Metal halide-based metal organic framework material as well as preparation method and application thereof

Abstract

The invention discloses a metal halide-based metal organic framework material as well as a preparation method and application thereof, and belongs to the technical field of crystalline materials. According to the preparation method disclosed by the invention, 1, 10-phenanthroline derivatives with different substituent groups are used as ligands to be assembled with CdCl2, the prepared metal halide-based metal organic framework material adopts alternate arrangement of cadmium halide chains and pi conjugated ligands, and abundant intermolecular interaction including halogen bonding and stacking is also introduced, so that the metal halide-based metal organic framework material is prepared. The generation of stable triplet excitons is facilitated; meanwhile, different substituent groups on the ligand generate different molecular arrangements and electronic structures, and jointly provide color-adjustable aggregation state phosphorescence properties.

Description

Technical Field

[0001] The invention belongs to the technical field of crystalline materials, and in particular relates to a metal halide-based metal organic framework material and a preparation method and application thereof. Background Art

[0002] Highly efficient room temperature phosphorescent materials have potential application prospects in the fields of information encryption, chemical sensors, optoelectronic devices, etc., and have attracted widespread attention. Metal-free organic phosphorescent compounds have the advantages of low cost, rich excited state properties, and modifiable structures. However, such pure organic materials often encounter inefficient intersystem crossing (ISC) and high non-radiative transitions of triplet excitons. These two unfavorable factors together make it difficult for organic light-emitting sources to effectively generate stable triplet excitons, making it difficult to achieve ultra-long room temperature phosphorescence (RTP) and long persistent luminescence (LPL) performance. Enhancing spin-orbit coupling (SOC) is an effective way to reduce the spin prohibition between singlet and triplet excitons. Constructing a rigid environment can effectively suppress molecular motion and reduce non-radiative transitions of excited states. Several strategies have been proposed for these two aspects, including introducing n-π* transitions, introducing heavy atoms, constructing H aggregation, crystallization, and polymerization. Summary of the invention

[0003] The purpose of the present invention is to provide a method for preparing a metal halide-based metal organic framework material, which is used to solve the technical problem of long afterglow luminescence color regulation that is difficult to achieve with existing methods.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention discloses a method for preparing a metal halide-based metal organic framework material, comprising the following steps: It was prepared by assembling 1,10-phenanthroline derivatives as ligands with CdCl2; The 1,10-phenanthroline derivative has a substituent; the substituent includes -H, -CH3, -Cl or -Br.

[0005] Furthermore, the specific process of using 1,10-phenanthroline derivatives as ligands and assembling with CdCl2 is as follows: When the substituent is -H, the steps include: 1,10-phenanthroline, CdCl2·2.5H2O, solvent and deionized water were mixed and reacted to obtain MOF-Z1 crystals; When the substituent is -CH3, the steps include: 2,9-dimethyl-1,10-phenanthroline, CdCl2·2.5H2O, solvent and deionized water were mixed and reacted to obtain MOF-Z2 crystals; When the substituent is -Cl, the steps include: 2,9-dichloro-1,10-phenanthroline, CdCl2·2.5H2O, solvent and deionized water were mixed and reacted to obtain MOF-Z3 crystals; When the substituent is -Br, the steps include: After 2,9-dibromo-1,10-phenanthroline, CdCl2·2.5H2O, a solvent and deionized water are mixed and reacted, MOF-Z4 crystals are obtained.

[0006] Furthermore, when the substituent is -H, the reaction temperature is 120-150 °C and the reaction time is 72-96 h; The dosage ratio of the 1,10-phenanthroline, CdCl2·2.5H2O, solvent and deionized water is (1-2): (4-10): (2-5): (2-3).

[0007] Furthermore, when the substituent is -CH3, the reaction temperature is 120~150℃, and the reaction time is 72~96 h; The dosage ratio of the 2,9-dimethyl-1,10-phenanthroline, CdCl2·2.5H2O, solvent and deionized water is (1-2): (4-10): (2-5): (2-3).

[0008] Furthermore, when the substituent is -Cl, the reaction temperature is 120-140 °C and the reaction time is 72-84 h; The dosage ratio of the 2,9-dichloro-1,10-phenanthroline, CdCl2·2.5H2O, solvent and deionized water is (1-2): (4-12): (2-5): (2-3).

[0009] Furthermore, when the substituent is -Br, the reaction temperature is 120-140 °C and the reaction time is 72-84 h; The dosage ratio of the 2,9-dibromo-1,10-phenanthroline, CdCl2·2.5H2O, solvent and deionized water is (1-2): (4-12): (2-5): (2-3); The solvent is methanol, acetonitrile, acetone or chloroform.

[0010] The invention also discloses a metal halide-based metal organic framework material prepared by the preparation method.

[0011] The invention also discloses the application of the metal halide-based metal organic framework material in information encryption.

[0012] The invention also discloses the application of the metal halide-based metal organic framework material in drawing patterns.

[0013] Furthermore, the MOF-Z2 crystal is made into anti-counterfeiting ink for drawing patterns.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The invention discloses a method for preparing a metal halide-based metal organic framework material. By assembling 1,10-phenanthroline derivatives with different substituents as ligands with CdCl2, the prepared metal halide-based metal organic framework material adopts an alternating arrangement of cadmium halide chains and π conjugated ligands. The cadmium halide chains not only bring about a heavy atom effect, but also introduce abundant intermolecular interactions, including halogen bonding and stacking, which are beneficial to the generation of stable triplet excitons. At the same time, different substituents on the ligands produce different molecular arrangements and electronic structures, which together provide aggregated phosphorescent properties with adjustable colors.

[0015] The present invention also discloses the application of the above-mentioned metal halide-based metal organic framework materials, and further develops the information encryption application of these MOFs based on the dynamic color-adjustable LPL characteristics of the complexes that depend on the excitation wavelength, temperature and time evolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of an asymmetric unit and one-dimensional link of the metal halide-based metal organic framework material of the present invention; Among them: ad, asymmetric unit of MOF-Z1~Z4 crystal; eh, one-dimensional chain structure in MOF-Z1-Z4 crystal; Figure 2 The instantaneous and delayed emission spectra of the original ligand and metal halide-based metal organic framework materials of the present invention, the delayed emission comparison, the time-gated emission spectra at 77 K, the time-gated emission spectra of the four ligand solids at room temperature, and the time-gated emission spectra of the metal halide-based metal organic framework materials at room temperature and 77 K; Among them: a, b, four original ligands (Phen-H, Phen-CH 3, Phen-Cl and Phen-Br) and the instantaneous and delayed (2 ms) emission spectra of the four MOFs; c, comparison of the delayed (2 ms) emission of the four MOFs and their corresponding ligands; d, acetonitrile solutions of Phen-H, Phen-CH3, Phen-Cl and Phen-Br at 77K (1×10 -3 mol·L -1 ) at room temperature (delay of 2 ms); time-gated emission spectra of four ligand solids at room temperature (delay of 2 ms); time-gated emission spectra of MOF-Z1~Z4 at room temperature and 77 K (delay of 2 ms). ex = 365 nm; Figure 3 The lifetimes of two phosphorescent emission bands of the metal halide-based metal organic framework material of the present invention at room temperature and the phosphorescent emission spectra under excitation at 365 nm and 450 nm, respectively; Wherein: ad, the lifetime of the two phosphorescence emission bands of MOF-Z1~Z4 at room temperature; eh, the phosphorescence emission spectra of MOF-Z1~Z4 under 365 nm and 450 nm excitation at different temperatures; Figure 4 Afterglow information and application information of the metal halide-based metal organic framework material of the present invention; Among them: ac, afterglow spectra of MOF-Z1~Z3 at room temperature; d, afterglow photos of MOF-Z1~Z3 at room temperature; ef, logic gates and information encryption applications based on four MOFs; g, anti-counterfeiting application based on the LPL characteristics of MOF-Z2 that can be adjusted with temperature and excitation wavelength. DETAILED DESCRIPTION

[0017] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0018] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0019] In this article, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0020] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0021] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0022] The present invention provides a metal halide-based metal organic framework material, which is assembled by 1,10-phenanthroline derivatives with different substituents (-H, -CH3, -Cl and -Br) as ligands and CdCl2.

[0023] The present invention also discloses a method for preparing the metal halide-based metal organic framework material, comprising the following steps: When the substituent is -H, the preparation process is as follows: 1,10-phenanthroline, CdCl2·2.5H2O, acetonitrile and deionized water were mixed and reacted to obtain MOF-Z1 crystals; When the substituent is -CH3, the preparation process is as follows: 2,9-dimethyl-1,10-phenanthroline, CdCl2·2.5H2O, acetonitrile and deionized water were mixed and reacted to obtain MOF-Z2 crystals; When the substituent is -Cl, the preparation process is as follows: 2,9-dichloro-1,10-phenanthroline, CdCl2·2.5H2O, acetonitrile and deionized water were mixed and reacted to obtain MOF-Z3 crystals; When the substituent is -Br, the preparation process is as follows: After 2,9-dibromo-1,10-phenanthroline, CdCl2·2.5H2O, acetonitrile and deionized water were mixed and reacted, MOF-Z4 crystals were obtained.

[0024] According to relevant tests and analysis, among the four MOFs prepared above, the ligand of MOF-Z2 introduced -CH3, which increased the steric resistance near the Phen plane and had the smallest plane overlap area compared with other MOFs; this also led to the minimization of annihilation between triplet states, thereby promoting aggregated phosphorescence emission; The insertion of Cd(II) halide chains not only effectively promotes ISC due to the heavy atom effect, but also locks the organic ligands, greatly inhibiting molecular motion and thus reducing non-radiative transitions; due to the heavy atom effect, the RTP decay lifetimes of these MOFs are significantly better than those of the corresponding ligands; MOF-Z2 has the longest decay lifetime of 91.10 ms, MOF-Z3 has the shortest decay lifetime of 11.47 ms, and MOF-Z1 has a medium decay lifetime of 21.34 ms, while Br superheavy atoms quench (Phen-Br, 6.84 ms).

[0025] MOF-Z1, MOF-Z2 and MOF-Z3 achieve color tunability of LPL by switching between single-molecule state and aggregated state phosphorescence, which is specifically manifested as follows: The three MOFs show dual LPL emission, including LPL I and LPL II from high-energy phosphorescence (Phos. I) and low-energy delayed emission (Phos. II); at RT, LPL II around 620 nm dominates the LPL spectrum of MOF-Z2, producing obvious red LPL with a duration of 1 s; for MOF-Z1 and MOF-Z3, Phos. I and Phos. II, their LPL I and LPL II appear simultaneously after 365 nm ultraviolet irradiation, providing orange LPL with a broad emission band in the range of 500 nm to 700 nm. Since the presence of heavier bromine favors more non-radiative decay, MOF-Z4 has the shortest phosphorescence lifetime of about 6 ms. Consistent with this phenomenon, at RT, the LPL of MOF-Z4 is invisible to the naked eye; The sensitivity of triplet emission to temperature, all four MOFs showed obvious LPL at 77 K; Due to the different decay rates of the two phosphorescent emissions, time-dependent LPL can be achieved. For MOF-Z1, MOF-Z2, and MOF-Z3, the decay lifetime of Phos I at 77 K is significantly longer than that of Phos II. Therefore, LPL I lasts longer than LPL II, resulting in a real-time change in the intensity ratio of LPL I / LPL II; after removing the excitation of 365 nm at 77 K, the LPL of the three MOFs gradually fades within 2 seconds, and the color changes from yellow to green or yellow-green; for MOF-Z4, the lifetime values ​​of Phos I and Phos II at 77 K are very close, and are significantly shorter than those of the other MOFs; therefore, after MOF-Z4 is excited with 365 nm at 77 K, the LPL duration is short and there is no obvious color change.

[0026] The present invention also discloses the application of the above-mentioned metal halide-based metal organic framework material in information encryption, wherein MOF-Z2 can be used as anti-counterfeiting ink for drawing patterns thanks to the temperature and excitation-related LPL.

[0027] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0028] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0029] Example 1 A method for preparing a metal halide-based metal organic framework material comprises the following steps: The reaction mixture of 1,10-phenanthroline (18.02 mg, 0.10 mmol), CdCl2·2.5H2O (128.12 mg, 0.60 mmol), 3.4 mL of acetonitrile and 0.6 mL of deionized water was added into a 25 mL stainless steel container lined with polytetrafluoroethylene and heated at 120 °C for 72 h to obtain white needle-shaped MOF-Z1 crystals; yield: 85% (based on 1,10-phenanthroline).

[0030] Example 2 A method for preparing a metal halide-based metal organic framework material comprises the following steps: The reaction mixture of 2,9-dimethyl-1,10-phenanthroline (10.41 mg, 0.05 mmol), CdCl2·2.5H2O (68.51 mg, 0.30 mmol), 2 mL of acetonitrile and 2 mL of deionized water was added into a 25 mL stainless steel container lined with polytetrafluoroethylene and heated at 120 °C for 72 h to obtain white needle-shaped MOF-Z2 crystals; yield: 52% (based on 2,9-dimethyl-1,10-phenanthroline).

[0031] Example 3 A method for preparing a metal halide-based metal organic framework material comprises the following steps: The reaction mixture of 2,9-dichloro-1,10-phenanthroline (12.46 mg, 0.05 mmol), CdCl2·2.5H2O (45.67 mg, 0.20 mmol), 3.3 mL acetonitrile and 0.7 mL deionized water was added to a 25 mL stainless steel container lined with polytetrafluoroethylene and heated at 120 °C for 72 hours. MOF-Z3 obtained white needle-like crystals; yield: 34% (based on 2,9-dichloro-1,10-phenanthroline).

[0032] Example 4 The reaction mixture of 2,9-dibromo-1,10-phenanthroline (16.90 mg, 0.05 mmol), CdCl2·2.5H2O (57.09 mg, 0.25 mmol), 3.6 mL acetonitrile and 0.4 mL deionized water was added to a 25 mL stainless steel container lined with polytetrafluoroethylene and heated at 120 °C for 72 hours. White block crystals of MOF-Z4 were obtained; yield: 70.2% (based on 2,9-dibromo-1,10-phenanthroline).

[0033] The crystal materials prepared in the above examples were subjected to structural analysis. The single crystal structure analysis showed that: MOF-Z1 and MOF-Z3 were monoclinic crystals, belonging to the P21 / c and C2 space groups, respectively; MOF-Z2 and MOF-Z4 were orthorhombic and triclinic crystals with Pbcn and P-1 as space groups, respectively. Due to the steric effect of the substituents, the four MOFs showed different stacking modes, resulting in differences in symmetry; Figure 1 As shown in a, there are two crystallographically independent Cd(II) ions, one Phen-H molecule, and four Cl - ions; such as Figure 1 b, in MOF-Z2, it consists of a crystal-independent Cd(II) ion, half a Phen-CH3 molecule, and two Cl - Similarly, MOF-Z3 contains 4 crystal-independent Cd(II) ions, 2 Phen-Cl molecules, and 8 Cl - ( Figure 1 c); Finally, in MOF-Z4, there are three crystal-independent Cd(II) ions accompanied by two Phen-Br molecules and six Cl - ( Figure 1 d); Among these MOFs, MOF-Z1~Z2 has two metal centers, MOF-Z3 has four metal centers, and MOF-Z4 has three metal centers; among them, the metal ions in MOF-Z1-Z3 are all hexacoordinated; one of the fragments is bound by 4 Cl - and 2 N atoms, while the other fragment consists of 6 Cl - coordination, showing a distorted CdN2Cl4 / CdCl6 octahedral geometry; however, in MOF-Z4, the three metal centers are pentacoordinated due to the large steric hindrance of the bromine atoms; Cd1 is bounded by five Cl - Surrounded by 3 Cl -The μ2Cl- bridge extends the asymmetric unit in MOF-Z1 to form a coordination polymer (CP) chain containing two rows of metal halides ( Figure 1 e); The one-dimensional chains of MOF-Z2 and MOF-Z3 have high similarity with MOF-Z1, but the single crystal structure of MOF-Z3 is partially disordered ( Figure 1 f, 1g); for MOF-Z4, the asymmetric unit grows outward to form a CP composed of a single metal halide chain ( Figure 1 h); These cadmium halide chains not only bring more heavy atom effects, but also introduce abundant intermolecular interactions, which are beneficial to the generation of stable triplet excited states and promote phosphorescence emission.

[0034] The photophysical properties of the crystal material prepared above were analyzed, such as Figure 2 As shown in ab, all organic ligands and MOF-Z1 show a narrow emission band centered at 460 nm in the prompt emission spectra; in contrast, MOF-Z2 and MOF-Z3 have three emission peaks at 460 nm, 530 nm, and 610 (590) nm, respectively, while MOF-Z4 has a red-shifted emission peak at 580 nm. To identify these peaks, the decay curves and time-gated emission spectra (2 ms delay) of these MOFs were measured at room temperature under 365 nm excitation; when delayed by 2 ms, the emission near 460 nm disappears, and the relevant decay lifetime is only a few nanoseconds, showing fluorescence characteristics; as shown in Figure 2 As shown in (c), the delayed spectra of these ligands and MOFs contain two emission bands at RT, and the maximum wavelength of MOFs is almost consistent with the maximum wavelength of the corresponding ligands; based on these experimental results, it is believed that the two delayed emission bands are generated by different ligand triplet excited states; Figure 2 As shown in Figure 1, the four ligand solutions exhibit delayed emission in the high energy region that is close to the phosphorescence of the corresponding MOFs. It is believed that the high-energy phosphorescence (Phos.I) of MOFs originates from the single-molecule triplet state (T1) of the ligand and the low-energy delayed emission (Phos.II) originates from the aggregated triplet state (T2) of the ligand. Due to the heavy atom effect, the RTP decay lifetimes of these MOFs are significantly better than those of the corresponding ligands. It is worth noting that with the increase of the electron-donating ability of the substituent, the Phos.II emission of the four MOFs is significantly red-shifted. In addition, except for the quenching of the Br superheavy atom (Phen-Br, 6.84 ms), their decay lifetimes are basically the same: MOF-Z2 has the longest decay lifetime of 91.10 ms, MOF-Z3 has the shortest decay lifetime of 11.47 ms, and MOF-Z1 has a medium decay lifetime of 21.34 ms ( Figure 3ad). The above test results show that the longest phosphorescence lifetime of MOF-Z2 can be attributed to the strongest electron donating ability of the substituents on its ligands.

[0035] The four MOFs mentioned above have different relative intensities of multiple emissions in the PL spectra, resulting in different luminescent colors under 365 nm ultraviolet excitation. In particular, MOF-Z2 emits cold white light under 365 nm excitation, with CIE 1931 color coordinates of (0.29, 0.32), while the original ligand emits blue light; regardless of 365 nm or 450 nm irradiation, the four MOFs exhibit double delayed emission near 530 nm and 590 nm at 300K, and the emission intensity and phosphorescence lifetime increase with decreasing temperature. Taking MOF-Z2 as an example, Figure 3 As shown in eh, when λ ex When λ is 365 nm, as the temperature decreases, the phosphorescence in the high-energy region gradually dominates, resulting in an overall blue shift. In addition, due to the splitting of single-molecule energy levels at low temperatures, the high-energy emission is split into multiple peaks at 77 K. Under 450nm excitation, as the temperature decreases, the low-energy phosphorescence gradually increases and the high-energy phosphorescence gradually weakens, indicating that the energy transfers from the T1 state to the T2 state during the cooling process. Overall, when the temperature decreases from 300 K to 77 K, the delayed emission maximum undergoes a significant red shift from 530 nm to 610 nm. Similar phenomena were observed for the other three MOFs. The color of the phosphorescence is adjusted by changing the excitation wavelength. Under different excitations, only the MOF-Z2 phosphorescence emission has obvious color changes. Green, red or yellow phosphorescence can be obtained by adjusting the excitation wavelength. The remaining MOFs exhibit a wider phosphorescence band covering the two emission peaks, and when λ ex There was little change from 275 nm to 450 nm, but at 77 K, all four MOFs showed significant changes. Short-wavelength phosphorescence was dominant under excitation from 275 nm to 405 nm. Under excitation at 450 nm, the four MOFs mainly exhibited low-energy phosphorescence emission, resulting in a significant red shift in the overall delayed emission. The excitation-dependent phosphorescence at 77 K produced similar color-tunable LPL, as described below. The quantum yields of these MOFs were measured under optimal excitation. The photoluminescence quantum yields from MOF-Z1 to MOF-Z4 were 14.62, 11.89, 3.92, and 3.62%, respectively.

[0036] Due to the excellent RTP performance, the obvious LPL of MOF-Z1, MOF-Z2, and MOF-Z3 were successfully captured at room temperature after removing the 365 nm excitation source ( Figure 4 d). Figure 4As shown in Figures ac, the three MOFs show dual LPL emission, including LPL I and LPL II from Phos. I and Phos. II. Among the four MOFs, MOF-Z2 has the longest Phos. II lifetime at room temperature, which is 91.10 ms. However, the Phos. I lifetime of MOF-Z2 at room temperature is only 11.35 ms. Therefore, at RT, LPL II around 620 nm dominates the LPL spectrum of MOF-Z2, producing obvious red LPL with a duration of 1 s ( Figure 4 d). For MOF-Z1 and MOF-Z3, Phos. I and Phos. II, their LPL I and LPL II, appear simultaneously after 365 nm UV irradiation, providing orange LPL with a broad emission band in the range of 500 nm to 700 nm. Since the presence of heavier bromine favors more non-radiative decay, MOF-Z4 has the shortest phosphorescence lifetime of about 6 ms, so at room temperature, the LPL of MOF-Z4 is invisible to the naked eye.

[0037] Due to the sensitivity of triplet emission to temperature, all four MOFs exhibited obvious LPL at 77 K. As mentioned above, the four MOFs showed different phosphorescence when irradiated with 365 nm and 450 nm at 77 K. Based on the optimal energy match, they mainly emitted Phos. I around 530 nm under 365 nm excitation. When excited with 450 nm, Phos. II around 590 nm dominated. Therefore, MOF-Z1~Z3 have excitation-dependent color-tunable LPL characteristics. After stopping 365 nm irradiation at 77 K, LPL I dominated, producing obvious yellow-green or green LPL. The color of LPL at 77 K is obviously different from that at RT. In addition, after excitation with 450 nm at 77 K, their LPL spectra were significantly red-shifted due to the greater contribution of LPL II. The results show that MOF-Z1 and MOF-Z2 exhibit red LPL, and MOF-Z3 and MOF-Z4 exhibit yellow LPL. In addition to the tunable temperature- and excitation-dependent LPL colors, time-dependent LPL can be achieved due to the different decay rates of the two phosphorescent emissions. For MOF-Z1, MOF-Z2, and MOF-Z3, the decay lifetime of Phos I at 77 K is significantly longer than that of Phos II. Therefore, LPLI lasts longer than LPL II, resulting in a real-time change in the intensity ratio of LPL I / LPL II. After removing the excitation of 365 nm at 77 K, the LPL of the three MOFs gradually faded within 2 seconds, and the color changed from yellow to green or yellow-green. For MOF-Z4, the lifetime values ​​of Phos I and Phos II at 77 K are very close and are significantly shorter than those of the other MOFs. Therefore, after excitation with 365 nm at 77 K, the LPL of MOF-Z4 is short-lived and has no obvious color change.

[0038] In summary, 1,10-phenanthroline derivatives with different substituents (-H, -CH3, -Cl and -Br) were selected as ligands to assemble with CdCl2 to prepare four Cd-MOFs. These MOFs adopt an alternating arrangement of cadmium halide chains and π-conjugated ligands. Among the four MOFs, MOF-Z2 exhibits the longest-lasting red LPL, which is due to the strongest electron-donating ability of -CH3 in the ligand. These MOFs exhibit dynamic color-tunable LPL characteristics that depend on the excitation wavelength, temperature and time evolution.

[0039] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a metal halide-based metal organic framework material, characterized in that: The following steps are involved: It was prepared by assembling 1,10-phenanthroline derivatives as ligands with CdCl2; The 1,10-phenanthroline derivative has a substituent; the substituent includes -H, -CH3, -Cl or -Br.

2. The method for preparing a metal halide-based metal organic framework material according to claim 1, characterized in that: The specific process of using 1,10-phenanthroline derivatives as ligands and assembling with CdCl2 is as follows: When the substituent is -H, The following steps are involved: 1,10-phenanthroline, CdCl2·2.5H2O, solvent and deionized water were mixed and reacted to obtain MOF-Z1 crystals; When the substituent is -CH3, the steps include: 2,9-dimethyl-1,10-phenanthroline, CdCl2·2.5H2O, solvent and deionized water were mixed and reacted to obtain MOF-Z2 crystals; When the substituent is -Cl, the steps include: 2,9-dichloro-1,10-phenanthroline, CdCl2·2.5H2O, solvent and deionized water were mixed and reacted to obtain MOF-Z3 crystals; When the substituent is -Br, the steps include: After 2,9-dibromo-1,10-phenanthroline, CdCl2·2.5H2O, a solvent and deionized water are mixed and reacted, MOF-Z4 crystals are obtained.

3. The method for preparing a metal halide-based metal organic framework material according to claim 2, characterized in that: When the substituent is -H, the reaction temperature is 120~150℃ and the reaction time is 72~96 h; The dosage ratio of the 1,10-phenanthroline, CdCl2·2.5H2O, solvent and deionized water is (1-2): (4-10): (2-5): (2-3).

4. The method for preparing a metal halide-based metal organic framework material according to claim 2, characterized in that: When the substituent is -CH3, the reaction temperature is 120~150℃ and the reaction time is 72~96 h; The dosage ratio of the 2,9-dimethyl-1,10-phenanthroline, CdCl2·2.5H2O, solvent and deionized water is (1-2): (4-10): (2-5): (2-3).

5. The method for preparing a metal halide-based metal organic framework material according to claim 2, characterized in that: When the substituent is -Cl, the reaction temperature is 120~140℃ and the reaction time is 72~84 h; The dosage ratio of the 2,9-dichloro-1,10-phenanthroline, CdCl2·2.5H2O, solvent and deionized water is (1-2): (4-12): (2-5): (2-3).

6. The method for preparing a metal halide-based metal organic framework material according to claim 2, characterized in that: When the substituent is -Br, the reaction temperature is 120~140℃ and the reaction time is 72~84 h; The dosage ratio of the 2,9-dibromo-1,10-phenanthroline, CdCl2·2.5H2O, solvent and deionized water is (1-2): (4-12): (2-5): (2-3); The solvent is methanol, acetonitrile, acetone or chloroform.

7. A metal halide-based metal organic framework material, characterized in that: The method is prepared by any one of claims 1 to 6.

8. Use of the metal halide-based metal organic framework material according to claim 7 in information encryption.

9. Use of the metal halide-based metal organic framework material according to claim 7 in drawing patterns.

10. The use of the metal halide-based metal organic framework material in drawing patterns according to claim 9, characterized in that: The MOF-Z2 crystal is made into anti-counterfeiting ink for drawing patterns.

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