Photostimulation responsive rare earth functionalized HOFs material, and preparation method and application thereof

Abstract

The invention relates to a photostimulation responsive rare earth functionalized HOFs material as well as a preparation method and application thereof. The material comprises a hydrogen bond organic framework and a luminescent rare earth complex, the mass ratio of the luminous rare earth complex to the hydrogen bond organic framework is 0.1-0.2; the method comprises the following steps: constructing HOFs by using 4, 4 '-((perfluorocyclopent-1-ene-1, 2-diyl) bis (5-methylthiophene-4, 2-diyl)) dibenzoic acid (DAE) as a skeleton trunk and 4, 4', 4 '', 4'' '-methane tetrabenzamidine (TAM); according to the obtained material, DAE is subjected to a ring opening / closing isomerization reaction under ultraviolet / visible light illumination, meanwhile, topological configuration conversion of HOFs is carried out, fluorescence on / off reversible light regulation and control of the rare earth functionalized HOFs are achieved by coating a rare earth complex through the porosity of the HOFs, and the material is further used for multiple times of reciprocating light-operated encryption and decryption of information.

Description

Technical Field

[0001] The present invention belongs to the fields of hydrogen-bonded organic framework (HOFs) materials and rare-earth hybrid luminescent materials, and particularly relates to a light-stimulus-responsive rare-earth functionalized HOFs material, a preparation method thereof, and an application thereof. Background Art

[0002] Crystalline porous materials, including but not limited to molecular sieves, metal-organic frameworks, covalent organic frameworks, and hydrogen-bonded organic frameworks, have become one of the hot research fields due to their characteristics such as structural designability, permanent porosity, high specific surface area, and functional tunability, and have been widely applied in the fields of gas adsorption and separation, water purification, proton conduction, catalysis, fluorescence sensing, biomedicine, and electronic devices. Stimulus-responsive materials, also known as smart materials, are a class of materials that can undergo changes in microstructure and macroscopic physical or chemical properties in response to external stimuli (such as mechanical force, electric field, magnetic field, temperature, ionic strength, or pH value, etc.). Among them, light stimulation has advantages such as being remote, clean, fast, and efficient, and can minimize the damage to the framework caused by invasive stimuli. Currently, there are mainly three strategies for introducing light-stimulus-responsive groups into crystalline porous materials: as the backbone of the framework, as the side chain of the framework, or as guest molecules.

[0003] Using diarylethene compounds as the backbone of the framework to construct light-stimulus-responsive crystalline porous materials, their isomerization usually causes overall configuration changes in the interpenetrating network and pore structure, thereby bringing a greater functional regulation range to the properties and functions of the materials. However, the filling effect of the rigid backbone occupies the direction and volume required for photoisomerization, resulting in the inability to guarantee the isomerization efficiency of diarylethene. The literature numbers DOI: 10.1002 / anie.201702484 and DOI: 10.1016 / j.cej.2022.139004 reported two metal-organic frameworks based on diarylethene, which achieved photocontrolled separation of ethylene / acetylene and krypton / nitrogen respectively, but the isomerization efficiencies of diarylethene were 61% and 43% respectively; at the same time, the energy of light irradiation is usually not sufficient to cause the cleavage and reconstruction of coordination bonds and covalent bonds, etc., resulting in the configuration transformation of light-driven crystalline porous materials still being a major challenge.

[0004] Rare-earth luminescent materials show application potential in the field of fluorescence anti-counterfeiting due to their advantages such as strong light absorption ability, long fluorescence lifetime, large Stokes shift, high fluorescence quantum efficiency, and rich emission spectra. However, due to their fixed signal output characteristics, the information and patterns stored in them are often easy to identify and decipher under ultraviolet light or sunlight irradiation, and it is difficult to meet the growing demand for advanced anti-counterfeiting. Summary of the Invention

[0005] In view of the generally low photoisomerization efficiency of the backbone of the above-mentioned crystalline porous materials, the difficulty in realizing the regulation of the photonic topological structure, and the easy decryption of traditional fluorescent anti-counterfeiting materials, the present invention proposes a photo-responsive rare-earth functionalized HOFs material, a preparation method and an application thereof. In this method, 4,4'-((perfluorocyclopent-1-ene-1,2-diyl)bis(5-methylthiophene-4,2-diyl))dibenzoic acid (DAE) is used as the backbone to construct HOFs with 4,4',4'',4'''-methanetetraphenylformamidine (TAM). Under ultraviolet / visible light irradiation, DAE undergoes ring-opening / ring-closing isomerization reaction, accompanied by the topological configuration transformation of HOFs. The porosity of HOFs is used to encapsulate rare-earth complexes to achieve reversible fluorescence on / off photo-regulation of rare-earth functionalized HOFs, which is further used for multiple reciprocating photo-encryption and decryption of information.

[0006] The technical solution of the present invention is as follows:

[0007] A photo-responsive rare-earth functionalized HOFs material, comprising: a hydrogen-bonded organic framework and a luminescent rare-earth complex; the mass ratio of the luminescent rare-earth complex to the hydrogen-bonded organic framework is 0.1-0.2;

[0008] The hydrogen-bonded organic framework is an open-ring HOFs (HOF-OF) and a closed-ring HOFs (HOF-CF), and the molecular formula is C 87 H 64 F 12 N8O8S4;

[0009] Among them, HOF-OF is formed by connecting open-ring DAE (OF-DAE) and TAM through hydrogen bonds, belonging to the tetragonal system, the space group is I-42d, and the unit cell parameters are: a = 44.897(14), b = 44.897(14), c = 7.478(3), α = 90°, β = 90°, γ = 90°, Z = 4; HOF-CF is formed by connecting closed-ring DAE (CF-DAE) and TAM through hydrogen bonds, belonging to the monoclinic system, the space group is C2 / c, and the unit cell parameters are: a = 17.9910(11), b = 14.8263(11), c = 42.857(3), α = 90°, β = 90°, γ = 101.601(5)°, Z = 4.

[0010] The luminescent rare-earth complex is: Ln·L3; among them, the rare-earth element Ln is specifically: Tb 3+ and Eu 3+ one of them;

[0011] The ligand L is one of pyridine-2,6-dicarboxylic acid (DPA), acetylacetone (ACAC), 2-thenoyltrifluoroacetone (TTA), hexafluoroacetylacetone (HFAC), 1,1,1-trifluoro-2,4-pentanedione (TFAC), benzoylacetone (BZAC), benzoyltrifluoroacetone (BTFAC), and dibenzoylmethane (DMA).

[0012] The preparation method of the photo-responsive rare earth functionalized HOFs material includes the following steps:

[0013] (a) Disperse OF-DAE in the first mixed solvent at room temperature, add an alkali solution for deprotonation until pH = 6 - 8, and ultrasonicate for 10 - 20 minutes to obtain a dicarboxylic acid ligand solution;

[0014] Among them, in the dicarboxylic acid ligand solution, the molar concentration of OF-DAE is 1 mM - 8 mM;

[0015] Separately, add TAM to the second mixed solvent of ethanol and water at room temperature, and ultrasonicate for 10 - 20 minutes to obtain a tetraamidine ligand solution;

[0016] Among them, in the tetraamidine ligand solution, the molar concentration of TAM is 0.5 mM - 4 mM;

[0017] The first mixed solvent and the second mixed solvent are the same or different, and the composition is ethanol and water, and the volume ratio of ethanol to water is 0.4 - 2;

[0018] (b) Mix the dicarboxylic acid ligand solution and the tetraamidine ligand solution to obtain a mixed solution, let it stand at room temperature for 5 - 48 hours, colorless needle-like crystals are formed, filter and collect, and wash with ethanol 2 - 5 times to obtain a colorless hydrogen-bonded organic framework HOF-OF;

[0019] Among them, the molar ratio is dicarboxylic acid ligand:tetraamidine ligand = 2:1,

[0020] The alkali is sodium hydroxide, potassium hydroxide, or tetrabutylammonium hydroxide.

[0021] (c) Rare earth functionalization:

[0022] Take HOF-OF in a reactor, add an ethanol solution of a luminescent rare earth complex at room temperature, soak for 12 - 36 hours, filter and collect, and wash with ethanol 2 - 5 times to obtain Ln·L3@HOF-OF, that is, rare earth functionalized HOF-OF;

[0023] Among them, the concentration of the ethanol solution of Ln·L3 is 0.2 mM - 1.5 mM, and the mass ratio of Ln·L3 to HOF-OF is 0.1 - 0.2.

[0024] The application of the light-stimulated responsive rare-earth functionalized HOFs material is used for light-controlled intelligent anti-counterfeiting.

[0025] Specifically, it includes the following steps: Add ethanol to Ln·L3@HOF-OF in a reactor and ultrasonicate for 10 - 20 minutes to obtain a dispersion; Use the dispersion as printing ink and coat it on a polyethylene terephthalate film to obtain a pattern.

[0026] The pattern obtained by the coating is invisible under sunlight; When irradiated under an ultraviolet lamp, a red pattern immediately appears; When continuously irradiated with ultraviolet light for 20 - 60 seconds, the pattern on the film does not appear under sunlight or ultraviolet lamp irradiation, and at this time, a secure mode with invisible information is achieved, realizing information encryption.

[0027] Then, irradiate the pattern with visible light with a wavelength of 450 nm - 700 nm for 30 - 120 seconds, and the pattern can be completely restored and re-identified under an ultraviolet lamp, and the information is decrypted again; This information encryption / decryption process can be cycled multiple times.

[0028] Among them, the concentration of the dispersion is 0.3 mg / mL - 1 mg / mL.

[0029] The substantial features of the present invention are:

[0030] In the current technology, due to the generally low photoinduced isomerization efficiency of the backbone of crystal porous materials such as molecular sieves, metal-organic frameworks, and covalent organic frameworks, it is difficult to achieve light-controlled topological structure regulation. The present invention utilizes the characteristics of HOFs formed by hydrogen-bond self-assembly, such as mild preparation conditions, strong solution processability, and good self-healing and regeneration abilities. The low bond energy of hydrogen bonds and the good solution processability of HOFs provide an opportunity for the cleavage and reconstruction of hydrogen bonds under mild conditions.

[0031] The present invention connects DAE as the backbone with TAM through hydrogen bonds to form HOFs. Under ultraviolet / visible light irradiation, DAE undergoes ring-opening / ring-closing isomerization reactions, accompanied by a topological configuration transformation of HOFs. The porosity of HOFs is used to coat rare-earth complexes to achieve reversible fluorescence on / off light regulation of rare-earth functionalized HOFs materials, and further used for multiple reciprocating light-controlled encryption and decryption of information.

[0032] The beneficial effects of the present invention are:

[0033] (1) In the backbone of the photo-responsive HOFs provided by the present invention, DAE can undergo ring-opening / ring-closing isomerization under ultraviolet / visible light irradiation, and the isomerization efficiency can reach more than 99%, overcoming the deficiency of generally low isomerization efficiency in existing crystalline porous materials. At the same time, due to the low bond energy of hydrogen bonds and the excellent solution processability of HOFs, the photo-controlled topological configuration transformation of HOFs is realized, overcoming the challenge of difficult topological configuration transformation of photo-driven crystalline porous materials.

[0034] (2) The application of the photo-responsive rare-earth functionalized HOFs material provided by the present invention can realize reversible regulation of fluorescence on / off under ultraviolet / visible light irradiation, overcoming the technical bottleneck of easy recognition, deciphering and counterfeiting in the application of traditional fluorescent materials with fixed signal output characteristics, and providing an advanced dynamic anti-counterfeiting system for remote multiple reversible erasure and manifestation of photo-controlled information.

[0035] (3) This dynamic anti-counterfeiting system exhibits good reversibility and excellent anti-fatigue performance. After at least twenty alternations of ultraviolet light and visible light stimulation, the fluorescence intensity does not show obvious attenuation. The light stimulation is simple and convenient, with high regulation precision, and the fluorescence response is rapid (≤5 seconds). Brief Description of the Drawings

[0036] Figure 1 It is the crystal structure of HOF-OF obtained in Example 1, where Figure 1 (a) TAM connects 4 OF-DAEs through intermolecular N-H···O hydrogen bonds; Figure 1 (b) is the dia network constructed by the two; Figure 1 (c) is the one-dimensional channel along the c-axis direction; Figure 1 (d) is the 15-fold interpenetrating network.

[0037] Figure 2 It is the powder X-ray diffraction patterns of single-crystal X-ray diffraction simulation and test of HOF-OF, HOF-CF and regenerated HOF-OF materials obtained in Example 1.

[0038] Figure 3 It is the crystal structure of HOF-CF obtained in Example 1, where Figure 3 (a) TAM connects 4 CF-DAEs through intermolecular N-H···O hydrogen bonds; Figure 3 (b) and Figure 3 (c) are monolayer and 8-fold interpenetrating two-dimensional layered structures; Figure 3 (d) is the 8-fold interpenetrating sql network; Figure 3 (e) is the three-dimensional framework stacked by two-dimensional layered structures.

[0039] Figure 4For the acid digestion of OF-DAE(i), HOF-OF(ii), HOF-CF(iii), regenerated HOF-OF(iv) and TAM(v) obtained in Example 1 1 1H NMR spectra.

[0040] Figure 5 For the photophysical property diagrams of the rare earth functionalized HOFs materials obtained in Example 1, where Figure 5 (a) is the emission spectrum of the Eu·L3@HOF-OF material dispersion (i), and the UV-Vis absorption spectra of DAE before (ii) and after (iii) 60 seconds of UV light irradiation at 300 nm; Figure 5 (b) is the emission spectrum of the Eu·L3@HOF-OF dispersion under UV light irradiation at 300 nm, and the inset shows the change in fluorescence intensity at 615 nm; Figure 5 (c) are the confocal laser scanning microscopy images of Eu·L3@HOF-OF material (i, ii) and Eu·L3@HOF-CF material (iii, iv) under daylight (i, iii) and 254 nm UV light (ii, iv); Figure 5 (d) is the emission spectrum of the Eu·L3@HOF-CF dispersion under visible light irradiation at 450 nm, and the inset shows the change in fluorescence intensity at 615 nm.

[0041] Figure 6 For the fluorescence diagrams of the Eu·L3@HOF-OF material obtained in Example 1 under 20 consecutive alternate irradiations of UV and visible light, where Figure 6 (a) is the fluorescence emission spectrum; Figure 6 (b) is the change in fluorescence intensity at 615 nm.

[0042] Figure 7 For the two-dimensional code on the commercial blue polyethylene terephthalate film (size: 5×5 cm 2 ) obtained in Example 1, digital photos under alternate irradiations of 300 nm UV light (60 seconds) and 450 nm visible light (80 seconds); (i, iii) are digital photos under daylight; (ii, iv) are digital photos under 254 nm UV light. Detailed implementation manners

[0043] To illustrate the present invention more clearly, the following examples are listed, but they have no limitation on the scope of the invention.

[0044] OF-DAE, CF-DAE and TAM of the present invention are well-known materials, where

[0045] The structural formula of the said OF-DAE is:

[0046]

[0047] The structural formula of the CF-DAE is as follows:

[0048]

[0049] The structural formula of the TAM is as follows:

[0050]

[0051] The specific methods for obtaining these materials can be found in Ke Peng, Fengting Lv*, Huan Lu, Jianwu Wang, Hao Zhao, Libing Liu, Shu Wang. Conjugated polymer nanoparticles as fluorescence switch for selective cell imaging. Chin. Chem. Lett. 2020, 31, 755 - 758; Mahbod Morshedi, Michael Thomas, Andrew Tarzia, Christian J. Doonan and Nicholas G. White*. Supramolecular anion recognition in water: synthesis of hydrogen-bonded supramolecular frameworks. Chem. Sci., 2017, 8, 3019 - 3025.

[0052] However, it is not limited thereto.

[0053] The structural formulas of the DPA, ACAC, TTA, HFAC, TFAC, BZAC, BTFAC and DMA are as follows:

[0054]

[0055] The lanthanide complex of the present invention is: Ln·L3 is a well-known material,

[0056] The specific rare earth element Ln is: Tb 3+ and Eu 3+ one of them;

[0057] The ligand L is one of pyridine-2,6-dicarboxylic acid, acetylacetone, 2-thiophenecarbonyltrifluoroacetone, hexafluoroacetylacetone, 1,1,1-trifluoro-2,4-pentanedione, benzoylacetone, benzoyltrifluoroacetone and dibenzoylmethane.

[0058] For the specific obtaining method, see Qing-Feng Li*, Gen-Wu Ge, Yanke Sun, Mingshen Yu and Zhenling Wang*. Influence of counter ions on structure, morphology, thermal stability of lanthanide complexes containing dipicolinic acid ligand. Spectrochim. Acta, Part A 2019, 214, 333-338; Harry G. Brittain* and Carl R. Johnson. Circularly polarized luminescence studies of the adduct complexes formed by (R)-methyl p-tolyl sulfoxide with various europium(III) β-diketonate complexes. Inorg. Chem. 1985, 24, 4465-4469.

[0059] Example 1

[0060] (1) At room temperature, 5.8 mg of OF-DAE was placed in a 2 mL centrifuge tube, 1.2 mL of a mixed solution of water and ethanol (volume ratio = 1) was added, 20 μL of an aqueous solution of sodium hydroxide (1 mol / L) was added to adjust the pH to 7, and ultrasonic treatment was carried out for 15 minutes at room temperature. The concentration of OF-DAE was 8 mM.

[0061] (2) At room temperature, 3.0 mg of TAM was placed in a 2 mL centrifuge tube, 1.2 mL of a mixed solution of water and ethanol (volume ratio = 1) was added, and ultrasonic treatment was carried out for 15 minutes at room temperature. The concentration of TAM was 4 mM.

[0062] (3) Subsequently, the solutions obtained in (2) and (3) were mixed in equal volumes. Colorless needle-like crystals formed after standing at room temperature for 6 hours. They were collected by filtration, washed 3 times with 2 mL of ethanol to obtain HOF-OF, and single-crystal X-ray diffraction and powder X-ray diffraction tests were carried out. For the single-crystal X-ray diffraction test, a Bruker D8 Venture PhotonⅡ single-crystal X-ray diffractometer of Bruker Company in Germany (using Ga target as the target material) was used to characterize the single crystals of HOFs. For the powder X-ray diffraction test, a D8 Focus X-ray diffractometer of Bruker Company in Germany was used, with the current fixed at 40 mA, the voltage fixed at 40 kV, the scanning range of 2θ = 5-40°, and the scanning speed of 6° / min.

[0063] Figure 1 It is the HOF-OF crystal structure, where (a) shows that TAM connects 4 OF-DAEs through intermolecular N-H···O hydrogen bonds; (b) shows the dia network constructed by the two; (c) shows the one-dimensional channel along the c-axis direction; (d) shows the 15-fold interpenetrating network. It can be seen from the figure that the molecular formula of HOF-OF is C 87 H 64 F 12 N8O8S4, which crystallizes in the space group I-42d of the tetragonal system. The unit cell parameters are: a = 44.897(14), b = 44.897(14), c = 7.478(3), α = 90°, β = 90°, γ = 90°, Z = 4. Half of the OF-DAE and one-fourth of the TAM are in the asymmetric unit. As the building block of the tetrahedral structure, TAM forms four pairs of parallel hydrogen bonds (the N-H···O distances are 1.908 and ) between the N-H group in the "forward" amide and the oxygen atom in the carboxylic acid, connecting four OF-DAE units into a diamond framework, with angles of 169.6° and 170.3° respectively. It is worth noting that due to the large void space in a single network, a rare 15-fold interpenetrating three-dimensional framework can be further formed. However, there is still a one-dimensional pore channel in the crystallographic

[001] direction, and the pore size is The pore volume accounts for 50% of the total unit cell.

[0064] Figure 2 They are the single-crystal X-ray diffraction simulations and powder X-ray diffraction patterns of the HOF-OF, HOF-CF, and regenerated HOF-OF materials. The powder X-ray diffraction pattern of HOF-OF is in good agreement with its single-crystal X-ray diffraction simulation results, indicating the successful preparation of HOF-OF.

[0065] (4) Take HOF-OF and disperse it in a mixed solution of ethanol and water (0.2 mg / mL, volume ratio = 1), and perform ultraviolet light irradiation with a mercury lamp equipped with a 300 nm filter. The dispersion is 40 cm away from the light source. After 5 hours, HOF-OF dissolves, and at the same time, the solution turns blue; after standing at room temperature for 1 hour, HOF-CF with different topological structures precipitates; take HOF-CF and disperse it in a mixed solution of ethanol and water (1 mg / mL, volume ratio = 1), and perform visible light irradiation with a xenon lamp equipped with a 450 nm filter. The dispersion is 40 cm away from the light source. After 2 hours, the hydrogen-bonded organic framework dissolves, and at the same time, the solution turns colorless; after standing at room temperature for 1 hour, HOF-OF re-precipitates, and single-crystal X-ray diffraction, powder X-ray diffraction, and 1 1H NMR tests are carried out. 1The \(^1\)H NMR test was carried out using a Bruker 400 nuclear magnetic spectrometer produced by Bruker Corporation, Switzerland. The test temperature was 25 °C, and the solvent used was a mixed solution of 550 μL of deuterated dimethyl sulfoxide and deuterated hydrochloric acid (volume ratio = 10).

[0066] Figure 3 It is the crystal structure of HOF-CF, where Figure 3 (a) TAM connects four CF-DAEs through intermolecular N-H···O hydrogen bonds; Figure 3 (b-c) are monolayer and eight-fold interpenetrated two-dimensional layered structures; Figure 3 (d) is an eight-fold interpenetrated sql network; Figure 3 (e) is a three-dimensional framework stacked by two-dimensional layered structures. The molecular formula of HOF-CF is C 87 H 64 F 12 N₈O₈S₄, which crystallizes in the monoclinic space group C2 / c, and the unit cell parameters are: a = 17.9910(11), b = 14.8263(11), c = 42.857(3), α = 90°, β = 90°, γ = 101.601(5)°, Z = 4. An asymmetric unit includes one TAM molecule and half a CF-DAE molecule. Although HOF-CF adopts four pairs of N-H···O hydrogen bonds similar to those of HOF-OF (the distance is the angle is 162.7 - 176.8), the organic building unit TAM acts as a pseudo-square planar structure connecting four CF-DAE units, forming a single sql network. The void space in the single network allows the structure to present an eight-fold interpenetrated two-dimensional layered structure. Finally, it is stacked into a three-dimensional framework through C-H···F supramolecular interactions, and the porosity in the total unit cell is 37%.

[0067] Figure 2 It shows that the powder X-ray diffraction pattern of HOF-CF is in good agreement with the simulated results of single-crystal X-ray diffraction, indicating the successful preparation of HOF-CF. The powder X-ray diffraction pattern of the regenerated HOF-OF is in good agreement with the simulated results of single-crystal X-ray diffraction, indicating the successful regeneration of HOF-OF and realizing the photo-controlled topological structure transformation of the HOF-OF backbone.

[0068] Figure 4 For the acid digestion of OF-DAE (i), HOF-OF (ii), HOF-CF (iii), regenerated HOF-OF (iv) and TAM (v) obtained in Example 1 11H NMR spectrum. The methyl protons (H1) showed an obvious downfield shift, moving from 1.94 ppm to 2.06 ppm, and the thiophene protons (H2) showed an obvious upfield shift, moving from 7.60 ppm to 7.05 ppm. At the same time, the aromatic protons (H3 and H4) showed a downfield shift (Δδ = 0.05 ppm (H3) and 0.10 ppm (H4)). According to the integration of proton H1, it can be determined that in HOF-OF, OF-DAE can be almost completely quantitatively isomerized to CF-DAE (~99%), indicating the realization of the photoinduced isomerization quantitative reversible conversion of the HOFs backbone.

[0069] (5) Take 20 mg of the HOF-OF prepared in (4) in a reactor, add 1 mL of an ethanol solution of 1 mM Eu·L3 (L is pyridine-2,6-dicarboxylic acid) at room temperature, soak for 24 hours, filter and collect, wash 3 times with 3 mL of ethanol to obtain rare earth functionalized HOF-OF, i.e., Eu·L3@HOF-OF, and perform plasma spectroscopy tests. The mass ratio of Eu·L3 and HOF-OF was calculated to be 0.16. The plasma spectroscopy test was carried out using an Agilent 730 (OES) inductively coupled plasma spectrometer of Agilent Technologies.

[0070] (6) Eu·L3@HOF-OF was dispersed in a mixed solution of ethanol and water (0.2 mg / mL, volume ratio = 1), and ultraviolet light irradiation was carried out with a mercury lamp equipped with a 300 nm filter. The dispersion was 40 cm away from the light source. After 5 hours, Eu·L3@HOF-OF dissolved, and at the same time the solution turned blue. The fluorescence emission spectrum of this process was measured at the maximum excitation wavelength of 280 nm and the maximum emission wavelength of 615 nm; after standing at room temperature for 1 hour, Eu·L3@HOF-CF with different topological structures precipitated out; Eu·L3@HOF-CF was taken and dispersed in a mixed solution of ethanol and water (1 mg / mL, volume ratio = 1), and visible light irradiation was carried out with a xenon lamp equipped with a 450 nm filter. The dispersion was 40 cm away from the light source. After 2 hours, Eu·L3@HOF-CF dissolved, and at the same time the solution became colorless. The fluorescence emission spectrum of this process was measured at the maximum excitation wavelength of 280 nm and the maximum emission wavelength of 615 nm. The ultraviolet-visible absorption spectrum was used to characterize the ultraviolet absorption spectrum of the sample by using a Carry 100 ultraviolet-visible spectrophotometer of Agilent Company, USA, with a scanning range of 200 - 800 nm; the fluorescence test was carried out by using an Edinburgh FS920P spectrometer of the UK to measure the fluorescence spectrum. A 450 W xenon lamp was used as the excitation light source, equipped with a double excitation monochromator, an emission monochromator, and a semiconductor-cooled Hamamatsu RMP928 type photomultiplier tube. The fluorescence emission spectrum was measured with 280 nm as the maximum excitation wavelength and 615 nm as the maximum emission wavelength; the laser confocal image was taken by using an Olympus FV1000-IX81 laser confocal microscope of Japan.

[0071] Figure 5 (a) is the emission spectrum of Eu·L3@HOF-OF dispersion (i), and the ultraviolet-visible absorption spectra of DAE before (ii) and after (iii) 60 seconds of 300 nm ultraviolet light irradiation; Figure 5 (b) is the emission spectrum of Eu·L3@HOF-OF dispersion under 300 nm ultraviolet light irradiation, and the inset is the change in fluorescence intensity at 615 nm; Figure 5 (c) are the laser confocal images of Eu·L3@HOF-OF (i, ii) and Eu·L3@HOF-CF (iii, iv) under sunlight (i, iii) and 254 nm ultraviolet light (ii, iv); Figure 5 (d) is the emission spectrum of Eu·L3@HOF-CF dispersion under 450 nm visible light irradiation, and the inset is the change in fluorescence intensity at 615 nm. It can be seen from the figure that the absorption of HOF-OF and Eu 3+There is no spectral overlap between the emissions, no fluorescence resonance energy transfer occurs, and under 254 nm ultraviolet light irradiation, Eu·L3@HOF-OF exhibits red fluorescence. After irradiation with 300 nm ultraviolet light, new ultraviolet-visible absorption peaks appear in the range of 500 - 700 nm, overlapping with the emission spectrum of Eu 3+ The red fluorescence gradually quenches, and at the same time, Eu·L3@HOF-OF dissolves into a blue solution. Within 60 seconds, the red fluorescence completely quenches and reaches a photostable state. After standing at room temperature for 1 hour, Eu·L3@HOF-CF precipitates. When further irradiated with 450 nm visible light, the fluorescence intensity gradually increases and returns to the initial level within 80 seconds, while Eu·L3@HOF-CF dissolves into a colorless solution.

[0072] Figure 6 (a) Fluorescence emission spectra of Eu·L3@HOF-OF under 20 consecutive alternating irradiations of ultraviolet and visible light; Figure 6 (b) Variation of the fluorescence intensity at 615 nm. It can be seen from the figure that the rare-earth functionalized HOFs photoresponsive fluorescence switch has excellent reversibility. After 20 cycles of alternating ultraviolet-visible light irradiation, its fluorescence intensity shows almost no obvious change. Therefore, this rare-earth functionalized HOFs material has excellent anti-fatigue properties, which are crucial for subsequent intelligent anti-counterfeiting applications.

[0073] (7) Take 3.0 mg of Eu·L3@HOF-OF in a reactor, add 6 mL of ethanol, and ultrasonicate for 15 minutes to obtain a dispersion with a concentration of 0.5 mg / mL; use the dispersion as printing ink and coat a two-dimensional code on a polyethylene terephthalate film.

[0074] Figure 7 The fluorescence two-dimensional code on a commercial blue polyethylene terephthalate film (size: 5×5 cm 2 ) Digital photos under alternating irradiation with 300 nm ultraviolet light (60 seconds) and 450 nm visible light (80 seconds); (i, iii) Digital photos under daylight; (ii, iv) Digital photos under 254 nm ultraviolet light. It can be seen from the figure that since the Eu·L3@HOF-OF dispersion is colorless, the printed two-dimensional code is invisible under daylight. However, it shows bright red fluorescence under 254 nm ultraviolet light, and the information in the two-dimensional code can be quickly and accurately identified by a smartphone. When irradiated with 300 nm ultraviolet light for 60 seconds, DAE is isomerized from the open-ring form to the closed-ring form, and reacts with Eu 3+The fluorescence resonance energy transfer that occurs causes the fluorescence quenching of the QR code. Therefore, the QR code is invisible under 254 nm ultraviolet light. Although the QR code turns blue under sunlight, it can be masked by the blue background of the polyethylene terephthalate film. Therefore, a secure mode with invisible information is achieved both under sunlight and ultraviolet light. At the same time, when irradiated with 450 nm visible light for 80 seconds, the erased pattern can be completely restored and recognized again under ultraviolet light.

[0075] When the information encryption / decryption process loops twenty times, recognition can still be achieved;

[0076] Example 2

[0077] Steps (1)(2)(3)(4)(5)(7) are the same as in Example 1. Change Eu·L3 in step (5) to Tb·L3, with other conditions remaining unchanged. The product performance is the same as in Example 1.

[0078] Example 3

[0079] Steps (1)(2)(3)(4)(5)(7) are the same as in Example 1. Change L in Eu·L3 of step (5) to acetylacetone, with other conditions remaining unchanged. The product performance is the same as in Example 1.

[0080] Example 4

[0081] Steps (1)(2)(3)(4)(5)(7) are the same as in Example 1. Change L in Eu·L3 of step (5) to 2 - thenoyltrifluoroacetone, with other conditions remaining unchanged. The product performance is the same as in Example 1.

[0082] Example 5

[0083] Steps (1)(2)(3)(4)(5)(7) are the same as in Example 1. Change L in Eu·L3 of step (5) to hexafluoroacetylacetone, with other conditions remaining unchanged. The product performance is the same as in Example 1.

[0084] Example 6

[0085] Steps (1)(2)(3)(4)(5)(7) are the same as in Example 1. Change L in Eu·L3 of step (5) to 1,1,1 - trifluoro - 2,4 - pentanedione, with other conditions remaining unchanged. The product performance is the same as in Example 1.

[0086] Example 7

[0087] Steps (1)(2)(3)(4)(5)(7) are the same as in Example 1. Change L in Eu·L3 of step (5) to benzoylacetone, with other conditions remaining unchanged. The product performance is the same as in Example 1.

[0088] Example 8

[0089] Steps (1), (2), (3), (4), (5), and (7) are the same as those in Example 1. Change L in Eu·L3 in step (5) to benzoyltrifluoroacetone, and keep other conditions unchanged. The product performance is the same as that in Example 1.

[0090] Example 9

[0091] Steps (1), (2), (3), (4), (5), and (7) are the same as those in Example 1. Change L in Eu·L3 in step (5) to dibenzoylmethane, and keep other conditions unchanged. The product performance is the same as that in Example 1.

[0092] Matters not described in this invention are well-known technologies.

Claims

1. A light-stimulus-responsive rare-earth-functionalized HOFs material, characterized in that, The composition of the material includes: hydrogen-bonded organic framework and luminescent rare earth complex; the mass ratio of the luminescent rare earth complex to the hydrogen-bonded organic framework is 0.1 - 0.2; The hydrogen-bonded organic framework is an open-ring HOFs (HOF-OF) or a closed-ring HOFs (HOF-CF), with the molecular formula C 87 H 64 F 12 N8O8S4; Among them, HOF-OF is formed by connecting open-ring DAE (OF-DAE) and TAM through hydrogen bonds, belonging to the tetragonal crystal system, with the space group I-42d. The unit cell parameters are: a = 44.897(14), b = 44.897(14), c = 7.478(3), α = 90°, β = 90°, γ = 90°, Z = 4; HOF-CF is formed by connecting closed-ring DAE (CF-DAE) and TAM through hydrogen bonds, belonging to the monoclinic crystal system, with the space group C2 / c. The unit cell parameters are: a = 17.9910(11), b = 14.8263(11), c = 42.857(3), α = 90°, β = 90°, γ = 101.601(5)°, Z = 4; The described luminescent rare earth complex is: Ln·L3; where Ln is a rare earth element; The ligand L is one of pyridine-2,6-dicarboxylic acid (DPA), acetylacetone (ACAC), 2-thiophenecarbonyltrifluoroacetone (TTA), hexafluoroacetylacetone (HFAC), 1,1,1-trifluoro-2,4-pentanedione (TFAC), benzoylacetone (BZAC), benzoyltrifluoroacetone (BTFAC), and dibenzoylmethane (DMA).

2. The photo-stimulus-responsive rare-earth functionalized HOFs material according to claim 1, characterized in that, Ln is Tb 3+ or Eu 3+ .

3. The preparation method of the light-stimulus-responsive rare earth-functionalized HOFs material according to claim 1, characterized in that, It includes the following steps: (a) Disperse OF-DAE in the first mixed solvent at room temperature, add an alkali solution for deprotonation until pH = 6 - 8, and ultrasonicate for 10 - 20 minutes to obtain a dicarboxylic acid ligand solution; Among them, in the dicarboxylic acid ligand solution, the molar concentration of OF-DAE is 1 mM - 8 mM; Separately, add TAM to the second mixed solvent at room temperature and ultrasonicate for 10 - 20 minutes to obtain a tetraamidine ligand solution; Among them, in the tetraamidine ligand solution, the molar concentration of TAM is 0.5 mM - 4 mM; The first mixed solvent and the second mixed solvent are the same or different, and the composition is ethanol and water, and the volume ratio of ethanol to water is 0.4 - 2; (b) Mix the dicarboxylic acid ligand solution and the tetraamidine ligand solution to obtain a mixed solution, let it stand at room temperature for 5 - 48 hours, colorless needle-like crystals will form, filter and collect them, and wash them with ethanol to obtain colorless hydrogen-bonded organic framework HOF-OF; Among them, the molar ratio is, dicarboxylic acid ligand: tetraamidine ligand = 2:1, (c) Rare earth functionalization: Take HOF-OF in a reactor, add an ethanol solution of the luminescent rare earth complex at room temperature, soak for 12 - 36 hours, filter and collect, and use ethanol to obtain rare earth-functionalized HOF-OF, that is, Ln·L3@HOF-OF; Among them, the concentration of the ethanol solution of Ln·L3 is 0.2 mM - 1.5 mM, and the mass ratio of Ln·L3 to HOF-OF is 0.1 - 0.

2.

4. The preparation method of the light-stimulus-responsive rare-earth-functionalized HOFs material according to claim 3, characterized in that The alkali in step (a) is sodium hydroxide, potassium hydroxide or tetrabutylammonium hydroxide; the concentration of the alkali solution is 0.1 - 5 mol / L.

5. The application of the photo-stimulus responsive rare earth functionalized HOFs material according to claim 1, characterized in that, It is used for photo-controlled intelligent anti-counterfeiting.

6. Application of the photo-stimulus responsive rare earth functionalized HOFs material according to claim 5, characterized by comprising the following steps: In the reactor of Ln·L3@HOF-OF, ethanol was added and ultrasonicated for 10 to 20 minutes to obtain a dispersion; the dispersion was used as printing ink and coated on a polyethylene terephthalate film to obtain a pattern; The pattern obtained by the coating is invisible under sunlight; when irradiated under an ultraviolet lamp, a red pattern immediately appears; When continuously irradiated with ultraviolet light for 20 to 60 seconds, the pattern on the film does not appear under sunlight or ultraviolet lamp irradiation. At this time, a secure mode with invisible information is achieved, realizing information encryption; After irradiating the pattern with visible light with a wavelength of 450 nm to 700 nm for 30 to 120 seconds, the pattern can be completely restored and re-identified under an ultraviolet lamp, and the information is decrypted again; Among them, the concentration of the dispersion is 0.3 mg / mL to 1 mg / mL.

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