are triggered when the metal precursors are brought into contact with water. The solvents of the precursors may be chosen in particular from alcohols, ethers of which THF or CH ₂ Cl ₂ , CHCl ₃ . Thus, the hydrolysis of the metal oxides occurs first and then the condensation of the hydrolysed products leads to the gelation of the matrix. The solvent may also correspond to a mixture of the solvents mentioned above.

Surfactants may also optionally be used either to induce structuring of the porous matrix and to form pores of modulable size, or to solubilize a probe molecule of low polar content and poorly soluble in the mixture of precursors and solvent, such as a mixture of alcohol and water, or for their dual property.

According to a preferred embodiment of the process according to ^the invention, the metal precursor is a metal oxide, ^the step of preparing the porous sol-gel matrix (a) comprises a step of ^hydrolysis of at least one metal oxide said hydrolysis step preferably being carried out in the presence of an organic solvent, such as an alcohol such as methanol or ethanol.

During the condensation, the hydrolyzed products react with one another to form polymers that continually s ^{increase until obtaining a} three-dimensional polymeric network. At first, the clusters of metal oxide remain in suspension without precipitation, it is the ground. These clusters progressively occupy an increasing volume fraction. The viscosity then becomes important and the liquid eventually gels in a matrix. The matrix thus obtained is therefore constituted by ^* a polymeric network which has a porosity that Ton can be varied as required. The pore diameter of the sol-gel matrix can also be adapted by selecting particular metal oxides. For example, the metal oxides of formula (VI) for which R ₃₈ and R ₃₀ are alkyls, preferably methyl or ethyl radicals. allow to generate matrices whose pores have a reduced diameter. Those for which R ₃₈ or R ₃ 9 is an aminoalkyl, preferably aminopropyl. allow to generate matrices whose pores have high diameters.

According to a particular embodiment, the stage of preparation of the sol-gel matrix (a) and that of incorporation of at least one probe molecule (b) are carried out simultaneously. Indeed, the preparation conditions are sufficiently mild. so that the probe molecules are incorporated into the sol-gel matrix without being altered.

It is desirable that an additional step of ^{homogenization} and / or drying is performed. The drying step allows, among other things, the evaporation of the solvent (s), such as water and alcohols, present in the matrix. Advantageously, the incorporation of at least one probe molecule is provided before the homogenization step, preferably during ^the hydrolysis step.

According to another preferred embodiment, ^the incorporation of at least one probe molecule may be in the porous matrix also by impregnation in solution or in vapor phase according to well known techniques to those skilled in the art, including sublimation .

For the implementation of the previously mentioned processes, the composition presented above and in particular the material according to the ^invention can be integrated into devices, including sensors, generally based on the detection of spectrophotometric properties. The present invention therefore also relates to a device or in particular sensor for compounds of BX3 type. HX or X2 in gaseous form characterized in that it comprises at least one material or a composition, preferably in the form of a matrix, according to ^the invention.

To increase the exchange surface it is preferable that the composition comprises a matrix if the probe molecule it contains does not itself form a matrix, when a sensor is employed.

According to a preferred embodiment, one sensor comprises a material or composition, in accordance with ^the invention deposited on a suitable substrate, preferably in the form ^of a thin film on a transparent substrate. The substrate may be chosen from those conventionally used in the field of spectrophotometric analysis, in particular slides or plates of glass, mica quartz or fluorite.

Typically, the deposition is carried out according to well known techniques to those skilled in the art including, without limitation, dipping, spin coating, by spray (liquid or gas), deposition and spreading ^of a drop. Advantageously, the deposit is made by dipping where possible. ^This is especially the case in the preparation of materials according to ^the invention. Those ^skilled in the art will adjust the withdrawal speed of deposition substrate material which is deposited, preferably a speed close to 25 mm. min ^".

Soaking can be done at room temperature (22-25 ° C) with a relative air humidity between 15 and 50%.

For increased efficiency, blades or plates are installed parallel battery.

According to another preferred embodiment, usable especially when chimiqes physicochemical properties are spectral properties, devices according to the invention or sensors for the detection include at least one source ^of light excitation and a collector.

They mainly consist of a first compartment, ^a second compartment, and ^a screen. The gas is introduced into the sensor through a specific inlet and then passes through a thermostat that controls the temperature and a particle filter. A micropump system, which can be located both upstream and downstream of the material, allows to ^accelerate the diffusion of the gas to the probe molecules, included or not in a material according to the invention.

It is also useful for the sensor to be equipped with a measurement system making it possible to determine the volume of gas that has passed through the inlet. It should be noted that the composition, which corresponds in particular to the material discussed above, is protected from ^the outside by a protective envelope in sealed manner through an O-ring for example. If the gas contains a compound of type BX ₃ , HX or X ₂ . it will react with the probe molecules contained in the composition that correspond to it. The reaction with the probe molecule will be detected after light excitation by a collector and played on ^the screen.

Advantageously, the light source is constituted by a deuterium lamp, halogen ^or a light emitting diode, and the collector ^of a diode array or a photomultiplier low voltage. When the detection method is based on a change in absorbance of the doped film, it is preferable to use a system composed of two doped thin films each deposited on a reflective substrate in order to ^optimize the absorption of the light source by the molecules probes. The photons bouncing multiple times on the walls covered with films will be strongly absorbed by the probe molecules contained in the composition. When the probe molecules are fluorescent or when the product of the reaction between the probe molecule and the gas gives rise to the formation of a fluorescent compound, a metal layer of aluminum or silver may be deposited on the substrate to create resonance plasmons in the excitation wavelength range of the probe molecule or the reaction product to exalt the fluorescence of these compounds. A gas outlet is provided as part of this sensor. Miniaturized devices or sensors are preferred.

It is desirable that the device or sensor further comprises a support for the composition, more particularly a support adapted to the detection method. Advantageously, the device or sensor will also include a system for accelerating the diffusion of the medium to be analyzed, particularly a gaseous medium. Preferably, the system for accelerating the diffusion of the gas is a pneumatic system such as a piston, a discharge pump or a pump. micropump. Such a system will be particularly useful in the case ^of a pollution control device. Sensors with direct optical transduction are thus especially concerned by the invention.

The sensor can also be a multiple sensor, or multi-sensor, for simultaneously detecting different gases and determine their concentration. For this it is possible to use one or more compositions comprising one or more types of probe molecules reacting with different compounds. The different compositions may be mixed in the same film or placed on the same support or on different supports. Compositions comprising different probe molecules may be installed in the same compartment or different compartments.

The material according to ^the invention has many advantages that enable it to be used in the metrology of halogenated compounds as well as clearance. Due to its method of preparation, the material according to ^the invention is nanoporous and therefore provides a very large specific surface area for adsorption. This structural characteristic ^is even more important in the context of the pollution control device. The material according to the invention can be implemented in methods for detecting and / or strength and / or trapping halogen compounds whatever the conditions including the rate ^of humidity.

Finally, compositions, as the material, in accordance with the invention can easily be integrated to a sensor or a device which allows the in situ detection, direct and simple halogen, ^with halogen acids or gaseous boron halide. Advantageously, the sensors can be used in network and permanently ensure quality control ^of a high risk of contamination by environmental boron halides. The devices or sensors can also be associated with a visual or audible alarm which is triggered when the content of boron halide in ^the test environment reaches a certain critical level.

The preferred conditions of implementation of ^a gaseous compound detection method of BX _3, HX or X ₂ in an above-described gas also apply to the other objects of the invention referred to above, in particular to the trapping method.

The invention will be understood more precisely through the attached figures and embodiments which follow and illustrate it.

Figure 1 shows different probe molecules (MsI to Ms15).

FIG 2 is the diagram of a sensor according to ^the invention.

3 shows a top view of the compartment ^of a sensor according to the invention. Figure 4 corresponds to a cross section of the compartment comprising a material according to ^the invention.

FIG. 5 represents a detection system integrated into a sensor comprising two films of the material.

FIG. 6 represents the absorption spectrum of KI in methanol and its evolution during the addition of BCI ₃ as a function of time

Figure 7 shows the absorption spectrum of NaI in a porous matrix and its evolution when the matrix is exposed to a gaseous mixture containing chlorine

FIG. 8 represents the absorption spectrum of a trimethylammonium methylglycol chitosan iodide film and its evolution when the film is exposed under reduced pressure of BCI ₃

9 shows the absorption spectrum of CTAB (C ₅ H33) (Me) 3N ^+, Br in a porous matrix and its evolution when the matrix is exposed to the gaseous BF _3, inset the change in ^absorbance function of the introduced pressure (in Torr) is shown.

Figure 10 shows the absorption spectrum of HO (CH ₂ ) (Me) ₃ N ⁺ J ^- in a porous matrix and its evolution when the matrix is exposed to Cl ₂ gas (40 ppb).

FIG. 11 represents the absorption spectrum of decamethonium dibromide ^" Br ₅ (Me) ₃ N ² - (C 1uH ₂₂ J-NT (Me) ₃ Br ^" in a porous matrix and its evolution when the matrix is exposed to Cl ₂ gas (200 ppb). 12 shows the absorption spectrum ^of a coumarin in ^ethanol and its evolution during the addition of aliquots of BF _3.

Figure 13 shows the ^absorption spectrum ^of a coumarin in a porous matrix and its development during ^the exposure of the HCl gas to die (45 ppm)

Figure 14 shows the absorption spectrum of a magnesium phthalocyanine in ^ethanol and its development during the addition ^of aliquots of BF _3.

15 shows the absorption spectrum ^of a magnesium phthalocyanine deposited on a glass plate by evaporation of the solvent and its development during the exposure of the reduced pressure the film BF ₃ (1 torr).

FIG. 16 represents the monitoring of the kinetics of appearance of the product of the reaction between magnesium phthalocyanine and BF ₃ at 800 nm

FIG. 17 represents the absorption spectrum of a silicon phthalocyanine in ethanol and its evolution during the addition of aliquots of BF ₃ (1.3M)

Figure 18 shows the absorption spectrum ^of a silicon phthalocyanine in ^water and its evolution during ^the addition of HCl (1 and 12M).

Figure 19 shows the absorption spectrum ^of fluorescein in methanol and its development during the addition of aliquots of BF _3. Figure 20 shows the absorption spectrum of a composition containing fluorescein and CTAB deposited on a glass slide and its development during ^the exposure of the film under reduced pressure BCl ₃ gas.

Figure 21 shows the absorption spectrum of crystal violet in methanol and its evolution when adding aliquots of BF ₃ . Figure 22 shows the ^absorption spectrum of the crystal violet deposited on a quartz substrate by evaporating the solvent and its development during ^the exposure of the film under reduced pressure gaseous HCl (4 torr)

Figure 23 shows the ^absorption spectrum of a composition of BIC® deposited on glass and its development during ^the exposure of the pressure reduced movie BF ₃ (2 torr).

24 shows the absorption spectrum ^of a composition of BIC in ethanol and its development during ^the addition of aliquots of HCl. FIG. 25 is an example of a calibration curve obtained for a thin film doped with MS7 and dipped onto each face of a quartz slide.

FIG. 26 is an example of a calibration curve obtained for a thin film doped with MS8 and deposited by dipping. As shown in Figure 3, sensors or devices for use in the ^invention for detection include at least one excitation light source (10) and a collector (1 1).

They include, as shown in Figure 2, composed of a first compartment (4), ^a second compartment (5), and a display screen (7). The gas can be introduced into the sensor via a specific input

(1) then passes through a thermostat that controls the temperature and a particle filter (3). A micro pump system (8), which can be located both upstream ^that downstream of the material accelerates the diffusion of the gas ^up to the probe molecules, included or not in a material (9) according to the invention . The composition (9), which corresponds in particular to the material presented above, is protected from the outside by a protective envelope (13) in a sealed manner by means of a ring for example toric (12) as shown in Figure 4. If the gas contains a compound of type BX ₃ , HX or X ₂ , it will react with the probe molecule or molecules contained in the composition that correspond. The reaction with the probe molecule will be detected after light excitation

(10) by a collector (1 1) and read on the screen (7).

In the example above, the light source comprises a deuterium lamp, halogen ^or a light emitting diode, and the collector of a diode array. When the detection method is based on an absorbance variation of the doped film, it is preferable to use a system consisting of two doped thin films each deposited on a reflective substrate in order to optimize the absorption of the light source by the probe molecules. . The photons bouncing multiple times on the walls covered with films will be strongly absorbed by the probe molecules contained in the composition as shown in FIG. 5. A gas outlet

(2) is provided as part of this sensor. Miniaturized devices or sensors are preferred. In order to illustrate the ^invention are described below experiments which were conducted either with the reactants in solution or in solid medium (film deposited on the substrate) under reduced pressure of gaseous pollutant or under flow of gaseous mixture consisting of nitrogen and pollutants considered (BX ₃ , HX or X ₂ ) at varying concentrations.

In a solid medium, the probe molecules may be incorporated into a matrix or deposited on a substrate from ^a solution. Whereas the health and economic issue ^that they represent for the electronics industry, the compounds whose detection is illustrated are BCIA, BF _3, HCl and Cl _2.

Because of the ease of implementation of the spectral measurements and the easy accessibility to the means for measuring the spectrophotometric properties, the physicochemical properties of the compositions / probe molecules whose variations are here illustrated are the spectrophotometric properties. Spectrophotometric measurements were performed either with a UV-visible UNICAM spectrophotometer or with an OCEAN OPTICS miniature spectrophotometer.

The products needed to implement the examples were obtained commercially; no additional purification was performed.

1. PREPARATION OF THE COMPOSITION

a) Some probe molecules were used directly, without incorporating them into a matrix. It is ^a question of Ms9 particular, a derivative of chitosan, which forms by itself a matrix. b) Some probe molecules (such as Ms 14, fluorescein, MsI 1, magnesium phthalocyanine, Ms 15. crystal violet) or probe molecule mixtures (such as MsI 3-KMsI 5) were employed after a simple deposition by evaporation on a quartz plate of their solution in FethanoL c) Matrices containing probe molecules were prepared from tetraalkoxides of silicon according to the sol-gel process technique as known in the art. Thus, Si (OMe) ₄ (or TMOS) was hydrolyzed with stirring in the presence of ethanol at a neutral pH; the mixture is in the following proportions TMOS / EtOH / H ₂ O = 1/4/4 or 8.38 / 10.13 / 3.96 g.

During the hydrolysis and condensation of the silicon precursors, one or more probe molecules were added to the solution. After a maturation time that may range from a few minutes to several days, a mesoporous thin film, possibly nanostructured, containing the molecule (s) probes is obtained by dipping and then removing a carrier from the solution. A preferred support is a quartz slide and a preferred deposition protocol utilizes constant soaking and removal rates.

The MsI to Ms4 probe molecules correspond to a first family of probe molecules. These are the alkali metal halides. These molecules have been selected for their high availability, low cost and ease of use. Five probe molecules (Ms5 to Ms9) illustrate the use of halides ^of quaternary ammonium. Ms5 and Ms7 are both probe molecules and structuring agents capable of inducing the formation of porous nanostructured matrices. For Ms5 for example, the shape of the pores (here spheres of 48 Å diameter) is imposed by the relative concentrations of the various constituents of the soil (acidic pH, TEOS / EtOH / H ₂ O / HCl / Ms5 mixture = 1/20 / 5 / 0.004 / 0.1).

Ms6 and Ms8 are also used with sol-gel matrices.

Ms9 forms an organic polymer matrix.

Figures 6 to 1 1 illustrate the spectra corresponding to the reactions between these various alkali metal halides and ammonium halides and BF ₃ , BCI ₃ and Cl ₂ .

MsIO corresponds to a derivative of coumarin These probe molecules react effectively in solution with BF-, BCL ,, L1Cl forming the protonated or complexed coumarin whose absorption spectrum is very different from the initial spectrum (see Figures 12 and 13) . Coumarins do not react with X ₂ . The MsI probe molecules l. Ms 12 and Ms 13 correspond to phthalocyanines.

The Ms14 probe molecule is fluorescein. It will serve as an example to illustrate the detection of BF ^. BCI ₃ , HCl in solution.

The Ms 15 probe molecule is crystal violet. This molecule belongs to the family of triarylmethanes.

2. DETECTION OF COMPOUNDS OF TYPE BX ₃ , HX OR X ₂

A physico-chemical property detectable by an analysis technique has previously been determined for each of the above probe molecules.

Each of the samples was then exposed for a variable period of time to a gas to be detected composed mainly of the pure BX ₃ , HX OR X ₂ compound under reduced pressure, with a gaseous nitrogen gas mixture containing the pollutant at levels which were has varied (40 ppb to 500 ppm) or by contacting a solution in which a gas bubbling is performed.

The following experiments were carried out:

Figure 6 shows the spectral variations, in absorption spectroscopy, resulting from the reaction of Ms2 with BCI ₃ in methanol. A solution of 5 Ms2 IQ ^"5 mol. ^L" in methanol to which is added an aliquot of a concentrated solution of BCI ₃ so that the concentration of BCl ₃ is in excess with respect to that of Ms2 (1.3 10 ^" mol.L ^" ). An initial absorption spectrum of the Ms2 solution is collected (dotted curve) before addition of BCI ₃ . A spectrum is collected every 20 minutes after addition of and especially. The strip of the disappearance is observed ^of MS2 absorption centered at 220 nm and ^the appearance of two new ^absorption bands centered at 288 and 358 nm. From the 288 and 358 nm absorbance variation measurements as a function of the concentration of BC I ₃ , calibration curves can be plotted which will be used for the quantitative measurement of BCI ₃ in solution.

7 shows the absorbance change of MSl incorporated in a porous matrix prepared by the sol-gel process ^when it is exposed to a flow of Cl ₂ (gas). The doping of the porous matrix is carried out according to the "one-pot" method used in the sol-gel process. MsI is directly incorporated in the precursor solution whose composition is: TMOS / EtOH / H ₂ O / MSl = 1/4/4 / 0.1 1.

The mixture is stirred under ultrasound for 5 minutes. MsI-doped porous films are prepared by soaking quartz substrates in the solution and removing them at a constant rate (9.6 cm min-1). When the film is exposed to a flux (50 ml.min-1) of gaseous mixture containing 400 ppb of CI ₂ , the decrease in the MsI absorption band centered at 220 nm is observed in favor of the appearance of two new bands centered at 288 and 350 nm. In the same way, from measurements of absorbance variation at 288 and 350 nm as a function of the content of Cl ₂ in the gas stream and for the same flow rate, it will be possible to draw calibration curves to from which we can determine the content of Cl ₂ in a gas stream by exposing a film doped with MsI to this flow.

Four examples of reactivity of the ammonium halide probe molecules are shown in FIGS. 8 to 11. Ms5, Ms7 and Ms8 are at the same time structuring agents which make it possible to obtain nanostructured porous thin films, whereas Ms9 serves both probe molecule and matrix because Ms9 is a polymer. Ms5 is incorporated as micelles in mesoporous thin films of 3D-hexagonal structure based on hybrid organic-inorganic silicon polymers according to a protocol known from the literature [Bourgeois. AT. ; Brunet Bruneau,

AT. ; Fisson, S.; Demarets, B.; Grosso, D.; Cagnol. F. Sanchez, C.; Rivory, J., Thin Solid Films. (2004), 447-448, 46-50] and described below.

The first step is to prepare a pre-S _p hvdrolysée solution of molecular precursors containing tetra ethoxy silane (TEOS), ^ethanol, water and hydrochloric acid in the molar proportions: TEOS: EtOH: H: O: HCl = 1: 3: 1: 5.10 ^" This mixture is refluxed for one hour and a second solution containing ethanol, acidic water (0.055 mol, L ^" HCl) and MS5 is then added. added to the solution S _p . The final composition of the soil is then given by the following molar proportions: TEOS: EtOH; H ₂ O: HCl: MS 5 = 1: 20: 5: 0.004: 0.10. This mixture is stirred for 72 hours at room temperature in an airtight container. The thin films of the mesoporous material are obtained by depositing a thin layer of the soil on a quartz slide by the method of "dip-coating". The removal speed applied in most cases is 3 mm. s ^". During the deposition, the humidity in the chamber of the device is set at a value between 40% and 60%. The film is heated with an epi-radiator for 15 minutes at a moderate temperature (16O ⁰ C) to stiffen the inorganic network without destroying Ms5 The Ms5 micelles are contained in spherical pores of 4.5 ± 0.5 nm in mean diameter, arranged in a 3D-hexagonal structure and separated from each other by a porous wall of Inorganic polymer 2.5 ± 0.5 nm thick During exposure of the thin film to BF ₃ , the pollutant molecules diffuse rapidly through the porous network of the polymer to the micelles of Ms5 The detection of BF ₃ is optical The absorbance of Ms5 in FUV is measured, which decreases quantitatively with the addition of Bfi gas (see Figure 9).

Multiple organized structures of Ms5 micelles can be obtained according to the proportions of TEOS and Ms5 such as the cubic structure

(0.1 <MS5 / TEOS <1), or mixed cubic-hexagonal or lamellar. In all In these cases, the Ms5 cells react in the same way with BF ₃ . Alone. the initial absorbance of Ms5 varies with its initial concentration.

Ms7 is also a structuring agent. Due to the terminal position of the two ammoniums, which makes it possible to obtain thin films of lamellar structure.

The protocol used for the preparation of mesoporous thin films is identical to that presented for Ms5, the proportions and values of the parameters indicated are similar. The resulting film is heated with an epi-radiator for 15 minutes at a moderate temperature (160 ^° C.) to stiffen the inorganic network without destroying the probe molecules. During ^exposure of the thin film doped Ms7 to Cl _2, the pollutant molecules diffuse rapidly through the porous network of the polymer to Ms7. The detection of Cb is optical. The absorbance of Ms7 in FUV is measured. This decreases quantitatively with the addition of Cl ₂ gas (see Figure 1 1).

The absorption spectrum of Ms7 is similar to that of Ms5. UV absorption is observed with a maximum centered around 192 nm. When the doped Ms7 film is exposed to a flux (250 ml.min-1) of gaseous mixture containing 200 ppb of Cl ₂ , the disappearance of the Ms7 absorbance is observed in favor of the appearance of a new band. absorption centered around 267 nm. The reaction is very fast and the species formed at 267 nm has a high molar extinction coefficient. From measurements of absorbance variation at 192 nm or at 267 nm as a function of the content of Cl ₂ in the gas stream for a fixed flow rate, calibration curves can be drawn which will be used to measure the content of Cl ₂ in a gaseous mixture of unknown composition, exposing a film doped with Ms7 to this gaseous mixture.

The protocol used for the preparation of mesoporous thin films doped with Ms8 is identical to that presented for Ms5. the proportions and values of the parameters indicated are similar. The film is heated with an epi-radiator for 15 minutes at a moderate temperature (160 ^° C.) to stiffen the inorganic network without destroying the probe molecules. When ^the exposure of thin film Cl ₂ - pollutant molecules diffuse rapidly through the porous network of the polymer to Ms8. The detection of Cl ₂ is optical. Measuring the ^absorbance of MS8 in UVF. This decreases quantitatively with the addition of Cl? in favor of the appearance of two new bands centered at 295 and 370 nm (see Figure 10).

Ms9 the film is prepared from ^a MS9 solution in water by spreading a drop of the solution on a quartz substrate. The solvent was evaporated by heating the film at 80 ⁰ C. The Ms9 reaction with BCl ₃ was studied by exposing a film doped Ms9 under reduced pressure BCl ₃ gas in a vacuum manifold (see Figure 8). MS9 reacts with BCI ₃ as MsI, Ms2 and Ms8. The disappearance of the Ms9 absorption band centered at 220 nm is observed in favor of the appearance of two new bands centered at 295 and 370 nm. The same experiments were carried out at atmospheric pressure by exposing the film to a gaseous mixture containing a known content of BF ₃ . From the measurements ^of change of absorbance at 295 and 370 nm depending on the content of BCl ₃ in the gas mixture and for a fixed flow rate of the stream, were plotted ^calibration curves. From these curves, the content of BC13 in a gaseous mixture was determined by exposing a film doped with Ms9 to this mixture.

The reactivity of the probe molecules of the coumarin family is shown in FIGS. 12 and 13 with the examples of coumarin 120, Ms10, in solution and incorporated in a porous matrix.

In the first example, a solution of 10 ^-4 mol L- ¹ of coumarin 120 in methanol is prepared. Aliquots are taken from a stock solution of BF ₃ 1.3 mol. L ^" in methanol to prepare several solutions of coumarin 5 ^" 10 mol. L ^"1 containing 10 ^" . 10 ^" and 10 ^" mol L ^"1 of BF ₃ . The spectral changes observed in Figure 12 show the disappearance of the ^absorption bands of coumarin 120 in favor ^of a new species having two ^absorption bands between 230 and 330 nm, in a range of ^wavelength where the coumarin absorbs little. One can observe the same spectral changes during the addition ^of aliquots from an aqueous solution of hydrochloric acid (HCl). From the variation of the absorbances at 350 nm or 270 nm as a function of the concentration of BF ₃ , calibration curves can be drawn which will be used for the detection and measurement of BF ₃ . Since coumarin 120 is fluorescent, it has also benefited

^• variations ⁱⁿ fluorescence intensity of coumarin in the presence of BX ₃ for measuring these pollutants. Other coumarines and more particularly the C522,

C500, C 102 or C47 have also been used for the measurement BX ₃ or HX by absorption or fluorescence.

In the ^second example, coumarin is incorporated into a nanoporous matrix. For this, a solution of precursors containing tetra-methoxy silane (TMOS), ^ethanol, the tetrahydroxyfuran. water and coumarin 120 in molar proportions TMOS: EtOH: THF: H ₂ O: C 120 = 1: 1, 95: 1, 4: 4: 0.0124. This mixture is stirred under ultrasound for 5 minutes and then allowed to mature for 24 hours in an airtight bottle. The thin films of the mesoporous material are obtained by depositing a thin layer of the ground on a quartz plate by the method of soaking at a constant rate of shrinkage. The applied speed is 3 mm. s ^"1. During the deposition, the humidity in the chamber of the device is set at a value between 15 and 30%. Upon exposure of the thin film HCl, coumarin reacts with HCl and detection The coumarin is fluorescent, it is possible to follow the variations of the absorbance spectra on film and fluorescence at the same time.The initial absorption spectrum of the film comprises three bands having a maximum of 206, 234 and 348 nm (see Figure 13) Before exposure, when the film is excited at 350 nm, it is fluorescent with a maximum intensity at 440 nm When the doped MsIO film is exposed to a flux (50 mL.min -1) of gaseous mixture containing 45 ppm of HCl, there is a decrease in absorbance at 234 and 348 nm and the appearance of two bands of absorbance at 265 and 278 nm.Concomitantly, we observe the decrease of the fluorescence emission of the film. from the measurements of variation ^of abs orbance and / or fluorescence as a function of the HCl content in the gas stream for a fixed flow rate, calibration curves can be drawn which will be used to measure the content of HCl in a gaseous mixture of unknown composition.

The reactivity of tetrabenzoporphyrazines is also used for the detection of BX ₃ or HX in solution and in the gas phase. ¹ is an example shown to be used either in solution or deposited on a glass slide (see FIGS. 14-16).

In the first case, a solution of ^"5 mol L ^" of MsI 1 in ethanol is prepared to which are added aliquots of a stock solution of BF ₃ 1.3 mol. L ^"1 Kéthanol. This provides various solutions to the MSI containing BF ₃ in different concentration, 1.3 ^{10" 3} and 1.3 10 ^{"mol L" 1.} In the presence of BF ₃ , the band "Q", typical of the visible absorption spectrum of a tetrabenzoporphyrazine of symmetry D4h, decreases and disappears in favor of a new absorption band of different symmetry, corresponding to the species resulting from the reaction of BF ₃ with the nitrogen atoms of the aza bridges of the macrocycle (see Figure 14). By measuring changes ⁱⁿ absorbance beyond 700nm in the region where only the new species absorbs and depending on the concentration of BF _3, were plotted calibration curves. From these, dissolved BF ₃ was assayed in a solution containing MsI 1. The tetrabenzoporphyrazines being fluorescent, the fluorescence intensity variations were also measured as a function of the concentration of BF ₃ .

MsI was also plated by spreading a drop of MsI solution in ethanol on glass. After drying, an absorption spectrum of

MsI l different from that obtained in solution and which corresponds to the aggregation of MsI 1 molecules on the substrate. When the MsI 1 film is exposed to a reduced pressure of BF ₃ under a vacuum ramp, a significant bathochromic displacement of the absorption spectrum of MsI 1 is observed as in solution (see FIGS. 15 and 16). The variation in the intensity of the new ^absorption band in a range of ^wavelength where the MSI does not absorb can be quantitatively correlated to the concentration of BF _3.

A second example of a study of the reactivity of a tetrabenzoporphyrazine, Ms 12, which differs from MsI 1 by the nature of the central metal, is shown in FIG. 17. In solution, the reactivity of Ms 12 with respect to BF ₃ and HCl is very different. A weak bathochromic displacement is observed in the presence of BF ₃ in large excess while the successive protonation of azotes of aza bridges of the macrocycle is observed in the presence of HCl (see Figure 18).

The reactivity of fluorescein (Ms 14) with BX? and HCl in solution or gas phase has been studied. MsI 4 reacts very effectively in solution with BF ₃ , BCI ₃ and HCl. An example of the reaction Msl4 10 ^{"mol. L" 1} in methanol in the presence of BF ₃ at various concentrations (10 ^{"', 10" 2} and 10 ^"' mol. ^L" ') is shown in Figure 19 During the interaction of BF ₃ with one of the two ternary nitrogen atoms, the disappearance of the two UV absorption bands of Ms14 between 230 and 330 nm is observed. With larger additions of BF _3, the ^interaction of BF ₃ with the last ternary nitrogen atom completely interrupts the delocalization of the electrons in the macrocycle. The ^absorption band of Ms 14, very intense in the visible between 425 and 550 nm. disappears in favor of a new band moved to blue. The absorbance variation of Ms 14 at 260 nm and at 510 nm can be correlated quantitatively with the concentration of BF ₃ . Furthermore, since Ms14 is highly fluorescent, the variations in the intensity of the Ms 14 fluorescence band were correlated with the concentration of BF ₃ . The same reactions are observed with BCI ₃ and HCl.

Ms 14, solubilized with a surfactant (CTAB) in methanol was also deposited on a quartz slide and then exposed to a reduced pressure of BCI ₃ (0.48 torr) (Figure 20). The reaction observed in the solid phase is similar to that in solution. By measuring the variations in absorbance at 525 nm (or fluorescence at 600 nm) of Ms 14 as a function of the content of BX ₃ gas, the calibration curves for the determination of BX ₃ in a gaseous mixture can be established.

Crystal violet (MSI 5) illustrates ^the use of the triarylmethane and more particularly aminotriarylmethanes as probe molecules. Ms 15 reacts with BX ₃ and HCl both in solution and gas phase. Figure 21 shows the spectral variations observed when adding aliquots ^of a solution of BF ₃ 1.3 mol. L ^" in methanol to a 10 ^" mol solution. L ^"1 Msl 5. In a first step L, so that hardly observed spectral variation of 15 Ms in the visible, UV band intensity between 200 and 330 nm decreases with increasing the BF ₃ concentration from 10 ^" to 10 ^" "mol. L ^"1. Increasing the intensity of the new bands in PUV can be quantitatively correlated to the concentration of BF ₃ reacted with Fun nitrogen sites MSI 5. In ^step 2, in ^the presence of a large excess BF ₃ (1 mol. L ^"1), the ^absorption band of Msl5 in the \ isible (570 nm) and UV bands between 230 and 330 nm disappears in favor of two nomelles bands in the visible. Tune of low intensity centered at 430 nm and the second of higher intensity whose maximum absorption is located at 630 nm. These new bands correspond to Ms 15, all the nitrogenous sites reacted with BF ₃ . The variation of ^the intensity of the band at 570 or at 650 nm can be quantitatively correlated to the concentration of molecules of BF _3. BCI ₃ and HCl react in the same way with MsI 5.

Ms 15 may be deposited on a quartz substrate by spreading a drop of a solution of Ms 15 5-10 ^{~ 4} mol. ^{1 "} in methanol on the substrate After drying, the film of Ms 15 has a spectrum similar to that found in solution (Figure 22) The film is exposed under reduced pressure (4 torr) of gaseous HCl in a ramp to At this pressure, the number of HCl molecules is high and the reaction with the first nitrogenous site of Ms 15 is immediate.The collection of the spectra 2 minutes after the exposure already shows the second reaction of HCl with the second nitrogenous site. of MsI 5. The same spectral variation is obtained as that observed in solution with the excess of BF ₃ , namely the disappearance of the band at 570 and bands in FUV in favor of the appearance of two new bands at 430 and 660 nm (see Figure 22).

The reaction is reversible. By vacuum pumping the film of Ms 15, we find the initial spectrum of Ms 15

Finally, a mixture of two probe molecules, Ms 13 and Ms 15, present in the formulation of BICl ⁾ (the formulation contains 3 dyes: Yellow 47 (CAS: 71077-14-0), Violet 9 (CAS: 467- 63-0) and the non-matrix Solvent blue 38 (CAS: 1330-38-7) was used either directly on a mica slide or in solution.

A first experiment is carried out by depositing the mixture on a glass substrate. The sample was then exposed under reduced pressure of BF ₃ in a empty ramp. In the presence of 1 torr of BF _3, we note that MS 15 is the BF reactive vis-à-vis the ₃ because the spectral variations already correspond to step 2 of complexation of the ^2nd nitrogen site of MS 15, the Step 1 of complexation of a nitrogenous site by BF3 being already finished (see Figure 23). A similar result is observed when the Ms 13 + Ms 15 mixture is in solution in ethanol. The addition of HCl induces rapid protonation of the nitrogen sites MSI 5. spectral variations corresponding to the end of ^the step 2, during which HCl also reacts with MS 13 (Figure 24).

Thus, it is possible to mix different probe molecules with each other.

3. QUANTIFICATION OF TYPE X ₂ COMPOUNDS

It is also possible to quantify the content of halogen compounds from ^a gas stream by quantitatively measuring a physicochemical property whose change is dependent on the content of halogenated gaseous compounds.

For example, for an MS7-doped thin film, a new absorption band with a maximum at 267 nm is observed when exposed to a gaseous flow containing chlorine. The intensity of this band increases as exposure increases. The measurement of the rate of the variation of the absorbance at 267 nm for different chlorine content has shown that this speed varies with the chlorine content and that it is therefore possible to establish a calibration curve of the sensor by representing the rate of change of absorbance as a function of the chlorine content in the stream.

Figure 25 is an example of a calibration curve obtained for a thin film doped MS7 and deposited by dipping on each face ^of a quartz plate. This film was continuously exposed to a flow of nitrogen of 500 ml.min-1 in which for short periods (<5min) the Cl ₂ content varied between 40 and 200 ppb. The sequence applied in this example is as follows: 0. 50:50; 100; 100; 150; 150; 200 and 200 ppb. Another example relates to a thin film doped with MS8. In this case, two new ^absorption bands with maxima at 288 and 350 nm are observed when the film is exposed to a gas flow containing chlorine. The intensity of these bands increases progressively from ^exposure. Measuring the rate of change in absorbance at 292 nm for different chlorine levels showed that this rate varies with the chlorine content in the stream and the initial amount of MS8 in the film. It is therefore possible to establish a calibration curve of the sensor by representing the rate of variation of the normalized absorbance with respect to the content of MS8 in the film as a function of the chlorine content in the stream.

FIG. 26 is an example of a calibration curve obtained for a thin film doped with MS8 and deposited by dipping. This film was continuously exposed to a flow of nitrogen of 500 mL ^/ min in which for short periods (<5min) the Cl ₂ content varied between 40 and 160 ppb. The sequence applied in this example is the 40, 40, 40, 80, 80, 120, 120 and 160 ppb.

4. CELLS FOR TRAPPING COMPOUNDS OF TYPE BX ₃ , HX OR

X2

Trapping cells were made from a glass tube 1.6 cm in diameter and 1000 cm in length helically wrapped about a central axis. This provides a total volume of 2 liters for the treatment of polluted air and a surface of 5024 cm ^"for the deposition ^of a porous material film doped with probe molecules. The helical structure of the trapping cell makes it possible to slow down the diffusion of the gas and to improve the contact between the pollutant molecules and the porous film and thus the trapping of the pollutant.

From 500 cm ^J of Sol-Gel solution of silica precursor containing probe molecules 5 10 ^"4 mol ^L" 'MSI 5, a thin film of porous material doped Ms 15 is deposited on the inner wall of the helical tube using a rotavapor. The tube being closed at one end by a stopper, it is rotated about its axis until gelation of the soil. After evaporation of the residual solvents, the deposited film has a thickness of about 124 microns and has a violet color.

The system was exposed to a flow containing the pollutant. When the purple color s ^is dimmed until complete disappearance, trapping system was saturated. Downstream of the tube, a suction pump was mounted. 5. TRAPPING OF BX-TYPE COMPOUNDS ₃ . HX or X ₂

With the trapping cell described above, the total number of moles of MsI 5 is 2.5 × 10 ^-4 mole Air can be drawn through this cell containing 100 ppb of BF ₃ at a flow rate of 1 L min ^-1 for 930 hours. In this case, the volume of air treated is 55.8 m

Claims

1. A method for detecting a type ^of gaseous compound BX _3. HX or X ₂ BX ₃ . HX or X ₂ in a gas ^{using a} composition containing a probe molecule, characterized in that the probe molecule is a molecule whose reaction with one or more compounds of BX _3, HX or Xj leads a variation of at least one of its physico-chemical properties this variation being measurable by a suitable analysis technique and measuring said physicochemical property of the probe molecule, such that ^a spectral property, having previously been performed, and in that the following steps are carried out in this order: a) measurement of said physico-chemical property of the probe molecule, such as a spectral property, b) new measurement of said property, c) correlation of the variation said spectral property between the step of preliminary measurement of said physicochemical property of the composition and step (b) with the presence of said gaseous compound of BX ₃ , HX or X _{2 type} .

2. A method according to claim 1, characterized in that it further comprises ^the step of measuring said physico-chemical property.

3. A method according to claim 1 or 2, characterized in that said physicochemical property of the composition is a spectral property.

4. A method according to one of claims 1 to 3, characterized in that said physicochemical property is absorbance or fluorescence

5. A method according to one of claims 1 to 4, characterized in that the probe molecule is selected from alkali metal halides, ^quaternary ammonium, coumarin and its derivatives, porphyrazine and its derivatives, fluorescein and its derivatives, triarylmethanes, rhodamines, cresyl violet, phenoxazine derivatives and oxazones.

6. A method according to one of claims 1 to 5, characterized in that the probe molecule is incorporated in a matrix.

7. A method according to one of claims 1 to 5, characterized in that the probe molecule is of polymeric structure.

8. A method according to one of claims 1 to 7. characterized in that the gas is contacted with the composition comprising the probe molecule in the form of a gas stream.

9. A process for trapping gaseous compounds of type BX ₃ , HX or X ₂ contained in a gas. characterized in that ^the contacting takes said gas with a composition containing a probe molecule, the reaction with one or more compounds of BX _3, HX or X ₂ causes a variation ^of at least one of its physicochemical properties this variation being measurable by an appropriate analysis technique.

10. A material capable of reacting with at least one type of compound BX ₃ , HX or X2 in gaseous form comprising a porous matrix consisting of a matrix of inorganic or hybrid organic-inorganic polymers produced by the sol-gel process, said matrix porous containing at least one probe molecule, the reaction with one or more compounds of BX _3, HX or X ₂ causes a variation ^of at least one of its physicochemical properties, this variation being measured by a ^technique appropriate analysis .

1. A sensor for type BX ₃ , HX or X ₂ compounds in gaseous form, characterized in that it comprises at least one material or a composition containing a probe molecule, the reaction of which with one or more compounds of BX ₃ type, HX or X2 leads to a variation of at least one of its physicochemical properties, this variation being measurable by a suitable analysis technique, said material or composition is deposited on a substrate suitable for ^analysis technique such as a blade or glass plate, mica quartz or fluorite.

12. A sensor according to claim 1 1, characterized in that it further comprises at least one light excitation source and a collector.