3-hydroxy-4-(4-pyridylazo) anilino-N, N-bis (ethyl-2-phosphonic acid) and preparation method thereof

Abstract

The 3-hydroxy-4-(4-pyridylazo) anilino-N, N-bis (ethyl-2-phosphonic acid) is prepared by taking 4-aminopyridine and 3-hydroxyanilino-N, N-bis (ethyl-2-phosphonic acid) as main raw materials through diazotization reaction and azo reaction, and the 3-hydroxy-4-(4-pyridylazo) anilino-N, N-bis (ethyl-2-phosphonic acid) not only can strongly absorb ultraviolet rays in a 250-450nm region, but also has good solubility in solvents such as water, methanol and ethanol, and can be used for preparing the ultraviolet light absorber. The compound also has a pH response function, also responds to stimulation of light, electricity, heat, fields and the like, and is suitable for being used as a water-soluble small organic molecule photoelectric functional material or an anti-ultraviolet SAM hole transport material for a perovskite solar cell.

Description

TECHNICAL FIELD

[0001] The present application relates to an azobenzene compound and a preparation method thereof, in particular to 3-hydroxy-4-(4-pyridine azo) aniline-N, N-bis(ethyl-2-phosphonic acid) and a preparation method thereof, which can be used as an organic small molecule photoelectric functional material and belongs to the field of organic functional materials. BACKGROUND

[0002] Phenyl azo compound, also known as azobenzene, is a diphenyl diazene, which is equivalent to the product obtained by replacing two hydrogens of diazene (H-N=N-H) with phenyl. Generally, the molecular configuration of phenyl azo compound can be conditionally converted between cis and trans. For example, at room temperature, the molecular configuration of phenyl azo compound is usually the thermodynamically stable trans form, when it is irradiated by ultraviolet light of a certain wavelength, the molecule of phenyl azo compound absorbs the energy of ultraviolet light wave, and its molecular trans form will be converted into the high-energy cis form; when the ultraviolet light is stopped, the cis form of phenyl azo compound will spontaneously return to the thermodynamically stable trans form, and usually release energy in the form of heat. The cis-trans conversion of the molecular configuration of phenyl azo compound will cause changes in its color, dipole, conductivity and other physical properties, so some phenyl azo compounds are not only used as dyes, but also often used as stimuli-responsive functional materials such as electricity, light and heat in recent years, and some phenyl azo compounds have become alternative raw material substances for modern artificial intelligent sensing materials. Therefore, it is meaningful to design and create some water-soluble phenyl azo compounds with specific structure and performance for the preparation of biomimetic hydrogel materials which are stimulated by light, electricity, field, temperature, humidity, pH, mechanical force and other stimuli.

[0003] In 2008, foreign scholars first tried to use phenyl phosphonic acid or carbazyl ethyl phosphonic acid as a self-assembled monolayer (SAM) hole transport material between the components of perovskite solar cells for innovative research, and achieved surprising results. For example, by dissolving various carbazyl alkyl phosphonic acids such as 2-(3,6-dimethoxy-9H-carbazol-9-yl) ethyl phosphonic acid and 4-(3,6-dimethoxy-9H-carbazol-9-yl) butyl phosphonic acid in ethanol solvent, a self-assembly monolayer was formed on the surface of the ITO electrode by simple immersion method, which was used as the interface modification material and hole transport layer material between the transparent conductive oxide electrode (ITO) and the light-absorbing layer CH3NH3PbI3 of perovskite solar cells. This material can not only eliminate the interface band gap between ITO and perovskite light-absorbing layer, but also help to reduce the series resistance between the layers of perovskite solar cells, passivate interface lattice defects, regulate energy levels, and achieve high-efficiency extraction and transmission of holes with high flux. Many research results show that perovskite solar cells using such interface modification materials and hole transport layer materials have reached or even surpassed the photoelectric conversion efficiency (PCE) of 27% of silicon-based solar cells. Therefore, in the past three years, many domestic scholars have also created various SAM hole transport materials such as carbazyl alkyl phosphonic acid, diphenylamine alkyl phosphonic acid, and phenothiazine alkyl phosphonic acid, such as CN202311417935.5, CN202310646577.9, CN202310646586.8, CN202311767735.2, CN202411879122.2, CN202411329780.4, CN202411510308.0, CN202411594303.0, CN202411331898.0, CN202410302624.2, CN202410767796.7, CN202410137478.2, CN202410108998.0, CN202411310693.4, CN202510359778.X, CN202510144713.3, and CN202510053296.1.From the above molecular structure of SAM hole transport material, the professionals in the field know that the SAM hole transport material molecule contains three structural units: ① the electron-donating aromatic ring structural unit at one end of the molecule, such as substituted or unsubstituted diphenylamine, substituted or unsubstituted carbazole, or substituted or unsubstituted phenothiazine, etc., which functions to passivate interface defects, regulate energy levels, achieve efficient extraction of holes and transport; ② the anchoring group (phosphonic acid group or bisphosphonic acid group) on the ITO surface, Ar-PO3H2 has good solubility in aqueous or ethanol media, and is easy to form P-O-M (M refers to Sn or In) bonding with the ITO surface semiconductor metal ions, forming a firm SAM film on the ITO semiconductor surface; ③ the intermediate structural unit connecting the aromatic ring structural unit and the anchoring group, mainly 1,4-benzene ring, 1,4-bis methylene benzene, 1,2-ethylene, 1,4-butylene or 1,5-pentylene, etc. For details, please refer to the article “A Comprehensive Review of Self-Assembled Monolayers as Hole-Transport Layers in Inverted Perovskite Solar Cells” by Hao Xia's research group of Sichuan University published in Energies, 2025, 18(10), 2577, which elaborates on the development status, existing problems and future development strategies of SAM hole transport materials for perovskite solar cells.

[0004] Although domestic and foreign scholars have optimized the components of perovskite solar cells from the aspects of ITO-coated glass electrodes, graphene flexible electrodes, light-absorbing layer materials, electron transport materials, hole transport materials, and packaging processes, and have conducted extensive research and development on how to improve photoelectric conversion efficiency, and have obtained surprising results, but the commercialization process is still challenged by some factors. A significant factor is the degradation of perovskite solar cells exposed to natural light, oxygen, moisture, and heat for a long time. The most serious problem is that the raw materials of the components in perovskite solar cells, such as perovskite materials, electron transport materials, or hole transport materials, are all organic or inorganic compounds, which may be degraded due to ultraviolet light induction, leading to the attenuation of the efficiency of perovskite solar cell devices, limiting their long-term stability and durability, which has attracted the attention of some domestic and foreign scholars. For example: Wang et al. in Angew. Chem. Int. Ed. 2021, 60, 8675~8679 《Tautomeric Molecule Acts as a “Sunscreen” for Metal Halide Perovskite Solar Cells》, disclosed the use of benzophenone derivatives as ultraviolet absorbers for perovskite, which effectively improved the ultraviolet resistance of perovskite solar cells. ZL202510670415.8 discloses a pyridinium compound doped perovskite solar cell, which still maintains 92.5% of the initial photoelectric conversion efficiency after 1500 hours of ultraviolet light irradiation, while the control group only has 67.3%. However, there are still few reports on organic small molecules with simple preparation, good solubility, and practicality as multifunctional SAM hole transport materials.

[0005] According to the chemical molecular design principle, based on the structure, performance, and application of artificial skin and biomimetic hydrogel of existing azobenzene compounds, as well as the molecular structure, charge distribution characteristics, application technical requirements, and ultraviolet stability of SAM hole transport materials for perovskite solar cells, the inventors used molecular fragment splicing method to create 3-hydroxy-4-(4-pyridine azo) aniline-N,N-bis(ethyl-2-phosphonic acid) or 3-hydroxy-4-(4-pyridine azo) aniline-N,N-bis(ethyl-2-phosphonic acid disodium salt), which has multiple properties and multiple purposes. The preparation raw materials are widely available, the preparation method is simple, the purification technology is easy and safe to operate, and it not only has strong absorption of ultraviolet light in the 250~400nm region, good solubility in water, methanol, ethanol and other solvents, but also has pH response function, multi-stimulus-response color change to light, electricity, heat, field, etc. It is suitable for use as an organic small molecule optoelectronic functional material of water-soluble pyridine-azo-benzene amino bisphosphonic acid, or as an anti-ultraviolet SAM hole transport material for perovskite solar cells. SUMMARY

[0006] The 3-hydroxy-4-(4-pyridine azo) anilino-N,N-bis(ethyl-2-phosphonic acid) provided by the present application has the structure shown in formula (I):

[0007]

[0008] According to the IUPAC naming principle of organic compounds, the name of the compound of formula (I) provided by the present application is 3-hydroxy-4-(4-pyridine azo) anilino-N,N-bis(ethyl-2-phosphonic acid), which can also be called 3-hydroxy-4-(4'-pyridine azo)-N,N-bis(ethyl-2''-phosphonic acid) aniline. According to the theory of organic chemical structure, those skilled in the art can see from formula (I) that:

[0009] ① The 3-hydroxy-4-(4-pyridine azo) anilino-N,N-bis(ethyl-2-phosphonic acid) provided by the present application is a D-π-A conjugated molecule formed by an amine group benzene as an electron donor (D), a diazene as an intermediate conjugated bridge (π bond), and a pyridine ring as an electron acceptor (A), which are chemically bonded. It has intramolecular charge transfer and typical molecular charge separation characteristics, so the 3-hydroxy-4-(4-pyridine azo) anilino-N,N-bis(ethyl-2-phosphonic acid) belongs to an intrinsic dipole molecule, which is a medium for electric field polarization and has a stimulus-response characteristic to the electric field.

[0010] ② The 3-hydroxy-4-(4-pyridine azo) anilino-N,N-bis(ethyl-2-phosphonic acid) provided by the present application has multiple tautomers:

[0011]

[0012] .

[0013] ③ The 3-hydroxy-4-(4-pyridine azo) anilino-N,N-bis(ethyl-2-phosphonic acid) provided by the present application has intramolecular hydrogen bonding between the hydroxyl group and the azo group in the molecular structure, which can absorb ultraviolet light and release heat in the relaxation process, effectively reducing the temperature rise caused by light irradiation. See the following formula:

[0014] .

[0015] ④ The 3-hydroxy-4-(4-pyridine azo) anilino-N,N-bis(ethyl-2-phosphonic acid) provided by the present application has good water solubility and pH response color change characteristics. See the following formula:

[0016]

[0017] ⑤The 3-hydroxy-4-(4-pyridine azo) aniline-N,N-bis(ethyl-2-phosphonic acid) molecule has O,O and O,N chelating ligands, which have chelating color change reaction or precipitation reaction with heavy metal ions.

[0018] ⑥The 3-hydroxy-4-(4-pyridine azo) aniline-N,N-bis(ethyl-2-phosphonic acid) can strongly absorb ultraviolet light in the 250-400 nm region in a neutral or weakly alkaline aqueous solution, see Figure 1 .

[0019] The preparation method of the 3-hydroxy-4-(4-pyridine azo) aniline-N,N-bis(ethyl-2-phosphonic acid) is as follows: 4-aminopyridine is weighed and dissolved in 20-30% hydrochloric acid to prepare a 30-40% 4-aminopyridine solution, and the temperature of the 4-aminopyridine solution is controlled at -5-0°C for standby; sodium nitrite is weighed and added to deionized water to prepare a 10-40% sodium nitrite aqueous solution, and the temperature of the sodium nitrite aqueous solution is controlled at -5-0°C for standby; 3-hydroxyaniline-N,N-bis(ethyl-2-phosphonic acid) is weighed and dissolved in deionized water to prepare a 30-60% 3-hydroxyaniline-N,N-bis(ethyl-2-phosphonic acid) aqueous solution, and the pH value of the 3-hydroxyaniline-N,N-bis(ethyl-2-phosphonic acid) aqueous solution is adjusted to 7.5-9.5 using an appropriate amount of 30% aqueous alkali solution, and the temperature of the 3-hydroxyaniline-N,N-bis(ethyl-2-phosphonic acid) aqueous solution is controlled at -5-0°C for standby; in the order of 4-aminopyridine solution, sodium nitrite aqueous solution, and 3-hydroxyaniline-N,N-bis(ethyl-2-phosphonic acid) aqueous solution, batch by batch, with an interval of 3-30 minutes, they are alternately added to a continuous reactor, and diazotization reaction and azoization reaction are carried out under sufficient stirring; after the addition of 4-aminopyridine solution, sodium nitrite aqueous solution, and 3-hydroxyaniline-N,N-bis(ethyl-2-phosphonic acid) aqueous solution is completed, stirring is continued for 0.5-5.0 hours; excess nitrous acid is decomposed using an appropriate amount of urea, and the pH value of the reaction product system is adjusted to 4.5-5.5, 7.5-9.0 using 20-30% hydrochloric acid or 30% aqueous alkali solution; after sedimentation, filtration, recrystallization, and drying to constant weight, the products, i.e., 3-hydroxy-4-(4-pyridine azo) aniline-N,N-bis(ethyl-2-phosphonic acid) or 3-hydroxy-4-(4-pyridine azo) aniline-N,N-bis(ethyl-2-phosphonic acid disodium salt), are obtained, respectively, see the structural formula of formula (I) or the disodium salt of formula (I),

[0020]

[0021] The molar ratio of 4-aminopyridine, sodium nitrite and 3-hydroxyanilino-N,N-bis(ethyl-2-phosphonic acid) is 1-2:1-4:1.

[0022] The preparation method of the 3-hydroxyanilino-N,N-bis(ethyl-2-phosphonic acid) is as follows: the solvent, m-aminophenol is sequentially added into a reaction kettle, the temperature of the material in the reaction kettle is controlled to 60-65 DEG C under N2 protection, and then the vinyl phosphonate is slowly added into the reaction kettle, after the vinyl phosphonate is completely added, the temperature of the material in the reaction kettle is increased to 80-90 DEG C, and the stirring reaction is continued for 8-24 hours, and then the consumption of m-aminophenol is tested, and after the solvent is recovered by distillation, the excessive vinyl phosphonate is recovered by negative pressure rotary evaporation; then, the molar concentration of hydrochloric acid is 5.0-10.0 mol / L, the residual material in the reaction kettle after distillation is dispersed and dissolved, the stirring reflux reaction is carried out for 22 hours, and then the pH of the hydrolysis product system in the reaction kettle is adjusted to 2.5-4.5 and 7.5-8.5 by using the mass percentage concentration of 30% sodium hydroxide aqueous solution after cooling, and then the 3-hydroxyanilino-N,N-bis(ethyl-2-phosphonic acid) with the chemical structure shown in formula (II) or the 3-hydroxyanilino-N,N-bis(ethyl-2-phosphonic acid disodium salt) with the structure of the disodium salt of formula (II) is prepared by filtration, washing, recrystallization and vacuum drying to constant weight.

[0023] .

[0024] The mass ratio of the amount of m-aminophenol, vinyl phosphonate, solvent and hydrochloric acid is 1:0.5-3:0.5-3:0.5-5.

[0025] The vinyl phosphonate refers to one of dimethyl vinyl phosphonate, diethyl vinyl phosphonate, dipropyl vinyl phosphonate and dibutyl vinyl phosphonate.

[0026] The solvent refers to one or more than two of methanol, ethanol, propanol, chloroform, tetrahydrofuran, 1,4-dioxane, acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide and N,N-dimethylacetamide.

[0027] The 3-hydroxy-4-(4'-pyridine azo) anilino-N,N-bis(ethyl-2-phosphonic acid) has the following beneficial effects:

[0028] ① The raw materials for preparing the 3-hydroxy-4-(4-pyridine azo) anilino-N,N-bis(ethyl-2-phosphonic acid) are all commercially available, the preparation method is simple, the product yield is high, the purification technology is simple, and the process is easy to implement.

[0029] The water solubility of the 3-hydroxy-4-(4-pyridine azo) anilino-N,N-bis(ethyl-2-phosphonic acid) or 3-hydroxy-4-(4-pyridine azo) anilino-N,N-bis(ethyl-2-phosphonic acid disodium salt) is good. If it is used in artificial hydrogel materials with photoelectric function, the addition amount is large, the dispersibility is high, the material stability is high, and the stimulus response degree is high; if the 3-hydroxy-4-(4-pyridine azo) anilino-N,N-bis(ethyl-2-phosphonic acid) or 3-hydroxy-4-(4-pyridine azo) anilino-N,N-bis(ethyl-2-phosphonic acid disodium salt) is used as a hole transport material or an ultraviolet-resistant stabilizer in a perovskite solar cell, a water solution can be sprayed or immersed, a P-O-M (M refers to Sn or In metal ions) bonding effect is formed between the ITO film and the bisphosphonic acid, and a firm SAM thin film is formed on the surface of the ITO film; meanwhile, the pyridine ring at the other end of the molecular structure can coordinate with heavy metal ions of the perovskite light-absorbing layer, and a firm adsorption effect on the perovskite light-absorbing layer is generated, which can achieve the effect of killing two birds with one stone in eliminating the interlayer gap of the perovskite solar cell assembly, reducing the interlayer series resistance of the perovskite solar cell, and improving the stability of the perovskite solar cell. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is the ultraviolet-visible light absorption spectrum diagram of 3-hydroxy-4-(4-pyridine azo) anilino-N,N-bis(ethyl-2-phosphonic acid) in different pH value aqueous solutions. DETAILED DESCRIPTION

[0031] In order to further understand the present application, the 3-hydroxy-4-(4-pyridine azo) anilino-N,N-bis(ethyl-2-phosphonic acid) and the preparation method thereof are specifically described by examples and comparative examples, and the purpose is to better understand the content of the present application.

[0032] Example 1 Preparation of 3-hydroxy-4-(4-pyridine azo) anilino-N,N-bis(ethyl-2-phosphonic acid)

[0033] Weigh 30 g of isopropanol and 10.2 g of m-aminophenol and add them sequentially to a reaction vessel. Under N2 protection, adjust the temperature of the materials in the reaction vessel to 60-65°C and stir until completely dissolved. Then, slowly add 40 g of dimethyl vinylphosphonate to the reaction vessel. After the dimethyl vinylphosphonate has been added, raise the temperature of the materials in the reaction vessel to 80-90°C and continue stirring for 8 hours. After the m-aminophenol has been consumed, distill to recover the isopropanol, and then recover the excess dimethyl vinylphosphonate by rotary evaporation under negative pressure. Finally, add 50 g of molybdenum... The residue in the reaction vessel after distillation was dispersed and dissolved in 5.5 mol / L hydrochloric acid. The mixture was stirred and refluxed for 22 hours to complete the acid-catalyzed hydrolysis reaction. After cooling, the pH of the hydrolysis product system in the reaction vessel was adjusted to 8.0–8.5 using a 30% sodium hydroxide aqueous solution. Following precipitation, filtration, washing with isopropanol, recrystallization with water, and vacuum drying to constant weight, 28.6 g of a white powder product was obtained. Based on m-aminophenol as the limited raw material, the yield of the white crystalline product was 82.9%, with a melting point >300℃ (thermal decomposition). Elemental analysis of the white crystalline product showed: C 32.27%, H 3.93%, N 3.97%, P 16.13%, consistent with the molecular formula C 10 H 15 The calculated values ​​of NO7P2Na2 (32.54%), H (4.01%), N (3.79%), and P (16.78%) are consistent. The FT-IR spectrum of the white crystalline product (cm²) is also shown. -1 The characteristic peaks of KBr tablets include: 3346 cm⁻¹ -1 The characteristic absorption peak of POH is at 3273 cm⁻¹. -1 The characteristic absorption peak of OH on the hydroxyl benzene ring is 3037 cm⁻¹. -1 These are characteristic absorption peaks of the benzene ring CH, at 1608 and 1452 cm⁻¹. -1 The characteristic absorption peak of the C=C ring of benzene is 1343 cm⁻¹. -1 1231 is the characteristic absorption peak of CN, and 1259 cm⁻¹ is the characteristic absorption peak of CNC. -1 The characteristic absorption peak of the P=O double bond is 936 cm⁻¹. -1 The characteristic absorption peak of POH is located at [value missing]. White crystalline product. 1 ¹H-NMR spectra (TMS as internal standard, D₂O, ẟ): 1.64 (t, 4H), 3.42 (t, 4H), 5.12 (s, 1H), 6.06~7.03 (m, 3H). Based on the above analytical characterization results, the white crystalline product was confirmed to be 3-hydroxyaniline-N,N-bis(ethyl-2-phosphonic acid disodium salt) with the structural characteristics shown by the disodium salt of formula (II).

[0034] .

[0035] 28.6 g of 3-hydroxyaniline-N,N-bis(ethyl-2-phosphonate disodium salt) was dissolved in deionized water at room temperature to prepare a saturated aqueous solution. The pH was adjusted to 2.8–3.2 using an appropriate amount of 30% hydrochloric acid. The solution was allowed to stand for 24 hours at 0–2 °C. After precipitation, filtration, recrystallization with ethanol, and drying to constant weight, 24.2 g of a white crystalline product with a melting point of 111.5–114.0 °C was obtained. Elemental analysis of the white crystalline product showed: C 36.66%, H 5.28%, N 4.27%, P 19.03%, which is consistent with the designed molecular formula C 10 H 17 The calculated values ​​of NO7P2 (36.93%), H (5.27%), N (4.31%), and P (19.05%) are consistent. The infrared spectrum (IR(cm⁻¹) of the white crystalline product is also consistent. -1 The characteristic peaks of KBr tablets include: 3342 cm⁻¹ -1 This is the characteristic absorption peak of POH, at 3276 cm⁻¹. -1 The characteristic absorption peak of OH on the hydroxyl benzene ring is 3032 cm⁻¹. -1 These are characteristic absorption peaks of the benzene ring CH, at 1634 and 1438 cm⁻¹. -1 The characteristic absorption peak of the C=C ring of benzene is 1345 cm⁻¹. -1 The characteristic absorption peak of CN is at 1261 cm⁻¹. -1 The characteristic absorption peak of the P=O double bond is 937 cm⁻¹. -1 The characteristic absorption peak of POH is located at [value missing]. White crystalline product. 1 ¹H-NMR spectra (TMS as internal standard, D₂O, ẟ): 1.62 (t, 4H), 3.41 (t, 4H), 5.04 (s, 1H), 6.06~6.93 (m, 3H). Based on the above analytical characterization results, the white crystalline product was confirmed to be 3-hydroxyaniline-N,N-bis(ethyl-2-phosphonic acid) with the chemical structure shown in formula (II).

[0036] .

[0037] Example 2 Preparation of 3-hydroxy-4-(4-pyridiniazo)aniline-N,N-bis(ethyl-2-phosphonic acid)

[0038] Take 16 grams (0.17 mol) of 4-aminopyridine and dissolve it in 40 grams of 30% mass concentration hydrochloric acid to prepare a 4-aminopyridine solution, control the temperature of the 4-aminopyridine solution to be -5~0 ℃, and prepare it for use; take 18.6 grams (0.26 mol) of sodium nitrite and add it to 50 grams of deionized water to prepare a sodium nitrite aqueous solution, and control the temperature of the sodium nitrite aqueous solution to be -5~0 ℃, and prepare it for use; take 33 grams (0.11 mol) of 3-hydroxyanilino-N,N-bis(ethyl-2-phosphonic acid) and dissolve it in 60 grams of deionized water, use an appropriate amount of 30% mass concentration aqueous alkali to adjust the pH value of the 3-hydroxyanilino-N,N-bis(ethyl-2-phosphonic acid) aqueous solution to be 8.5~9.5, and control the temperature of the 3-hydroxyanilino-N,N-bis(ethyl-2-phosphonic acid) aqueous solution to be -5~0 ℃, and prepare it for use; in the order of time, in batches, and with an interval of 3~5 minutes, alternately add the 4-aminopyridine solution, the sodium nitrite aqueous solution, and the 3-hydroxyanilino-N,N-bis(ethyl-2-phosphonic acid) aqueous solution into the continuous reactor to carry out diazotization and azo coupling reactions. After the 4-aminopyridine solution, the sodium nitrite aqueous solution, and the 3-hydroxyanilino-N,N-bis(ethyl-2-phosphonic acid) aqueous solution are added, continue to stir for 2 hours, use an appropriate amount of urea to decompose excess nitrous acid, and then use an appropriate amount of 30% mass concentration aqueous alkali to adjust the pH value of the product system after the azo coupling reaction to be 7.5~8.3, carry out sedimentation, filtration, recrystallization, and drying to constant weight to prepare 45.1 grams of an orange yellow powdery product. The orange yellow powdery product is analyzed by elemental analysis (%): C 37.81, H 3.73, N 11.83, P 12.64, which is consistent with the calculated values of C 15 H 18 N4O7P2Na2: C 37.99, H 3.83, N 11.81, P 13.06. The IR (KBr pellet, cm -1 ): 3434, 3337, 2928, 2867, 1634, 1544, 1441, 1361, 1262, 1102, 1028, 924 of the orange yellow powdery product are respectively attributed to O-H, methyl C-H, methylene C-H, C=C, C-N, P=O, C-O, and P-O characteristic vibration absorption peaks; 1 H-NMR (TMS as an internal standard, D2O, δ): 1.67 (t, 4H), 3.44 (t, 4H), 5.57 (s, 1H), 6.06~6.13 (m, 2H), 6.89 (m, 1H), 8.08 (d, 2H), 8.78 (d, 2H); the orange yellow powdery product is analyzed by elemental analysis, IR, and 1H-NMR analysis results, comprehensive confirmation of the orange powder product is the structure of the 3-hydroxy-4-(4-pyridine azo) aniline N, N-bis (ethyl-2-phosphonic acid disodium salt) of formula (1) :

[0039]

[0040] 45.1 grams of 3-hydroxy-4-(4-pyridine azo) aniline N, N-bis (ethyl-2-phosphonic acid disodium salt) was dissolved in deionized water to prepare a saturated aqueous solution at room temperature, and the pH was adjusted to 5.4-5.5 using an appropriate amount of 30% mass concentration hydrochloric acid. The solution was allowed to stand at 0-2°C for 24 hours. After precipitation, filtration, ethanol recrystallization and drying to constant weight, 37.6 grams of orange red powder product was obtained. The elemental analysis of the orange red powder product (%): C 41.81, H 4.63, N 12.93, P 14.38, which is consistent with the calculated value of C 15 H 20 N4O7P2 C 41.87, H 4.68, N 13.02, P 14.40. The IR (KBr pellet, cm -1 ): 3436, 3341, 2931, 2866, 1638, 1545, 1443, 1362, 1261, 1108, 1023, 927 respectively belong to O-H, methyl C-H, methylene C-H, C=C, C-N, P=O, C-O, P-O characteristic vibration absorption peaks; 1 H-NMR (TMS as internal standard, D2O, ẟ): 1.66 (t, 4H), 3.42 (t, 4H), 5.37 (s, 1H), 6.06-7.02 (m, 3H), 8.07 (d, 2H), 8.77 (d, 2H); MS m / z: 429.0781 (M-1). According to the elemental analysis, IR, 1 H-NMR and MS analysis results of the orange red powder product, it is confirmed that the 3-hydroxy-4-(4-pyridine azo) aniline N, N-bis (ethyl-2-phosphonic acid) of formula (I) is shown in the chemical structure:

[0041]

[0042] Preparation of 3-hydroxy-4-(phenyl azo) aniline N, N-bis (ethyl-2-phosphonic acid) in Comparative Example 1

[0043] According to the preparation steps and methods of Example 2, 4-aminopyridine is replaced by aniline, and bright yellow 3-hydroxy-4-(phenyl azo) aniline N, N-bis (ethyl-2-phosphonic acid) can be prepared, and its chemical structure is as follows:

[0044] 。

[0045] Dissolubility of the product of Example 2, the product of Comparative Example 1

[0046] In 10 grams of deionized water, ethanol, ethyl acetate, acetonitrile, or toluene, respectively, 3-hydroxy-4-(4-pyridine azo) anilino-N,N-bis(ethyl-2-phosphonic acid) in Example 2, 3-hydroxy-4-(phenyl azo) anilino-N,N-bis(ethyl-2-phosphonic acid) in Comparative Example 1 were added, and dissolved by temperature control oscillation for 24 hours, and the dissolution was observed, and the results are shown in Table 1.

[0047] Table 1 Dissolubility of the product of Example 2, the product of Comparative Example 1 ＊

[0048]

[0049] *Note: The easy solubility means that the room temperature dissolution amount of the product of Example 2 or the product of Comparative Example 1 in 10 grams of solvent is greater than 2 grams; the hot solubility means that the dissolution amount of the product of Example 2 or the product of Comparative Example 1 in 10 grams of solvent at a temperature of 60°C is greater than 1 gram; and the poor solubility means that the dissolution amount of the product of Example 2 or the product of Comparative Example 1 in 10 grams of solvent at room temperature and at a temperature of 80°C is less than 0.5 gram.

[0050] Example 3 Absorption light properties of the product of Example 2 and the product of Comparative Example 1 in aqueous solutions of different pH values

[0051] The product of Example 2 and the product of Comparative Example 1 were dissolved in deionized water to prepare aqueous solutions with a molar concentration of 10 -5 mol / L, and the pH value of the reaction product system was adjusted to 2-11 using 20-30% hydrochloric acid or 30% aqueous sodium hydroxide solution with a mass percentage, and the maximum absorption wavelength of the ultraviolet-visible light absorption spectrum of the aqueous solution of the product of Example 2 and the product of Comparative Example 1 in aqueous solutions of different pH values was tested using a prism 759S type ultraviolet-visible light spectrophotometer, and the results are shown in Table 2.

[0052] Table 2 Absorption light properties

[0053]

[0054] The results shown in Table 2 show the maximum absorption wavelength of the ultraviolet-visible light absorption spectrum of 3-hydroxy-4-(4-pyridine azo) anilino-N,N-bis(ethyl-2-phosphonic acid) in aqueous solutions of different pH values ​The change is significant. This can be due to the color base and auxiliary color base in the molecular structure of 3-hydroxy-4-(4-pyridine azo) aniline-N,N-bis(ethyl-2-phosphonic acid) in aqueous solution at different pH values, the protonation and deprotonation reaction occurs, and different degrees of push-pull electron effect is formed, which affects the electron cloud distribution in the D-π-A conjugated system of the molecule, so that the π-π * The energy level of electronic transition changes significantly, thereby causing the ultraviolet-visible light absorption of 3-hydroxy-4-(4-pyridine azo) aniline-N,N-bis(ethyl-2-phosphonic acid) in aqueous solution at different pH values The change is significant, so 3-hydroxy-4-(4-pyridine azo) aniline-N,N-bis(ethyl-2-phosphonic acid) can be used as a pH response color-changing functional material. In the comparative example 1, the color base and auxiliary color base in the molecular structure of 3-hydroxy-4-(phenyl azo) aniline-N,N-bis(ethyl-2-phosphonic acid) are difficult to appear similar protonation reaction and deprotonation reaction of pyridine ring in aqueous solution at different pH values, of course, it will not significantly affect the electron cloud distribution of the benzene ring-π-benzene ring conjugated system in its molecular structure, so the π-π * The change of electronic transition energy level is not obvious, so the maximum absorption wavelength of the ultraviolet-visible light absorption spectrum of 3-hydroxy-4-(phenyl azo) aniline-N,N-bis(ethyl-2-phosphonic acid) in aqueous solution at different pH values The change is not significant.

[0055] The above are preferred embodiments of the present application. For those skilled in the art, various equivalent forms of the present application can be modified without departing from the principles of the present application, and all modifications within the scope of the appended claims are within the protection scope of the present application.

Claims

1. 3-Hydroxy-4-(4-pyridiniazo)anilino-N,N-bis(ethyl-2-phosphonic acid), characterized in that: It has the chemical structure shown in formula (Ⅰ): 。 2. A method for preparing the 3-hydroxy-4-(4-pyridiniazo)anilino-N,N-bis(ethyl-2-phosphonic acid) according to claim 1, characterized in that: The preparation method is as follows: Weigh 4-aminopyridine and dissolve it in 20-30% hydrochloric acid to prepare a 30-40% 4-aminopyridine solution. Maintain the temperature of the 4-aminopyridine solution at -5-0℃ for later use. Separately, weigh sodium nitrite and add it to deionized water to prepare a 10-40% sodium nitrite aqueous solution, maintaining the temperature of the sodium nitrite aqueous solution at -5-0℃ for later use. Next, weigh 3-hydroxyaniline-N,N-bis(ethyl-2-phosphonic acid) and dissolve it in deionized water to prepare a 30-60% 3-hydroxyaniline-N,N-bis(ethyl-2-phosphonic acid) aqueous solution. Adjust the pH of the 3-hydroxyaniline-N,N-bis(ethyl-2-phosphonic acid) aqueous solution to 7.5-9.5 using an appropriate amount of 30% sodium hydroxide aqueous solution, and maintain the pH of the 3-hydroxyaniline-N,N-bis(ethyl-2-phosphonic acid) aqueous solution at -5-0℃ for later use. The aqueous solution of 2-phosphonic acid is cooled to -5~0℃ and set aside. In a sequential, batch-by-batch manner with intervals of 3~30 minutes, 4-aminopyridine solution, sodium nitrite aqueous solution, and 3-hydroxyaniline-N,N-bis(ethyl-2-phosphonic acid) aqueous solution are alternately added to a continuous reactor. Diazotization and azotization reactions are carried out under thorough stirring. After the addition of 4-aminopyridine solution, sodium nitrite aqueous solution, and 3-hydroxyaniline-N,N-bis(ethyl-2-phosphonic acid) aqueous solution is complete, the reaction is stirred for another 0.5~5.0 hours. Excess nitrite is decomposed using an appropriate amount of urea. The pH of the reaction product system is adjusted to 4.5~5.5 using 20~30% hydrochloric acid or 30% sodium hydroxide aqueous solution. After precipitation, filtration, recrystallization, and drying to constant weight, the product obtained is 3-hydroxy-4-(4-pyridineazo)aniline-N,N-bis(ethyl-2-phosphonic acid). The molar ratio of 4-aminopyridine, sodium nitrite, and 3-hydroxyaniline-N,N-bis(ethyl-2-phosphonic acid) is 1~2:1~4:1; The 3-hydroxyaniline-N,N-bis(ethyl-2-phosphonic acid) has the chemical structure shown in formula (II): 。 3. The method for preparing 3-hydroxy-4-(4-pyridiniazo)anilino-N,N-bis(ethyl-2-phosphonic acid) according to claim 2, characterized in that: The preparation method of the 3-hydroxyaniline-N,N-bis(ethyl-2-phosphonic acid) is as follows: Solvent and m-aminophenol are weighed and sequentially added to a reaction vessel. Under N2 protection, the temperature of the material inside the reaction vessel is adjusted to 60-65°C, and the mixture is stirred until completely dissolved. Then, vinyl phosphonate is slowly added to the reaction vessel. After the vinyl phosphonate is added, the temperature of the material inside the reaction vessel is increased to 80-90°C, and the reaction is continued with stirring for 8-24 hours. After confirming that the m-aminophenol has been completely consumed, the solvent is recovered by distillation, and then the mixture is subjected to negative pressure cyclone reaction. Excess vinyl phosphonate was recovered by distillation; then, hydrochloric acid with a molar concentration of 5.0~10.0 mol / L was added to the reactor to disperse and dissolve the residue in the reactor after distillation. The mixture was stirred and refluxed for 22 hours. After cooling, the pH of the hydrolysis product system in the reactor was adjusted to 2.5~4.5 with a 30% sodium hydroxide aqueous solution. After filtration, washing, recrystallization, and drying to constant weight, 3-hydroxyaniline-N,N-bis(ethyl-2-phosphonic acid) with the chemical structure shown in formula (II) was obtained. The mass ratio of intermediate aminophenol, vinyl phosphonate, solvent, and hydrochloric acid is 1:0.5~3:0.5~3:0.5~5.

4. The method for preparing 3-hydroxy-4-(4-pyridiniazo)aniline-N,N-bis(ethyl-2-phosphonic acid) according to claim 3, characterized in that... The vinyl phosphonate refers to one of vinylphosphonate dimethyl ester, vinylphosphonate diethyl ester, vinylphosphonate dipropyl ester, or vinylphosphonate dibutyl ester.

5. The method for preparing 3-hydroxy-4-(4-pyridiniazo)aniline-N,N-bis(ethyl-2-phosphonic acid) according to claim 3, characterized in that... The solvent refers to one or more of methanol, ethanol, propanol, chloroform, tetrahydrofuran, 1,4-dioxane, acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide, or N,N-dimethylacetamide.

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