Preparation method and use of iridium-chlorophenyl Schiff base metal complex

Abstract

The invention discloses a preparation method and use of an iridium-chlorophenyl Schiff base metal complex, and is specifically related to a phenylpyrazole ring metal iridium dimer as a metal organic precursor and a 2-(4-chlorophenyl) Schiff base auxiliary ligand for coordination, and synthesizing a cation configuration of an iridium-chlorophenyl Schiff base metal complex. The iridium-chlorophenyl Schiff base metal complex prepared by the present invention has good fluorescence emission and electrochemical properties, and can be applied to light-emitting electrochemical cells (LECs), chemical sensors and other fields. The electrochemical properties of the metal complex are determined in an acetonitrile solution by a cyclic voltammetry (CV) method, and it exhibits a reversible redox process, and its oxidation potential is +2.08V, the reduction potential is -0.66V, and the electrode potential is 2.74V, which is used to prepare the positive electrode material of a solid-state battery.

Description

Technical Field

[0001] The invention belongs to the field of electrochemical materials, and specifically relates to a preparation method and application of an iridium-chlorophenyl Schiff base metal complex. Background Art

[0002] In recent years, phosphorescent electronic transition metal complexes, especially iridium-containing metal complexes, have received increasing attention. Due to their good photothermal stability, long excited state lifetime, and tunable emission color, iridium-containing metal complexes have been widely used in the fields of luminescent electrochemical cells, chemical sensors, solid-state lighting, bioimaging, and nonlinear optics, and have gradually expanded to the field of energy storage batteries. With the growing demand for energy storage in the whole society, the performance of positive electrode materials for energy storage batteries needs to be further improved. In traditional positive electrode materials based on layered transition metal compounds, the 3d orbital energy level of the metal is higher than the 2p orbital energy level of O, and the main process of charge and discharge is the redox of cations. Studies have shown that by improving the covalency between the transition metal and the ligand ion, the electrochemical capacity and redox reversibility can be improved.

[0003] In iridium-containing metal complexes, iridium metal and ligands are mainly bound to each other through metal-carbon bonds (MC) and coordination between iridium and nitrogen, oxygen and other ligand atoms, and the metal-carbon bond has a high degree of covalency. Therefore, introducing a chelating ligand into the iridium-containing metal complex to form a metal-carbon bond, and at the same time modifying the structure of the auxiliary ligand, such as increasing the conjugation effect of the system or introducing electron-donating and electron-withdrawing groups, can effectively adjust its electrochemical properties. Schiff bases are a class of organic compounds containing imino or methylimino characteristic groups (-RC=N-), which not only have a conjugated structure, but also have a strong coordination ability. They can be introduced into iridium-containing metal complexes and ultimately used in the preparation of positive electrode materials. Summary of the invention

[0004] The main content of the present invention is: a cationic iridium-chlorophenyl Schiff base metal complex is obtained by using the coordination point on the phenylpyrazole ring metal iridium dimer and the nitrogen atom on the 2-(4-chlorophenyl) Schiff base for bidentate chelate coordination. The electrochemical performance test shows that the complex has good redox performance.

[0005] The present invention first provides a cationic iridium-chlorophenyl Schiff base metal complex, the structural formula of the metal complex is as follows:

[0006]

[0007] The present invention also provides a method for preparing a cationic iridium-chlorophenyl Schiff base metal complex, comprising the following steps:

[0008] Step 1: Phenylpyrazole cyclometallated iridium dimer [Ir(ppz) 2 (μ-Cl)] 2 Synthesis of:

[0009] Hydrated iridium trichloride and 1-phenylpyrazole ligand were added to the reaction flask in a molar ratio of 1:2, and a mixed solvent of ethylene glycol ethyl ether and distilled water in a volume ratio of 5:1 was added. 2 Under the protection of condensation reflux reaction at 130-140 ° C for 24-36 hours, the degree of reaction was monitored by TLC during the reaction. After the reaction was completed, the solution was cooled to room temperature and filtered with a small Buchner funnel. The resulting precipitate was washed with ethanol and petroleum ether to remove the reaction raw materials and by-products, and then washed with CH 2 Cl 2 and H 2 O were extracted separately for further purification, and the organic phase was finally dried to obtain a light yellow solid [Ir(ppz) 2 (μ-Cl)] 2 .

[0010] Step 2 Preparation of auxiliary ligand 2-(4-chlorophenyl) Schiff base (ChloroSchiffbase):

[0011] 4-Chloroaniline and 2-quinolinecarboxaldehyde were dissolved in anhydrous ethanol at a molar ratio of 1:1, and heated to reflux under condensation at 20-30°C for 24-36 hours. During the reaction, the degree of the reaction was monitored by TLC. After the reaction, the solvent was dried by rotary evaporator to obtain a golden solid, which was then dried in vacuo to obtain the target product 2-(4-chlorophenyl) Schiff base.

[0012] Step 3 Iridium-chlorophenyl Schiff base metal complex [Ir(ppz) 2 (ChloroSchiffbase)][PF 6 Synthesis of ]:

[0013] The phenylpyrazole ring metal iridium dimer prepared in step (1) and the auxiliary ligand 2-(4-chlorophenyl) Schiff base prepared in step (2) are added to a reaction bottle in a certain molar ratio, and then dichloromethane, methanol and potassium hexafluorophosphate are added in sequence. 2 The mixture was placed in a dark environment at 80-85°C for condensation reflux reaction for 24-36 hours under protection, and the degree of reaction was monitored by TLC during the reaction. After the reaction, column chromatography was used to purify (V 二氯甲烷 :V 石油醚 =3:1), to obtain a solid of iridium-chlorophenyl Schiff base metal complex.

[0014] Furthermore, in step 3, the molar ratio of the phenylpyrazole ring metal iridium dimer to the auxiliary ligand 2-(4-chlorophenyl) Schiff base is 1:2 to 1:3, the volume ratio of dichloromethane to methanol is 2:1 to 4:1, and the molar ratio of the added amount of potassium hexafluorophosphate to the added amount of the auxiliary ligand 2-(4-chlorophenyl) Schiff base is 2:1.

[0015] Step 4: Crystal cultivation of iridium-chlorophenyl Schiff base metal complex:

[0016] The solid sample of the iridium-chlorophenyl Schiff base metal complex obtained in step (3) is dissolved in dichloromethane, filtered and transferred to a crystal culture tube, and then a certain amount of buffer solution is slowly dripped on the solution, and finally a certain amount of n-hexane is slowly dripped on the buffer solution as an inert solvent diffusion layer. After the crystal culture tube is kept away from light for a period of time, a red crystal is obtained, i.e., the crystal material of the iridium-chlorophenyl Schiff base metal complex.

[0017] Furthermore, the buffer solution in step 4 is a mixed solvent of dichloromethane and n-hexane in a volume ratio of 1:1 to 1:2.

[0018] Furthermore, in step 4, the volume ratio of the sample solution to the buffer solution is 1:1 to 1:2.

[0019] Furthermore, in step 4, the volume ratio of the buffer solution to the diffusion solution is 1:2 to 1:3.

[0020] Furthermore, the crystal culture tube in step 4 is kept away from light for more than one week.

[0021] The iridium-chlorophenyl Schiff base metal complex prepared by the present invention is used as a positive electrode material in a solid-state battery due to its good electrochemical properties.

[0022] Principle of the present invention:

[0023] This patent starts from the structure-activity relationship of metal complex structure and performance, takes phenylpyrazole ring metal iridium dimer with good photothermal stability as the precursor building unit, and introduces 2-(4-chlorophenyl) Schiff base with large conjugated structure and electron-withdrawing group (chloride ion) as auxiliary ligand; utilizes the coordination ability of bidentate nitrogen atom with chelating structure on 2-(4-chlorophenyl) Schiff base ligand to replace the weaker coordination ability of chloride ion in phenylpyrazole ring metal iridium dimer, thus obtaining iridium-chlorophenyl Schiff base metal complex. Finally, the principle of crystal engineering is applied to obtain the corresponding crystal material by solvent diffusion method.

[0024] Beneficial effects of the present invention:

[0025] (1) The iridium-chlorophenyl Schiff base metal complex crystal material prepared by the present invention has a new crystal structure obtained by single crystal diffraction characterization, and its crystal system is monoclinic and the space group is P2 1 / n.

[0026] (2) The present invention selects a phenylpyrazole ring metal iridium dimer with 1-phenylpyrazole as a chelating ligand to coordinate with a 2-(4-chlorophenyl) Schiff base having a conjugated structure and an electron-withdrawing group, thereby obtaining an iridium-chlorophenyl Schiff base metal complex with good thermal stability and solubility. In addition, the synthesis time of the auxiliary ligand 2-(4-chlorophenyl) Schiff base is short, the raw materials are cheap and easy to obtain, and the economic efficiency is good.

[0027] (3) The iridium-chlorophenyl Schiff base metal complex prepared by the present invention exhibits a reversible redox process. The oxidation potential of the complex is relatively high, reaching +2.08V, which is due to the fact that the highest bonding orbital (HOMO) mainly occurs on the covalent σ band Ir-C orbital and the phenyl ring of the 1-phenylpyrazole ligand. The reduction potential of -0.66V mainly occurs on the chlorophenyl Schiff base ligand located in the lowest non-bonding orbital (LUMO). BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The invention discloses a preparation route of the phenylpyrazole ring metal iridium dimer (A), the 2-(4-chlorophenyl) Schiff base auxiliary ligand (B) and the iridium-chlorophenyl Schiff base metal complex (C).

[0029] Figure 2 The unit structure of iridium-chlorophenyl Schiff base metal complex

[0030] Figure 3 The ultraviolet-visible absorption spectra are those of the phenylpyrazole ring metal iridium dimer and the iridium-chlorophenyl Schiff base metal complex prepared by the invention.

[0031] Figure 4 The steady-state fluorescence emission spectra are of the phenylpyrazole ring metal iridium dimer and the iridium-chlorophenyl Schiff base metal complex prepared by the present invention.

[0032] Figure 5 The thermogravimetric curve of the iridium-chlorophenyl Schiff base metal complex crystal material prepared by the present invention.

[0033] Figure 6 This is the electrochemical diagram of the iridium-chlorophenyl Schiff base metal complex crystal material prepared by the present invention. DETAILED DESCRIPTION

[0034] The present invention is described or further illustrated below in conjunction with the accompanying drawings and specific examples, and detailed implementation methods and specific operating processes are given, the purpose of which is to better understand the technical connotation of the present invention, but the protection scope of the present invention is not limited thereto.

[0035] Embodiment 1:

[0036] (1) Phenylpyrazole ring metal iridium dimer [Ir(ppz) 2 (μ-Cl)] 2 Synthesis of:

[0037] Figure 1 A is a phenylpyrazole ring metal iridium dimer [Ir(ppz) 2 (μ-Cl)] 2 Synthesis route map.

[0038] Add 300 mg (0.86 mmol) of iridium trichloride hydrate and 0.227 mL (1.7 mmol) of 1-phenylpyrazole ligand into the reaction flask, then add 40 mL of ethylene glycol ether and 8 mL of distilled water as reaction solvent, and stir under N 2 Under the protection of condensation and reflux at 135 ° C for 24 hours, the degree of reaction was monitored by TLC during the reaction. After the reaction was completed, the solution was cooled to room temperature and filtered with a small Buchner funnel. The resulting precipitate was washed with a large amount of ethanol and petroleum ether to remove the reaction raw materials and by-products, and then washed with CH 2 Cl 2 and H 2 O was extracted and further purified, and the organic phase was finally dried to obtain 245 mg of light yellow solid. [Ir(ppz) 2 (μ-Cl)] 2 (55.3%)

[0039] (2) Synthesis of auxiliary ligand 2-(4-chlorophenyl) Schiff base (ChloroSchiffbase):

[0040] Figure 1 B is the synthetic route of the auxiliary ligand 2-(4-chlorophenyl) Schiff base.

[0041] 318.5 mg (2.5 mmol) of 4-chloroaniline and 393.5 mg (2.5 mmol) of 2-quinolinecarboxaldehyde were dissolved in 30 mL of anhydrous ethanol, and heated to condense under reflux at 25°C for 24 h. After the reaction, the solvent was dried with a rotary evaporator to obtain a golden solid, which was then dried in vacuo to obtain 452 mg of the target product.

[0042] (3) Iridium-chlorophenyl Schiff base metal complexes [Ir(ppz) 2 (ChloroSchiffbase)][PF 6Synthesis of ]:

[0043] Figure 1 C is the synthetic route of the metal complex iridium-chlorophenyl Schiff base.

[0044] 102 mg (0.1 mmol) of phenylpyrazole ring metal iridium dimer and 55.28 mg (0.2 mmol) of auxiliary ligand 2-(4-chlorophenyl) Schiff base were added to a 150 mL eggplant-shaped bottle, and then 40 mL of dichloromethane and 10 mL of methanol were added in sequence, and finally 70 mg of potassium hexafluorophosphate was added. 2 Under protection, the mixture was placed in a light-proof environment at 85°C for condensation reflux reaction for 24 hours. After the reaction, it was purified by column chromatography (the volume ratio of dichloromethane to petroleum ether was 3:1) to obtain 70.4 mg of iridium-chlorophenyl Schiff base solid.

[0045] (4) Crystal diffusion culture of iridium-chlorophenyl Schiff base metal complexes at room temperature:

[0046] Weigh 1 mmol of solid iridium-chlorophenyl Schiff base metal complex and dissolve it in 1 mL of dichloromethane. Ultrasonicate until completely dissolved. After filtering, transfer the solution to a 5 mL crystal culture tube, and then slowly add 1 mL of buffer solution (dichloromethane and n-hexane in a volume ratio of 1:1). Finally, slowly add n-hexane diffusant on the upper layer of the buffer layer until the transistor is filled. Seal the transistor with plastic wrap and place it in a dark place for dispersed culture for ten days to obtain 37 mg of dark red iridium-chlorophenyl Schiff base metal complex crystals.

[0047] In order to determine its structure, the crystal structure of the complex iridium-chlorophenyl Schiff base metal complex was tested by single crystal X-ray diffraction method, and the crystal structure of the complex was obtained after analysis using SHELXTL97 program. Figure 2 It is the unit structure of iridium-chlorophenyl Schiff base metal complex. The crystallographic data, main bond length data and bond angle data of the complex are shown in Table 1, Table 2 and Table 3.

[0048] Table 1. Crystallographic data of iridium-chlorophenyl Schiff base metal complexes

[0049]

[0050]

[0051] Table 2. Some bond lengths of iridium-chlorophenyl Schiff base metal complexes data

[0052]

[0053] Table 3. Partial bond angle data (°) of iridium-chlorophenyl Schiff base metal complexes

[0054]

[0055] Embodiment 2:

[0056] Steps (1) and (2) are the same as in Example 1, and the other steps are as follows:

[0057] (3) Iridium-chlorophenyl Schiff base metal complexes [Ir(ppz) 2 (ChloroSchiffbase)][PF 6 Synthesis of ]:

[0058] 102 mg (0.1 mmol) of phenylpyrazole ring metal iridium dimer and 55.28 mg (0.2 mmol) of auxiliary ligand 2-(4-chlorophenyl) Schiff base were added to a 150 mL eggplant-shaped bottle, and then 20 mL of dichloromethane and 10 mL of methanol were added in sequence, and finally 70 mg of potassium hexafluorophosphate was added. 2 Under protection, the mixture was placed in a light-proof environment at 85°C for condensation reflux reaction for 24 hours. After the reaction, it was purified by column chromatography (the volume ratio of dichloromethane to petroleum ether was 3:1) to obtain 66.8 mg of iridium-chlorophenyl Schiff base metal complex.

[0059] (4) Room temperature diffusion culture of iridium-chlorophenyl Schiff base metal complex crystal materials:

[0060] Weigh 1 mmol of solid iridium-chlorophenyl Schiff base metal complex and dissolve it in 1 mL of dichloromethane. Ultrasonicate until completely dissolved. After filtering, transfer the solution to a 5 mL crystal culture tube, and then slowly add 1.5 mL of buffer solution (the volume ratio of dichloromethane and n-hexane is 1:1). Finally, slowly add n-hexane diffusant on the upper layer of the buffer layer until the transistor is filled. Seal the transistor with plastic wrap and place it in a dark place for dispersion culture for one week to obtain 35.6 mg of dark red iridium-chlorophenyl Schiff base metal complex crystals.

[0061] Figure 3 The UV-visible absorption spectra of phenylpyrazole ring metal iridium dimer and iridium-chlorophenyl Schiff base metal complex were dissolved in dichloromethane and measured. It can be seen from the figure that iridium-chlorophenyl Schiff base metal complex and phenylpyrazole ring metal iridium dimer have the same characteristic absorption peak at about 225nm, which is due to the absorption band generated by the chelating ligand 1-phenylpyrazole π→π* transition. The strong characteristic absorption peak at 225-300nm can be attributed to the charge transfer from metal to ligand (MLCT) and ligand to ligand charge transfer (LLCT). In addition, iridium-chlorophenyl Schiff base metal complex has a weaker characteristic absorption peak at 350-450nm, which can be attributed to the influence of auxiliary ligands.

[0062] Figure 4 The steady-state fluorescence emission spectra of phenylpyrazole ring metal iridium dimer and iridium-chlorophenyl Schiff base metal complex dissolved in dichloromethane solution. It can be seen from the figure that under the same test parameters, phenylpyrazole ring metal iridium dimer has almost no fluorescence emission, while iridium-chlorophenyl Schiff base metal complex has strong fluorescence emission.

[0063] Embodiment 3:

[0064] Steps (1) and (2) are the same as in Example 1, and the other steps are as follows:

[0065] (3) Iridium-chlorophenyl Schiff base metal complexes [Ir(ppz) 2 (ChloroSchiffbase)][PF 6 Synthesis of ]:

[0066] 102 mg (0.1 mmol) of phenylpyrazole ring metal iridium dimer and 55.28 mg (0.2 mmol) of auxiliary ligand 2-(4-chlorophenyl) Schiff base were added to a 150 mL eggplant-shaped bottle, and then 10 mL of dichloromethane and 10 mL of methanol were added in sequence, and finally 70 mg of potassium hexafluorophosphate was added. 2 Under protection, the mixture was placed in a light-proof environment at 85°C for condensation reflux reaction for 24 hours. After the reaction, it was purified by column chromatography (the volume ratio of dichloromethane to petroleum ether was 3:1) to obtain 57.6 mg of iridium-chlorophenyl Schiff base metal complex.

[0067] (4) Room temperature diffusion culture of iridium-chlorophenyl Schiff base metal complex crystal materials:

[0068] Weigh 1 mmol of solid iridium-chlorophenyl Schiff base metal complex and dissolve it in 1 mL of dichloromethane. Ultrasonicate until completely dissolved. After filtering, transfer the solution to a 5 mL crystal culture tube, and then slowly add 2 mL of buffer solution (the volume ratio of dichloromethane and n-hexane is 1:1). Finally, slowly add n-hexane diffusant on the upper layer of the buffer layer until the transistor is filled. Seal the transistor with plastic wrap and place it in a dark place for dispersion culture for one week to obtain 32.8 mg of dark red iridium-chlorophenyl Schiff base metal complex crystals.

[0069] The prepared iridium-chlorophenyl Schiff base crystal material was heated to N 2 Under protection, the temperature was raised to 800°C at a heating rate of 10°C / min for thermogravimetric analysis. Figure 5The thermogravimetric curve of the obtained iridium-chlorophenyl Schiff base metal complex crystal material. As can be seen from the figure, the crystal material has almost no weight loss before 120°C, and loses 2% of its weight at 186°C. The heat loss at this stage is caused by the evaporation of the solvent molecules in the complex, indicating that it has good thermal stability. The crystal material experienced the first obvious weight loss at 458°C, with a weight loss of 40.5%. The heat loss at this stage was caused by the cracking of the chelating ligand ppz due to heat. Continuing heating can lead to the cracking of the carbon skeleton of the metal complex.

[0070] Figure 6 It is the electrochemical property of iridium-chlorophenyl Schiff base metal complexes measured by cyclic voltammetry (CV) in acetonitrile solution.

[0071] In summary, the iridium-chlorophenyl Schiff base metal complex has good thermal stability, and the decomposition temperature reaches 458°C; the CV curve measured by cyclic voltammetry in acetonitrile solution shows that the complex exhibits a reversible redox process; its oxidation potential is +2.08V, compared with traditional layered positive electrode materials, this is because the highest bonding orbital (HOMO) mainly occurs on the highly covalent σ band Ir-C orbital and the phenyl ring of the 1-phenylpyrazole ligand; the reduction potential is -0.66V, which mainly occurs on the chlorophenyl Schiff base ligand positioned by the lowest non-bonding orbital (LUMO); therefore, the iridium-chlorophenyl Schiff base metal complex constructed based on the cyclometallated iridium dimer has potential application value as a positive electrode material for solid-state batteries.

[0072] Table 4 Summary of electrochemical data of iridium-chlorophenyl Schiff base metal complexes

[0073]

Claims

1. An iridium-chlorophenyl Schiff base metal complex, characterized in that: The structural formula is as follows:

2. The method for preparing the iridium-chlorophenyl Schiff base metal complex according to claim 1, characterized in that: The steps include: Step 1 Synthesis of phenylpyrazole ring metal iridium dimer [Ir(ppz)2(μ-Cl)]2: Add hydrated iridium trichloride and 1-phenylpyrazole ligand into a reaction bottle in proportion, and add a mixed solvent of ethylene glycol ethyl ether and distilled water, and carry out condensation reflux reaction under the protection of N2. During the reaction, the degree of reaction is monitored by TLC. After the reaction is completed, the solution is cooled to room temperature, filtered, washed, extracted and purified, and finally the organic phase is spin-dried to obtain a light yellow solid [Ir(ppz)2(μ-Cl)]2; Step 2 Preparation of auxiliary ligand 2-(4-chlorophenyl) Schiff base: Dissolve 4-chloroaniline and 2-quinolinecarboxaldehyde in anhydrous ethanol in proportion, heat, condense and reflux for reaction, monitor the degree of reaction by TLC during the reaction, and dry the solvent by rotary evaporator to obtain a golden solid after the reaction is completed, and vacuum dry to obtain the target product 2-(4-chlorophenyl) Schiff base; Step 3 Synthesis of iridium-chlorophenyl Schiff base metal complexes: The phenylpyrazole ring metal iridium dimer prepared in step (1) and the auxiliary ligand 2-(4-chlorophenyl) Schiff base prepared in step (2) are added to a reaction bottle in a certain molar ratio, and then dichloromethane, methanol and potassium hexafluorophosphate are added in sequence. The reaction is placed in a light-proof environment under the protection of N2 for condensation reflux reaction. During the reaction, the degree of reaction is monitored by TLC. After the reaction is completed, it is purified by column chromatography to obtain a solid iridium-chlorophenyl Schiff base metal complex.

3. The preparation method according to claim 2, characterized in that: In step 1, The molar ratio of hydrated iridium trichloride to 1-phenylpyrazole ligand is 1:

2. In the mixed solvent of ethylene glycol ethyl ether and distilled water, the volume ratio of ethylene glycol ethyl ether to distilled water is 5:

1.

4. The preparation method according to claim 2, characterized in that: In step 1, the temperature of the condensation reflux reaction is 130-140° C. for 24-36 hours; ethanol and petroleum ether are used for washing respectively; and CH2Cl2 and H2O are used for extraction.

5. The preparation method according to claim 2, characterized in that: In step 2, the molar ratio of 4-chloroaniline to 2-quinolinecarboxaldehyde is 1:

1.

6. The preparation method according to claim 2, characterized in that: In step 2, the temperature of the heating condensation reflux reaction is 20 to 30° C. and the time is 24 to 36 hours.

7. The preparation method according to claim 2, characterized in that: In step 3, The molar ratio of the phenylpyrazole ring metal iridium dimer to the auxiliary ligand 2-(4-chlorophenyl) Schiff base is 1:2-1:3, the volume ratio of dichloromethane to methanol is 2:1-4:1, and the molar ratio of the added amount of potassium hexafluorophosphate to the added amount of the auxiliary ligand 2-(4-chlorophenyl) Schiff base is 2:

1.

8. The preparation method according to claim 2, characterized in that: In step 3, The temperature of the condensation reflux reaction is 80-85°C and the time is 24-36h; When purified by column chromatography, V 二氯甲烷 :V 石油醚 =3:

1.

9. Use of the iridium-chlorophenyl Schiff base metal complex according to claim 1 as a positive electrode material in a solid-state battery.

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