WO2019096965A1 - Per-substituted cyclodextrins for selective and reversible adsorption of trichlorofluoromethane - Google Patents

Abstract

The present invention relates to the use of per-substituted cyclodextrins for the adsorption of trichlorofluoromethane, and more particularly use of same for the selective detection of trichlorofluoromethane in gas samples and for the reversible storing of trichlorofluoromethane. The invention also relates to a method and a device for detecting trichlorofluoromethane in gas samples and a method for the reversible storing of trichlorofluoromethane. The present invention further relates to a crystalline complex of hexakis(2,3,6-tri-O-methyl)-α-cyclodextrin with trichlorofluoromethane.

Description

 PER SUBSTITUTED CYCLODEXTRINS FOR THE SELECTIVE AND REVERSIBLE ADSORPTION OF TRICHLOROFLUOROMETHANE

The present invention relates to the use of per-substituted cyclodextrins for the adsorption of trichlorofluoromethane, and more particularly to their use for the selective detection of trichlorofluoromethane in gas samples and for the reversible storage of trichlorofluoromethane. The invention also relates to a method and apparatus for detecting trichlorofluoromethane in gas samples, and to a method of reversibly storing trichlorofluoromethane. Furthermore, the present invention relates to a crystalline complex of hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin with trichlorofluoromethane.

BACKGROUND OF THE INVENTION

Trichlorofluoromethane, also known as Freon 1 1, belongs to the class of chlorofluorocarbons (CFCs). These low molecular weight, organic

Compounds are used in particular as propellants, refrigerants or solvents. However, chlorofluorocarbons such as trichlorofluoromethane are high in levels

Environmentally hazardous, which is why their use was banned in many applications today. Due to the environmentally hazardous properties, there is a high demand for efficient methods for absorption or storage, as well as for the detection of

Trichlorofluoromethane.

A commercial method for the detection of trichlorofluoromethane in gas samples uses test tubes, for example Dräger Detection Tubes. Here, the gas to be analyzed is first thermally treated in a first test tube, which is formed by decomposition of the CFCs contained in the gas samples hydrogen chloride (HCl), which is determined in a second test tube with the aid of a pH indicator. This process is not selective towards Freon 1 1 but detects all highly chlorinated, volatile hydrocarbons. In addition, the test tubes allow only the one-time, indirect detection of chlorofluorocarbons and are on a

Concentration range of 100-1400 ppm limited.

Moritz et al. (Sensor, Actuat, B-Chem., 1999, 58, 486-490 and Anal. Chim. Acta, 1999, 393, 49-57) describe a method for detecting trichlorofluoromethane by means of semiconductor sensors. This method is also based on an indirect detection, in which the hydrogen fluoride formed in an upstream thermal decomposition is detected. This method thus does not allow the selective detection of Freon 1 1, but detects all halogenated (fluorinated) volatile hydrocarbons. Furthermore, optical gas sensors for the detection of trichlorofluoromethane are commercially available based on the method of infrared spectroscopy (IR gas sensors). In these sensors, Freon 1 1 is detected by measuring specific absorption bands in the infrared spectrum. However, there are cross-sensitivities to other substances with halogen functionalities, since they usually have IR bands in the same wavelength range. In addition, the IR gas sensors have a high measurement inaccuracy at low Freon 1 1 concentrations of less than 1000 ppm.

Pankow et al. (Anal. Chem., 1998, 70, 5213-5221) describe a method for

Absorption and thermal desorption of volatile organic compounds, such as

Trichlorofluoromethane, on carbon molecular sieves (CMS), and their detection by GC-MS.

O'Doherty et al. (J. Chromatogr. Sci., 1992, 30, 201-205) describe a method for detecting chlorofluorocarbons such as trichlorofluoromethane by means of

Gas Chromatography (GC) using a commercially available GC column containing a cyclodextrin-containing stationary phase.

The methods described in the prior art for the detection of trichlorofluoromethane in gas samples have various disadvantages. Often they do not permit selective detection of trichlorofluoromethane. However, the few known methods for the selective detection of trichlorofluoromethane are very expensive and expensive and can not be used for on-line and / or real-time monitoring. In addition, only a few of the methods described in the prior art can be made difficult

Use measuring conditions, for example in potentially explosive atmospheres or in the presence of strong electromagnetic fields.

Zhang et al. (J. Hazard, Mater., 201 1, 186, 1816-1822) and Ruan et al. (Waste Manage., 201 1, 31, 2319-2326) describe a process for the adsorption of trichlorofluoromethane on activated carbon. These methods can also be used on an industrial scale. For this purpose, the Freon 1 1 containing exhaust air is passed through a filled with activated carbon filter and collected. A selective adsorption of Freon 1 1 is not achieved in this method, since almost all substances are adsorbed in the gas to be purified. In addition, the bound in the activated carbon Freon 11 can only partially desorb, so neither the Freon 11 nor the activated carbon can be reused.

Kurtsuna et al. (J. Atmos. Chem., 1992, 14, 1-10) describe the adsorption of freon 1 1 on various metalloid oxides such as silica, alumina, iron oxide, titania and zinc oxide. DE 4233577 A and Hiraiwa et al. (J. Ceram Soc Jpn., 1996, 104, 264-267) describe the adsorption of halogenated hydrocarbons on zeolites (molecular sieves), using as zeolites various crystalline aluminosilicates different pore sizes are used. Since the adsorption volatile

These substances are not selective for the adsorption of freon 1 1. In addition, water is also adsorbed, which increases the adsorption efficiency with respect to halogenated hydrocarbons

Water content of the sample decreases sharply. In addition, Freon 1 1 can only be desorbed from zeolites at very high temperatures (400 ° C).

Atwood et al. (Science, 2002, 296, 2367-2369) describe the co-crystallization of freon 1 1 with calix [4] arene, with calix [4] arene and freon 1 1 in a ratio of 1: 1

crystallize. However, crystalline calix [4] arene has cavity structures in which, besides Freon 1 1, molecules of similar size can also be taken up, so that no selective adsorption of freon 1 1 can be achieved here. In addition, the adsorption of Freon 1 1 is not effective, i. it requires large amounts of these substances.

In summary, it is found that the known methods for the absorption and storage of trichlorofluoromethane have a number of disadvantages and generally do not allow selective or reversible adsorption and thus do not allow separation of trichlorofluoromethane or its reversible storage.

Girschikofsky et al. describe in IMCS 2012, 14th International Meeting on Chemical Sensors (Ed .: R. Moos), AMA Service, Wunstorf, 2012, and Anal. Chim. Acta, 2013, 791, 51-59, Bragg grating sensors coated with ethyl- or allyl-substituted cyclodextrins as affinity material for the detection of volatile aromatic compounds

Hydrocarbons.

SUMMARY OF THE INVENTION

The object of the present invention is therefore to provide a method for the selective and reversible adsorption of trichlorofluoromethane, thus enabling the selective detection and reversible storage of trichlorofluoromethane. In particular, the method should allow an economical adsorption or storage of trichlorofluoromethane. Another object is to provide a method by which trichlorofluoromethane can be detected selectively as well as online and / or in real time. Moreover, this method should be sufficiently sensitive to detect trichlorofluoromethane even at low concentrations, i. in concentrations of less than 1000 ppm. Furthermore, the method should be made more difficult

Measuring conditions can be used.

It has surprisingly been found that are per-substituted cyclodextrins, in which the hydrogen atoms of all the hydroxyl groups by an organic radical which is selected from Ci-C ₆ alkyl and C ₂ -C ₆ alkenyl, replaced, in particular corresponding per-substituted a-, ß- and g-cyclodextrins, selective and reversible

Adsorb trichlorofluoromethane. It is believed that per-substituted cyclodextrins selectively form stable molecular complexes with trichlorofluoromethane, which cleave at elevated temperature to release trichlorofluoromethane, thus allowing for selective and reversible storage of trichlorofluoromethane. Thus, a crystalline complex of hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin could be prepared and characterized with trichlorofluoromethane containing 4 molecules of trichlorofluoromethane per hexakis (2,3,6-tri-O-methyl). contains -a-cyclodextrin molecule. In this connection it has also been found that gas sensors whose sensitive layer comprises a per-substituted cyclodextrin have a considerably increased sensitivity to trichlorofluoromethane and therefore trichlorofluoromethane can be detected selectively and reliably with such sensors.

Therefore, the present invention relates to the use of per-substituted

Cyclodextrins, in particular of per-substituted a-, ß- and / or g-cyclodextrins, for adsorption, in particular for the selective adsorption of trichlorofluoromethane.

In particular, the present invention relates to the use of per-substituted cyclodextrins, in which the hydrogen atoms of all the hydroxyl groups by an organic radical which is selected from Ci-C ₆ alkyl and C ₂ -C ₆ alkenyl, replaced, in particular in accordance with per substituted a-, ß- and / or g-cyclodextrins, for the reversible storage of trichlorofluoromethane, and a method for the reversible storage of trichlorofluoromethane, in which bringing trichlorofluoromethane with a solid adsorbent in contact, which is a per-substituted cyclodextrin, in particular a contains per-substituted a-, ß- and / or g-cyclodextrin.

Are a further object of the present invention is the use of per- substituted cyclodextrins, in which the hydrogen atoms of all the hydroxyl groups by an organic radical which is selected from Ci-C ₆ alkyl and C ₂ -C ₆ alkenyl, replaced, in particular of per-substituted a-, ß- and / or g-cyclodextrins, for the selective detection of trichlorofluoromethane in gas samples and a method for the detection of trichlorofluoromethane in gas samples, in which

 a gas sample comprising at least one gas sensor having a sensitive layer region containing a per-substituted cyclodextrin, in particular a per-substituted a-, ß- and / or g-cyclodextrin,

detects the changes produced by trichlorofluoromethane in the gas samples in the sensitive layer of the sensor in the form of electrical or optical signals and evaluates the signals in a conventional manner. The present invention also relates to an apparatus for carrying out the method according to the invention for the selective detection of trichlorofluoromethane in gas samples, the apparatus having the following constituents:

 Detection means which, when in contact with the gas sample, generate signals which depend on the concentration of trichlorofluoromethane in the gas sample, the

 Detection means comprise at least one gas sensor having an area with a sensitive layer containing a per-substituted cyclodextrin, in which the

Are hydrogen atoms of all the hydroxyl groups by an organic radical which is selected from Ci-C ₆ alkyl and C ₂ -C ₆ alkenyl, substituted, comprising; and

 Evaluation means, which calculate the concentration of the trichlorofluoromethane contained in the gas sample from the signals supplied by the detection means.

The present invention also relates to a crystalline complex of

Hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin with trichlorofluoromethane.

DETAILED DESCRIPTION OF THE INVENTION

Cyclodextrins are homochiral cyclic oligosaccharides consisting of cyclic a-1, 4-linked D-glucose units. Cyclodextrins with six cyclic a-1, 4-linked D-glucose units are referred to as a-cyclodextrins, cyclodextrins with seven or eight cyclic a-1, 4-linked D-glucose units are referred to as ß- and g-cyclodextrins. Cyclodextrins have a conical-toroidal structure with a larger and a smaller opening on the opposite sides. The

Openings of unfunctionalized cyclodextrins have a highly hydrophilic region, whereas the interior of the structure is lipophilic in nature. The properties of

Cyclodextrins are strongly influenced by the nature of the functionalization of the hydroxy groups. Thus, the type and size of the substituents on the OH groups of the cyclodextrins influence the hydrophilicity and lipophilicity of the cyclodextrin edges and also the size of the openings and thus the accessibility of the lipophilic interior of the

Cyclodextrins.

The term "per-substituted cyclodextrins" refers to here and below

Cyclodextrins in which the hydrogen atoms of all the hydroxyl groups of the cyclodextrins are replaced by an organic radical, which is selected from Ci-C ₆ alkyl and C ₂ -C ₆ - alkenyl. The substituents of the per-substituted cyclodextrins may be different or identical. Preferably, the substituents of the per-substituted cyclodextrins are identical.

The per-substituted cyclodextrins used according to the invention are preferably per-substituted α-, β- and γ-cyclodextrins. In terms of her

Use for the reversible storage of trichlorofluoromethane are the per- substituted cyclodextrins preferably selected from per-substituted a-cyclodextrins, especially under per-Ci-C ₆ alkyl-substituted a-cyclodextrins and especially under per-Ci-C ₄ alkyl-substituted a-cyclodextrins, ie a-cyclodextrins at where the hydrogen atoms of all hydroxy groups are replaced by C ₁ -C ₆ -alkyl, in particular by C ₁ -C ₄ -alkyl. Also preferably, the per-substituted cyclodextrins are selected from _per-C2-C6 alkenyl-substituted a-cyclodextrins, ie a-cyclodextrins, in which the hydrogen atoms of all the hydroxyl groups are replaced by C ₂ -C ₆ alkenyl.

In the context of the present invention, the expression "C ₁ -C ₆ -alkyl" stands for a linear or branched saturated hydrocarbon radical having 1 to 6 C atoms and

in particular 1 to 4 C atoms (C 1 -C 4 -alkyl), such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, 2-pentyl, 3-pentyl, 2-methylbutyl, 3-methylbutyl, 3-methyl-2-butyl, 2,2-dimethylpropyl, n-hexyl, 2-hexyl, 3-hexyl, 2-methylpentyl, 2-methyl-2-pentyl, 3-methylpentyl, 4-methylpentyl, 3-methyl-2-pentyl, 2,3-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 2-ethylbutyl and the like.

In the context of the present invention, the term "C 2 -C ₆ -alkenyl" is a linear or branched monounsaturated hydrocarbon radical having 1 to 6 C atoms, for example vinyl, 1-propenyl, allyl (prop-2-en-1 yl), but-2-en-1-yl, but-3-en-1-yl, but-3-en-3-yl, 2-methylprop-2-en-1-yl, pent-2-ene 1-yl, pent-3-en-1-yl, pent-3-en-2-yl, pent-4-en-1-yl, pent-4-en-2-yl, 2-methylbut-2 -en-1-yl, 2-methylbut-3-en-1-yl, 3-methylbut-3-en-1-yl, 3-methylbut-3-en-2-yl, hex-2-ene-1 -yl, hex-3-en-1-yl, hex-3-en-2-yl, hex-4-en-1-yl, hex-4-en-2-yl, hex-4-ene-3 -yl, hex-5-en-1-yl, hex-5-en-2-yl, hex-5-en-3-yl, 2-methylpent-2-en-1-yl, 2-methylpent-3 -en-1-yl, 3-methylpent-3-en-1-yl, 3-methylpent-3-en-2-yl and the like.

The substituents of the per-substituted cyclodextrin are particularly preferably selected from among methyl, ethyl, propyl, n-butyl, vinyl, allyl and 3-methylbut-3-en-1-yl (isopentenyl). Most preferably, the substituents of the per-substituted cyclodextrin are selected from methyl, ethyl and allyl.

Examples of preferred per-substituted cyclodextrins according to the invention are

Hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin, hexakis (2,3,6-tri-O-ethyl) -a-cyclodextrin, hexakis (2,3,6-tri-O) allyl) -α-cyclodextrin, heptakis (2,3,6-tri-O-methyl) -β-cyclodextrin, heptakis (2,3,6-tri-O-ethyl) -β-cyclodextrin, heptakis (2,3 , 6-tri-0-allyl) -beta-cyclodextrin,

Octakis (2,3,6-tri-O-methyl) -cyclodextrin, octakis (2,3,6-tri-O-ethyl) -cyclodextrin and octakis (2,3,6-tri-O) allyl) -Y-cyclodextrin. Among them, hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin is particularly preferable among them for use for reversibly storing trichlorofluoromethane.

The per-substituted cyclodextrins are known per se, for example from Guieu, S. et al. Advances in Cyclodextrin Chemistry, in: Modern Synthetic Methods in Carbohydrate Chemistry: From Monosaccharides to Complex Glycoconjugates (ed. DB Werz and S. Vidal), Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany, 2013 and the literature cited therein, or can be prepared in a manner known per se by functionalizing the free OH groups of the cyclodextrin (see eg G. Schomburg et al., HRC 1992, 15, 579-584 and H. Dodziuk, Cyclodextrins and their Complexes, Wiley-VCH, Weinheim, 2006 (ISBN 3-527-31280-3)) ,

For example, one can cyclodextrins which are per-substituted with alkyl or alkenyl radicals, by reacting unsubstituted cyclodextrins with an alkylation or

Alkenylating agent in the sense of a nucleophilic substitution hersteilen. suitable

Alkylating or alkenylating agents are, for example, alkyl halides and

Alkenyl halides, especially alkyl bromides, alkyl iodides, alkenyl chlorides and

Alkenyl bromides and alkyl or alkenyl sulfonic acid esters, e.g. Alkyl or

Alkenyltoluolsulfonsäureester. The alkylating agents are usually used in excess, based on the OH groups contained in the cyclodextrin, e.g. in an amount of 1, 5 to 5 mol per mol of OH group. Usually, the reaction takes place in the presence of a base, in particular in the presence of an alkali metal hydroxide and / or

Alkalimetallhydrids such as sodium hydroxide, potassium hydroxide or sodium hydride. The base is also usually used in excess, based on the OH groups contained in the cyclodextrin, e.g. in an amount of 1, 5 to 5 molar equivalents per mol of OH group. Usually, the reaction will be carried out in an aprotic polar solvent, e.g. Perform dimethyl sulfoxide, sulfolane, dimethylformamide, acetonitrile, N-methylpyrrolidione. The reaction is usually carried out at temperatures in the range of 10 to 120 ° C.

Alkylcarbonyl groups can be prepared, for example, by acylating the free OH groups with activated carboxylic acid derivatives, for example carboxylic acid halides, in particular with C 1 -C ₄ -alkylcarbonyl chlorides, such as acetyl chloride or propionyl chloride, or

Carboxylic anhydrides such as acetic anhydride, propionic anhydride or

Butyric anhydride, are introduced. Methods for this are known, e.g. from H. Dodziuk, Cyclodextrins and their Complexes, Wiley-VCH, Weinheim, 2006 (ISBN 3-527-31280-3), AA Sutyagin et al., Russian Journal of General Chemistry 2002, 72, 147-150 and from DE 4414138 ,

Because of their ability to adsorb trichlorofluoromethane in gas samples with increased selectivity, per-substituted cyclodextrins, as previously defined, are useful for the selective detection or selective detection of trichlorofluoromethane in gas samples. Selective detection of trichlorofluoromethane is understood to mean that trichlorofluoromethane can be selectively detected in the presence of substances that interfere in conventional detection methods

Trichlorofluoromethane, such as, for example, halogenated hydrocarbons, In particular, chlorinated hydrocarbons such as dichloromethane, trichloromethane, dichloroethane and the like, and chlorofluorocarbons. Through the use of per-substituted cyclodextrins in the sensitive layers of gas sensors, the

Sensitivity and selectivity of these gas sensors compared to trichlorofluoromethane significantly increased. The use of per-substituted cyclodextrins in the sensitive layers of gas sensors thus enables the detection of

Trichlorofluoromethane even at trichlorofluoromethane concentrations of less than 1000 PPm.

For the detection of the trichlorofluoromethane in gas samples, the per-substituted cyclodextrin in the form of a gas sensor will usually be used, which is a sensitive

Having range, which comprises a per-substituted cyclodextrin to be used according to the invention, wherein the range is designed in particular as a sensitive layer comprising a per-substituted cyclodextrin.

For the detection of the trichlorofluoromethane are in principle all common and known in the art types of gas sensors having a sensitive area, in particular a sensitive layer and, for the chemical substance to be detected, here trichlorofluoromethane, a specific measurable variable in an evaluable signal, for example in an electrical or optical signal, implement. Such sensors are also referred to as chemosensors. According to the gas sensors are modified so that the sensitive layer comprises a per-substituted cyclodextrin. In other words, the sensitive layer is chemically sensitized with the per-substituted cyclodextrins used in the present invention, i. chemically functionalized with the per-substituted cyclodextrins used in the invention. Upon contact of the sensitive layer with the trichlorofluoromethane-containing sample, it is due to the

Presence of the per-substituted cyclodextrin in the sensitive layer to a specific adsorption of trichlorofluoromethane in the sensitive layer. This adsorption in turn causes a change in the measured variable and thus generates an evaluable signal. The measurand can be based on different physical measuring principles, e.g.

optically or gravimetrically.

As a rule, such sensors have a direct, often even one

approximately linear relationship between the concentration of the analyte, here trichlorofluoromethane, in the gas sample and the specific measurand. In addition, such sensors are advantageously characterized by a low hysteresis, because when the concentration of the trichlorofluoromethane in the gas sample drops, this is released again from the adsorption layer. Therefore, one can easily by means of

Reference samples with defined concentrations create a calibration curve. Thus, sensors are provided which are provided with a sensitive layer, which is a per-substituted Contains cyclodextrin, for online determination of the concentration of trichlorofluoromethane in gas samples.

For functionalization, the per-substituted cyclodextrin will usually be applied to the sensitive area in the form of a layer. The thickness of the layer containing the per-substituted cyclodextrin depends on the type of sensor and is typically in the range from 1 nm to 500 nm, in particular in the range from 10 nm to 250 nm. The layer containing the per-substituted cyclodextrin can exclusively consist of the respective per-substituted cyclodextrin or contain a binder which causes a better fixation of the per-substituted cyclodextrin on the sensitive area. Preferably, the layer consists of at least 80 wt .-% and in particular at least 90 wt .-% or completely of the per-substituted cyclodextrin.

The production of such layers is familiar to the person skilled in the art and can be carried out, for example, by electrospray coating, by dip coating or by spin coating, wherein the per-substituted cyclodextrin is usually present in the form of a solution, in particular a dilute solution in a volatile organic solvent is used. The concentration of the per-substituted cyclodextrin in the solution depends in a manner known per se according to the coating method and can be in the range from 0.01 to 100 mg / ml. In the case of dip-coating, for example, it is in the range from 1 to 100 mg / ml, in particular in the range from 5 to 80 mg / ml. When the coating is applied by electrospray, the solution has a concentration of the per-substituted cyclodextrin, for example in the range of 0.01 to 5 mg / ml, in particular in the range of 0.05 to 1 mg / ml.

Suitable solvents are, above all, polar organic solvents which have a boiling point at normal pressure of not more than 120 ° C. in order to allow uniform evaporation. These include, in particular, aliphatic and alicyclic ethers, such as diethyl ether, methyl tert-butyl ether, tetrahydrofuran and dioxane, and mixtures thereof with C 1 -C ₄ -alkanols, such as methanol, ethanol, n-propanol and isopropanol.

For the selective detection of trichlorofluoromethane in gas samples are in particular optical sensors, and mass-sensitive sensors which have functionalized with per-substituted cyclodextrins sensitive layer, since such sensors have a high sensitivity and it is therefore possible to trichlorofluoromethane in gases such as in Air, even at low concentrations.

Mass-sensitive sensors, also referred to as gravimetric sensors, are based on the principle that the adsorption or absorption of the analyte, here

Trichlorfluoromethane, in the chemoselective layer of the sensitive area of the sensor leads to a mass change in a change in the measured variable, usually one Resonant frequency, results. The functionalization of the sensitive region with the per-substituted cyclodextrins used according to the invention leads to a selective adsorption of trichlorofluoromethane and thus to a mass change which occurs in the

Change in the measured variable, often a resonant frequency, results.

Above all, mass-sensitive or gravimetric sensors are acoustic sensors which are based on the principle of surface resonance (surface acoustic wave resonators, surface acoustic wave devices SAW) or on the principle of bulk-wave resonance

(Volume Wave Resonators Bulk Acoustic Wave Devices - BAW sensors). Such sensors usually use a piezoelectric quartz material for

Generation of acoustic waves. An overview of acoustic sensors and their use as chemosensors can be found in W. Grate et al., Acoustic Wave

Microsensors (Part I), Anal. Chem., 65, 1993, 940A-948A and W. Grate et al., Acoustic Wave Microsensors (Part II), Anal. Chem., 65 (1993) 987A-997A, as well as in the literature cited therein (S.Fanget et al., Sensor, Actuat, B Chem 201: 160, 804-821; A. Afzal et al., Anal Chim. Acta 2013, 787, 36-49).

The BAW sensors include so-called quartz crystal microbalances, which are also referred to as quartz microbalances (QMB) or quartz crystal microbalances (QCM). The SAW sensors include, in particular, those which use Rayleigh waves (R-SAW sensors), those which use transversal surface waves (SSWB and STW sensors - see, for example, C. Zimmermann et al., Sensor, Actuat -Chem., 76 (2001) 86-94) and Acoustic Plate Mode Sensors (APM sensors).

In particular, the gravimetric sensor is a quartz oscillator microbalance. The basic principle of vibrating quartz microbalances is described in Günter Sauerbrey: Use of quartz crystals for weighing thin layers and for weighing, Z. Phys. 155, No. 2, 1959, p. 206. An overview of vibrating quartz microbalances and their use as Sensors are found in MR Deakin, et al, Anal. Chem., 61 (1989) 1147A-1 154A and J.W. Grate et al., Anal. Chem., 65 (1993) 940A-948A and in the literature cited therein. Quartz crystals and quartz microbalances are commercially available, e.g. from KVG Quartz Crystal Technology GmbH,

Neckarbischofsheim, Germany.

In quartz oscillator microbalances, a quartz oscillator made of a piezoelectric quartz material is integrated into an electrical resonant circuit. The quartz crystal is contacted with metallic electrodes and taking advantage of the reverse

piezoelectric effect is excited with a frequency typically lying in the radio frequency range, which corresponds to a mechanical natural frequency of the quartz. It then comes to the excitation of resonant vibrations that define a stable oscillation frequency of the resonant circuit. The resonant frequency now depends on the mass of the quartz oscillator, so that mass changes, for example by adsorption or absorption of a substance to be detected, can be detected as changes in the resonant frequency. By electrical bridge circuits, frequency changes in the range of 1 Hz can be measured.

By coating the quartz of a quartz microbalance with a sensitive layer containing or consisting in particular of a per-substituted cyclodextrin according to the invention, it is achieved that the trichlorofluoromethane obtained in a gas sample is selectively adsorbed in the layer and a mass change and thus also a change the resonance frequency causes. Thus, in such sensors, a direct relationship between the concentration of trichlorofluoromethane in the gas sample and the resonance frequency, so that you can create a calibration curve in a simple manner by reference samples with defined concentrations. Therefore, quartz microbalances provided with a sensitive layer containing a per-substituted cyclodextrin are suitable for the on-line determination of the concentration of trichlorofluoromethane in gas samples.

According to the invention suitable optical sensors are based on the principle that the

Adsorption or absorption of the analyte, here trichlorofluoromethane, in the chemoselective layer of the sensitive area of the sensor to a change in the optical

Properties of the sensor surface, such as the refractive index or the

Transmission, leads or causes luminescence or interference. These

Properties in turn result in a change in the measured variable, often one

Radiation intensity, a reflection angle or a wavelength shift. The functionalization of the sensitive region with the per-substituted cyclodextrins used according to the invention leads to a selective adsorption of trichlorofluoromethane and thus to a change in the optical properties of the sensor surface and thus in a change in the measured variable.

In particular, the optical sensor is a sensor in which the adsorption of the analyte leads to a change in the refractive index of the sensitive layer, and especially to an evanescent field sensor. An evanescent field sensor is an optical sensor that can detect the refractive index of an optically thinner medium based on the principle of evanescent field interaction. Evanescence refers to the penetration and exponential decay of waves in a medium in which they can not spread. So kick

evanescent waves in the vicinity of the interface of an optically denser medium to an optically thinner medium on (evanescent field) when the guided in the optically denser medium light at the interface undergoes a complete or total reflection. Now changes the refractive index of the optically thinner medium in the region of the evanescent field, for example by the adsorption of a detected

Substance in the optically thinner medium, the angle of total reflection of a light beam, which is reflected at the interface between the optically denser medium and the optically thinner medium changes (evanescent field interaction). This effect can be used for the detection of substances, for example, by using as the optically thinner medium, a layer or a coating, the one

Affinity material, here a per-substituted cyclodextrin, for binding of the analyte, here trichlorofluoromethane.

With evanescence field sensors, it is thus possible to detect changes in the refractive index in the layer containing the per-substituted cyclodextrin, which originates from the

Adsorption of the analyte from this layer result.

The change in the refractive index caused by adsorption of the analyte into the layer containing the per-substituted cyclodextrin can be detected in various ways. For this purpose, for example, in an optical waveguide, a periodic modification of the refractive index, resulting in a so-called Bragg grating, are introduced. When a light beam strikes such a Bragg grating, a part of the beam with a specific wavelength (Bragg wavelength) is reflected. If the refractive index now changes in the region of the Bragg grating, this leads to a shift in the wavelength (Bragg wavelength) of the light reflected back from the Bragg grating.

This wavelength shift can then be converted in a manner known per se to an evaluable signal, e.g. be converted by means of an optical transducer into an electrical signal.

Evanescent field sensors in which the change of a measured quantity results in the displacement of the Bragg wavelength guided in an optical waveguide are also referred to as Bragg grating sensors. Such Bragg grating sensors typically comprise an optical waveguide, that is, a light-guiding material derived from a cladding material, i. an optically transparent material having a lower refractive index than the light-guiding material is surrounded or sheathed. In which

Optical waveguides may be, for example, a glass fiber or a fiber of an optical organic polymer (e.g., polymethylmethacrylate or polycarbonate) or an area inscribed in an optically transparent material with higher

Refractive index act. Bragg planes in the form of a Bragg grating are introduced into this optical waveguide at at least one point. The light-guiding material is usually surrounded by a visually thinner sheath material (the so-called cladding). In the area of the Bragg grating, by exposing the light-guiding material a

Interaction of the guided light with the surrounding medium via the evanescent field are caused. In another area of the optical fiber, the cladding In addition, a further Bragg grating may be introduced into the optical waveguide, which as a rule serves to set a reference value to intrinsic

To provide cross sensitivities (e.g., temperature).

So-called planar Bragg grating sensors, so-called PBG sensors, are preferably used for the invention. Such planar Bragg grating sensors are known, e.g. from WO 2006/008447, WO 2006/008448, WO 2017098208, G. D. Emmerson et al. Applied Optics, 44 (2005), 5042-5044, C. Holmes et al., Meas. Be. Technol. 26 (2015) 1 1201, M.

Girschikofsky et al., IMCS 2012, 646-648 (DOI10.5162 / IMCS2012 / 7.5.1), M.

 Girschikofsky, et al., Anal. Chim. Acta 2013 791 51-59 and commercially available, e.g. from the company Stratophase, Ltd., South Hampton (UK).

The PBG sensor typically includes a flat sensor plate, also referred to as a chip, which includes an optical waveguide embedded in a planar substrate. Usually, the substrate is made of an optically transparent material. The optical waveguide can be, for example, a line-shaped, possibly branched, region with an increased refractive index, inscribed in the substrate, or a fiber made of an optically transparent material, e.g. a glass fiber or fiber of organic polymers (e.g., polymethylmethacrylate or polycarbonate). The optical waveguide is arranged in the substrate so that it passes through the sensor plate. In one area of the sensor plate is a sensor window in which the optical fiber is exposed, i. is in contact with the medium surrounding the chip, or is separated from the surrounding medium only by a thin layer. In the area of the sensor window, a Bragg grating is introduced into the optical waveguide. In the region of the sensor window, the chip, and thus also the exposed optical waveguide, is coated with an optically thinner, chemoselective medium which, according to the invention, contains the per-substituted cyclodextrin. In another area of the chip, a reference Bragg grating is introduced into the optical waveguide in order to provide a reference value and to exclude, for example, temperature influences.

In a specific embodiment, the PBG sensor is a chip which has a first layer of a cladding material, for example of SiO ₂ , arranged on a carrier, for example a silicon wafer, an average photosensitive layer arranged on the first layer Layer, for example, a doped with Ge Si0 ₂ layer in which by means of a laser, a region of higher refractive index is inscribed as optical waveguide, and arranged thereon another layer of a cladding material, for example of Si0 ₂ having. In this upper cladding layer, a window is introduced in the region of the optical waveguide. In the area of the window, a Bragg grating is inscribed in the optical waveguide. In addition, a Bragg grating is inscribed in a further region of the optical waveguide which is covered by the upper cladding layer. In this regard, WO 2006/008447, WO 2006/008448, WO 2017098208, GD Emmerson et al. Applied Optics, 44 (2005), 5042-5044, C. Holmes et al., Meas. Be. Technol. 26 (2015) 1 1201 in its entirety.

By coating the sensitive region of an optical sensor, in particular a PBG sensor with a sensitive layer containing or in particular consisting of a per-substituted cyclodextrin according to the invention, it is achieved that the trichlorofluoromethane contained in a gas sample is selectively adsorbed in the layer and a Refractive index change and thus causes a change in the Bragg wavelength. Thus, with such sensors, there is a direct relationship between the concentration of trichlorofluoromethane in the gas sample and the Bragg wavelength, so that one can easily create a calibration curve by means of reference samples with defined concentrations. Therefore, Bragg grating sensors provided with a sensitive layer containing a per-substituted cyclodextrin are suitable for the on-line determination of the concentration of trichlorofluoromethane in gas samples.

As already mentioned, the aforementioned sensors are suitable for the detection of

Trichlorofluoromethane in gas samples. Accordingly, such sensors can be used in methods for detecting trichlorofluoromethane in gas samples. In this case, the procedure is such that the gas sample to be analyzed is brought into contact with at least one gas sensor modified according to the invention which has an area with a sensitive layer which comprises or in particular consists of a per-substituted cyclodextrin as described above. With respect to preferred per-substituted cyclodextrins, the above applies mutatis mutandis to this process.

The bringing into contact of the gas sample with the gas sensor modified according to the invention can be carried out in a manner known per se, for example by passing a stream of the gas to be analyzed into a measuring chamber in which one or more of the gas sensors modified according to the invention are arranged. This measuring chamber will usually be designed as a flow chamber. Here, a gas sensor may be alone or a plurality of gas sensors, e.g. in the form of an array of gas sensors, the array may have similar sensor types or different sensor types. By using multiple gas sensors as described above, the selectivity and detection sensitivity to trichlorofluoromethane can be further increased. However, it is also possible to mount the sensor in an area where trichlorofluoromethane concentrations are likely to occur, for example in a trichlorofluoromethane production or disposal plant, in order to detect the release of trichlorofluoromethane into the ambient air, such as leaks find.

The nature of the gas sample to be analyzed is usually not critical. Thus, the commonly used sensor materials and the per-substituted cyclodextrins usually comparatively stable to corrosive substances. However, it is advantageous for the durability of the sensors if the gas sample contains no appreciable concentrations of reactive and / or corrosive substances, for example nitrous gases, ozone or acidic gases such as SO ₂ , SO ₃ , HCl or HF. The proportion of corrosive substances is preferably below 200 ppm. Optionally, before determining the trichlorofluoromethane content, remove the corrosive substances from the gas sample, for example by passing them through an adsorbent which binds the corrosive substance but not trichlorofluoromethane; in the case of acidic, corrosive substances by a basic adsorbent or in the case of oxidizing corrosive

Substances by a reducing adsorbent. Often the gas sample is an air sample.

In general, the method is suitable for detection of trichlorofluoromethane in

Gas samples with a concentration of trichlorofluoromethane in the range of 100 to 100,000 ppm.

The inventive method for the detection of trichlorofluoromethane is

usually at temperatures above the condensation point of

Trichlorfluoromethane carried out, preferably at least 20 ° C and in particular at least 25 ° C or at least 30 ° C. Preferably, the detection is carried out at temperatures below the temperature at which trichlorofluoromethane is desorbed desirably. In particular, the detection is carried out at temperatures in the range of 20 to 70 ° C, in particular in the range of 25 to 65 ° C and especially in the range of 30 to 60 ° C. For this purpose, the inventively modified sensor or the measuring chamber, in which the sensor modified according to the invention is arranged, is thermostated to the desired measuring temperature.

As already explained, the trichlorofluoromethane contained in the analyzed gas sample causes changes in the sensitive layer of the sensor, which can be detected in the form of electrical or optical signals. The type of primary signal generated by the inventively modified sensor naturally depends on the type of sensor. Optionally, the primary signal, which is generated by the sensor, before its evaluation in a suitable signal for the evaluation, preferably an electrical signal converted (signal processing). The signal processing takes place, for example, by means of an electronic component which can read out an oscillation or convert an optical signal into an electrical signal (optical converter). The resulting signal can then be evaluated in a known manner, for example by means of a computer and optionally displayed or stored or used to control a process. Methods for signal processing and signal evaluation are familiar to those skilled in the art, for example from the here in connection with The sensors mentioned in the literature and are often also offered by suppliers of sensors. For further details, please refer to the examples.

Another object of the present invention relates to a device for

Carrying out a method for detecting trichlorofluoromethane in gas samples as defined above. This device has detection means which in contact with the

Gas sample generate signals that depend on the concentration of trichlorofluoromethane in the gas sample, as well as evaluation means, which from the signals supplied by the detection means, the concentration of the contained in the gas sample

Calculate trichlorofluoromethane, on. According to the invention, the detection means comprise at least one gas sensor having an area with a sensitive layer comprising a per-substituted cyclodextrin.

According to the invention, the detection means of the device is at least one gas sensor modified according to the invention which has an area with a sensitive layer which comprises a per-substituted cyclodextrin. With regard to suitable and preferred gas sensors, reference is made to the above statements for the detection of trichlorofluoromethane in gas samples used gas sensors. Regarding the arrangement of the sensors in such a device, and the evaluation means also applies the previously said.

Surprisingly, per-substituted cyclodextrins are not only suitable

To selectively adsorb trichlorofluoromethane. Rather, can be desorbed by increasing the temperature trichlorofluoromethane, without requiring temperatures that lead to decomposition of trichlorofluoromethane or per-substituted cyclodextrin. The invention therefore also relates to a method for the reversible storage of

Trichlorofluoromethane, wherein trichlorofluoromethane is contacted with a solid adsorbent containing a per-substituted cyclodextrin as described herein. With regard to preferred per-substituted cyclodextrins, the same applies to this process as previously stated.

In the inventive method for the reversible storage of trichlorofluoromethane, the trichlorofluoromethane with the per-substituted cyclodextrin, in particular with the per-substituted a-cyclodextrin and especially with hexakis (2,3,6-tri-0-methyl) -a-cyclodextrin usually at Temperatures brought into contact, which are below the desorption temperature of the trichlorofluoromethane of per-substituted cyclodextrin. The desorption temperature can be determined by routine methods, e.g. via DSC or TGA methods. As a rule, storage takes place at temperatures of a maximum of 50 ° C and especially a maximum of 40 ° C. In particular, the contacting takes place at temperatures in the range of 0 to 50 ° C, in particular in the range of 5 to 35 ° C and especially in

Range of 10 to 25 ° C. In general, the process will be carried out by passing gaseous trichlorofluoromethane or a gas mixture containing trichlorofluoromethane and one or more further gases, for example nitrogen and / or oxygen, through a solid adsorbent containing at least one per-substituted cyclodextrin, in particular contains at least one per-substituted a-cyclodextrin and especially hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin. Here, the adsorbent can consist exclusively of the per-substituted cyclodextrin. However, the per-substituted cyclodextrin may also be applied to a solid particulate carrier material which as such has no particular adsorptive effect for trichlorofluoromethane. Suitable support materials are silica gel, alumina but also glass and ceramic materials. The solid adsorbent may be in the form of a bulk or packed bed or in the form of trays or in the form of a cyclodextrin-coated monolithic carrier.

Preferably, a gas mixture comprising trichlorofluoromethane and one or more further gases, e.g. Nitrogen and / or oxygen, pass through the solid adsorbent.

In particular, the concentration of trichlorofluoromethane in the gas which is contacted for storage with the solid adsorbent is in the range of 0.1 to 50% by volume, in particular in the range of 1 to 40% by volume. The flow rate depends naturally on the arrangement of the adsorbent through which the

Trichlorfluoromethane-containing gas is passed, and is typically in the range of 0.1 to 1 kg of trichlorofluoromethane per kg of per-substituted cyclodextrin and hour.

By heating, the adsorbed trichlorofluoromethane can be released again and thus reused. As a rule, the trichlorofluoromethane-laden, per-substituted cyclodextrin is heated to temperatures above the desorption temperature of the trichlorofluoromethane of the per-substituted cyclodextrin. In particular, desorption takes place at temperatures above 85 ° C., in particular above 90 ° C. or especially above 100 ° C. In general, one will not exceed temperatures of 200 ° C to decompose the

To avoid cyclodextrins. Optionally, the desorption will be accelerated by passing an inert gas stream, for example a nitrogen stream.

It has also been found that trichlorofluoromethane forms a crystalline complex with hexakis (2,3,6-tri-O-methyl) -α-cyclodextrin. The crystal lattice formed in this case generally contains 3.5 to 4.5 mol of trichlorofluoromethane, based on 1 mol of hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin and has an inclusion complex ratio of 1: 4 ( four Freon 1 1 molecules per molecule hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin) on. Accordingly, hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin has a high adsorption efficiency of typically about 30% by weight of trichlorofluoromethane, based on the total weight of the Kristalls up. Hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin is thus advantageously suitable for adsorption or for the storage of freon 11.

The crystalline complex according to the invention has a characteristic

X-ray diffractogram. Thus, in an X-ray powder diffraction pattern recorded at 120 K using Cu-Ka radiation, this complex shows at least 5, in particular at least 10 and especially all of the following reflections given as 20 values: 5.2 ± 0.2 °, 6.9 ± 0.2 °, 7.0 ± 0.2 °, 7.7 ± 0.2 °, 1 1, 2 ± 0.2 °, 1 1, 9 ± 0.2 °, 13.8 ± 0.2 °, 14.0 ± 0.2 °, 15.0 ± 0.2 °, 17.1 ± 0.2 °, 19.7 ± 0.2 ° and 19.9 ± 0.2 °.

An X-ray structure analysis on a single crystal at 120 K shows that the complex crystallizes in the tetragonal space group I 4i and possesses the following characteristic properties:

Room group I 4i (Tetragonal)

 Lattice constants a = b = 17.81508 (19) Ä

 c = 54.0850 (8) Ä

Volume unit cell V = 17165.3 (4) Ä ³

Units C54H96O30, 4 (CCI ₃ F) in

Unit cell: Z = 8

Density, calculated d _rön = 1, 373 like ³

The complex is prepared, for example, by dissolving hexakis (2,3,6-tri-o-methyl) -a-cyclodextrin in trichlorofluoromethane and concentrating the solution until the trichlorofluoromethane crystallizes. The crystallization can be assisted by cooling the solution.

The invention will be explained in more detail with reference to the figures described below and the examples. The following abbreviations are used in the following examples and the description of the figures:

Aquiv equivalents

CD cyclodextrin

DMSO dimethyl sulfoxide

FREON 1 1 T richlorfluoromethane

GC gas chromatography

ESI electrospray ionization

 HR-ESI-MS High resolution electrospray ionization mass spectrometry

 MS mass spectrometry

 PBG sensor planar Bragg grating sensor

per-Me-aCD Hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin per-Me-βCD heptakis (2,3,6-tri-O-methyl) -β-cyclodextrin

per-Me-yCD Octakis (2,3,6-tri-O-methyl) -cyclodextrin

per-Et-aCD Hexakis (2,3,6-tri-O-ethyl) -a-cyclodextrin

per-Et-βCD heptakis (2,3,6-tri-O-ethyl) -β-cyclodextrin

per-Et-yCD Octakis (2,3,6-tri-O-ethyl) -cyclodextrin

per-allyl-aCD hexakis (2,3,6-tri-O-allyl) -a-cyclodextrin

per-allyl-βCD heptakis (2,3,6-tri-O-allyl) -β-cyclodextrin

per-allyl-yCD octakis (2,3,6-tri-O-allyl) -Y-cyclodextrin

 RF Rp value

 RT room temperature, approx. 22 ° C

 TGA Thermogravimetric analysis

v / v volume ratio

DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic representation of the cross section through a coated PBG sensor. The PBG sensor comprises a flat plane sensor plate (chip) (1), which is arranged on a support, for example a silicon wafer (not shown), upper cladding layer (1 a) of a cladding material, for example of Si0 ₂ , a middle photosensitive layer arranged on the first layer, for example a Ge doped Si0 ₂ layer, into which by means of a laser a region (2) with a higher refractive index than

Waveguide core is inscribed, and an underlying lower cladding layer (1 c) of a cladding material, for example of Si0 ₂ , has. In the upper layer, a window (3) is introduced in the region of the optical waveguide (2). In the region of the window, a Bragg grating (4a) is inscribed in the optical waveguide (2). In addition, in another portion of the optical waveguide covered by the upper layer, a Bragg grating (4b) serving to supply a part of the light beams is inscribed

reflect to provide a reference value for temperature effects. In the region of the sensor window (3), the chip (1) and thus also the exposed optical waveguide (2) are coated with an optically thinner chemoselective medium (5) containing the per-substituted cyclodextrin. Changes in the refractive index of the optically thinner chemoselective medium (5), which are caused by the binding of the freon 11 to the per-substituted cyclodextrin, can now be detected as changes in the Bragg wavelength via the evanescent field interaction.

Figure 2 shows the schematic structure of the measuring arrangement used in the examples for the detection of trichlorofluoromethane in gas samples. The nitrogen gas used as the carrier gas is subdivided into two separate streams controlled by volumetric flow controllers (6) and (7) (MFC, Brooks Instrument Company, Model 5050S), hereinafter gas stream A and gas stream B. Gas stream A is charged to enrich with freon 1 1 passed through a tempered saturator (8) with freon 11. The Freon 1 1 saturated gas stream A is then mixed with pure nitrogen from gas stream B in a mixer (9), whereby a freon 1 1 containing nitrogen stream (10) with defined freon 1 1

Concentration in the range of 0-100 vol .-% is produced. This nitrogen stream (10) is then passed through the sequentially arranged flow cells (1 1) and (13), which in a modified GC oven (12) (eg Type: HP 5890 Fa. Hewlett Packard, Palo Alto, CA, USA ) are arranged and thus tempered to the desired measurement temperature. The exhaust gas stream leaving the flow cell (13) is replaced by a

Condenser (14) out and frozen the Freon 1 1 from the nitrogen stream. The measuring cell (1 1) has PBG sensors according to the invention and the measuring cell (13)

Quartz microbalances according to the invention. Both measuring cells are connected to evaluation units (15).

Figure 3 is a schematic representation of a coated quartz microbalance.

 At the heart of the quartz microbalance sensor is a circular disc

Quartz crystals (16). The quartz disk is provided with electrodes (17) (usually gold or aluminum) on the top and the bottom of the quartz disk (16) and by means of leads (18a, 18b) via a base (19) with electrical contacts (20a, 20b) in one integrated electrical oscillating circuit (not shown). The electrodes represent the sensor surfaces which can be provided with a coating (21) which is e.g. contains a per-substituted cyclodextrin.

FIG. 4a shows the reaction behavior of a Bragg lattice sensor coated with hexakis (2,3,6-tri-O-ethyl) -α-cyclodextrin to the respective Freon 1 1 concentrations (1%, 2%, 5% and 10%). the saturation vapor pressure). Plotted is the relative shift of the Bragg wavelength in nm (ordinate) against the time axis with the respective Freon 1 1 concentrations. FIG. 4b shows the reaction behavior of the uncoated Bragg grating sensor to the respective Freon 1 1 concentrations (1%, 2%, 5% and 10% of the

Saturation vapor pressure). Plotted is the relative shift of the Bragg wavelength in nm (ordinate) against the time axis with the respective Freon 1 1

Concentrations.

FIG. 5 shows the reaction behavior of a quartz microbalance coated with heptakis (2,3,6-tri-O-methyl) -β-cyclodextrin to different freon 1 1 concentrations (1%, 2%, 3%, 4% and 5% of the saturation vapor pressure ). Plotted is the change of

Oscillation frequency of the quartz microbalance in Hz (ordinate) against the time axis with the respective Freon 1 1 concentrations.

Figure 6a shows according to Example 1 certain calibration curves of the cyclodextrins per-Me-aCD, per-Me-ßCD or per-Me-yCD according to Preparation Example 10 coated PBG sensors 1 to 3. Plotted is the shift of the Bragg wavelength in nm against the concentration of trichlorofluoromethane in 10 ⁴ ppm. FIG. 6b shows, according to example 1, specific calibration curves of PBG sensors 4 to 6 coated with the cyclodextrins per-EtCD, per-Et-βCD or per-Et-yCD according to preparation example 10. The displacement of the Bragg wavelength is plotted in FIG nm against the concentration of trichlorofluoromethane in 10 ⁴ ppm.

Figure 6c shows according to Example 1 certain calibration curves of the cyclodextrins per allyl-aCD, per-allyl-ßCD or per-allyl-yCD according to Preparation Example 10 coated PBG sensors 7 to 9. Plotted is the shift of the Bragg wavelength in nm against the concentration of trichlorofluoromethane in 10 ⁴ ppm.

FIG. 7 shows the molecular structure of the hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin complex prepared according to Example 3 using 4 molecules of trichlorofluoromethane, which was determined by means of single-crystal X-ray structure analysis.

FIG. 8 shows the molecular structure of the hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin complex prepared by means of single-crystal X-ray structure analysis of the complex prepared according to Example 4 with one molecule of trichlorofluoromethane and 3 molecules of dichloromethane.

EXAMPLES

 I) Analytical Methods for the Characterization of Per-Substituted Cyclodextrins:

Unless otherwise stated, H-NMR spectra and C-NMR spectra were recorded at ambient temperature in a Bruker AM400 400 MHz spectrometer from Bruker.

MS (ESI-MS): The mass spectra of the per-substituted cyclodextrins were recorded in the ESI mode using a Bruker Microtof-Q spectrometer.

All prepared per-substituted cyclodextrins were using

Thin layer chromatography on Si0 ₂ plates identified by their RF value.

For the X-ray structure analysis, a diffractometer STOE IPDS 2T using Mo-K _a radiation (graphite monochromator) was used.

 Scan type w scans

 Scan width 1 °

Measuring range 2 ° <Q <28 ° Thermogavimetric investigations of the complexes of per-substituted cyclodextrins with Freon 1 1 were carried out by means of a TGA apparatus from the company. Perkin Elmer Eimer type Pyris 6.

II) Preparation Examples of Per-Substituted Cyclodextrins

1. General working instruction (AAV 1) for the presentation of per-methylated

 cyclodextrin derivatives

The respective a-, ß- or g-cyclodextrin is dissolved in DMSO (30 ml_ per mmol CD). Mix the mixture with ground NaOH pellets and stir at RT for 1 h. This solidifies the suspension. Then added dropwise methyl iodide or p-Toluolsulfonsäuremethylester in an ice bath slowly. The suspension becomes liquid again with vigorous stirring. The reaction mixture is then stirred at room temperature for 24 h, the resulting suspension is poured into ice-water (170 ml per mmol of CD) and the mixture is extracted with dichloromethane (3 × 1 ml -1 per mmol of CD). The organic phases are washed with saturated sodium chloride solution (3 × 1 1 mL per mmol of CD) and dried over magnesium sulfate. Then the solvent is removed under reduced pressure and the residue is dried under high vacuum at 60.degree.

2. General working instruction (AAV 2) for the presentation of per-allylated

 cyclodextrin derivatives

The respective α-, β- or γ-cyclodextrin is dissolved in DMSO (about 32 mL per mmol of CD) and pellets are added to this NaOH pellets. As soon as the suspension has hardened after stirring for 1 h at RT, allyl chloride is slowly added dropwise with cooling while cooling

 Water bath too. The suspension becomes liquid again with vigorous stirring.

 It is then stirred for 5 h at room temperature. The reaction is stopped by addition of ice-water (140 mL per mmol of CD) and the mixture is washed with

 Dichloromethane (4 x 9 mL per mmol of CD) extracted. The organic phases are dried over magnesium sulfate and the solvent is removed under reduced pressure. The crude product is purified by column chromatography on silica gel with an eluent of toluene-ethanol 50: 1. The product is dried under high vacuum at 60.degree.

3. General working instruction (AAV 3) for depicting per-ethylated

 cyclodextrin derivatives

Dissolve the respective α-, β- or g-cyclodextrin in DMSO (23 mL per mmol of CD) and give this mortared NaOH cookies. Once the suspension is stirred after about 1 h At RT, sodium iodide (1-9 mol% with respect to bromoethane) is added and slowly added dropwise bromide with cooling with a water bath. The suspension is then stirred for 16 h at room temperature. The reaction is poured into water-ice mixture (140 ml_ per mmol of CD) and the mixture is extracted with tert-butylmethyl ether (2 × 40 ml_ per mmol of CD). The organic phases are washed with water (4 × 10 ml_ per mmol of CD), dried over magnesium sulfate and the solvent is removed under reduced pressure. The product is dried under high vacuum at 60.degree.

Production Example 1: Hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin

8.82 g (9.1 mmol) of α-CD were prepared after AAV 1 with 24.00 g of sodium hydroxide (0.6 mol) and 65.18 g (53.0 ml, 0.35 mol) of p-toluenesulfonic acid methyl ester in 270 ml of methylated DMSO. After crystallization from hexane / dichloromethane, the product was obtained as a colorless crystalline solid.

Molecular Formula: C ₅₄ H ₉₆ O ₃₀ Molecular weight: 1225.322 g / mol

 Yield: 10.45 g (8.5 mmol, 93%)

 Melting point: 204 ° C

R _F (toluene-ethanol, 5: 1 v / v): 0.37

¹ H-NMR (400 MHz, CDCl ₃ ): d [ppm] = 3.14 (dd, 1H, 2-H), 3.38 (s, 3H, 6'-H), 3.47 (s, 3H, 2'- H), 3.54 (m, 2H, 4-H, 6a-H), 3.62 (s, 3H, 3'-H), 3.69 (m, 1H, 3-H), 3.79 (m, 2H, 5 H, 6b-H), 5.03 (d, 1 H, 1-H). Couplings: ³ _{1 2} = 3.3 Hz, ³ J _2.3 = 9.5 Hz.

MS (ESI (+), 10eV): m / z (fragment): 1247.6 (M + Na ⁺ ), 635.3 (M + 2Na ⁺ ).

Production Example 2: Heptakis (2,3,6-tri-O-methyl) -β-cyclodextrin

10.82 g (9.5 mmol) of β-CD were reacted according to AAV 1 with 24.00 g of sodium hydroxide (0.6 mol) and 49.7 g (21.8 ml, 0.35 mol) of methyl iodide in 300 ml of DMSO. The product was obtained as a colorless solid.

Molecular formula: C ₆₃ H ₁₁₂ 0 ₃₅ Molecular weight: 1429.542 g / mol

 Yield: 10.71 g (8.5 mmol, 79%).

R _F (toluene-ethanol, 5: 1 v / v): 0.35

¹ H-NMR (400 MHz, CDCl ₃ ): d [ppm] = 3.17 (dd, 1H, 2-H), 3.36 (s, 3H, 6'-H), 3.48 (s, 3H, 2'- H), 3.57 (m, 2H, 3-H, 6a-H), 3.62 (s, 3H, 3'-H), 3.81 (m, 3H, 4-H, 5-H, 6b-H), 5.1 1 (d, 1H, 1H). Couplings: ³ J _{1 2} = 3.7 Hz, ³ J _2.3 = 9.6 Hz.

MS (ESI (+), 10eV): m / z (fragment): 1451.7 (M + Na ⁺ ), 737.3 (M + 2Na ⁺ ).

Production Example 3: Octakis (2,3,6-tri-O-methyl) -cyclodextrin

1 1, 67 g (9.0 mmol) g-CD were after AAV 1 with 24.00 g of sodium hydroxide (0.6 mol) and 65.18 g (53.0 ml, 0.35 mol) p-Toluolsulfonsäuremethylester in 300 ml_ DMSO reacted. The product was obtained as a colorless solid.

Molecular Formula: C ₇₂ H ₁₂₈ 0 ₄ o Molecular Weight: 1633.763 g / mol

 Yield: 13.75 g (8.4 mmol, 93%).

RF (toluene-ethanol, 5: 1 v / v): 0.34 ¹ H-NMR (400 MHz, CDCl ₃ ): d [ppm] = 3.21 (dd, 1H, 2-H), 3.37 (s, 3H, 6'-H), 3.48 (s, 3H, 2'- H), 3.51-3.57 (m, 2H, 3-H, 6a-H), 3.65 (s, 3H, 3'-H), 3.68-3.74 (m, 2H, 5-H, 6b-H), 3.86 (dd, 1H, 4-H), 5.24 (d, 1H, 1 -H). Couplings: ³ _{1 2} = 3.7 Hz, ³ _2.3 = 9.7 Hz, ³ _3.4 = 10.5 Hz, ³ J _4.5 = 3.4 Hz

MS (ESI (+), 10eV): m / z (fragment): 1655.7 (M + Na ⁺ ), 839.4 (M + 2Na ⁺ ).

Production Example 4: Hexakis (2,3,6-tri-O-allyl) -a-cyclodextrin

10.73 g (1 1, 0 mmol) of α-CD were reacted according to AAV 2 with 23.76 g of sodium hydroxide (0.594 mol) and 45.46 g (48.4 ml, 0.594 mol) of allyl chloride in 350 ml of DMSO. The product was obtained as a yellow, viscous oil.

Molecular Formula: O ₉₀ H ₁₃₂ O ₃₀ Molecular Weight: 1693.93 g / mol

 Yield: 16.72 g (9.9 mmol, 89%).

R _F (toluene-ethanol, 25: 1 v / v): 0.17

¹ H-NMR (400 MHz, CDCl ₃ ): d [ppm] = 3.32 (dd, 1 H, 2-H), 3.68 (m, 2H, 3-H, 5-H), 3.75-3.82 (m, 2H, 4-H, 6a-H), 3.86 (dd, 1H, 6b-H), 3.96-4.12 (m, 3H, OCHHCH = CH ₂ ), 4.18-4.28 (m, 2H, OCHHCH = CH ₂ ) , 4:53 (dd, 1 H, OCHHCH = CH _2), 4.99 (d, 1 H, 1 H), 5:08 to 5:15 (m, 3H, OCH ₂ CH = C H H), 5:19 to 5:29 (m, 3H, OCH ₂ CH = CHH), 5.85-5.98 (m, 2H,

OCH ₂ CH = CH ₂ ), 6.06-6.16 (m, 1 H, OCH ₂ CH = CH ₂ ). Couplings: ³ J _{1 2} = 3.3 Hz, ³ J _2.3 = 9.8 Hz, ³ _{6a, 6b} ⁼ 10.5 Hz, ³ _5.6 = 3.7 Hz, ³ JOCHHCH = CH2 ⁼ 12.2, ³ JOCHHCH = CH2 ⁼ 6.2 Hz.

MS (ESI (+), 10eV): m / z (fragment): 1716.9 (M + Na ⁺ ), 869.9 (M + 2Na ⁺ ).

Production Example 5: Heptakis (2,3,6-tri-O-allyl) -β-cyclodextrin

12.60 g (1 1, 0 mmol) of β-CD were reacted according to AAV 2 with 27.72 g (0.693 mol) of sodium hydroxide and 53.04 g (56.5 ml, 0.693 mol) of allyl chloride in 350 ml of DMSO. The product was obtained as a yellow, viscous oil.

Molecular formula: C _IO 5H ₁₅₄ 03 ₅ Molecular weight: 1976.325 g / mol

 Yield: 18.51 g (9.3 mmol, 85%).

R _F (toluene-ethanol, 25: 1 v / v): 0.19

¹ H-NMR (400 MHz, CDCl ₃ ): d [ppm] = 3.33 (dd, 1 H, 2-H), 3.57 (d, 1 H, 6a-H), 3.72- 3.76 (m, 3H, 3 -H, 4-H, 5-H), 3.89 (dd, 1H, 6b-H), 3.97 (m, 2H, OCHHCH = CH ₂ ), 4.14 (m, 2H,

OCHHCH = CH _2), 4.25 (dd, 1 H, OCHHCH = CH _2), 4:49 (dd, 1 H, OCHHCH = CH _2), 5:05 to 5:13 (m, 3H, OCH ₂ CH = C H H), 5.15 (d , 1H, 1-H), 5.18-5.27 (m, 3H, OCH ₂ CH = CHH), 5.82-5.95 (m, 2H, OCH ₂ CH = CH ₂ ), 5.94-6.04 (m, 1H, OCH ₂ CH = CH ₂ ). Couplings: ³ J _{1 2} = 3.6 Hz, ³ _2.3

= 9.2 Hz, ² _{6a, 6b} ⁼ 10.3 Hz, ³ _5.6 = 2.1 Hz, ² JOCHHCH = CH2 ⁼ 12.2, ³ JOCHHCH = CH2 ⁼ 5.6 Hz.

MS (ESI (+), 10eV): m / z (fragment): 1999.1 (M + Na ⁺ ), 101 1.0 (M + 2Na ⁺ ). Production Example 6: Octakis (2,3,6-tri-O-allyl) -cyclodextrin

14.31 g (1 1.0 mmol) of g-CD were reacted according to AAV 2 with 45.76 g (1.14 mol) of sodium hydroxide and 87.55 g (93.2 ml, 1.14 mol) of allyl chloride in 350 ml of DMSO. The product was obtained as a yellow, viscous oil.

Molecular Formula: C ₁₂₀ H ₁₇₆ O ₄₀ Molecular weight: 2258.657 g / mol

Yield: 19.46 g (8.6 mmol, 78%).

R _F (toluene-ethanol, 25: 1 v / v): 0.20

¹ H-NMR (400 MHz, CDCl ₃ ): d [ppm] = 3.35 (dd, 1 H, 2-H), 3.59 (d, 1 H, 6a-H), 3.68- 3.76 (m, 3H, 3 -H, 4-H, 5-H), 3.87 (d, 1H, 6b-H), 3.92 - 4.04 (m, 2H, OCHHCH = CH ₂ ), 4.15 (d, 2H, OCHHCH = CH ₂ ), 4.24 (dd, 1H, OCHHCH = CH ₂ ), 4.50 (dd, 1H, OCHHCH = CH ₂ ), 5.06-5.16 (m, 3H, OCH ₂ CH = CHH), 5.20 (d, 1H, 1) H), 5.22-5.28 (m, 3H, OCH ₂ CH = CHH), 5.83-5.95 (m, 2H, OCH ₂ CH = CH ₂ ), 5.96-6.06 (m, 1 H, OCH ₂ CH = CH ₂ ) , Couplings: ³ J _{1 2} = 3.5 Hz, ³ _2.3 = 9.4 Hz, ² _{6a, 6b} ⁼ 10.5 Hz, ³ _5.6 = 2.1 Hz, ² JOCHHCH = CH2 = 12.2, ³ JOCHHCH = CH2 ⁼ 5.4 Hz.

MS (ESI (+), 10eV): m / z (fragment): 2281.2 (M + Na ⁺ ), 1 152.1 (M + 2Na ⁺ ).

Production Example 7: Hexakis (2,3,6-tri-O-ethyl) -a-cyclodextrin

10.54 g (10.8 mmol) of α-CD was converted to AAV 3 with 24.00 g (0.6 mmol) of sodium hydroxide,

76.28 g (52.2 mL, 0.7 mol) of bromoethane and 1.20 g of sodium iodide (8.0 mmol) in 250 mL

DMSO implemented. The product was obtained as a colorless solid.

Molecular Formula: C ₇₂ H ₁₃₂ O ₃₀ Molecular Weight: 1477.801 g / mol

 Yield: 13.88 g (8.5 mmol, 86%).

R _F (toluene-ethanol, 10: 1 v / v): 0.29

¹ H-NMR (400 MHz, CDCl ₃ ): d [ppm] = 1.20 (m, 9H, OCH ₂ CH ₃ ), 3.21 - 3.25 (dd, 1H, 2-H), 3.47 - 3.54 (m, 2 H, 6a-H, OCH ₂ CH ₃ ), 3.60- 3.69 (m, 4H, 3-H, OCH ₂ CH ₃ ), 3.72-3.79 (m, 3H, 4-H, 5-H, OCH ₂ CH ₃ ), 3.83 - 3.91 (m, 1H, 6bH), 4.00 - 4.08 (m, 1H, OCH ₂ CH ₃ ), 5.04 (d, 1H, 1-H). Couplings: ³ J _{1 2} = 3.4 Hz, ³ J _2.3 = 9.4 Hz. ¹³ C-NMR (100 MHz, CDCl ₃ ): d [ppm] = 15.2 (OCH ₂ CH ₃ ), 15.6 (OCH ₂ CH ₃ ), 15.7 (OCH ₂ CH ₃ ), 66.5 (OCH ₂ CH ₃ ), 66.5 (OCH ₂ CH ₃ ), 68.8 (OCH ₂ CH ₃ ), 69.4 (C6), 71.3 (C5), 79.8 (C4), 80.1 (C2), 80.7 (C3), 99.6 (C1).

MS (ESI (+), 10eV): m / z (%, fragment): 1499.8 (42%, M + Na ⁺ ), 1471.8 (32%, [M-CHCH ₃ ] + Na ⁺ ), 1443.8 (20%, [M-2CHCH _3] + ⁺ Na), 1415.7 (7%, [M-3CHCH _3] + ⁺ Na), 761 .4 (M + 2Na ^+), 733.4 ([M-2CHCH _3] + 2Na ⁺ ).

Preparation 8: Heptakis (2,3,6-tri-O-ethyl) -β-cyclodextrin

12.29 g (10.8 mmol) of β-CD were added to AAV 3 with 28.00 g (0.7 mol) of sodium hydroxide, 87.18 g (59.7 mL, 0.8 mol) of bromoethane and 6.00 g sodium iodide (40.0 mmol) in 230 ml DMSO. The product was obtained as a white-yellow solid.

Molecular Formula: C ₈ 4H ₁₅₄ 0 ₃ 5 Molecular weight: 1724.101 g / mol

 Yield: 15.44 g (9.0 mmol, 83%).

R _F (toluene-ethanol, 10: 1 v / v): 0.28

¹ H-NMR (400 MHz, CDCl ₃ ): d [ppm] = 1.17 (m, 9H, OCH ₂ CH ₃ ), 3.23 (dd, 1 H, 2-H), 3.41- 3.52 (m, 3 H, 6a-H, OCH ₂ CH ₃ ), 3.58-3.35 (m, 2H, 3-H, OCH ₂ CH ₃ ), 3.67-3.78 (m, 4H, 4-H, 5-H, OCH ₂ CH ₃ ), 3.90 (d, 1H, 6bH), 3.98 (m, 1H, OCH ₂ CH ₃ ), 5.16 (d, 1H, 1 -H).

Couplings: ³ J _{1 2} = 3.5 Hz, ³ J _2.3 = 9.7 Hz, ³ J _6a , 6b = 10.1 Hz.

MS (ESI (+), 10eV): m / z (fragment): 1746.0 (M + Na ⁺ ), 884.5 (M + 2Na ⁺ ).

Preparation 9: Octakis (2,3,6-tri-O-ethyl) -cyclodextrin

14.07 g (10.8 mmol) g-CD were added after AAV 3 with 32.00 g (0.8 mol) sodium hydroxide,

98.07 g (67.2 mL, 0.9 mol) of bromoethane and 1.1 g of sodium iodide (80.0 mmol) in 250 mL of DMSO. The product was obtained as a colorless solid.

Molecular Formula: C ₉₆ H ₁₇₆ 0 ₄ o Molecular Weight: 1970.401 g / mol

 Yield: 20.01 g (9.0 mmol, 94%).

R _F (toluene EtOH = 10: 1) = 0.29

¹ H-NMR (400 MHz, CDCl ₃ ): d [ppm] = 1.18 (m, 9H, OCH ₂ CH ₃ ), 3.23- 3.26 (m, 1H, 2-H), 3.46- 3.52 (m, 3H , 6a-H, OCH ₂ CH ₃ ), 3.54- 3.59 (m, 2H, 3-H, OCH ₂ CH ₃ ), 3.66- 3.72 (m, 4H, 4-H, 5-H, OCH ₂ CH ₃ ) , 3.88 (d, 1H, 6bH), 3.99 (m, 1H, OCH2CH3), 5.20 (d, 1H, 1H). Couplings: ³ J _{1 2} = 3.5 Hz, ² J _{6a, 6b} = 10.6 Hz, ³ J _5.6 = 3.1 Hz.

¹³ C-NMR (100 MHz, CDCl ₃ ): d [ppm] = 15.1 (OCH ₂ CH ₃ ), 15.7 (OCH ₂ CH ₃ ), 15.7 (OCH ₂ CH ₃ ), 66.4 (OCH ₂ CH ₃ ), 66.7 (OCH ₂ CH ₃ ), 69.0 (OCH ₂ CH ₃ ), 69.3 (C6), 71.1 (C5), 78.6 (C4), 80.1 (C2), 80.2 (C3), 98.5 (C1).

MS (ESI (+), 10eV): m / z (% content, fragment): 1993.2 (35%, M + Na ⁺ ), 1964.1 (46%,

[M-CHCH ₃ ] + Na ⁺ ), 1937.1 (19%, [M-2CHCH ₃ ] + Na ⁺ ), 1007.6 (M + 2Na ⁺ ), 994.1

([M-CHCH ₃ ] + 2Na ⁺ ), 979.5 ([M-2CHCH ₃ ] + 2Na ⁺ ).

III) Preparation of Clodextrin-Coated Gas Sensors:

Preparation Example 10: Preparation of cyclodextrin-coated Bragg grating sensors

For modification with per-substituted cyclodextrins, PBG sensors from Stratophase, Ltd. were used. based in South Hampton (UK) of the type "S7b", which correspond to the sensors according to FIG. For the coupling of the PBG sensors, prefabricated glass fibers (so-called fiber pigtails) from Reliable Photonics Co., Ltd., Shenzhen (China) with the designation "1 CH FA, G657A fiber, 40 cm, FC / APC connectors, 8 ° polishing angle "used. The pigtails were connected to the sensor chips by means of a UV-curing optical adhesive of the type "NOA 78" from Norland Products, Inc., Cranbury (NJ, USA).

The sensors are coated by means of dip coating (dip coating - see Table 1 for parameters) of the chip in the area of the exposed glass fibers using the dip coater "WPTL5-0.01" from MTI Corporation, located in Richmond (CA, USA).

The cyclodextrins were each dissolved in tetrahydrofuran at a concentration of 50 mg / ml. The chip was immersed in the solution at room temperature, perpendicular to complete wetting of the sensor window, at an immersion rate of 200 mm / min and after a residence time in the solution of 3 s at a constant

Speed (Table 1) pulled out of the solution. The resulting layer thickness was measured by tactile profilometry along a doctor edge using the

Profilometer DektakXT from the company Bruker determined.

Table 1: Parameters for dip coating of the PBG sensors

Preparation Example 1 1: Preparation of cyclodextrin-coated quartz microbalance sensors

In the case of those used for modification with per-substituted cyclodextrins

Quartz microbalances are 195 MHz quartz microbalances from KVG Quartz Crystal Technology GmbH, Neckarbischofsheim, Germany, type: XA 1600

(Aluminum electrodes, 195 MHz, see Wessels et al., Sensors 2013, 13, 12012-12029), which correspond to the sensors shown schematically in Figure 3. The

Quartz microbalances were prepared according to the method described by Brutschy et al., Anal. Chem. 2013, 85, 10526-10530. For this purpose, a 1.5 mM solution of 1 / - /, 1 / - /, 2 / - /, 2 / - / - perfluorooctyl-1-phosphonic acid (98%, ABCR) in ethanol was prepared and the quartz microbalances 48 hours at room temperature in the Solution immersed. Subsequently, the quartz microbalances were washed off with pure ethanol and dried in air.

For the coating of the sensor surface was a solution of the respective

Cyclodextrins in a mixture of tetrahydrofuran: methanol (9: 1) with a

Concentration of 0.1 mg / mL produced. This was applied by electrospray on the electrode surface until a frequency drop of 50.0 kHz was reached and this was maintained constant.

The sensors thus produced were used in a measuring cell (see Wessels et al., Sensors 2013, 13, 12012-12029), in which up to 12 quartz microbalances can be operated simultaneously.

IV) Detection of trichlorofluoromethane using cvcdextrin-coated sensors

For all measurements, controlled measurement conditions were observed. The structure of the measuring device is shown in FIG. Nitrogen gas with a purity of 99.998% was used as the carrier gas. Gas stream 1 was passed through the saturated at 15 ± 0.1 ° C saturator with the Freon contained therein 1 1 and according to the

Saturation vapor pressure of Freon 1 1 enriched with this. By controlling the volume flows of freon 1 1 saturated gas stream 1 and the pure nitrogen (gas stream 2), a defined concentration of Freon 1 1 was set in the range of 0-10 vol .-%. The flow rate of the total stream was always chosen to be 200 mL / min. The gas stream thus generated was passed through the respective flow cells, which were placed in the modified GC oven (Hewlett Packard, Palo Alto, Calif., Type: HP 5890) and heated to 35 ± 0.1 ° C. The exhaust gas from the measurements was passed through a condenser cooled to -90 ° C to freeze the freon 1 1 from the nitrogen stream.

Example 1: Detection of trichlorofluoromethane with PBG sensors

For the measurement of trichlorofluoromethane, the measuring apparatus shown in FIG. 2 was used, which for this purpose was equipped in each case with one type of the coated Bragg grating sensors produced according to Example 10. The measurements were carried out using an interrogation unit based on an interrogator of the sm125 type from Micron Optics, Ltd. based in Atlanta (GA, USA). The measurements for the sensor 4 are shown in FIG. 4a. As a comparison, measurements were carried out with an uncoated Bragg grating sensor, shown in FIG. 4b.

Compared to the uncoated sensor, the coated sensors achieved an approx. 300-fold increase in sensitivity compared to Freon 1 1. The sensors also show a high sensitivity to Freon 1 1, which allows the safe detection of Freon 1 1 even below a concentration of 1000 ppm. In addition, the coated Bragg grating sensors show a reversible reaction to Freon 1 1.

By calibration with different concentration of Freon 11 in the nitrogen stream (1%, 2%, 5% and 10% of saturation vapor pressure or 7409, 14819, 37047 and 74095 ppm, respectively), calibration curves were prepared which provide an online analysis of the concentration of Freon 1 1 in gas samples (air, nitrogen). The calibration curves were determined by averaging the equilibrium states of the sensor signal above the concentration used and Fit according to a Langmuir-Freundlich isotherm after the function

q = Qsat ^* K ^* c ⁿ / (1 + K ^* c ^s) created. With the loading of the sorbent q, the adsorption capacity Qsat, the concentration of the sorbate c, the sorption coefficient K and the

Heterogeneity Index n (see Turiel et al., DOI: 10.1039 / b210712k and Juppu et al., DOI: 10.1016 / j.jconhyd.201 1.12.001). The calibration cures for the sensors 1 to 9 are shown in FIGS. 6a to 6c.

Example 2 Detection of Trichlorofluoromethane with Quartz Microbalance Sensors

For the measurement of trichlorofluoromethane, the measuring device shown in FIG. 2 was used, which was equipped for this purpose with the cyclodextrin-coated quartz microbalance sensors produced in Example 11. The measurements were made using an aperiodically oscillating resonant circuit. Frequency readout was performed using an FPGA (field programmable gate array) which allows asynchronous 28-bit counting with a resolution of ± 0.5 Hz (see Wessels et al., Sensors 2013, 13, 12012-12029). The measurement results are shown in FIG. As a comparison, measurements were carried out with an uncoated quartz microbalance sensor.

With the coated quartz microbalance sensor could be compared to the

uncoated quartz microbalance sensor can be achieved an increase in sensitivity to Freon 1 1 by up to 35%. The coated quartz microbalance sensor also shows a high sensitivity to Freon 1 1, which enables the reliable detection of Freon 1 1 even below a concentration of 1000 ppm. In addition, this coated sensor also shows a reversible reaction to Freon 1 1.

By calibrating with different concentration of freon 1 1 in the nitrogen stream (1%, 2%, 3%, 4% and 5% of saturation vapor pressure or 7409, 14819, 22228, 29638 and 37047 ppm, respectively), calibration curves were prepared that provide an online analysis allow the concentration of Freon 1 1 in gas samples (air, nitrogen).

V) Preparation and X-ray crystallographic analysis of a crystalline complex of hexakis (2,3,6-tri-Q-methyl) -a-cvclodextrin with trichlorofluoromethane Example 3: Complex of hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin with trichlorofluoromethane

Hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin (15 mg) was dissolved in Freon 1 L (1 mL). By evaporation of excess Freon 1 1 at room temperature, the concentration of the dissolved per-methyl-a-cyclodextrin in the solution was slowly increased until a crystalline solid formed.

The complex was characterized by single-crystal X-ray crystallography at 120 K and proved to be a supramolecular complex of 4 molecules of freon 1 1 with 1 molecule of hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin. The maximum "loading" of the complex with Freon 1 1 is thus about 30% by weight.

The crystal size of the measured single crystal was 0.17 × 0.37 × 0.63 mm ³ (colorless block). The single crystal had the following parameters:

Absorption m = 0.468 mm ¹ correction with 6 crystal surfaces

Transmission T _min = 0.7814, T _max = 0.926

The complex had the following crystallographic data:

Molecular Formula C54H96O30, 4 (CCI ₃ F)

Mol Weight 1774.74 gmol ¹

 Room group I 4i (Tetragonal)

 Lattice constants a = b = 17.81508 (19) Ä

 c = 54.0850 (8) Ä

Volume unit cell V = 17165, 3 (4) Ä ³

Units C54H96O30, 4 (CCI ₃ F) in

Unit cell: Z = 8

Density, calculated d _rön = 1, 373 like ³

The single-crystal X-ray structure analysis was carried out with the following parameters:

1) Data collection

Measuring range 2 ° <0 <28 °

 -23 <h <23 -23 <k <23 -67 <I <71

 Albedo:

 measured 289547

independent 21068 (R _int = 0.0503)

observed 17237 (| F | / o (F)> 4.0) 2) The lattice constants were calculated from 222713 reflections in the range 1.8 ° <Q <28.4 °.

3) Data correction, structure solution and structure refinement

Corrections Lorentz and polarization correction.

 Solution Program: SIR-2004 (Direct Methods)

 Refinement Program: SHELXL-2014 (full matrix method).

1019 refined parameters, weighted refinement: W = 1 / [O ² (F ₀ ² ) + (0.1638 ^* P) ² +19.9 ^* P];

where P = (Max (F _o ² , 0) + 2 ^* F _c ² ) / 3.

 Hydrogen atoms were geometrically inserted and refined in riding style; Non-hydrogen atoms were refined anisotropically.

 Discrepancy factor wR2 = 0.2374 (R1 = 0.0761 for observed reflections,

 0.095 for all reflexes)

 Fit quality S = 1,039

 Flack parameter x = -0.007 (16)

 maximum change

the parameter 0.001 ^* esd

 maximum peak height in

diff. Fourier synthesis 0.94, -0.97 eA ³

Comment Cyclodextrin has C ₂ symmetry. Crystal is twinned and belies higher symmetric space group I4- _| 22 ago. Freon is in disorder.

Example 4: Complex of hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin with trichlorofluoromethane and dichloromethane

Hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin (15 mg) was dissolved in a previously prepared mixture of dichloromethane and Freon 1 L (95: 5 v / v, 1 mL) and also as described in Example 3, crystallized by evaporation of the solvents at room temperature.

The complex was characterized by single-crystal X-ray crystallography at 120 K and proved to be a supramolecular complex of 3 molecules of dichloromethane and 1 molecule of freon 1 1 with 1 molecule of hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin. The example shows that, despite the large excess of dichloromethane, there is no statistical incorporation of the two halogenated hydrocarbons, but rather the incorporation of

Trichlorfluoromethane, in particular in the inner cavity of the cyclodextrin, preferably takes place. The crystal size of the measured single crystal was 0.14 × 0.44 × 0.55 mm ³ (colorless block). The single crystal had the following parameters:

Absorption m = 0.41 mm ¹ correction with 6 crystal surfaces

Transmission T _min = 0.8361, T _max = 0.958

The complex had the following crystallographic data:

Molecular Formula C54H96O30, CCI ₃ F, 3 (CH ₂ Cl ₂ )

Molecular weight 1617.44 gmol ¹

 Space group P 2- | 2- | 2i (orthorhombic)

 Lattice constants a = 15.7397 (4) Ä

 b = 21 7162 (7) Ä

 c = 22.6475 (8) Ä

Volume unit cell V = 7741.1 (4) Ä ³

Units C ₅₄ H ₉₆ O ₃₀ , CCI ₃ F, 3 (CH ₂ Cl ₂ )

in unit cell: Z = 4

Density, calculated d _rön = 1, 388 like ³

The single-crystal X-ray structure analysis was carried out with the following parameters:

1) Data collection

Measuring range 2 ° <0 <28 °

 -20 <h <19 -28 <k <28 -29 <I <29

 Albedo:

 measured 67315

independent 18481 (R _int = 0.0486)

 observed 1 1363 (| F | / o (F)> 4.0)

2) The lattice constants were calculated from 62202 reflections with reflections in the range 2 ° <Q <27.8 °.

3) Data correction, structure solution and structure refinement

Corrections Lorentz and polarization correction.

 Solution Program: SHELXT-2014

 Refinement Program: SHELXL-2014 (full matrix method).

1040 refined parameters, weighted refinement: W = 1 / [O ² (F ₀ ² ) + (0.1502 ^* P) ² + 12.01 ^* P]

where P = (Max (F _o ² , 0) + 2 ^* F _c ² ) / 3. Geometrically inserted hydrogen atoms and refined riding,

Non-hydrogen atoms refined anisotropically. Discrepancy factor wR2 = 0.2994 (R1 = 0.0979 for observed reflections,

 0.1485 for all reflexes)

 Fit quality S = 1.026

 Flack parameter x = 0.01 (4)

 maximum change

the parameter 0.001 ^* esd

 maximum peak height in

diff. Fourier synthesis 0.83, -0.71 eA ³

Note crystal contains 3 molecules of solvent CH ₂ Cl ₂ and a strongly disordered molecule CCI ₃ F. position of the fluorine atom not fully determinable.

VI) Thermoqravimetric analysis of hexakis (2,3,6-tri-O-methyl) -occlodextrin

T richlorfluormethan complex

Example 5 Thermogravimetric analysis of the hexakis (2,3,6-tri-O-methyl) -α-cyclodextrin-trichlorofluoromethane complex

For the investigation, the complex of hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin crystallized according to Example 3 from pure Freon 1 1 with trichlorofluoromethane was used.

On the one hand, a stability study of the complex was carried out by holding a defined amount of the complex (10.1032 mg) at 25 ° C for 12 hours under a continuous stream of nitrogen gas (20 ml / min) and then the

Weight difference was determined. During this time, the weight of the sample decreased only by about 3.5% as a result of an initial Freon 1 1 escape from the complex.

Furthermore, a thermogravimetric analysis of the complex of hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin crystallized from pure Freon 1 1 according to Example 3 was carried out with trichlorofluoromethane. The TGA was equipped with a defined amount of

Complex carried out at a temperature ramp of 5 K / min and a starting temperature of 25 ° C using nitrogen as the carrier gas at a flow rate of 20 mL / min. An initial release of freon 11 from the complex was observed at a temperature of T _on = 85 ° C. Complete liberation (desorption) of Freon 1 1 was complete at T _en d = 195 ° C. The total weight loss was 28% by weight and thus corresponded to a loss of about 4 molecules of trichlorofluoromethane per molecule of hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin.

VII) Adsorption of freon 1 1 on hexakis (2,3,6-tri-Q-methyl) -a-cc-decodextrin

Example 6: Adsorption of freon 1 1 on hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin An adsorption tube filled with 0.71 g of powdered hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin (packing: length 121 mm, internal diameter 3.7 mm) at 20 ° C was a nitrogen gas stream with a volume flow of 50 mL / min containing Freon 1 1 at a concentration of 37040 ppm (ppm by volume). The concentration of freon 11 in the gas stream was measured at the outlet of the adsorption tube

 Quartz microbalance analysis (quartz microbalance coated with hexakis (2,3,6-tri-O-methyl) -α-cyclodextrin). The concentration of Freon 1 1 in the gas stream at the outlet of the adsorption tube was below 7400 ppm even after 0.55 h of passage. Accordingly, over a period of at least 0.5 h Freon 1 1 was adsorbed to more than 80% from the gas stream.

Example 7 Adsorption of Freon 11 on Unsubstituted α-Cyclodextrin (Comparative Example)

The experiment was carried out in the manner described for Example 6, wherein the adsorption tube was filled with α-cyclodextrin instead of hexakis (2,3,6-tri-O-methyl) -α-cyclodextrin. When passing the Freon 1 1 containing nitrogen gas stream Freon no 1 1 was adsorbed from the gas stream.

Claims

claims

1. Use of per-substituted cyclodextrins in which the hydrogen atoms of all hydroxy groups are replaced by an organic radical which is selected from C ₁ -C ₆ -alkyl and C 2 -C ₆ -alkenyl, for the adsorption of trichlorofluoromethane.

2. Use according to claim 1, wherein the per-substituted cyclodextrin is selected from per-substituted a-cyclodextrins, per-substituted ß-cyclodextrins and per-substituted y-cyclodextrins.

3. Use according to claim 1 or 2, wherein the per-substituted cyclodextrin

is selected from per-Ci-C ₆ alkyl-substituted a-cyclodextrins.

4. Use according to claim 1, wherein the per-substituted cyclodextrin is selected from hexakis (2,3,6-tri-O-methyl) -a-cyclodextrin, hexakis (2,3,6-tri-O-ethyl) - a-cyclodextrin, hexakis (2,3,6-tri-0-allyl) -cyclodextrin, hexakis (2,3,6-tri-O- (3-methylbut-3-en-1-yl)) - a- cyclodextrin, heptakis (2,3,6-tri-O-methyl) -β-cyclodextrin, heptakis (2,3,6-tri-O-ethyl) -β-cyclodextrin, heptakis (2,3,6-tri 0-allyl) -β-cyclodextrin, heptakis (2,3,6-tri-O- (3-methylbut-3-en-1-yl)) - β-cyclodextrin, 0ctakis (2,3,6-tri 0-methyl) -cyclodextrin, octakis (2,3,6-tri-O-ethyl) -Y-cyclodextrin, octakis (2,3,6-tri-O-allyl-y-cyclodextrin and octakis (2, 3,6-tri-0- (3-methylbut-3-en-1-yl)) - Y-cyclodextrin.

5. Use of per-substituted cyclodextrins according to one of the preceding claims for the selective detection of trichlorofluoromethane in gas samples.

6. Use according to claim 5, wherein the per-substituted cyclodextrin is used in the form of a gas sensor having an area with a sensitive layer comprising a per-substituted cyclodextrin.

7. Use according to claim 6, wherein the gas sensor is a gravimetric sensor, in particular a quartz oscillator microbalance.

8. Use according to claim 6, wherein the gas sensor is an optical sensor,

 In particular, an evanescent field sensor is.

9. Use of per-substituted cyclodextrins according to any one of claims 1 to 4 for the reversible storage of trichlorofluoromethane.

10. A method for the detection of trichlorofluoromethane in gas samples, wherein

a gas sample with at least one gas sensor, which has an area with a sensitive layer in contact, detected by trichlorofluoromethane in the gas samples detected changes in the sensitive layer of the sensor in the form of electrical or optical signals; and

 evaluates the signals,

 wherein the sensitive layer comprises a per-substituted cyclodextrin according to any one of claims 1 to 4.

1 1. The method of claim 10, wherein the gas sensor is selected from

 gravimetric sensors, in particular quartz crystal microbalances, and optical sensors, in particular evanescence field sensors.

12. A device for the detection of trichlorofluoromethane in gas samples, in particular for use in a method according to any one of claims 10 or 1 1, with

 Detection means which, when in contact with the gas sample, generate signals which depend on the concentration of trichlorofluoromethane in the gas sample, evaluation means which, from the signals supplied by the detection means, calculate the concentration of trichlorofluoromethane contained in the gas sample;

 wherein the detection means comprise at least one gas sensor having a sensitive layer region comprising a per-substituted cyclodextrin according to any one of claims 1 to 4.

13. A process for the reversible storage of trichlorofluoromethane, wherein

 Trichlorfluoromethane brings with a solid adsorbent in contact containing a per-substituted cyclodextrin according to any one of claims 1 to 4.

14. The method according to claim 13, wherein trichlorofluoromethane in the form of a

 Trichlorfluoromethane-containing gas or a Trichlorfluormethan-containing

 Passing liquid through a bed of solid adsorbent.

The method of claim 13 or 14, further comprising releasing the trichlorofluoromethane adsorbed by the solid adsorbent by heating.

16. The method according to any one of claims 13 to 15, wherein the per-substituted

 Cyclodextrin is a per-substituted a-cyclodextrin and especially hexakis (2,3,6-tri-0-methyl) -a-cyclodextrin.

17. Crystalline complex of hexakis (2,3,6-tri-0-methyl) -a-cyclodextrin with

Trichlorofluoromethane.

18. Crystalline complex according to claim 17, containing 3.5 to 4.5 moles of trichlorofluoromethane based on 1 mole of hexakis (2,3,6-tri-0-methyl) -a-cyclodextrin.

19. Crystalline complex according to claim 17 or 18, which shows in an X-ray powder diffraction pattern recorded at 120 K using Cu-Ka radiation at least 5 of the following reflections given as 20 values:

 5.2 ± 0.2 °, 6.9 ± 0.2 °, 7.0 ± 0.2 °, 7.7 ± 0.2 °, 1 1, 2 ± 0.2 °, 1 1, 9 ± 0.2 °, 13.8 ± 0.2 °, 14.0 ± 0.2 °, 15.0 ± 0.2 °, 17.1 ± 0.2 °, 19.7 ± 0.2 ° and 19,9 ± 0,2 °.