3-carboxylic acid ethyl ester-5-phenyl-pyrazole silver complex and its synthesis method and application

Abstract

The present application relates to a kind of 3-carboxylic acid ethyl ester-5-phenyl-pyrazole silver complex and its synthesis method and application, the chemical formula of the 3-carboxylic acid ethyl ester-5-phenyl-pyrazole silver complex is (AGLPh-COOC2H5) 3, structural formula is as follows: Preparation method includes: silver nitrate is dissolved with ammonia water to be clear, add methanol, then add the methanol solution of 3-carboxylic acid ethyl ester-5-phenyl-pyrazole with equal amount of substance, stir at room temperature, filter, wash, dry and then dissolve in dichloromethane, add n-hexane, slowly volatilize and diffuse crystallization at room temperature, obtain 3-carboxylic acid ethyl ester-5-phenyl-pyrazol trinuclear silver complex.The trinuclear silver complex of the present application has nine-atom Ag3N6 ring structure, there is silver affinity between molecules, silver-silver distance is 3.28-3.37 Å, less than the sum of van der waals radius 3.44 Å, emit blue-purple visible light in room temperature solid state, emission peak is located at 452nm and does not change with excitation wavelength, with good thermal stability and light stability;As luminescent material, it can be applied in optoelectronic devices, fluorescence probe or anti-fake mark and other fields.

Description

Technical Field

[0001] This invention belongs to the field of coordination chemistry and luminescent materials technology, specifically relating to a 3-ethyl carboxylate-5-phenyl-pyrazole silver complex, its synthesis method, and its application in luminescent materials. Background Technology

[0002] d10 transition metal (e.g., Cu¹, Ag¹, Au¹) complexes have attracted widespread attention due to their rich luminescent properties and diverse aggregation structures. Among them, pyrazole ligands, containing two adjacent nitrogen atoms, can form a bidentate bridging structure after deprotonation, resulting in polynuclear metal complexes with the coordinating metal. Metal-metal interactions are common in these complexes, and when the distance between metal atoms is less than the sum of their van der Waals radii, this interaction can significantly affect the photophysical properties of the complex.

[0003] Compared to gold and copper complexes, there are fewer studies on the luminescence properties of silver complexes, mainly because silver-containing complexes have poor thermal stability under normal conditions, are photosensitive, and are prone to photodecomposition. In the prior art, Catalano and Malwitz (Inorg. Chem., 2003, (42): 5483-5485) reported the synthesis of a trinuclear N-heterocyclic carbene-containing silver(Ⅰ), [(μ-NHC)3Ag3](BF4)3. In the crystal structure of the complex, the three silver atoms are arranged in an equilateral triangle. The distance between Ag and Ag is relatively short, ranging from 2.7249 to 2.7718 Å. Its acetonitrile solution has an emission peak at 435 nm, while the emission peak of the ligand NHC is at approximately 450 nm. Therefore, the luminescence of this type of trinuclear silver complex can be temporarily attributed to the luminescence of the ligand itself. Furthermore, the possibility of metal electrons transitioning to empty orbitals (MLCT) of the ligand cannot be ruled out. Dias et al. (Inorg. Chem., 2007, 46(8): 2979-2987) synthesized various fluorinated pyrazole trinuclear silver complexes and found that the steric volume of the substituents affects the intermolecular Ag-Ag interaction and aggregation mode. When the steric hindrance is large (such as tert-butyl substitution), the Ag-Ag distance increases to 5.376 Å, with no obvious silophilic interaction. Manal et al. (Chemistry: 2013, (33): 88-101) reported {[3,5-(CF3)2Pz]Ag}3, which does not emit light at room temperature but emits blue-violet light at low temperature. After the addition of aromatic hydrocarbons (such as benzene, toluene, trimethylbenzene), it can emit bright phosphorescence at room temperature. This luminescence originates from the acid-base excitation complex. However, most trinuclear silver complexes emit weak or no light in the solid state at room temperature and require low temperature or guest molecule induction to produce obvious luminescence, which limits their practical application. Therefore, it is of great significance to develop a novel trinuclear silver complex that is structurally stable, exhibits good solid-state luminescence at room temperature, and whose luminescence properties can be modulated through intermolecular interactions. Summary of the Invention

[0004] The purpose of this invention is to provide a 3-carboxylic acid ethyl ester-5-phenyl-pyrazole silver complex, its synthesis method and application, in order to solve the problems of weak solid-state luminescence at room temperature and the need for special excitation conditions in existing trinuclear silver complexes.

[0005] A 3-ethyl carboxylate-5-phenyl-pyrazole silver complex, with the chemical formula (AgLPh-COOC2H5)3, wherein LPh-COOC2H5 is 3-ethyl carboxylate-5-phenyl-pyrazole. The structural formula of the 3-ethyl carboxylate-5-phenyl-pyrazole silver complex is as follows: The trinuclear silver complex of this invention has a nine-membered ring Ag3N6 structure, in which three silver ions and three deprotonated pyrazole ligands form a nine-membered ring via an N-Ag-N linear coordination mode. Due to the steric hindrance of the benzene ring, this nine-membered ring is slightly off-planar. Intermolecular argentophilic interactions exist (Ag-Ag distance is 3.28–3.37 Å, less than the sum of the silver-silver van der Waals radii of 3.44 Å). Two adjacent trinuclear silver units form dimers through two pairs of intermolecular silver-silver interactions, and the dimers further form a ladder-like chain structure through silver-silver interactions.

[0006] The trinuclear silver complex of the present invention emits blue-violet visible light at 452 nm in the solid state at room temperature, and the emission peak position does not change with the excitation wavelength (emission at 452 nm is obtained from excitation at 300–380 nm), exhibiting good thermal and optical stability.

[0007] The method for preparing the 3-ethyl carboxylate-5-phenyl-pyrazole silver complex of the present invention includes the following steps: S1. Dissolve silver nitrate (AgNO3) in ammonia water (NH3·H2O) until completely clear, then add methanol to obtain a silver ammonia solution; S2. Dissolve 3-ethyl carboxylate-5-phenyl-pyrazole (LPh-COOC2H5) in methanol to obtain a ligand solution; S3. Add the ligand solution obtained in step S2 to the silver ammonia solution obtained in step S1, stir at room temperature, filter, wash 2-3 times, and dry. S4. Dissolve the product obtained in step S3 in dichloromethane, add n-hexane as a poor solvent, and allow it to evaporate and crystallize at room temperature. After 3-5 days, the 3-carboxylic acid ethyl ester-5-phenyl-pyrazole trinuclear silver complex is obtained.

[0008] Preferably, the ratio of the amount of silver ammonia solution obtained in step (1) to the amount of ligand solution obtained in step S2 in step S1 is 1:1.

[0009] Preferably, the volume ratio of dichloromethane to n-hexane added in step S4 is 1:2.

[0010] Applications of the above-mentioned ethyl carboxylate-5-phenyl-pyrazole silver complex in the field of luminescent materials The trinuclear silver complex of this invention emits bright blue-violet visible light under 365 nm ultraviolet light, which is clearly visible to the naked eye. It can be used as a luminescent material in solid-state light-emitting devices, fluorescent probes, or anti-counterfeiting labels.

[0011] Compared with the prior art, the present invention has the following technical advantages: (1) This invention provides a novel 3-carboxylic acid ethyl ester-5-phenyl-pyrazole silver complex with a nine-membered ring Ag3N6 structure. It exhibits strong solid-state luminescence at room temperature, and the emission peak position does not change with the excitation wavelength. It also has good thermal and light stability.

[0012] (2) The method for synthesizing the trinuclear silver complex of the present invention is simple. It adopts conventional coordination reaction and can obtain the target product by stirring at room temperature without the need for high temperature or inert atmosphere protection.

[0013] (3) The 3-carboxylic acid ethyl ester-5-phenyl-pyrazole silver complex of the present invention achieves a moderate silver-silver distance between molecules through the electronic effect and steric hindrance regulation of the phenyl and ethyl ester groups, and effectively suppresses nonradiative transitions. It can be used in solid-state light-emitting devices, fluorescent probes or anti-counterfeiting marks and other fields. Attached Figure Description

[0014] Figure 1 This is a single-molecule structural diagram of the 3-carboxylic acid ethyl ester-5-phenyl-pyrazole silver complex of the present invention; Figure 2 Here are the molecular aggregation structure diagrams of the 3-ethyl carboxylate-5-phenyl-pyrazole silver complex of the present invention, wherein (a) is a ladder-like chain aggregate structure diagram of the 3-ethyl carboxylate-5-phenyl-pyrazole silver complex; and (b) is a dimer structure diagram of the 3-ethyl carboxylate-5-phenyl-pyrazole silver complex. Figure 3 This is the powder X-ray diffraction pattern of the 3-ethyl carboxylate-5-phenyl-pyrazole silver complex of the present invention; Figure 4 This is the infrared spectrum of the 3-ethyl carboxylate-5-phenyl-pyrazole silver complex of the present invention; Figure 5 This is the ¹H NMR spectrum of the 3-ethyl carboxylate-5-phenyl-pyrazole silver complex of the present invention; Figure 6 This is the solid-state excitation emission spectrum of the 3-carboxylic acid ethyl ester-5-phenyl-pyrazole silver complex of the present invention. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0016] Example 1 The preparation of ethyl 3-carboxylate-5-phenyl-pyrazole silver complex (AgLPh-COOC2H5)3 includes the following steps: S1. Add ammonia water (NH3·H2O) dropwise to 0.17 g AgNO3 (1 mmol) until completely dissolved, then add 15 mL of methanol to obtain a silver ammonia solution.

[0017] S2. Dissolve 0.216 g of ethyl 3-carboxylate-5-phenyl-pyrazole (LPh-COOC2H5, 1 mmol) in 15 mL of methanol to obtain a ligand solution.

[0018] S3. Add the ligand solution obtained in step S2 to the silver ammonia solution obtained in step S1, stir at room temperature for 30 minutes, and a white precipitate will immediately form. Filter, wash the white precipitate 2-3 times with anhydrous ethanol, and dry to obtain a white powder. The reaction formula is as follows: S4. Dissolve the white powder obtained in step S3 in dichloromethane, add an appropriate amount of n-hexane (the volume ratio of dichloromethane to n-hexane is about 1:2), and allow it to slowly evaporate and crystallize at room temperature. After 3-5 days, colorless and transparent needle-like crystals are obtained, which are the target complex (AgLPh-COOC2H5)3.

[0019] Performance testing 1. Characterization of coordination compounds (1) Single-crystal X-ray diffraction: The crystal structure was determined using an Oxford Diffraction Gemini E single-crystal diffractometer. The results are as follows: Figure 1 and Figure 2 As shown in Tables 1 and 2, the complex belongs to the monoclinic crystal system with space group P21 / n. Bond lengths and bond angles are shown in Tables 1 and 2. Three silver ions form a slightly off-planar Ag3N6 nine-membered ring with three deprotonated pyrazole ligands. The intramolecular silver-silver distances are 3.28–3.37 Å, all less than the sum of the silver-silver van der Waals radii (3.44 Å), confirming the presence of argentophilic interactions. Two adjacent trinuclear silver units form dimers through two pairs of intermolecular silver-silver interactions, and these dimers further form a ladder-like chain structure through silver-silver interactions.

[0020] Table 1. Bond length data for (AgLPh-COOC2H5)

[0021] Table 2 (AgLPh-COOC2H5) 3-bond angle data

[0022] (2) Powder X-ray diffraction (PXRD): Tested using a Bruker D8 ADVANCE X-ray diffractometer. Results are as follows: Figure 3 As shown, the experimental spectrum and the simulated spectrum from single-crystal data are in high agreement, proving that the obtained product is a pure phase.

[0023] (3) Elemental analysis: Elemental analysis was performed using a Vario EL cube elemental analyzer. Measured values: C, 44.60; H, 3.43; N, 8.67. Theoretical values ​​(C... 36 H 33 Ag3N6O6): C, 44.61; H, 3.43; N, 8.67.

[0024] (4) FT-IR Spectroscopy: An AVATAR 360 FT-IR spectrometer was used, with potassium bromide (KBr) pellets. Main characteristic peaks (cm²) - ¹): 3440(m), 2981(w), 1719(s), 1628(w), 1496(w), 1463(w), 1416(m), 1385(w), 1239(s), 1137(s), 1050(m), 1029(w), 756(m), 691(m). The spectrum is as follows Figure 4 As shown.

[0025] (5) ¹H NMR: A Bruker Biospin Avance 400MHz NMR spectrometer was used, with dichloromethane (CD₂Cl₂) as solvent and tetramethylsilane (TMS) as internal standard. Chemical shifts (δ, ppm): 7.87 (d, 6H), 7.40 (d, 9H), 7.12 (s, 3H), 4.34 (q, 6H), 1.37 (t, 9H). The spectra are shown below. Figure 5 As shown.

[0026] 2. Solid-state luminescence property testing The solid-state emission spectra of the ethyl carboxylate-5-phenyl-pyrazole silver complex prepared in Example 1 were measured using an FLS920 single-photon counting emission spectrometer. The results are as follows: Figure 6 As shown, under ultraviolet light excitation at wavelengths ranging from 300 to 380 nm, the emission peak of the complex remained at 452 nm, with the peak position essentially unchanged. This indicates that excitation light of different energies has little effect on the emission band, and the luminescence likely originates primarily from π→π* transitions within the ligand or from excited states finely tuned by argyrophilic interactions. Under 365 nm ultraviolet light irradiation, the solid complex emits bright blue-violet visible light, clearly discernible to the naked eye.

[0027] Furthermore, experiments revealed that the 3-carboxylic acid ethyl ester-5-phenyl-pyrazole silver complex of the present invention exhibits good thermal and light stability.

[0028] As can be seen, the structure of the 3-ethyl carboxylate-5-phenyl-pyrazole silver complex of the present invention is well-defined and stable (the precise structure is confirmed by single-crystal X-ray diffraction, the purity is proven by powder diffraction, and it is stable in air), emitting bright blue-violet visible light that is clearly visible to the naked eye, and has the potential to be used in solid-state light-emitting devices, fluorescent probes, or anti-counterfeiting marks.

Claims

1. A 3-carboxylic acid ethyl ester-5-phenyl-pyrazole silver complex, characterized in that, The chemical formula is (AgLPh-COOC2H5)3, where LPh-COOC2H5 is ethyl 3-carboxylate-5-phenyl-pyrazole; the structural formula is as follows: 。 2. The method for synthesizing the 3-carboxylic acid ethyl ester-5-phenyl-pyrazole silver complex according to claim 1, characterized in that, Includes the following steps: (1) Dissolve silver nitrate in ammonia water, then add methanol to obtain a silver ammonia solution; (2) Dissolve 3-ethyl carboxylate-5-phenyl-pyrazole in methanol to obtain a ligand solution; (3) Add the ligand solution obtained in step (2) to the silver ammonia solution obtained in step (1), stir at room temperature, filter, wash and dry; (4) Dissolve the product obtained in step (3) in dichloromethane, add n-hexane, and volatilize and crystallize at room temperature to obtain 3-carboxylic acid ethyl ester-5-phenyl-pyrazole trinuclear silver complex.

3. The synthesis method according to claim 2, characterized in that, The ratio of the amount of silver ammonia solution obtained in step (1) to the amount of ligand solution obtained in step (2) is 1:

1.

4. The synthesis method according to claim 2, characterized in that, In step (4), the volume ratio of dichloromethane to n-hexane added is (1:1) to (1:3).

5. The application of the 3-carboxylic acid ethyl ester-5-phenyl-pyrazole silver complex according to claim 1 in the field of luminescent materials.

6. The application according to claim 5, characterized in that, The luminescent material can be a solid-state light-emitting device, a fluorescent probe, or an anti-counterfeiting mark.

7. A luminescent material, characterized in that, It comprises the 3-carboxylic acid ethyl ester-5-phenyl-pyrazole silver complex of claim 1.

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