A pyridinium porphyrin complex and a method for synthesizing the same

Abstract

The application belongs to the technical field of compound synthesis, and particularly relates to a pyridinium porphyrin complex and a synthesis method thereof. The pyridinium porphyrin complex has a structure as shown in formula (I). The application provides a synthesis method of the pyridinium porphyrin complex. The synthesis method takes p-nitrobenzaldehyde and pyrrole as raw materials, and realizes preparation of a target product through four core reactions. The method route is novel in design, each reaction condition is mild and controllable, the operation process is simple, the product yield and purity are high, and the method is suitable for scale-up synthesis, and provides an efficient and feasible technical path for preparation of the pyridinium porphyrin complex. Formula (I)

Description

Technical Field

[0001] This invention belongs to the field of compound synthesis technology, specifically relating to a pyridinium porphyrin complex and its synthesis method. Background Technology

[0002] Pyridinium porphyrin complexes, a class of compounds possessing both the macrocyclic structure of porphyrin and the functional properties of pyridinium groups, exhibit unique electronic structures and chemical properties, demonstrating significant application value in catalysis, biomedicine, and energy fields in recent years. With the increasing demand for functionalization, researchers have significantly improved photoelectric conversion efficiency and catalytic activity by introducing pyridine groups to construct two-dimensional or three-dimensional metal-organic frameworks (MOFs). The introduction of pyridinium groups further enhances the functionalization properties of porphyrin complexes. For example, converting pyridine nitrogen atoms into positively charged pyridinium ions through alkylation reactions can improve the water solubility and biocompatibility of compounds, while also endowing them with antibacterial and photoresponsive properties. These structures have shown excellent performance in photodynamic therapy and catalytic oxidation. Summary of the Invention

[0003] To address the shortcomings and deficiencies of existing technologies, the primary objective of this invention is to provide a pyridinium porphyrin complex.

[0004] Another object of the present invention is to provide a method for synthesizing pyridinium porphyrin complexes.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A pyridinium porphyrin complex has the structure shown in formula (I):

[0007] Formula (I);

[0008] In the formula, M is a transition metal element, L1 and L2 are monodentate ligands, and A is a counter anion.

[0009] Preferably, the transition metal is Fe, Cu, Co, or Ni; A is Cl, Br, BF4, or PF6; and n is 4.

[0010] The pyridinium porphyrin complex of this invention is prepared from p-nitrobenzaldehyde and pyrrole through a four-step core reaction. First, p-nitrobenzaldehyde and pyrrole undergo an oxidative cyclization reaction to construct a porphyrin core, yielding tetra(4-nitrophenyl)porphyrin. Subsequently, the nitro group is converted to an amino group via a reduction reaction, generating tetra(4-aminophenyl)porphyrin. Then, it undergoes a Zincke reaction with the 1-(2,4-dinitrophenyl)-4-phenyl-1-pyridinium salt obtained by nucleophilic substitution of 1-chloro-2,4-dinitrobenzene and 4-phenylpyridine to synthesize the tetrapyridinium porphyrin ligand. Finally, the tetrapyridinium porphyrin ligand is chelated with a metal salt to obtain the final pyridinium porphyrin complex. The synthetic route is as follows:

[0011] .

[0012] The preparation method of the pyridinium porphyrin complex of the present invention includes the following steps:

[0013] Step (1): p-Nitrobenzaldehyde and pyrrole are heated under acid catalysis and refluxed, and oxidative cyclization is carried out to generate tetra(4-nitrophenyl)porphyrin (compound (V));

[0014] Step (2): Tetra(4-nitrophenyl)porphyrin is reduced to amino group by a reducing agent to obtain tetra(4-aminophenyl)porphyrin (compound (IV)).

[0015] Step (3): Tetra(4-aminophenyl)porphyrin reacts with 1-chloro-2,4-dinitrobenzene (compound (III)) under reflux conditions to undergo a Zincke reaction, and the target product tetrapyridinium porphyrin, i.e. compound (II), is obtained by amine exchange.

[0016] Step (4): Compound (II) and metal salt undergo a chelation reaction under reflux to obtain the pyridinium porphyrin complex (compound (I)).

[0017] The reaction solvent used in step (4) of this invention is selected from at least one of tetrahydrofuran, 1,4-dioxane, pyridine, N,N-dimethylformamide, N,N-dimethylacetamide, or N-methylpyrrolidone; preferably, N,N-dimethylformamide is used as the solvent. The weight ratio of the reaction solvent to compound (II) is 20-100:1, preferably 50:1.

[0018] The salt-forming reagent (metal salt) in step (4) of the present invention is selected from at least one of the acetate, chloride and hydrate of transition metal elements, preferably acetate or chloride.

[0019] In step (4) of this invention, the molar ratio of reactant compound (II) to metal salt is compound (II): metal salt = 1:5-50, preferably 1:10.

[0020] The reaction time in step (4) of this invention is 6-12 hours, preferably 6-8 hours.

[0021] The reaction temperature in step (4) of the present invention is 80-140℃, preferably 80-100℃, 100-120℃ or 120-140℃, and more preferably 130-140℃.

[0022] The step (4) described in this invention further includes: after the reaction is completed, adding an extraction solvent to the reaction solution for extraction, collecting the upper organic phase, and concentrating the organic phase; then adding a slurrying solvent to the concentrate for slurrying, filtering, and finally drying the filter cake.

[0023] More preferably, the extraction solvent is selected from ethyl acetate, dichloromethane, tetrahydrofuran, n-butanol, acetonitrile, acetone, purified water, 15% sodium chloride aqueous solution, or saturated saline solution, with acetonitrile and saturated saline solution being preferred solvents.

[0024] More preferably, the pulping solvent is selected from at least one of methanol, ethanol, isopropanol, acetonitrile, acetone, water, or saturated brine, or a combination of two or more of them, preferably purified water or 2M dilute hydrochloric acid. The weight ratio of the pulping solvent to complex (II) is 50-200:1, preferably 100:1. The pulping temperature is 20-60℃, preferably 20-30℃, 30-40℃, 40-50℃, or 50-60℃; the pulping time is 2-10 hours, preferably 4-6 hours.

[0025] More preferably, the drying temperature is 40-70°C, more preferably 40-50°C, 50-60°C or 60-70°C; the drying time is 2-10 hours, more preferably 6-8 hours.

[0026] The reaction solvent used in step (3) of this invention is selected from at least one of methanol, ethanol, acetonitrile, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, or N-methylpyrrolidone; preferably, ethanol is used as the solvent. The weight ratio of the reaction solvent to compound (IV) is 20-100:1, preferably 50:1.

[0027] In step (3) of this invention, the molar ratio of tetra(4-aminophenyl)porphyrin (compound (IV)) to compound (III) is compound (IV):compound (III) = 1:5-50, preferably 1:8.

[0028] The reaction time in step (3) of this invention is 1-7 days, preferably 3-4 days.

[0029] The reaction temperature in step (3) of this invention is 50-80℃, preferably 50-60℃, 60-70℃ or 70-80℃.

[0030] The step (3) described in this invention further includes: filtering the reaction solution after the reaction is completed, washing the filter cake; then adding a slurrying solvent to the filter cake, slurrying, filtering, and finally drying the filter cake.

[0031] More preferably, the pulping solvent is selected from at least one of methanol, ethanol, isopropanol, acetonitrile, acetone, purified water, or saturated brine; preferably, the solvent is acetone or ethanol. The weight ratio of the pulping solvent to compound (II) is 5-50:1, preferably 10:1. The pulping temperature is 20-60℃, preferably 30-40℃, 40-50℃, 50-60℃, or 60-70℃; the pulping time is 2-10 hours, preferably 6-8 hours.

[0032] More preferably, the drying temperature is 40-70℃, more preferably 40-50℃, 50-60℃ or 60-70℃; the drying time is 2-12h, more preferably 4-6h.

[0033] The reaction solvent in step (2) of this invention is selected from at least one of methanol, ethanol, concentrated hydrochloric acid, 6 mol / L hydrochloric acid, acetonitrile, and tetrahydrofuran, with concentrated hydrochloric acid being the preferred solvent. The weight ratio of the reaction solvent to tetrakis(4-nitrophenyl)porphyrin (compound (V)) is 20-100:1, preferably 50:1.

[0034] In step (2) of this invention, the molar ratio of tetra(4-nitrophenyl)porphyrin to stannous chloride reducing agent is tetra(4-nitrophenyl)porphyrin:stannous chloride = 1:5-50, preferably 1:10.

[0035] In step (2) of this invention, the reaction time is 1-7h and the reaction temperature is 20-80℃, preferably 20-30℃ for 2-3h of stirring, and then heated to 70-80℃ for 1-2h of reaction.

[0036] Step (2) in this invention further includes: filtering the reaction solution after the reaction is completed, washing the filter cake; then adding a slurrying solvent to the filter cake, slurrying, filtering, and finally drying the filter cake.

[0037] More preferably, the pulping solvent is selected from at least one of methanol, ethanol, isopropanol, acetonitrile, acetone, methyl tert-butyl ether, tetrahydrofuran, and chloroform, with chloroform being the preferred solvent. The weight ratio of the pulping solvent to compound (V) is 2-20:1, preferably 4:1. The pulping temperature is 20-60℃, preferably 20-30℃, 30-40℃, 40-50℃, or 50-60℃; the pulping time is 2-10 hours, preferably 6-8 hours.

[0038] More preferably, the drying temperature is 40-60℃, more preferably 40-50℃ or 50-60℃; the drying time is 2-12h, more preferably 4-6h.

[0039] In step (1) of this invention, the reaction solvent is selected from at least one of acetic acid and propionic acid, with propionic acid being the preferred solvent. The weight ratio of the reaction solvent to p-nitrobenzaldehyde is 20-100:1, preferably 40:1.

[0040] In step (1) of this invention, the molar ratio of the reactants p-nitrobenzaldehyde, pyrrole and acetic anhydride is p-nitrobenzaldehyde:pyrrole:acetic anhydride = 1:1-10:1-10, preferably 1:1:2.

[0041] The reaction time in step (1) of this invention is 1-10h, preferably 2-3h.

[0042] The reaction temperature in step (1) of the present invention is 80-140℃, preferably 80-100℃, 100-120℃ or 120-140℃, and more preferably 130-140℃.

[0043] The step (1) described in this invention further includes: stirring the reaction solution to crystallize after the reaction is completed, filtering, washing the filter cake; then adding a slurrying solvent to the filter cake to slurry, filtering, and finally drying the filter cake.

[0044] More preferably, the crystallization temperature is -20-30℃, more preferably -20-0℃, 0-20℃ or 20-30℃, and even more preferably 0-10℃; the crystallization time is 12-24h, more preferably 12-20h.

[0045] More preferably, the pulping solvent is selected from at least one of methanol, ethanol, isopropanol, acetonitrile, acetone, pyridine, or purified water, with pyridine being the preferred solvent. The weight ratio of the pulping solvent to p-nitrobenzaldehyde is 10-50:1, preferably 10:1. The pulping temperature is 80-120℃, preferably 80-90℃, 90-100℃, 100-110℃, or 110-120℃; the pulping time is 2-8 hours, preferably 4-6 hours.

[0046] The starting materials known in this invention can be purchased from suppliers or synthesized by custom companies.

[0047] Unless otherwise specified in the embodiments of the present invention, the reactions can all be carried out under an argon or nitrogen atmosphere.

[0048] In this invention, an argon atmosphere or a nitrogen atmosphere refers to a continuous flow of nitrogen gas through the reaction flask, accompanied by bubbling.

[0049] Unless otherwise specified in the embodiments of this invention, "solution" refers to an aqueous solution.

[0050] Unless otherwise specified in the embodiments of the present invention, the reaction temperature is room temperature, which is 20-30℃.

[0051] The desiccant selected in the process of this invention is preferably anhydrous sodium sulfate.

[0052] The preferred concentration method described in this invention is vacuum concentration.

[0053] The preferred drying method described in this invention is vacuum drying under a nitrogen flow.

[0054] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0055] The method of this invention has a novel design, mild and controllable reaction conditions in each step, simple operation process, and high product yield and purity. It is suitable for large-scale synthesis and provides an efficient and feasible technical route for the preparation of pyridinium porphyrin complexes. Attached Figure Description

[0056] Figure 1 This is the UV-Vis absorption spectrum of compound (II-1) in N,N-dimethylformamide;

[0057] Figure 2 This is the UV-Vis absorption spectrum of the complex (I-1) in N,N-dimethylformamide;

[0058] Figure 3 This is the UV-Vis absorption spectrum of the complex (I-2) in N,N-dimethylformamide;

[0059] Figure 4 This is the UV-Vis absorption spectrum of the complex (I-3) in N,N-dimethylformamide;

[0060] Figure 5 This is the UV-Vis absorption spectrum of the complex (I-4) in N,N-dimethylformamide;

[0061] Figure 6This is a superimposed UV-Vis absorption spectrum of compounds (II-1), complex (I-1), complex (I-2), complex (I-3), and complex (I-4) in N,N-dimethylformamide;

[0062] Figure 7 It is compound (II-1) in d6-DMSO 1 H NMR spectrum;

[0063] Figure 8 It is compound (II-1) in d6-DMSO 13 C NMR spectrum. Detailed Implementation

[0064] The present invention will be further described in detail below with reference to embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto. All raw materials involved in the present invention can be purchased directly from the market. For process parameters not specifically specified, conventional techniques can be referred to.

[0065] Example 1

[0066]

[0067] first step

[0068]

[0069] At 25°C, propionic acid (600 mL, 30 V) was added to a 2 L three-necked flask. Stirring was started, and p-nitrobenzaldehyde (20 g, 1.0 eq) and acetic anhydride (27.02 g, 2.0 eq) were added. The temperature was raised to 115°C, and a solution of pyrrole (8.88 g, 1.0 eq) in propionic acid (200 mL, 10 V) was slowly added. The mixture was stirred at 135°C for 2 h, then cooled to 5°C and stirred for another 16 h. The mixture was filtered, and the filter cake was rinsed with purified water (40 mL, 2 V) and methanol (40 mL, 2 V). Pyridine (200 mL, 10 V) was added to the filter cake, and the mixture was stirred at 115°C for 5 h. After cooling to 25°C, the mixture was filtered, and the filter cake was rinsed with acetone (40 mL, 2 V). The filter cake was transferred to a vacuum drying oven and dried at 50°C under a nitrogen atmosphere to constant weight. The target compound (V) was obtained as a purplish-black solid in a yield of 22.4%. MS m / z (ESI) = 799.2 [M+H]⁺. ¹H NMR (400 MHz, Chloroform-d) δ 8.92 (d, J = 8.2 Hz, 8H), 8.78 (d, J = 8.4 Hz, 8H), 8.63 (s, 8H).

[0070] Step 2

[0071]

[0072] At 25°C, add concentrated hydrochloric acid (800 mL, 40 V) to a 2 L three-necked flask, start stirring, and slowly add compound (V) (20 g, 1.0 eq). After dispersing evenly, slowly add a solution of stannous chloride (47.6 g, 10 eq) in concentrated hydrochloric acid (200 mL, 10 V). Stir at 25°C for 2 h, then raise the temperature to 75°C and continue stirring for 1 h. Cool to 5°C and filter. Adjust the pH of the solution to approximately 7 with ammonia at 5°C. Filter and rinse the filter cake with methanol (40 mL, 2 V). Rinse with tetrahydrofuran (200 mL, 10 V) at 5°C, stir for 1 h, and filter. Concentrate the filtrate at 45°C until no condensate drips. Add chloroform (80 mL, 4 V) to the concentrate, slurry at 25°C for 7 h, filter, and rinse the filter cake with chloroform (40 mL, 2 V). The filter cake was transferred to a vacuum drying oven and dried to constant weight at 45 °C under a nitrogen atmosphere. The target compound (IV) was obtained as a purple solid, with a yield of 61%. MS m / z (ESI) = 674.3 [M+H]⁺. ¹H NMR (400 MHz, DMSO-d6) δ 8.88 (s, 8H), 7.86 (d, J = 8.2 Hz, 8H), 7.05 - 6.97 (m, 8H), 5.57 (s, 8H), 2.73 (s, 2H).

[0073] Step 3

[0074]

[0075] Ethanol (500 mL, 50 V) was added to a 2 L three-necked flask at 25 °C under a nitrogen atmosphere. Stirring was started, and compound (IV) (20 g, 1.0 eq) and compound (III-I) (83.61 g, 8.0 eq) were added. The temperature was raised to 75 °C. Stirring was continued for 4 days, followed by cooling to 25 °C. The mixture was filtered, and the filter cake was rinsed with acetone (40 mL, 2 V). Acetone (200 mL, 10 V) was added to the filter cake, and the mixture was stirred at 55 °C for 7 h. The temperature was then lowered to 25 °C, and the mixture was filtered, rinsing the filter cake with acetone (40 mL, 2 V). The filter cake was transferred to a vacuum drying oven and dried to constant weight at 45 °C under a nitrogen atmosphere. The target compound (II-I) was obtained with a yield of 72%. MS (ESI) = 308.1 [(M-4Cl) / 4]⁺. 1 H NMR (400 MHz, d 6-DMSO) 9.79 (d, = 6.9 Hz, 8H), 9.04 (s,8H), 8.95 - 8.86 (m, 8H), 8.71 - 8.57 (m, 8H), 8.48 - 8.39 (m, 8H), 8.37 -8.27 (m, 8H), 7.78 (dd, = 5.0, 2.0 Hz, 12H), 2.82 (s, 2H). 13 C NMR (101 MHz, d 6 -DMSO) 155.87, 145.09, 143.65, 142.20, 142.18, 135.46, 133.30, 132.76, 132.74, 129.94, 128.56, 124.55, 123.43, 118.77.

[0076] Step 4

[0077]

[0078] Under a nitrogen atmosphere at 25°C, N,N-dimethylformamide (500 mL, 50 V) was added to a 2 L three-necked flask. Stirring was started, and compound (II-1) (10 g, 1.0 eq) and copper acetate (13.24 g, 10 eq) were added. The temperature was raised to 135°C. The mixture was stirred for 7 h, and the reaction solution was concentrated until no condensate dripped. Acetonitrile (500 mL, 50 V) and saturated saline solution (500 mL, 50 V) were added to the concentrate. The mixture was stirred for 30 min, allowed to stand for 30 min, and then separated. The upper organic phase was collected. The organic phase was concentrated until no condensate dripped. Purified water (100 mL, 10 V) was added to the concentrate, and the mixture was stirred at 25°C for 5 h. The mixture was filtered, and the filter cake was rinsed with purified water (40 mL, 2 V). The filter cake was transferred to a vacuum drying oven and dried to constant weight at 55°C under a nitrogen atmosphere. The target complex (I-1) was obtained as a brownish-red solid with a yield of 75%. MS m / z (ESI) = 323.2 [(M-4Cl) / 4] + .

[0079] Example 2

[0080]

[0081] Under a nitrogen atmosphere at 25°C, N,N-dimethylformamide (500 mL, 50 V) was added to a 2 L three-necked flask. Stirring was started, followed by the addition of compound (II-I) (10 g, 1.0 eq) and ferric chloride (11.81 g, 10 eq). The temperature was raised to 135°C. The mixture was stirred for 7 h, and the reaction solution was concentrated until no condensate dripped. Acetonitrile (500 mL, 50 V) and saturated brine (500 mL, 50 V) were added to the concentrate, and the mixture was stirred for 30 min. After standing for 30 min, the mixture was separated, and the upper organic phase was collected. The organic phase was concentrated until no condensate dripped. 2 M dilute hydrochloric acid (100 mL, 10 V) was added to the concentrate, and the mixture was stirred at 25°C for 5 h. The mixture was filtered, and the filter cake was rinsed with purified water (40 mL, 2 V). The filter cake was transferred to a vacuum drying oven and dried to constant weight at 55°C under a nitrogen atmosphere. The target complex (I-2) was obtained as a brownish-red solid with a mass yield of 74%. MS m / z (ESI) = 321.6 [(M-5Cl) / 4]⁺.

[0082] Example 3

[0083]

[0084] Under a nitrogen atmosphere at 25°C, N,N-dimethylformamide (500 mL, 50 V) was added to a 2 L three-necked flask. Stirring was started, and compound (II-I) (10 g, 1.0 eq) and cobalt acetate (12.90 g, 10 eq) were added. The temperature was raised to 135°C. The mixture was stirred for 7 h, and the reaction solution was concentrated until no condensate dripped. Acetonitrile (500 mL, 50 V) and saturated brine (500 mL, 50 V) were added to the concentrate, and the mixture was stirred for 30 min. After standing for 30 min, the mixture was separated, and the upper organic phase was collected. The organic phase was concentrated until no condensate dripped. Purified water (100 mL, 10 V) was added to the concentrate, and the mixture was stirred at 25°C for 5 h. The mixture was filtered, and the filter cake was rinsed with purified water (40 mL, 2 V). The filter cake was transferred to a vacuum drying oven and dried to constant weight at 55°C under a nitrogen atmosphere. The target complex (I-3) was obtained as a brownish-red solid with a yield of 77%. MS (ESI) = 321.9 [(M-4Cl) / 4]⁺.

[0085] Example 4

[0086]

[0087] Under a nitrogen atmosphere at 25°C, N,N-dimethylformamide (500 mL, 50 V) was added to a 2 L three-necked flask. Stirring was started, and compound (II-I) (10 g, 1.0 eq) and nickel acetate (12.89 g, 10 eq) were added. The temperature was raised to 135°C. The mixture was stirred for 7 h, and the reaction solution was concentrated until no condensate dripped. Acetonitrile (500 mL, 50 V) and saturated brine (500 mL, 50 V) were added to the concentrate, and the mixture was stirred for 30 min. After standing for 30 min, the mixture was separated, and the upper organic phase was collected. The organic phase was concentrated until no condensate dripped. Purified water (100 mL, 10 V) was added to the concentrate, and the mixture was stirred at 25°C for 5 h. The mixture was filtered, and the filter cake was rinsed with purified water (40 mL, 2 V). The filter cake was transferred to a vacuum drying oven and dried to constant weight at 55°C under a nitrogen atmosphere. The target complex (I-4) was obtained as a brownish-red solid with a mass yield of 76%. MS m / z (ESI) = 321.6 [(M-4Cl) / 4]⁺.

[0088] Example 5

[0089]

[0090] At 25°C under a nitrogen atmosphere, ethanol (1000 mL, 100 V) was added to a 2 L three-necked flask, and stirring was started. Compound (IV) (20 g, 1.0 eq) and compound (III-I) (83.61 g, 8.0 eq) were added, and the temperature was raised to 75°C. The mixture was stirred for 4 days, then cooled to 25°C. The mixture was filtered, and the filter cake was rinsed with ethanol (40 mL, 2 V). Ethanol (200 mL, 10 V) was added to the filter cake, and the mixture was heated to 65°C and stirred for 7 h. The temperature was then lowered to 25°C, and the mixture was filtered, and the filter cake was rinsed with ethanol (40 mL, 2 V). The filter cake was transferred to a vacuum drying oven and dried to constant weight at 50°C under a nitrogen atmosphere. The target compound (II-1) was obtained with a yield of 75%. MS (ESI) = 308.1 [(M-4Cl) / 4]⁺. ¹H NMR (400 MHz, d6-DMSO) δ 9.79 (d, = 6.9 Hz, 8H), 9.04(s, 8H), 8.95 – 8.86 (m, 8H), 8.71 – 8.57 (m, 8H), 8.48 – 8.39 (m, 8H), 8.37– 8.27 (m, 8H), 7.78 (dd, = 5.0, 2.0 Hz, 12H), -2.82 (s, 2H). ¹³C NMR (101MHz, d6-DMSO) δ 155.87, 145.09, 143.65, 142.20, 142.18, 135.46, 133.30,132.76, 132.74, 129.94, 128.56, 124.55, 123.43, 118.77.

[0091] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A pyridinium porphyrin complex, characterized in that, Its structure is shown in equation (I): Equation (I); In the formula, M is a transition metal element, L1 and L2 are monodentate ligands, and A is a counter anion.

2. The pyridinium porphyrin complex according to claim 1, characterized in that, The transition metal is Fe, Cu, Co, or Ni; A is Cl, Br, BF4, or PF6; and n is 4.

3. A method for preparing a pyridinium porphyrin complex, characterized in that, Includes the following steps: Step (1): p-Nitrobenzaldehyde and pyrrole are heated under reflux with acetic anhydride catalysis, and oxidative cyclization is performed to generate tetra(4-nitrophenyl)porphyrin; Step (2): Tetra(4-nitrophenyl)porphyrin is reduced to amino group by a reducing agent to obtain tetra(4-aminophenyl)porphyrin; Step (3): Tetra(4-aminophenyl)porphyrin reacts with 1-chloro-2,4-dinitrobenzene under reflux conditions via a Zincke reaction, and the target product tetrapyridinium porphyrin is obtained by amine exchange. Step (4): Tetrapyridinium porphyrin reacts with a metal salt under reflux to prepare the pyridinium porphyrin complex.

4. The preparation method according to claim 3, characterized in that, The reaction solvent used in step (4) is selected from at least one of tetrahydrofuran, 1,4-dioxane, pyridine, N,N-dimethylformamide, N,N-dimethylacetamide or N-methylpyrrolidone; The metal salt in step (4) is selected from at least one of the acetate, chloride and hydrate of transition metal elements.

5. The preparation method according to claim 3, characterized in that, The molar ratio of the reactant tetrapyridinium porphyrin to the metal salt in step (4) is tetrapyridinium porphyrin: metal salt = 1:5-50; The reaction time in step (4) is 6-12 hours and the reaction temperature is 80-140℃.

6. The preparation method according to claim 3, characterized in that, The reaction solvent used in step (3) is selected from at least one of methanol, ethanol, acetonitrile, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide or N-methylpyrrolidone; the weight ratio of the reaction solvent to 1-chloro-2,4-dinitrobenzene is 20-100:1; The molar ratio of tetra(4-aminophenyl)porphyrin to 1-chloro-2,4-dinitrobenzene in step (3) is tetra(4-aminophenyl)porphyrin: 1-chloro-2,4-dinitrobenzene = 1:5-50.

7. The preparation method according to claim 3, characterized in that, The reaction time in step (3) is 1-7 days and the reaction temperature is 50-80℃.

8. The preparation method according to claim 3, characterized in that, The reaction solvent in step (2) is selected from at least one of methanol, ethanol, hydrochloric acid, acetonitrile and tetrahydrofuran, and the weight ratio of the reaction solvent to tetra(4-nitrophenyl)porphyrin is 20-100:1; In step (2), the molar ratio of tetra(4-nitrophenyl)porphyrin to stannous chloride reducing agent is tetra(4-nitrophenyl)porphyrin:stannous chloride = 1:5-50.

9. The preparation method according to claim 3, characterized in that, The reaction time in step (2) is 1-7 hours and the reaction temperature is 20-80℃.

10. The preparation method according to claim 3, characterized in that, The reaction solvent in step (1) is selected from at least one of acetic acid and propionic acid; the weight ratio of the reaction solvent to p-nitrobenzaldehyde is 20-100:1; The molar ratio of the reactants p-nitrobenzaldehyde, pyrrole and acetic anhydride in step (1) is p-nitrobenzaldehyde:pyrrole:acetic anhydride = 1:1-10:1-10; The reaction time in step (1) is 1-10h, and the reaction temperature is 80-140℃.

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