MOF-based alkaline earth metal phosphorescent material as well as preparation method and application thereof

Abstract

The invention belongs to the field of room-temperature phosphorescent materials, and particularly discloses an MOF-based alkaline-earth metal phosphorescent material as well as a preparation method and application thereof. The molecular formula of the compound is [X (tda) (H2O) 2] n, X represents alkaline earth metal, tda represents dehydrogenated H2tda, and H2tda is 1, 2, 3-triazole-4, 5-dicarboxylic acid. The preparation method comprises the following steps: adding H2tda and a water-soluble salt of alkaline earth metal into a mixed solvent composed of DMF and H2O, uniformly stirring, carrying out a hydrothermal reaction at 70-85 DEG C for 2.5-3.5 d, and cooling to room temperature to obtain a solid which is the target product MOF-based alkaline earth metal phosphorescent material. The MOF-based alkaline earth metal phosphorescent material is applied to photoelectric materials, biological imaging or information encryption. The method adopts a hydrothermal method, is simple and quick, is high in product purity and is suitable for industrial large-scale popularization; according to the MOF-based alkaline earth metal phosphorescent material, the afterglow of 3 s can be observed by naked eyes, and the MOF-based alkaline earth metal phosphorescent material has potential application prospects in the fields of photoelectric materials, biological imaging or information encryption.

Description

Technical Field

[0001] The invention belongs to the field of room temperature phosphorescent materials, and in particular relates to a MOF-based alkaline earth metal phosphorescent material and a preparation method and application thereof. Background Art

[0002] Ultra-long room temperature phosphorescence (ULRTP) materials have a wide range of applications in optoelectronic materials, bio-imaging, information encryption, etc. In recent years, among ULRTP materials, organic compounds have attracted much attention due to their advantages such as good solubility, abundant resources, low cost, clear structure, and convenient preparation. In order to suppress the non-radiative transition of organic compounds and promote intersystem crossing (ISC) from singlet to triplet through effective spin-orbit coupling (SOC), researchers in the materials science community have adopted a variety of methods such as heavy atom effects, H aggregation, crystal engineering, and host-guest doping to achieve long-lived RTP materials. Among the above methods, MOFs materials have long been a good choice for exploring the field of phosphorescent materials due to their structural flexibility, multifunctional properties, and stable rigid structure brought about by coordination. Up to now, the use of transition metal ions (such as Zn 2+ 、Cd 2+ The phosphorescence lifetime of MOFs constructed with alkaline earth metal ions (such as Sr 2+ , Ba 2+ MOFs with alkaline earth metals as the core generally show the characteristics of short phosphorescence lifetime due to the inherent weak spin-orbit coupling (SOC) of the central light metal ions. However, it cannot be ignored that alkaline earth metals are abundant in the earth's crust, and compared with transition metals and rare earth metals, they have the obvious advantage of being non-toxic or low-toxic. In view of this, alkaline earth metal ions have great potential to become an ideal choice for creating efficient luminescent MOFs. Summary of the invention

[0003] In view of the deficiencies in the prior art, the object of the present invention is to provide a MOF-based alkaline earth metal phosphorescent material and a preparation method and application thereof.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A MOF-based alkaline earth metal phosphorescent material, the molecular formula of which is [X(tda)(H2O)2] n , wherein X represents an alkaline earth metal, tda represents H2tda after dehydrogenation, H2tda is 1,2,3-triazole-4,5-dicarboxylic acid, and the structural formula of H2tda is as follows: .

[0005] Preferably, X is an alkaline earth metal Sr, and the corresponding MOF-based alkaline earth metal phosphorescent material has the molecular formula [Sr(tda)(H2O)2] n.

[0006] Preferably, [Sr(tda)(H2O)2] n The crystal structure is monoclinic, and the space group is P twenty one / c , the unit cell parameters are: a=7.1789(3) Å, b=16.7104(6) Å, c=6.9627(3) Å, α=90°, β=107.832(5) °, γ=90°.

[0007] A preparation method of the MOF-based alkaline earth metal phosphorescent material: H2tda and a water-soluble salt of an alkaline earth metal are added together into a mixed solvent consisting of DMF and H2O, stirred evenly, subjected to a hydrothermal reaction at 70-85°C for 2.5-3.5 days, and then cooled to room temperature. The obtained solid is the target product, the MOF-based alkaline earth metal phosphorescent material.

[0008] Preferably, in the mixed solvent, DMF:H2O=1:2 by volume ratio; the water-soluble salt of the alkaline earth metal is measured by the alkaline earth metal element therein, and in a molar ratio, H2tda:water-soluble salt of the alkaline earth metal=1:1, and the amount of the mixed solvent used is 2.5-3.5 mL for every 0.025 mmol H2tda.

[0009] Preferably, the water-soluble salt of the alkaline earth metal is a nitrate or chloride salt.

[0010] Preferably, the cooling rate is (5-15)°C / 40min.

[0011] An application of the MOF-based alkaline earth metal phosphorescent material in optoelectronic materials, bio-imaging or information encryption.

[0012] Beneficial effects: (1) The present invention adopts a hydrothermal method, which is simple and fast, has a high product purity, and is suitable for large-scale industrial promotion; (2) The MOF-based alkaline earth metal phosphorescent material of the present invention has an afterglow of 3 s that can be observed by the naked eye, and has potential application prospects in the fields of optoelectronic materials, biological imaging or information encryption. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 : [Sr(tda)(H2O)2] prepared in Example 1 n Coordination environment diagram.

[0014] Figure 2 : [Sr(tda)(H2O)2] prepared in Example 1 n PXRD spectrum of .

[0015] Figure 3: [Sr(tda)(H2O)2] prepared in Example 1 n Luminescence spectrum at room temperature: Fluor. is the fluorescence emission spectrum, Phos. is the phosphorescence emission spectrum.

[0016] Figure 4 : [Sr(tda)(H2O)2] prepared in Example 1 n Afterglow image after irradiation with UV light at 365 nm excitation.

[0017] Figure 5 : [Sr(tda)(H2O)2] prepared in Example 1 n Lifetime decay curves at room temperature: the left figure is the fluorescence lifetime decay curve, and the right figure is the phosphorescence lifetime decay curve. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described below in conjunction with specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the described embodiments, all other embodiments obtained by those skilled in the art without creative work belong to the protection scope of the present invention.

[0019] In the following examples: all chemical reagents used were purchased from commercial sources with analytical purity and no additional purification steps were performed; the drug 1,2,3-triazole-4,5-dicarboxylic acid (H2tda) was purchased from Zhengzhou Anmusi Chemical Products Co., Ltd.; the water used during the experiment was deionized water.

[0020] Test instrument: The infrared spectroscopy (IR) analysis of the samples was carried out using a Bruker Tensor 27 infrared spectrometer. Potassium bromide was used for tableting during the test, and the test covered a wavelength range of 400 to 4000 cm -1 ; Elemental analysis (for C, H, and N elements) was performed using a FLASH EA 1112 elemental analyzer; solid-state fluorescence and phosphorescence spectra of the samples were acquired using a Hitachi F-4600 fluorescence spectrometer; powder X-ray diffraction (PXRD) analysis was performed using a PANalytical X'Pert diffractometer, using Cu-K a X-rays were used as the radiation source; the room temperature phosphorescence lifetime rate was determined by an Edinburgh FLS980 steady-state transient fluorescence spectrometer.

[0021] Data collection and analysis of crystal structure: First, carefully select the samples of appropriate size, regular shape and transparency from the crystals. Then, use Bruker APEX-II CCD diffractometer with Cu-Ka ray (λ=0.71073 Å) as the radiation source to collect the diffraction data of these crystals. The crystal structure is directly solved by SHELXS-97 program, and the SHELXL-2014 program is used to use the full matrix least squares method F 2 After structural optimization, detailed information such as crystallographic parameters, crystallization data, bond lengths, and bond angles were finally collated and listed in the attached table.

[0022] Example 1

[0023] The preparation route is as follows: .

[0024] Preparation process: Accurately weigh H2tda (3.9 mg, 0.025 mmol) and Sr(NO3)2 (5.3 mg, 0.025 mmol), add DMF and H2O (1 mL, 2 mL) together, stir with a glass rod for 5 min, transfer to a 25 mL polytetrafluoroethylene liner, put into a reactor and heat to 80 ° C, react at a constant temperature for 3 days, then cool to room temperature at 10 ° C / 40 min, and take out and observe pale yellow transparent block crystals [Sr(tda)(H2O)2] n , yield (based on Sr): 65%.

[0025] Molecular formula: C4H5N3O6Sr (278.73), elemental analysis calculated values ​​(%): C, 17.24; H, 1.81; N, 15.08; measured values: C, 17.78; H, 1.64; N, 15.41. It can be seen that the calculated values ​​are basically consistent with the measured values.

[0026] IR (KBr, cm -1 ): 3383.51s, 2929.54w, 2747.40w, 2542.83m, 2279.45w, 1951.56m, 1606.89s, 1486.39m, 1349.08s, 1225.78w, 1144.52w, 841.87s, 662.53m, 525.22w.

[0027] [Sr(tda)(H2O)2] prepared in Example 1 n The crystallographic data are shown in Table 1.

[0028]

[0029] [Sr(tda)(H2O)2] prepared in Example 1 n The coordination environment diagram is as follows Figure 1 As shown (for clarity, all hydrogen atoms have been omitted). 2+ It is nine-coordinated, in which O1A from the ligand and the oxygen atoms (O5, O6) from the water molecule are monodentate coordinated, and (O1, O2), (O2B, O3B) and (N3C, N4C) from the same ligand are coordinated in a bidentate chelation manner; bond length Sr-O: 2.57(3) Å~2.99(3) Å, [the bond angle around Sr(II) is 22.6(9)~158.2(10)º], and the above bond lengths and bond angles are consistent with those reported for Sr(II) complexes.

[0030] Figure 2 [Sr(tda)(H2O)2] prepared in Example 1 n PXRD spectrum. From the analysis of the PXRD spectrum, all the main strong diffraction peaks are consistent with the single crystal structure simulation results, and only a few weak diffraction peaks have slight deviations from the simulated peak values. This deviation may be due to the limitation of the instrument resolution, which makes it difficult for some weak diffraction signals to be clearly displayed on the existing diffractometer. These signals may be effectively distinguished on a high-resolution diffractometer, but may be masked by background noise under current conditions. Overall, the experimentally measured diffraction peaks are highly consistent with the simulated diffraction peaks, which indicates that the tested samples are of extremely high purity and low impurity content, and are therefore suitable for testing and research on photophysical properties.

[0031] Figure 3 [Sr(tda)(H2O)2] prepared in Example 1 n The emission spectrum at room temperature: Fluor. is the fluorescence emission spectrum, Phos. is the phosphorescence emission spectrum. Figure 3 It can be observed that the maximum fluorescence emission (Em) wavelength is 445nm, and at the same time, the corresponding maximum fluorescence excitation (Ex) wavelength of the crystal is 345nm; the maximum phosphorescence emission (Em) wavelength is 500nm, and at the same time, the corresponding maximum phosphorescence excitation (Ex) wavelength of the crystal is 357nm.

[0032] Figure 4 [Sr(tda)(H2O)2] prepared in Example 1 n Afterglow image after irradiation with ultraviolet light at 365nm excitation. Figure 4 As shown: When the UV light is turned off, the crystal emits yellow phosphorescence in the initial 0~1s period, then turns to green and lasts for about 3s.

[0033] In order to understand the luminescence of the crystal more accurately, we tested its transient lifetime using a double exponential fitting mode. I 0= I+A 1exp( t / τ 1)+ A 2exp( t / τ 2)( I 0 and I They are τ =0 and τ = t Fluorescence or phosphorescence intensity at ; τ 1 and τ 2 represents the fluorescence or phosphorescence decay lifetime; A 1 and A2 are the amplitudes of each component) to fit the crystal. Figure 5 [Sr(tda)(H2O)2] prepared in Example 1 n Lifetime decay curves at room temperature: the left figure is the fluorescence lifetime decay curve, and the right figure is the phosphorescence lifetime decay curve. Figure 5 As shown, when the fluorescence emission wavelength of the crystal is 445 nm, the fluorescence lifetime of the crystal is 2.23 ns, and when the phosphorescence emission wavelength of the crystal is 500 nm, the phosphorescence lifetime of the crystal is 417.29 ms.

Claims

1. A MOF-based alkaline earth metal phosphorescent material, characterized in that: Its molecular formula is [X(tda)(H2O)2] n , wherein X represents an alkaline earth metal, tda represents H2tda after dehydrogenation, and H2tda is 1,2,3-triazole-4,5-dicarboxylic acid.

2. The MOF-based alkaline earth metal phosphorescent material according to claim 1, characterized in that: X is alkaline earth metal Sr, and the corresponding molecular formula of MOF-based alkaline earth metal phosphorescent material is [Sr(tda)(H2O)2] n .

3. The MOF-based alkaline earth metal phosphorescent material according to claim 2, characterized in that: [Sr(tda)(H2O)2] n The crystal structure is monoclinic, and the space group is P twenty one / c , the unit cell parameters are: a=7.1789(3) Å, b=16.7104(6) Å, c=6.9627(3) Å, α=90°, β=107.832(5) °, γ=90°.

4. A method for preparing a MOF-based alkaline earth metal phosphorescent material as claimed in any one of claims 1 to 3, characterized in that: H2tda and a water-soluble salt of an alkaline earth metal are added to a mixed solvent consisting of DMF and H2O, stirred evenly, and subjected to a hydrothermal reaction at 70-85°C for 2.5-3.5 days, and then cooled to room temperature. The obtained solid is the target product, a MOF-based alkaline earth metal phosphorescent material.

5. The method for preparing the MOF-based alkaline earth metal phosphorescent material according to claim 4, characterized in that: In the mixed solvent, DMF:H2O=1:2 by volume ratio; the water-soluble salt of alkaline earth metal is measured by the alkaline earth metal element therein, and in the molar ratio, H2tda:water-soluble salt of alkaline earth metal=1:1, and the amount of the mixed solvent used is 2.5-3.5 mL for every 0.025 mmol H2tda.

6. The method for preparing the MOF-based alkaline earth metal phosphorescent material according to claim 4, characterized in that: The water-soluble salts of alkaline earth metals are nitrates or chlorides.

7. The method for preparing the MOF-based alkaline earth metal phosphorescent material according to claim 4, characterized in that: The cooling rate is (5~15)℃ / 40min.

8. Use of the MOF-based alkaline earth metal phosphorescent material according to any one of claims 1 to 3 in optoelectronic materials, bio-imaging or information encryption.

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