Microporous sio 2 particles

Abstract

The present invention relates to particles for absorbing gas molecules, wherein the particles are based on silicon dioxide, have pores with a defined pore size of 0.7 to 2 nm, and have a pore volume of less than 1 cm3 / g, wherein the particles contain silicon compounds having an organic functional group which is selected from the group consisting of C1-C8 alkyl, C2-C3 alkenyl, and phenyl, wherein this organic functional group modifies the pores of the particles.

Description

[0001] Microporous SiO2 particles

[0002] Zeolite L crystals with straight through channels can serve as hosts for the supramolecular organization of molecules, complexes, clusters, and quantum-sized particles. These host-guest systems can be used, for example, in the production of infrared-emitting diodes for telecommunications, as color-change materials, in dye-nanostructured materials for optical data storage, or for improving the chemical-physical properties of polymers.

[0003] W02019 / 018951A1 discloses the incorporation of guest molecules into the channels of zeolite crystals. By incorporating fluorescent dye molecules into the channels of zeolite L, an antenna system can be created in which the excitation energy is transferred from a donor dye to an acceptor dye by Förster resonance energy transfer.

[0004] EP 3 470 371 discloses mesoporous silica particles and their preparation. These are produced using bile acids and quaternary ammonium surfactants.

[0005] WO2009 / 10945 discloses a process for synthesizing mesoporous silica microparticles. This occurs by forming a sol from an ammonium-catalyzed hydrolysis and condensation reaction. The pre-sol solution used contains a silica precursor and a template, which is a surfactant, in a mixed solvent system of water and an alcohol (e.g., ethanol, methanol).

[0006] MU Xue (A facile and general approach for the synthesis of fluorescent silica nanoparticles doped with inert dyes, Chinese Sei Bull, 2011, 56: 3242-3246) describes the preparation of dye-loaded silicon dioxide nanoparticles. The dyes are incorporated during the synthesis of the nanoparticles. This requires that the dyes be soluble in the solvent used, which significantly limits their application.

[0007] Commercially available zeolites such as zeolite L (Linde Type L) have a linear channel system with a diameter of approximately 0.75 nm. This severely limits the number of guest molecules that can be incorporated into the channels. Fluorescent dyes such as rhodamine B cannot be incorporated into the channels of zeolite L because the molecule is too large. In addition, aluminosilicates such as zeolite L sometimes have strong acid centers in the channels because of the SiO ions in the lattice structure.4+ partly by Al 3+ which can greatly reduce the stability of guest molecules.

[0008] US 2019 / 256363 A1 discloses a process for producing a micron-sized spherical silica aerogel with adjustable particle size. The particle size is several micrometers.

[0009] WO 2016 / 167494 A1 describes a process for producing a silica aerogel-containing rubber blanket. In a first step, a reaction solution is prepared by reacting a silazane surface modifier with an alcohol compound, which is converted into a silica sol by adding a silica precursor, water, and a polar organic solvent. In a final step, the rubber blanket is produced by immersing the substrate for a rubber blanket, gelling, and drying the silica sol under subcritical conditions.

[0010] EP 2930147 A1 describes a process for producing a hydrophobic silica aerogel using Soxhlet extraction and also a hydrophobic silica aerogel.

[0011] Silica aerogels, as described for example in the documents US 2019 / 256363, WO 2016 / 167494 A1 and EP 2930147 A1, have a pore volume of more than 3.5 cm 3 / g. This explains the excellent thermal insulation properties of these materials. At the same time, however, aerogels are brittle and therefore unsuitable for the incorporation of guest molecules.

[0012] Sohmiya Minoru et al., "Host-guest chemistry of mesoporous silicas: precise design of location, density, and orientation of molecular guests in mesopores," published in SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS, Volume 16, No. 5, on October 22, 2015, pages 54201, DOI: 10.1088 / 1468-6996 / 16 / 5 / 054201, reveal the properties of mesoporous solids, including high surface area, porosity, and variable pore size. Morphosynthesis enables shapes ranging from monolithic blocks to nanoparticles.

[0013] Kamimura Y. et al.: "Fabrication of microporous amorphous silica glass by pyrolysis of phenyl groups intercalated in sol-gel derived phenyl-modified silica glass", published in * JOURNAL OF NON-CRYSTALLINE SOLIDS*, NORTH-HOLLAND PHYSICS PUBLISHING, Amsterdam, NL, Volume 356, No. 35-36, on August 1, 2010, pages 1842-1847, disclose the production of microporous silica glass by thermal decomposition of phenyl groups intercalated in the glass matrix. The production is carried out using a sol-gel process from mixtures of TEOS and PTES. Heat treatment at 600 °C for 4 hours completely removes the phenyl groups.

[0014] The object of the present invention is to provide microporous silicon dioxide particles in which the pore size can be adjusted so that interference between individual guest molecules can be reduced or avoided.

[0015] The object is achieved by the particles according to claim 1. Further preferred embodiments are the subject of the dependent claims.

[0016] The particles are based on silicon dioxide, have pores with a defined pore size of 0 . 7 to 2 nm and have a pore volume of less than 1 cm 3 / g . The particles also contain silicon compounds with an organic radical selected from the group consisting of Ci-C8alkyl, C2-C3alkenyl and phenyl, this organic radical modifying the pores of the particles.

[0017] It was found that such particles can be produced by a simple, cost-effective process. Depending on the porogen used, the pore size can be adjusted as desired. By mixing tetraalkoxysilanes and organotrialkoxysilanes, the polarity of the pores and also the pore size after removal of the porogen can be varied, since the organic residues remain inside the pores. During the production of the particles according to the invention, the tetraalkoxysilanes and the organotrialkoxysilanes are hydrolyzed and then further polymerized, which leads to the formation of a three-dimensional network containing the organic residues of the organotrialkoxysilane. This is understood under the term «modifying the pores». By constructing the host material without Al 3+In particular, the strong acid centers inside the pores can be partially or completely avoided, allowing even acid-labile guest molecules to be incorporated into the particles according to the invention. Due to the simple production of the particles according to the invention with the well-defined pores, the loading of the particles can be completely decoupled from the manufacturing process, which also enables loading with guest molecules that are insoluble in polar solvents or water.

[0018] The particles according to the invention have a pore volume of less than 1 cm 3 / g and preferably a pore volume of 0 . 3 to 0 . 6 cm 3 / g . The pore volume and pore size distribution are determined using the NLDFT method (nonlocalized density functional theory) according to ISO standard 15901-2:2022, which is based on the analysis of the desorption isotherm of nitrogen. Nitrogen is adsorbed at 77 K and gradually desorbed while the relative pressure is varied. Using the NLDFT method, pore size distributions in microporous and mesoporous systems can be determined particularly reliably. The method provides a pore size distribution, the BET surface area and the cumulative pore volume (total pore volume), enabling precise characterization of the pore structure.

[0019] The particles of the present invention typically have a BET of 100 to 1000 m 2 / g on .

[0020] Within the present invention, the term "particle diameter" refers to the average particle diameter, which is determined by measuring the dye-loaded particles using fluorescence microscopy (see, for example, Examples 5-12). The particles according to the invention preferably have an average particle diameter of 100 to 900 nm.

[0021] In the present invention, the term Cx-Cs alkyl represents a linear or branched alkyl group having a chain length of 1 to 8 carbon atoms. Examples are methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, and n-octyl.

[0022] In the present invention, the term C2-C3alkenyl refers to alkenyl groups having 2 to 3 carbon atoms. Examples include vinyl and allyl.

[0023] Preferably, 0.5 to 25 mol% of the Si atoms contained in the particles according to the invention contain an organic residue. The content of the organic residues can be easily controlled by the molar ratio of tetraalkoxysilanes and organotrialkoxysilanes. During the condensation reaction, both correspondingly hydrolyzed compounds are incorporated into the three-dimensional network.

[0024] The invention further relates to a particle-guest complex in which the particles according to the invention contain at least one type of guest molecule. The "at least one type of guest molecule" can be any type of uncharged or charged, organic or inorganic molecule that needs to be accommodated in the pores of the particles, such as dyes or pharmaceuticals. The guest molecule can be either natural (e.g. from plant sources) or synthetic. The pores of the particles according to the invention allow a specific arrangement of the guest molecules within the particles. The pores of the particles according to the invention can be adapted to the size of the guest molecules by the choice of porogen and the attachment of the organic radicals, so that the guest molecules are arranged in the particles in such a way that they preferably do not overlap and do not form dimers.Of particular interest are dyes, especially those that absorb in the green, yellow, orange, red, or infrared regions of the light spectrum, as these have particularly extended, conjugated pi systems. Fluorescent dyes that absorb light of a specific wavelength and then emit light of a longer wavelength are particularly preferred. Loading the particles with fluorescent dyes enables the production of highly luminescent materials. Due to the pores contained in the particles according to the invention, very high concentrations of monomeric fluorescent dye molecules can be achieved. The short distances between them lead to rapid, non-radiative Förster energy migration, in which the excitation energy is transferred directly from molecule to molecule.This phenomenon has been previously described in: 'Forster-Type Energy Transfer along a Specified Axis' by Claudia Minkowski and Gion Calzaferri, published in Angew. Chem.Int. Ed., 2005, 44, 5325-5329. Particularly preferred dyes are those selected from the group consisting of Rhodamine 6G, Rhodamine 101, Rhodamine B, Rhodamine 123, Rhodamine WT, Fluorescein, Porphyrin, Merocyanine, Phthalocyanine, Perylenebisimide dyes such as N,N'-bis(3-pentyl)perylene-3,4,9,10-bis(dicarboximide), Perylene diimide and bay-substituted Perylene diimide dyes, terrylene diimide and bay-substituted Terrylene diimide dyes, Quaterrylene diimide and bay-substituted Quaterrylene diimide dyes, Naphthalimide dyes, Perinone, Biphenyls, Terphenyls, Quaterphenyls, Tetracenes, Triphendioxazines, Acridines, Stilbenes, Azobenzenes, Oxazolyl benzenes, Styryl benzenes, Fluorenone, Isoviolanthrones, H-anthra (2, 1, 9-mna) thioxanthen—one (CISolvent Orange 63) , 1H- thioxantheno2 , 1, 9-def isoquinoline-1 , 3 (2H) -dione (C.I. Solvent Yellow 98) , 36-amino-2- (2, 4-dimethylphenyl) -1H- benz [de] isoquinoline-1, 3 (2H) -dione (C.I. Solvent Yellow 44) , diisobutyl perylene-3, 9-dicarboxylate, diisobutyl 3,9- perylenedicarboxylate (C.I. Solvent Green 5) , thioindigo compounds, 14H-anthra [2 , 1 , 9- mna] thioxanthen-14-one (Hostasol Red GG) , 1 , 4-Bis ( 4-methyl-5-phenyl-2-oxazolyl ) benzene (Dimethyl-POPOP) , 1, 4-Bis ( 5-phenyl-2-oxazolyl ) benzene (POPOP) , Spiropyrans, Naphthopyrans, Carotenoids, Carotenes, Xanthenophylles , Flavines, Pyronines, Oxazines, Thionines, Resorufine, Squaraine Farbstoffe, Boron-dipyrromethene Farbstoffe (BODIPY-Farbstof fe) , Silizium-substituierte Rhodamin Farbstoffe, Sulf one-Rhodamin Farbstoffe, Methylviologen, Carbocyanines und Sulforhodamin.Further preferred guest molecules are UV absorbers, preferably selected from the group consisting of triazines, oxalanilides, benzophenones, benzotriazoles, anthracenes and phenanthrenes or biocides or fungicides such as zinc pyrithione, 3-iodo-2-propynyl butylcarbamate or butylbenzisothiazolinone.

[0025] In one embodiment, the particles according to the invention can contain at least two types of guest molecules. It is possible for them to be randomly distributed in the pores of the particles, i.e. for both the inner and the outer part of the pores in the particles to contain both or more types of guest molecules. However, it is also possible for at least two types of guest molecules to be added sequentially one after the other during loading. In this way, particles can be obtained which have a shell-wise gradient, for example guest molecules of type A are taken up in the inner region of the pores and guest molecules of type B are taken up in the outer region of the pores.However, it is also possible to have guest molecules with a radial gradient, in which the guest molecules of type A are taken up in the innermost region of the pores, whose concentration decreases steadily towards the outside, while the concentration of the guest molecules of type B sets in slowly and increases steadily towards the outside.

[0026] A further aspect of the present invention relates to the use of the particles according to the invention for the absorption of guest molecules. Due to the precisely tailored production of the pores in the particles according to the invention, guest molecules can be absorbed into the pores without interference between the individual guest molecules. The pore walls serve as physical barriers to prevent the movement and / or

[0027] to limit interaction of the guest molecules.

[0028] The pores of the particles according to the invention are preferably designed so that they can accommodate guest molecules which have a maximum diameter of 1.9 nm in a molecular axis.

[0029] Preferably, the guest molecules are selected from the group of dyes that absorb in the green, yellow, orange, red or infrared region of the light spectrum, and in particular fluorescent dyes thereof, since these do not fit into zeolite channels due to the more extended, conjugated pi systems. Particularly good results were achieved with dyes selected from the group consisting of Rhodamine 6G, Rhodamine 101, Rhodamine B, Rhodamine 123, Rhodamine WT, fluorescein, porphyrin, merocyanines, phthalocyanine, sulforhodamine, perylene diimide, bay-substituted perylene diimide dyes, terrylene diimide, bay-substituted terrylene diimide dyes, quaterrylene diimide, bay-substituted quaterrylene diimide dyes, naphthalimide dyes, perinones, biphenyls, terphenyls, quaterphenyls, tetracenes, triphendioxazines, acridines, stilbenes, azobenzenes, oxazolylbenzenes, styrylbenzenes, fluorenones, isoviolanthrones, H-anthra (2, 1, 9-mna) thioxanthen-one (CISolvent Orange 63) , 1H-Thioxantheno2 , 1 , 9-def isoquinolin-1 , 3 (2H) -dione (CI Solvent Yellow 98) , 36-Amino-2- (2, 4-dimethylphenyl) -1H- Benz [de] isoquinolin-1, 3 (2H) -dione (CI Solvent Yellow 44) , Diisobutyl perylene-3 , 9-dicarboxylate , Diisobutyl 3 , 9-perylene dicarboxylate (CI Solvent Green 5) , Thioindigo compounds, 14H-Anthra [2,1, 9-mna] thioxanthen-14-one (Hostasol Red GG) , 1 , 4-Bis (4-methyl-5-phenyl-2-oxazolyl) benzene (Dimethyl-POPOP) , 1 , 4-Bis (5-phenyl-2-oxazolyl) benzene (POPOP), spiropyran, naphthopyran, carotenoids, carotenes, xanthenophylls, flavins, pyronines, oxazines, thionines, resorufin, squaraine dyes, boron-dipyrromethene dyes (BODIPY dyes), silicon-substituted rhodamine dyes, sulfone-rhodamine dyes, methyl viologen and carbocyanines can be obtained.

[0030] A further aspect of the present invention relates to the process for producing microporous particles. This comprises the following steps: a. Mixing a porogen in a solution of alcohol and water, which preferably contains 0-75% by weight, particularly preferably 10-40% by weight of alcohol in water, where the alcohol is preferably methanol or ethanol; b. Addition of a mixture of a C 1 -C 2 tetraalkoxysilane and an organotrialkoxysilane, where the organo radical is selected from the group consisting of C 1 -C 8 alkyl, C 2 -C 3 alkenyl and phenyl, and where a precipitate is formed during the mixing after a latency time of 2 seconds to 10 minutes, c. Separation of the particles formed in b) by centrifugation or filtration, d. Drying of the particles and aging of the powder to continue the condensation reaction e. Removal of the porogen.

[0031] In the context of the present invention, the term porogen refers to a substance that forms pores of a well-defined size in the particles. Ideally, the porogen forms micelles in the solvent, which then define the pore size in the resulting silicon dioxide particle. For example, quaternary ammonium compounds such as hexadecyltrimethylammonium bromide or linear amines such as decylamine or hexylamine can be used as porogens. The porogen is removed after production, leaving behind the microporous SiO2 structure, i.e., pores, with a pore size of 0.7 to 2 nm. These have a pore volume of less than 1 cm 3 / g .

[0032] Drying and aging are preferably carried out for 5-100 days at 30-100 ° C and a pressure of 1 Ombar to atmospheric pressure .

[0033] Preferably, the tetraalkoxysilane is selected from the group consisting of tetramethoxysilane and tetraethoxysilane or a mixture thereof, since these starting materials are readily available and can be easily hydrolyzed and subsequently condensed to SiO2.

[0034] The organotrialkoxysilane is preferably selected from the group consisting of vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, n-butyltrimethoxysilane, n-pentyltrimethoxysilane, n-hexyltrimethoxysilane or n-octyltrimethoxysilane, ethyltriethoxysilane, n-propyltriethoxysilane, n-butyltriethoxysilane, n-pentyltriethoxysilane, n-hexyltriethoxysilane or n-octyltriethoxysilane, phenyltrimethoxysilane and phenyltriethoxysilane. These organotrialkoxysilanes can interact with the porogen and are thus incorporated in particular into the pore inner walls. This allows the polarity of the pores and also the pore size to be varied after removal of the porogen, since the organic residues remain inside the pores.

[0035] Particularly good results were obtained when the porogen was a quaternary ammonium compound or a linear amine with at least 6 carbon atoms, since the amines act as a condensation catalyst, which makes the use of an additional base catalyst such as ammonia solution unnecessary.

[0036] Very good results were obtained with neutral, linear amines, since these compounds can be removed from the particles essentially without leaving residues.

[0037] The porogen is preferably removed by calcination at 400 °C to 650 °C, heating under vacuum to 100 °C to 300 °C, extraction with a solvent in a Soxhlet evaporator, or by ultrasonic extraction. Heating under vacuum to 100 °C to 300 °C, extraction with a solvent in a Soxhlet evaporator, and by ultrasonic extraction have the advantage that porogens used as neutral amines can be recovered, and the organic residues of the organotrialkoxysilane are not destroyed under these conditions, as is the case with calcination.

[0038] Preferably, the particles according to the invention are loaded with a guest molecule, the pores of the particles having a defined pore size of 0.7 to 2 nm and the pore surface of which is optionally at least partially modified with a radical selected from the group consisting of Ci-C8alkyl, C2-C3alkenyl and phenyl, by a. the particles, which have optionally been predried under vacuum, the guest molecule and a cyclic

[0039] Siloxane, b. the mixture obtained in step a) is heated to at least 100°C to incorporate the guest molecules into the pores. The incorporation is therefore preferably carried out in a similar way to that described for zeolites L in W02019 / 018951.

[0040] The cyclic siloxane used for the incorporation of the guest molecules is preferably selected from the group consisting of 1,3,5-trimethylcyclotrisiloxane, 1,3,5-triethylcyclotrisiloxane, 1,3,5-trivinylcyclotrisiloxane, 1,3,5-triphenylcyclotrisiloxane, hexamethylcyclotrisiloxane, hexaethylcyclotrisiloxane, hexavinylcyclotrisiloxane, hexaphenylcyclotrisiloxane, 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane, 1,3,5-tri-methyl-1,3,5-triphenylcyclotrisiloxane, 1,3,5-tris(3,3,3-trifluoropropyl)-1,3,5-trimethylcyclotri- siloxane, 1, 3, 5, 7-tetramethylcyclotetrasiloxane, 1, 3,5,7-tetraethylcyclotetrasiloxane, 1,3,5, 7-tetravinylcyclotetrasiloxane, 1, 3, 5, 7-tetraphenylcyclotetrasiloxane, octamethylcyclotetrasiloxane, Octaethylcyclotetrasiloxane, octavinylcyclotetrasiloxane, octaphenylcyclotetrasiloxane, 1,3,5, 7-tetravinyl-l, 3, 5, 7-tetramethylcyclotetrasiloxane, 1,3,5, 7-tetramethyl-1, 3, 5, 7-tetraphenylcyclotetrasiloxane, 1,3,5, 7- Tetrakis (3.3,3-Trifluoropropyl-1, 3,5, 7-Tetramethylcyclotetrasiloxane, 1, 3, 5, 7, 9-Pentamethylcyclopentasiloxane, 1, 3, 5,7,9-Pentaethylcyclopentasiloxane, 1, 3, 5, 7, 9-Pentavinylcyclopentasiloxane, 1 , 3 , 5 , 7 , 9-pentaphenylcyclopentasiloxane, decamethylcyclopentasiloxane, decaphenylcyclopentasiloxane, 1, 3, 5,7,9-pentavinyl-1, 3,5,7, 9-pentamethylcyclopentasiloxane, 1, 3, 5, 7, 9-pentamethyl-1, 3,5,7, 9 -Pentaphenyl -Cyclopentasiloxane, 1,3,5,7,9,11-hexamethylcyclohexasiloxane, 1,3,5,7,9,11-hexavinylcyclohexasiloxane, 1,3,5,7,9,11-hexaphenylcyclohexasiloxane, dodecamethylcyclohexasiloxane, dodecavinylcyclohexasiloxane and dodecaphenylcyclohexasiloxane or mixtures thereof.,

[0041] The guest molecules can be incorporated into the pores as a mixture, or added and incorporated sequentially. By incorporating suitable fluorescent dye molecules, a Förster energy transfer system can be constructed.

[0042] In order to keep the guest molecules inside the particles, the surface of the loaded particles can be modified and thus the pore openings at least partially reduced or closed. This can be done, for example, by the particles loaded with the guest molecule a. being reacted with a polyalkoxysilane: By binding the polyalkoxysilanes to the SiO2 surface, the pores are at least partially closed. b. being reacted with an organometallic precursor compound that decomposes thermally: An example of this is Zn(acac)2. During the thermal decomposition of Zn(acac)2, the organic acetylacetonate is broken down, leaving behind zinc oxide (ZnO). This ZnO can be deposited on the surface of the SiO2 particles, forming a Zn0-SiO2 composite structure that at least partially closes the pores. c.Alkoxysilane is hydrolyzed and condensed with water: By binding the alkoxysilanes to the SiO2 surface, the pores are at least partially closed. d. Alkoxyaluminum is hydrolyzed and condensed with water: The aluminum hydroxide groups can interact with the hydroxyl groups on the surface of SiO2 particles and thus coat or modify the SiO2 surface of the particles. e. Alkoxytitanate is hydrolyzed and condensed with water: The titanium hydroxide groups can interact with the hydroxyl groups on the surface of SiO2 particles and thus coat or modify the SiO2 surface of the particles. f. are reacted with a polysilazane: which can react thermally or by hydrolysis to form SiO2. g. with a sodium silicate : the formation of the silicate network on the surface can at least partially close the pores . h .is covered by atomic layer deposition: The coating takes place by adding an excess of a first reactant to the particles according to the invention, mixing the dispersion thus obtained to allow the first reactant to react with the SiO2 groups on the surface of the particles, removing the excess of the first reactant by vacuum or by distillation or by azeotropic distillation, adding an excess of a second reactant to the reactive groups on the surface obtained in the previous step and mixing the dispersion to allow the second reactant to react with the first reactant on the surface of the particles, and then removing the excess of the second reactant by vacuum or by distillation or by azeotropic distillation.The first reactant is preferably selected from the group consisting of trimethylaluminum, triethylaluminum, tripropylaluminum, triisopropylaluminum, triisobutylaluminum, titanium chloride, tantalum chloride, hafnium chloride, diethylzinc, silicon tetrachloride, tridimethylaminosilicon, tetrakis(dimethylamido)titanium, tetrakis(ethylmethylamido)zirconium, and (methylcyclopentadienyl)trimethylplatinum. The second reactant is preferably selected from the group consisting of water, ozone, organic peroxides, organic peracids, alcohols, diols, and ammonia. This process is described in detail in WO2022 / 200184.

[0043] A combination of several of the methods described under a) to h)

[0044] Methods can be used to close the pores.

[0045] The methods proposed above are all so mild that the guest molecules are not affected by the pore closure. Closing the pores makes the particles more durable and more stable. Furthermore, by only reducing the pore openings and not completely closing them, a system can be created in which the guest molecules are slowly released into the environment. This is of particular interest in pharmaceutical applications or with biocides.

[0046] A further aspect of the present invention relates to the use of particles which are based on silicon dioxide and have pores, wherein the pores of the particles have a defined pore size of 0.7 to 2 nm and whose pore surface is optionally at least partially modified with a radical which is selected from the group consisting of C1-C8 alkyl, C2-C3 alkenyl and phenyl, and wherein these particles are loaded with at least one type of guest molecule, in diagnostics, in fluorescence microscopy, in pharmaceutical applications, as a fungicide or biocide for sealing compounds, as systems in which the guest molecules are slowly released into their environment, as UV protection in sunscreen and in adhesives and sealants.

[0047] Character description:

[0048] Fig. 1 to 14 show excitation and emission spectra of the particles described in the examples.

[0049] Fig. 15 shows an SEM image of the particles from Example 9

[0050] Example 1: Production of microporous SiO2 particles

[0051] 5 ml of hexylamine was stirred in 50 g of methanol and 150 g of distilled water for 5 minutes at room temperature. 10.6 ml of tetramethoxysilane (TMOS) was added to the solution. A white precipitate formed within approximately 10 seconds. The dispersion was stirred for 4 hours at room temperature, then centrifuged and washed twice with ethanol. The samples were dried in a vacuum oven at approximately 70°C and 500 mbar and aged for at least 5 days.

[0052] Example 2: Preparation of organosilane-modified SiO2 particles

[0053] 4.06 ml of hexylamine was stirred in 50 g of methanol and 150 g of distilled water for 5 minutes at room temperature. A premixed solution of 9.36 ml of TMOS and 1.24 ml of n-propyltrimethoxysilane (propyl-TMS) was added. A white precipitate formed within approximately 10 seconds. The dispersion was stirred for 4 hours at room temperature, then centrifuged and washed twice with ethanol. The samples were dried in a vacuum oven at approximately 70°C and 500 mbar and aged for at least 5 days. Example 3

[0054] To remove the hexylamine, 2 g of the powder from Example 1 was heated from RT to 600°C in a muffle furnace over 3 h and calcined at 600°C for 1.5 h. 1 g of the calcined powder was dried in a vacuum flask at 200°C. Subsequently, the SiO2 particles were dispersed in 25 ml of decamethylcyclopentasiloxane (CM50hp, BRB), 10 mg of tb-DXP, and 0.5 mg of Rhodamine B and stirred for 1 h under N2 at 200°C to incorporate the two dyes into the pores. To seal the pores, 440 μl of TMOS and 140 μl of water were added after cooling, and the mixture was stirred at RT for 16 h. The dispersion was centrifuged and washed twice with dichloromethane, and the powder was then dried in a vacuum oven at 70 °C. Figure 1 shows the excitation and emission spectra of the loaded particles from Example 3 dispersed in NMP.

[0055] Example 4

[0056] To remove the hexylamine, 2 g of the powder from Example 2 was heated from RT to 250 °C under vacuum in a vacuum flask for 2 h. After cooling, the SiO2 particles were dispersed in 25 ml of decamethylcyclopentasiloxane (CM50hp, BRB), 20 mg of N,N'-bis (3-pentyl) perylene-3,4,,10-bis (dicarboximide) (PBI), and 1 mg of Solvent Red 196 (NR196) and stirred for 1 h under N2 at 200 °C to incorporate the two dyes into the pores. Subsequently, 1.054 g (4 mmol) of zinc (II) acetylacetonate were added and stirred for 16 h at 170 °C. The dispersion was centrifuged and washed twice with dichloromethane, and the powder was then dried in a vacuum oven at 70°C. Figure 2 shows the excitation and emission spectra of the loaded particles from Example 4 dispersed in NMP. The emission spectra in Figures 1 and 2 demonstrate efficient Förster energy transfer from the donor dye (PBI and tb-DXP, respectively) to the acceptor dye (Rhodamine B and NR196, respectively).With selective excitation of the donor dye, only the emission of the acceptor dye is predominantly visible. Förster.

[0057] Energy transfer is strongly dependent on the distance between the donor and acceptor dye and only occurs if this distance is smaller than approximately 10nm.

[0058] Examples 5-12

[0059] Table 1:

[0060] TMOS: Tetramethoxysilane

[0061] Prop-TMS: Propyltrimethoxysilane, Hex-TMS: Hexyltrimethoxysilane,

[0062] VTMO: Vinyltrimethoxysilane

[0063] HA: Hexylamine, OA: Octylamine, DA: Decylamine Examples 5-12 were prepared according to Table 1. The specified amount of porogen is stirred in 50g methanol and 150g distilled water for 5 minutes at room temperature. A premixed solution of SiO2 source and organosilane (if used) is added. A white precipitate forms within approx. 10 seconds. The dispersions are stirred for a further 4 hours at room temperature, then centrifuged and washed twice with ethanol. The samples are dried in a vacuum oven at approx. 70 °C and 500 mbar and aged for at least 5 days.

[0064] To remove the porogen, 2 g of the powder from Examples 5-12 are heated from RT to 250 °C in a vacuum flask for 4 h under vacuum. Comparable results are obtained when the porogen is removed by repeated washing with 0.1M HCl in ethanol or by Soxhlet extraction. After cooling, 0.5 g each are dispersed in 20 ml CM50hp with 4 mg PBI and incorporated for 1 h at 200 °C. After cooling, an excitation (emission 600 nm) and an emission spectrum (excitation 490 nm) are measured in CM50hp (Figures 3-10). To close the pores, 250 μl of tetrapropoxysilane (TPOS) is then added and stirring is continued for 18 h at 180 °C.

[0065] Perylenebisimide dyes such as PBI are known to aggregate at high concentrations, resulting in an increase in fluorescence at approximately 620 nm (J-aggregates). Despite the small change in pore diameter in Examples 5-12, a significant change in the emission spectrum is observed; the larger the pore diameter, the greater the fraction of emission from the dye aggregates and thus the relative intensity of the emission spectrum in Example 13:

[0066] 5 ml of hexylamine is stirred in 50 g of methanol and 150 g of distilled water for 5 minutes at room temperature. 15 ml of TEOS (tetraethoxysilane) is added as a SiO2 source. Within a few minutes, a white precipitate forms (TEOS is significantly less reactive than TMOS). The dispersion is stirred for 4 hours at room temperature, then centrifuged and washed twice with ethanol. The sample is dried in a vacuum oven at approximately 70 °C and 500 mbar and aged for at least 5 days.

[0067] To remove the porogen, 2 g of the powder was heated from RT to 250 °C under vacuum for 4 h in a vacuum flask. Comparable results were obtained when the porogen was removed by repeated washing with 0.1M HCl in ethanol or by Soxhlet extraction. After cooling, 0.5 g each was dispersed in 20 ml of CM50hp containing 4 mg PBI and incorporated for 1 h at 200 °C. After cooling, an excitation (emission 600 nm) and an emission spectra (excitation 490 nm) were measured in CM50hp (Figure 11). To close the pores, 250 μl of tetrapropoxysilane (TPOS) was added, and stirring was continued for 18 h at 180 °C. The relative intensity at 620 nm was 0.193.

[0068] Example 14

[0069] 1 g of the particles from Example 9, from which the porogen was removed by vacuum at 250°C for 4 h, is dispersed in 20 ml of CM50hp with 7.2 mg PBI and 0.3 mg Rhodamine B and incorporated for 1 h at 200°C. After cooling, an excitation (emission 600 nm) and an emission spectrum (excitation 490 nm) are measured in CM50hp (Figure 12). Upon excitation of the donor dye PBI, an efficient energy transfer to the acceptor dye Rhodamine B is visible, i.e. that both dyes are incorporated into the pores and thus the distance between the two dyes is sufficiently small for Förster energy transfer to take place. To close the pores, 500 μl of tetraethoxysilane (TEOS) is then added and stirring is continued for 18 h at 180°C.

[0070] Example 15

[0071] 1g of the particles from Example 9, from which the porogen was removed by vacuum at 250°C for 4h, is dispersed in 20ml of CM50hp with 7.2mg PBI and 0.3mg Rhodamine 101 and incorporated for 1h at 200°C. After cooling, an excitation (emission 600nm) and an emission spectrum (excitation 490nm) are measured in CM50hp (Figure 13). Upon excitation of the donor dye PBI, hardly any energy transfer to the acceptor dye Rhodamine 101 is visible, but practically only the emission from PBI. This means that the acceptor dye Rhodamine 101 cannot be incorporated into the pores because the molecule is too large and thus the distance between the two dyes is too great for Förster energy transfer to take place. To close the pores, 500 μl of tetraethoxysilane (TEOS) is then added and stirring is continued for 18 h at 180°C.

[0072] Example 16

[0073] 1 g of the particles from example 8, from which the porogen has been removed by vacuum at 250°C for 4 h, is dispersed in 20 ml CM50hp with 7.2 mg PBI and 0.3 mg Rhodamine 101 and incorporated for 1 h at 200 °C. After cooling, an excitation (emission 600 nm) and an emission spectrum (excitation 490 nm) are measured in CM50hp (Figure 14). Upon excitation of the donor dye PBI, an efficient energy transfer to the acceptor dye Rhodamine 101 is visible, i.e. in contrast to example 15, Rhodamine 101 can now also be incorporated into the slightly larger pores (1 . 4 nm compared to 1 . 3 nm) and thus the distance between the two dyes is sufficiently small for Förster energy transfer to take place. To close the pores, 500ul of tetraethoxysilane (TEOS) is then added and stirring is continued for 18h at 180 °C.

[0074] The two dyes Rhodamine B and Rhodamine 101 have the following structural formulas:

Claims

Patent claims 1 . Particles for the absorption of guest molecules, wherein the particles are based on silicon dioxide, have pores with a defined pore size of 0 . 7 to 2 nm and a pore volume of less than 1 cm 3 / g, characterized in that the particles contain silicon compounds with an organic radical which is selected from the group consisting of Ci-C8alkyl, C2-C3alkenyl and phenyl, wherein this organic radical modifies the pores of the particles. 2 . Particles according to claim 1 , characterized in that 0 . 5 to 25 mol% of the Si atoms have an organic residue .

3. Particle-guest complex with particles according to one of the preceding claims, characterized in that they contain at least one type of guest molecule.

4. Particle-guest complex according to claim 3, characterized in that the at least one type of guest molecule is selected from the group of dyes which absorb in the green, yellow, orange, red or infrared region of the light spectrum, preferably fluorescent dyes, most preferably selected from the group consisting of Rhodamine 6G, Rhodamine 101, Rhodamine B, Rhodamine 123, Rhodamine WT, fluorescein, porphyrin, merocyanine, Phthalocyanine, Sulforhodamine, Perylene diimide, bay-substituted perylene diimide dyes, Terrylene Diimide, bay-substituted terrylene diimide dyes, Quaterrylene diimide, bay-substituted quaterrylene diimide dyes, naphthalimide dyes, perinone, Biphenyls, terphenyls, quaterphenyls, tetracenes, triphendioxazines, acridines, stilbenes, azobenzenes, Oxazolylbenzenes, styrylbenzenes, fluorenones, Isoviolanthrone, H-Anthra(2,1,9-mna)thioxanthen-one (CI Solvent Orange 63), 1H-Thioxanthene2,1,9-def isoquinoline-1,3(2H)-dione (CI Solvent Yellow 98), 36-Amino-2-(2,4-dimethylphenyl)-IH-Benz[de]isoquinoline-1,3(2H)-dione (CI Solvent Yellow 44), Diisobutyl-Perylene-3,9-dicarboxylate, Diisobutyl-3,9- Perylenedicarboxylate (CI Solvent Green 5), Thioindigo compounds, 14H-Anthra[2,1,9-mna]thioxanthen-I4-one (Hostasol Red GG), 1,4-Bis(4-methyl-5-phenyl-2-oxazolyl)benzene (Dimethyl-POPOP), 1,4-Bis(5-phenyl-2-oxazolyl)benzene (POPOP), Spiropyran, Naphthopyran, Carotenoids, Carotenes, Xanthenophylls, Flavins, Pyronines, Oxazines, Thionines, Resorufin, Squaraine dyes, Boron-Dipyrromethene dyes (BODIPY dyes), silicon-substituted rhodamine dyes, sulfone-rhodamine dyes, methyl viologen and carbocyanines.

5. Particle-guest complex according to claim 4, characterized in that it contains at least two types of guest molecules which are contained in the particles either as a mixture or in layers.

6. Particle-guest complex according to one of claims 3 to 5, characterized in that the guest molecules have a maximum diameter of 1.9 nm in a molecular axis.

7. A process for producing particles according to one of claims 1 to 2, comprising the following steps: a. Mixing a porogen in a solution of alcohol and water, b. Adding a mixture of a C1-C2 tetraalkoxysilane and an organotrialkoxysilane, wherein the organo radical is selected from the group consisting of C1-C8 alkyl, C2-C3 alkenyl and phenyl, and wherein a precipitate is formed during the mixing after a latency period, c. Separating the particles formed in b) by centrifugation or filtration, d. Drying the particles and aging the powder to continue the condensation reaction e. Removing the porogen.

8. Process according to claim 7, characterized in that the tetraalkoxysilane is selected from the group consisting of tetramethoxysilane and tetraethoxysilane or a mixture thereof.

9. Process according to one of claims 7 to 8, characterized in that the organotrialkoxysilane is selected from the group consisting of vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, Allyltriethoxysilane, ethyltrimethoxysilane, n- Propyltrimethoxysilane, n-Butyltrimethoxysilane, n- Pentyltrimethoxysilane, n-hexyltrimethoxysilane or n- Octyltrimethoxysilane, ethyltriethoxysilane, n- Propyltriethoxysilane, n-Butyltriethoxysilane, n- Pentyltriethoxysilane, n-hexyltriethoxysilane or n- Octyltriethoxysilane, phenyl trimethoxysilane and Phenyltriethoxysilane .

10. A process according to any one of claims 7 to 9, wherein the porogen is a quaternary ammonium compound or a linear amine having at least 6 carbon atoms.

11. A process for producing a particle-guest complex according to any one of claims 3 to 6 with at least one type of guest molecules, wherein the particles are based on silicon dioxide and have pores which have a defined pore size of 0.7 to 2 nm and a pore volume of less than 1 cm 3 / g and whose pore surface is optionally at least partially modified with a radical selected from the group consisting of Ci-C8alkyl, C2-C3alkenyl and phenyl by a. the particles, the at least one type of guest molecules and a cyclic siloxane are mixed, b. the mixture obtained in step a) is heated to at least 100 ° C in order to incorporate the guest molecules into the pores.

12. A method according to claim 11, characterized in that the pores of the particles loaded with the at least one type of guest molecules are at least partially closed. 13 . Method according to claim 12 , characterized in that the particles loaded with the at least one type of guest molecules are a . reaction with a polyalkoxysilane; b . thermal decomposition of an organometallic precursor compound; c . hydrolysis and condensation of an alkoxysilane with water; d . hydrolysis and condensation of an alkoxyaluminum with water; e . hydrolysis and condensation of an alkoxytitanate with water; f . reaction with a polysilazane; g . condensation of sodium silicate or h . atomic layer deposition or a combination of ah be at least partially sealed .

14. Use of particle-guest complex according to one of claims 3 to 6, which are based on silicon dioxide and have pores, wherein the pores of the particles have a defined pore size of 0.7 to 2 nm and a pore volume of less than 1 cm 3 / g, and whose pore surface is optionally at least partially modified with a radical selected from the group consisting of Ci-C8alkyl, C2-C3alkenyl and phenyl, and wherein these particles are loaded with the at least one type of guest molecules, in diagnostics, in fluorescence microscopy, in pharmaceutical applications, as a fungicide or biocide for sealants, as systems in which the guest molecules are slowly released into their environment, as UV protection in sunscreen and in adhesives and sealants.

Images