A room temperature phosphorescent material based on metal-organic halide and preparation method thereof

Abstract

The present invention relates to the field of crystalline functional materials, and in particular provides a room temperature phosphorescent material based on metal-organic halides and a preparation method thereof. The room temperature phosphorescent material of the metal-organic halide contains three complexes. The chemical formula of Complex 1 is: [ZnCl2(bidpe)]; the chemical formula of Complex 2 is: [ZnBr2(bidpe)]; the chemical formula of Complex 3 is: [ZnI2(bidpe)]·DMF, where bidpe is 4,4'-bis(imidazol-1-yl)diphenyl ether. The complexes belong to the triclinic system and the space group is P-1. The preparation methods of the three complexes are simple, with good stability and high yield. Under environmental conditions, under irradiation of a 365 nm ultraviolet lamp, blue fluorescence emission is shown, and after turning off the ultraviolet light, long-lived yellow-green phosphorescence is shown.

Description

Technical Field

[0001] The invention relates to the field of crystalline functional materials, and in particular provides a room temperature phosphorescent material based on metal-organic halide and a preparation method thereof. Background Art

[0002] Until recently, room temperature phosphorescent (RTP) materials have been widely used in organic light-emitting diodes (OLEDs), bioimaging, information security and other fields. Compared with pure inorganic RTP materials, pure organic RTP materials have the advantages of large Stokes shift, low toxicity and good processing performance. However, organic compounds usually have weak spin-orbit coupling (SOC), and triplet excitons under ambient conditions are easily deactivated through non-radiative transitions such as molecular vibration, rotation, oxygen, and water, which limits the generation of their RTP.

[0003] Metal-organic halides (MOHs) have attracted extensive attention as a new type of photofunctional material. MOHs have the ability to control metal centers and halogen units, and can regulate the heavy atom effect (HAE) to enhance SOC. Strong SOC can break the constraints of spin-forbidden transitions from singlet to triplet states and promote the intersystem crossing (ISC) process. Halogen elements can also regulate luminescence behavior by regulating the heavy atom effect and ligand field effect. Considering these advantages, MOHs bring new opportunities for exploring and developing new RTP materials.

[0004] The information disclosed in this background technology section is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art known to those skilled in the art. Summary of the invention

[0005] The object of the present invention is to provide a room temperature phosphorescent material based on metal-organic halide and a preparation method thereof. The raw materials for the synthesis of the material are readily available, the preparation method is simple, the stability is good, and the yield is high. The phosphorescence life is long, and the material has broad application prospects in the field of RTP materials.

[0006] A room temperature phosphorescent material based on metal-organic halide, the chemical formula of the room temperature phosphorescent material is: [ZnX 2 (bidpe)]·DMF n ; X is Cl, Br or I;

[0007] Wherein, when X is Cl or Br, n=0, when X is I, n=1, bidpe is 4,4'-bis(imidazole-1-yl)diphenyl ether; the complex belongs to the triclinic system, and the space group is P-1. Specifically, the room temperature phosphorescent material of metal-organic halide includes three complexes, and the chemical formula of complex 1 is: [ZnCl 2(bidpe)]; the chemical formula of complex 2 is: [ZnBr 2 (bidpe)]; the chemical formula of complex 3 is: [ZnI 2 (bidpe)]·DMF.

[0008] The present invention provides a room temperature phosphorescent material based on metal-organic halide, and its crystallographic data is shown in Table 1.

[0009] Table 1 Crystallographic data of three room temperature phosphorescent materials based on metal-organic halides

[0010]

[0011] As a preferred embodiment, Zn 2+ is four-coordinated, among which Zn 2+ Connected to two identical halogen atoms and two nitrogen atoms, the halogen atoms come from HX, and the two nitrogen atoms come from two bidpe ligands; each bidpe ligand is connected to two Zn 2+ Connect to form a one-dimensional chain structure.

[0012] Specifically, Zn in complex 1 2+ is four-coordinated, among which Zn 2+ Connected to two identical Cl atoms and two nitrogen atoms, the Cl atom comes from HCl, and the two nitrogen atoms come from two bidpe ligands; each bidpe ligand is connected to two Zn 2+ Connect to form a one-dimensional chain structure.

[0013] Zn in complex 2 2+ is four-coordinated, among which Zn 2+ Connected to two identical Br atoms and two nitrogen atoms, the Br atoms come from HBr, and the two nitrogen atoms come from two bidpe ligands; each bidpe ligand is connected to two Zn 2+ Connect to form a one-dimensional chain structure.

[0014] Zn in complex 3 2+ is four-coordinated, among which Zn 2+ Connected to two identical I atoms and two nitrogen atoms, the I atom comes from HI, and the two nitrogen atoms come from two bidpe ligands; each bidpe ligand is connected to two Zn 2+ Connect to form a one-dimensional chain structure.

[0015] The second object of the present invention is to provide a method for preparing a room temperature phosphorescent material based on metal-organic halide. The preparation method is simple, has good stability, and high yield. The phosphorescence life is long, and has broad application prospects in the field of RTP materials.

[0016] A method for preparing a room temperature phosphorescent material based on metal-organic halide, the reaction steps are as follows:

[0017] S01: Under nitrogen protection, 4,4'-dibromodiphenyl ether, imidazole, K 2 CO 3 and Cu 2 O is mixed in N,N'-dimethylformamide, and heated under reflux at 155°C to 165°C for 46 to 50 hours. After stopping the reaction, it is cooled to room temperature, filtered and washed several times until the filtrate becomes a clear liquid. The filtrate is collected, and ice distilled water is poured into the filtrate to produce a white solid, which is filtered and dried to obtain 4,4'-bis(imidazole-1-yl)diphenyl ether;

[0018] S02: Add a mixed solvent of zinc oxide, 4,4'-bis(imidazole-1-yl)diphenyl ether, N,N'-dimethylformamide and water to a reactor containing a polytetrafluoroethylene liner, drop HX into the reactor, and then heat to react, cool, wash and dry to obtain a complex. Specifically, zinc oxide provides zinc ions and HX provides free halogen ions, which can well connect metal ions with ligands and halogen atoms.

[0019] Preferably, in step S01, 4,4'-dibromodiphenyl ether, imidazole, K 2 CO 3 , Cu 2 The amounts of O used were 9.9-10.1 mmol, 39.9-40.1 mmol, 39.9-40.1 mmol, and 0.49-0.51 mmol, respectively. This range has the highest yield, and too much or too little may affect the yield of the final ligand.

[0020] Preferably, in step S01, the amount of ice distilled water added is 350 mL to 450 mL.

[0021] Preferably, in step S02, the amount of 4,4'-bis(imidazole-1-yl)diphenyl ether is 0.09-0.11 mmol. The crystal yield in this range is the highest and the quality is the best. Too much or too little will reduce the yield, or no crystal will be produced. The amount of zinc oxide is 0.25-0.5 mmol. When the amount of zinc oxide is 0.25 mmol, the proportion of each component is equivalent, which is suitable for generating a sufficient amount of complex crystals. Preferably, the amount of zinc oxide is excessive to ensure the yield of the complex crystals produced, but the maximum amount does not exceed 0.5 mmol to ensure the economic benefits of the preparation of the complex.

[0022] Preferably, in step S02, the dosage of N,N'-dimethylformamide and water is 0.9-1.1 mL and 1.9-2.1 mL respectively. Adding N,N'-dimethylformamide and water as solvents into the reactor improves the safety of the reactor.

[0023] Preferably, in step S02, the volume of HX required is 0.24-0.26 mL. Specifically, the preparation of complex 1 requires dripping HCl (0.24-0.26 mL) into the above-mentioned reaction kettle; the preparation of complex 2 requires dripping HBr (0.24-0.26 mL) into the above-mentioned reaction kettle; the preparation of complex 3 requires dripping HI (0.24-0.26 mL) into the above-mentioned reaction kettle.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The generation and enhancement of ultralong RTP requires two conditions: one is to promote the intersystem crossing of excitons from the excited singlet state to the triplet state by enhancing spin-orbit coupling, and the other is to inhibit the non-radiative transition of excitons from the excited state. 2+ As a four-coordinated metal center, and by connecting halogen units, the heavy atom effect (HAE) can be adjusted to enhance SOC. The halogen element can also adjust the luminescence behavior by adjusting the heavy atom effect and the ligand field effect. The strong intermolecular interaction between the ligand and the metal halide increases the rigidity and inhibits the quenching effect caused by oxygen and water, making the three complexes ideal to meet the requirements of persistent RTP and show afterglow characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 is the asymmetric unit structure diagram of the metal-organic halide material complex 1 of the present invention;

[0028] Figure 2 is the asymmetric unit structure diagram of the metal-organic halide material complex 2 of the present invention;

[0029] Figure 3 is the asymmetric unit structure diagram of the metal-organic halide material complex 3 of the present invention;

[0030] Figure 4 It is a one-dimensional chain diagram of three complexes of the metal-organic halide material of the present invention;

[0031] Figure 5 The X-ray diffraction and simulated diffraction comparison diagrams of three complexes of the metal-organic halide material of the present invention;

[0032] Figure 6 The thermogravimetric analysis diagram of three complexes of the metal-organic halide material of the present invention;

[0033] Figure 7 The fluorescence and phosphorescence emission spectra of the metal-organic halide material complex 1 of the present invention;

[0034] Figure 8 The fluorescence and phosphorescence emission spectra of the metal-organic halide material complex 2 of the present invention;

[0035] Fig. 9 The fluorescence and phosphorescence emission spectra of the metal-organic halide material complex 3 of the present invention;

[0036] Fig.10 The phosphorescence attenuation curves of three complexes of the metal-organic halide material of the present invention are shown;

[0037] Fig.11 These are photographs of three complexes of the metal-organic halide materials of the present invention before and after the ultraviolet light is turned off. DETAILED DESCRIPTION

[0038] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, a room temperature phosphorescent material based on metal-organic halide and a preparation method thereof proposed in accordance with the present invention, its specific implementation method, characteristics and effects are described in detail as follows.

[0039] Figure 1 is the asymmetric unit structure diagram of the metal-organic halide material complex 1 of the present invention, consisting of Figure 1 It can be seen that Zn 2+ It is four-coordinated, among which Zn 2+ It is connected to two chlorine atoms and two nitrogen atoms, where the chlorine atoms come from HCl and the two nitrogen atoms come from two bidpe ligands respectively. Figure 2 is the asymmetric unit structure diagram of the metal-organic halide material complex 2 of the present invention, consisting of Figure 2 It can be seen that Zn 2+ It is four-coordinated, among which Zn 2+ It is connected to two bromine atoms and two nitrogen atoms, where the bromine atoms come from HBr and the two nitrogen atoms come from two bidpe ligands respectively. Figure 3 is the asymmetric unit structure diagram of the metal-organic halide material complex 1 of the present invention, consisting of Figure 3 It can be seen that Zn 2+ It is four-coordinated, among which Zn 2+ It is connected to two iodine atoms and two nitrogen atoms, where the iodine atom comes from HI and the two nitrogen atoms come from two bidpe ligands respectively. Figure 4is a one-dimensional chain diagram of three kinds of complexes of metal-organic halide materials of the present invention, composed of Figure 4 It can be seen that each bidpe ligand binds two Zn 2+ Connect to form a one-dimensional chain structure.

[0040] Figure 5 The X-ray diffraction and simulated diffraction comparison diagrams of the three complexes of the metal-organic halide material of the present invention are shown in FIG. Figure 5 It can be seen that the powder X-ray diffraction pattern is consistent with the experimental simulation diffraction pattern, indicating that this metal-organic halide material has reliable phase purity, which provides a guarantee for its application as a long afterglow material.

[0041] Figure 6 The thermogravimetric analysis diagrams of the three complexes of the metal-organic halide material of the present invention are as follows: Figure 6 It can be seen that the thermogravimetric analysis characterization of this metal-organic halide material shows that its crystal structure begins to collapse at around 400°C, and it has good thermal stability.

[0042] Figure 7 is the fluorescence and phosphorescence emission spectrum of the metal-organic halide material complex 1 of the present invention, Figure 7 It can be seen that the fluorescence emission peak of complex 1 is around 435 nm, showing blue emission, and the phosphorescence emission peak of the complex is around 550 nm, showing green emission. Figure 8 is the fluorescence and phosphorescence emission spectrum of the metal-organic halide material complex 2 of the present invention, Figure 8 It can be seen that the fluorescence emission peak of complex 2 is around 450 nm, showing blue emission, and the phosphorescence emission peak of the complex is around 570 nm, showing yellow emission. Fig. 9 is the fluorescence and phosphorescence emission spectrum of the metal-organic halide material complex 3 of the present invention, Fig. 9 It can be seen that the fluorescence emission peak of complex 3 is around 450 nm, showing blue emission, and the phosphorescence emission peak of the complex is around 550 nm, showing green emission.

[0043] Fig.10 The phosphorescence attenuation curves of the three complexes of the metal-organic halide material of the present invention are as follows: Fig.10 It can be seen that the phosphorescence lifetime of complex 1 under ambient conditions is 1081.98 ms, the phosphorescence lifetime of complex 2 under ambient conditions is 438.22 ms, and the phosphorescence lifetime of complex 3 under ambient conditions is 86.20 ms.

[0044] Fig.11 The three complexes of the metal-organic halide material of the present invention are photographs before and after the ultraviolet light is turned off. Fig.11It can be seen that complex 1 shows blue luminescence under 365nm ultraviolet light at room temperature, and after turning off the ultraviolet light, the complex emits green luminescence visible to the naked eye for up to 4s. Complex 2 shows blue luminescence under 365nm ultraviolet light at room temperature, and after turning off the ultraviolet light, the complex emits yellow luminescence visible to the naked eye for up to 2.5s. Complex 3 shows blue luminescence under 365nm ultraviolet light at room temperature, and after turning off the ultraviolet light, the complex emits green luminescence visible to the naked eye for up to 1.5s.

[0045] The present invention provides a room temperature phosphorescent material based on metal-organic halide, the chemical formula of complex 1 is: [ZnCl 2 (bidpe)]; the chemical formula of complex 2 is: [ZnBr 2 (bidpe)]; the chemical formula of complex 3 is: [ZnI 2 (bidpe)]·DMF, where bidpe is 4,4'-bis(imidazole-1-yl)diphenyl ether. The three complexes all belong to the triclinic system, with space group P-1. The crystal parameters of complex 1 are α=78.052(3)°, β=75.365(2)°, γ=69.575(3)°, Z=2, The crystal parameters of complex 2 are α=77.055(2)°, β=74.165(2)°, γ=70.403(2)°, Z=2, The crystal parameters of complex 3 are α=70.025(2)°, β=78.417(2)°, γ=70.868(2)°, Z=2,

[0046] Under ambient conditions, under 365nm ultraviolet light, it shows blue fluorescence emission, and after turning off the ultraviolet light, it shows a long yellow-green phosphorescence emission. Compared with traditional RTP materials containing precious metals and rare earth elements, the room temperature phosphorescent material based on metal-organic halide provided by the present invention has low cost, simple preparation method, good stability and high yield.

[0047] Embodiment 1

[0048] Under a protective atmosphere (nitrogen, etc.), 10 mmol of 4,4'-dibromodiphenyl ether, 40 mmol of imidazole, and K 2 CO 3 40mmol, Cu 2O 0.50mmol was added to 30mL of N,N'-dimethylformamide, and the mixture was heated to 160°C and refluxed for 48 hours under stirring. After the reaction was stopped, the mixture was cooled to room temperature, filtered and washed until the washing liquid was clear, and the filtrate and washing liquid were combined. 400mL of ice distilled water was poured into the combined liquid to produce a white solid. After sufficient precipitation, the white solid was filtered out and dried to obtain 4,4'-bis(imidazole-1-yl)diphenyl ether.

[0049] A mixed solvent of 0.04 g zinc oxide, 0.0302 g 4,4'-bis(imidazole-1-yl)diphenyl ether, 2 mL N,N'-dimethylformamide and 1 mL water was added into a 25 ml polytetrafluoroethylene-lined reactor, and then 0.25 mL HCl was dropped into the reactor. The reaction was carried out at 120° C. for 72 hours. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain block crystals. The block crystals were separated and washed and dried in sequence to obtain complex 1.

[0050] Embodiment 2

[0051] A mixed solvent of 0.04 g zinc oxide, 0.0302 g 4,4'-bis(imidazole-1-yl)diphenyl ether, 2 mL N,N'-dimethylformamide and 1 mL water was added into a 25 ml polytetrafluoroethylene-lined reactor, and then 0.25 mL HBr was dropped into the reactor. The reaction was carried out at 120°C for 72 hours. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain block crystals. The block crystals were separated and washed and dried in sequence to obtain complex 2.

[0052] Embodiment 3

[0053] A mixed solvent of 0.04 g zinc oxide, 0.0302 g 4,4'-bis(imidazole-1-yl)diphenyl ether, 2 mL N,N'-dimethylformamide and 1 mL water was added into a 25 ml polytetrafluoroethylene-lined reactor, and then 0.25 mL HI was dropped into the reactor. The reaction was carried out at 120°C for 72 hours. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain block crystals. The block crystals were separated and washed and dried in sequence to obtain complex 3.

[0054] Embodiment 4

[0055] A mixed solvent of 0.02 g zinc oxide, 0.0302 g 4,4'-bis(imidazole-1-yl)diphenyl ether, 2 mL N,N'-dimethylformamide and 1 mL water was added into a 25 ml polytetrafluoroethylene-lined reactor, and then 0.25 mL HCl was dropped into the reactor. The reaction was carried out at 120° C. for 72 hours. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain block crystals. The block crystals were separated and washed and dried in sequence to obtain complex 1.

[0056] Embodiment 5

[0057] A mixed solvent of 0.02 g zinc oxide, 0.0302 g 4,4'-bis(imidazole-1-yl)diphenyl ether, 2 mL N,N'-dimethylformamide and 1 mL water was added into a 25 ml polytetrafluoroethylene-lined reactor, and then 0.25 mL HBr was dropped into the reactor. The reaction was carried out at 120°C for 72 hours. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain block crystals. The block crystals were separated and washed and dried in sequence to obtain complex 2.

[0058] Embodiment 6

[0059] A mixed solvent of 0.02 g zinc oxide, 0.0302 g 4,4'-bis(imidazole-1-yl)diphenyl ether, 2 mL N,N'-dimethylformamide and 1 mL water was added into a 25 ml polytetrafluoroethylene-lined reactor, and then 0.25 mL HI was dropped into the reactor. The reaction was carried out at 120°C for 72 hours. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain block crystals. The block crystals were separated and washed and dried in sequence to obtain complex 3.

[0060] In Examples 1 to 3, the amount of zinc oxide used is 0.5 mmol. In Examples 4 to 6, the amount of zinc oxide used is 0.25 mmol. The dosage of zinc oxide is reduced by half. After testing, the yields of the complexes generated under the two ratios are equivalent, indicating that the influence of the dosage of excess zinc oxide on the yield remains unchanged.

[0061] Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A room temperature phosphorescent material based on metal-organic halide, characterized in that: The chemical formula of the room temperature phosphorescent material is: [ZnX2(bidpe)]·DMF n ; The X is Cl, Br or I; wherein, when the X is Cl or Br, n=0, and the chemical formula of the complex is [ZnCl2(bidpe)] or [ZnBr2(bidpe)]; when the X is I, n=1, and the chemical formula of the complex is: [ZnI2(bidpe)]·DMF; The bidpe is 4,4'-bis(imidazole-1-yl)diphenyl ether; the complex belongs to the triclinic system, and the space group is P -1.

2. A room temperature phosphorescent material based on metal-organic halide according to claim 1, characterized in that: The Zn 2+ is four-coordinated, among which Zn 2+ Connected to two identical halogen atoms and two nitrogen atoms, the halogen atoms are from HX, and the two nitrogen atoms are from two bidpe ligands; each of the bidpe ligands is connected to two Zn 2+ Connect to form a one-dimensional chain structure.

3. The method for preparing a room temperature phosphorescent material based on metal-organic halide according to claim 2, characterized in that: S01: Under nitrogen protection, 4,4'-dibromodiphenyl ether, imidazole, K2CO3 and Cu2O were mixed in N,N'-dimethylformamide, and heated under reflux at 155°C~165°C for 46~50 hours. After stopping the reaction, the mixture was cooled to room temperature, filtered and washed several times until the filtrate became a clear liquid. The filtrate was collected, and ice distilled water was poured into the filtrate to produce a white solid, which was filtered and dried to obtain 4,4'-bis(imidazole-1-yl)diphenyl ether; S02: Add a mixed solvent of zinc oxide, 4,4'-bis(imidazole-1-yl)diphenyl ether, N,N'-dimethylformamide and water into a reaction kettle containing a polytetrafluoroethylene liner, drop HX into the reaction kettle, and then heat to react, cool, wash and dry to obtain the complex.

4. The method for preparing a room temperature phosphorescent material based on metal-organic halide according to claim 3, characterized in that: In step S01, the amounts of 4,4'-dibromodiphenyl ether, imidazole, K2CO3, and Cu2O are 9.9-10.1 mmol, 39.9-40.1 mmol, 39.9-40.1 mmol, and 0.49-0.51 mmol, respectively.

5. The method for preparing a room temperature phosphorescent material based on metal-organic halide according to claim 3, characterized in that: In step S01, the amount of ice distilled water is 350 mL to 450 mL.

6. The method for preparing a room temperature phosphorescent material based on metal-organic halide according to claim 3, characterized in that: In step S02, the amount of 4,4'-bis(imidazol-1-yl)diphenyl ether used is 0.09-0.11 mmol.

7. The method for preparing a room temperature phosphorescent material based on metal-organic halide according to claim 3, characterized in that: In step S02, the amount of zinc oxide used is 0.25-0.50 mmol.

8. The method for preparing a room temperature phosphorescent material based on metal-organic halide according to claim 3, characterized in that: In step S02, the amounts of N,N'-dimethylformamide and water are 0.9-1.1 mL and 1.9-2.1 mL, respectively.

9. The method for preparing a room temperature phosphorescent material based on metal-organic halide according to claim 3, characterized in that: In step S02, the required volume of HX is 0.24-0.26 mL.

10. The method for preparing a room temperature phosphorescent material based on metal-organic halide according to claim 3, characterized in that: In step S02, the required temperature is 115°C to 125°C, and the reflux reaction time is 70 to 74 hours.

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