Nitrogen-containing heterocyclic dyes, synthesis methods and applications thereof

Abstract

The present invention provides a nitrogen-containing heterocyclic dye, a preparation method, and applications thereof. The nitrogen-containing heterocyclic compound structure is shown in formula (II): #imgabs0#, where R is H, OMe, COOMe, Br, or Cl. The dye is synthesized from 1,8-naphtholactimide and a 3,3-dimethyl-2-styrylindole derivative via a one-step condensation reaction to form a nitrogen-containing heterocyclic fluorescent dye. The nitrogen-containing heterocyclic fluorescent dye provided by the present invention has a maximum fluorescence emission wavelength of 580 nm, exhibits significant fluorescence under ultraviolet light (365 nm), and exhibits an excellent Stokes shift, indicating its promising application in the field of fluorescent anti-counterfeiting. The preparation method is simple and the raw materials are readily available.

Description

Technical Field

[0001] The present invention relates to a fluorescent dye, and more particularly to a nitrogen-containing heterocyclic compound and its synthesis and application. The dye can be widely used in the field of fluorescent holographic anti-counterfeiting. Background Art

[0002] Fluorescent anti-counterfeiting film is a type of anti-counterfeiting material with a fluorescent effect, widely used in packaging and labeling of various products. Its primary function is to enhance product identification through its fluorescent properties, preventing counterfeiting and forgery. Fluorescent anti-counterfeiting film can be inspected using ultraviolet light, offering simple detection methods and strong anti-counterfeiting properties.

[0003] 1,8-Naphtholactam is a common organic fluorescent small molecule with multiple active sites and is easily modified in terms of structure and function. However, most heterocyclic compounds based on 1,8-naphtholactam suffer from short wavelengths, small Stokes shifts, and weak penetrance. This invention designs and synthesizes a novel nitrogen-containing heterocyclic fluorescent dye with a longer wavelength, larger Stokes shift, and good penetrance. It has great potential in the fields of fluorescent holographic anti-counterfeiting packaging films and OLDE. Summary of the Invention

[0004] The main purpose of this invention is to provide a novel nitrogen-containing heterocyclic dye based on 1,8-naphtholactam. This invention overcomes the shortcomings of existing nitrogen-containing fluorescent dyes, such as relatively small Stokes shift, easy fluorescence quenching, and limited raw material availability, by providing a novel method for producing nitrogen-containing heterocyclic fluorescent dyes with a larger Stokes shift. This series of dyes, combined with acrylic resin, can quickly form films, produce clear images under a 365nm ultraviolet light source, and have excellent anti-counterfeiting properties.

[0005] The technical solutions of the present invention are as follows:

[0006] A nitrogen-containing heterocyclic fluorescent dye, wherein the chemical structural formula of the dye is shown in formula (II), wherein R is H, OMe, COOMe, Br or Cl.

[0007] .

[0008] The synthesis method of the nitrogen-containing heterocyclic fluorescent dye includes the following synthesis path:

[0009] .

[0010] In formula (I) and formula (II), R is H, OMe, COOMe, Br or Cl.

[0011] The synthesis steps of compounds B1-B5 are as follows:

[0012] 1,8-Naphtholactam and compounds A1-A5 were dissolved in toluene. After heating, the catalyst POCl3 was added. After TLC monitoring, the reaction solution was evaporated to remove the solvent under reduced pressure. Finally, the reaction solution was separated by silica gel column chromatography to obtain the corresponding orange solid compounds B1-B5.

[0013] In the steps, the molar ratio of 1,8-naphtholactam, compounds A1-A5, and POCl3 is 1: 1-2: 1-7. By changing the feeding ratio, compounds B1-B5 can be obtained in a shorter time with a higher yield.

[0014] The reflux temperature in this step is 100-140°C, and the reflux time is 1-4 hours. Selecting an appropriate reflux temperature can appropriately save costs and ensure a higher yield of compounds B1-B5. The yield can be increased to more than 20%, more preferably to more than 30%, more preferably to more than 40%, more preferably to more than 50%, and even more preferably to more than 60%. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is the hydrogen spectrum of compound B1 obtained in Example 1.

[0016] Figure 2 This is the high-resolution mass spectrum of compound B1 obtained in Example 1.

[0017] Figure 3 is the hydrogen spectrum of compound B2 obtained in Example 10.

[0018] Figure 4 This is the hydrogen spectrum of compound B3 obtained in Example 11.

[0019] Figure 5 This is the hydrogen spectrum of compound B4 obtained in Example 12.

[0020] Figure 6 This is the hydrogen spectrum of compound B5 obtained in Example 13.

[0021] Figure 7 The UV spectra (a) and fluorescence spectra (b) of the compound B1 obtained in Example 1 in toluene, dichloromethane, acetone, acetonitrile and dimethyl sulfoxide solvents respectively.

[0022] Figure 8 (a) and (b) the corresponding UV spectra of compound B2 obtained in Example 10 in toluene, dichloromethane, acetone, acetonitrile and dimethyl sulfoxide solvents.

[0023] Figure 9(a) and (b) the corresponding UV spectra of compound B3 obtained in Example 11 in toluene, dichloromethane, acetone, acetonitrile and dimethyl sulfoxide solvents.

[0024] Figure 10 The UV spectra (a) and fluorescence spectra (b) of the compound B4 obtained in Example 12 in toluene, dichloromethane, acetone, acetonitrile and dimethyl sulfoxide solvents respectively.

[0025] Figure 11 The UV spectra (a) and fluorescence spectra (b) of the compound B5 obtained in Example 13 in toluene, dichloromethane, acetone, acetonitrile and dimethyl sulfoxide solvents respectively.

[0026] Figure 12 The photos were taken under sunlight after B1 was formed at different film forming ratios in Example 15.

[0027] Figure 13 The following are photos taken under sunlight after B1 in Example 16 was formed into films at different concentrations.

[0028] Figure 14 The film formation of B1 at different concentrations in Example 16 was photographed under a 365nm light source. DETAILED DESCRIPTION

[0029] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.

[0030] Example 1

[0031] 1,8-Naphtholactimide (169.0 mg, 1.0 mmol) and Compound A1 (249 mg, 1.0 mmol) were weighed and dissolved in 15 mL of toluene. The mixture was heated and stirred. When the temperature reached 100°C, POCl3 (93 μL, 1.0 mmol) was added and refluxed for 2 h. After completion of the reaction as monitored by TLC, the mixture was neutralized with NaOH to a pH of 7-8, extracted with dichloromethane, dried by spin drying, and purified by silica gel column chromatography to obtain an orange solid Compound B1 with a yield of 13%. The reaction process was as follows:

[0032] .

[0033] Example 2

[0034] 1,8-Naphtholactimide (169.0 mg, 1.0 mmol) and Compound A1 (299 mg, 1.2 mmol) were weighed and dissolved in 15 mL of toluene. The mixture was heated and stirred. When the temperature reached 100°C, POCl3 (93 μL, 1.0 mmol) was added and refluxed for 2 h. After completion of the reaction as monitored by TLC, the mixture was neutralized with NaOH to pH 7-8, extracted with dichloromethane, dried by spin drying, and purified by silica gel column chromatography to obtain an orange solid Compound B1 with a yield of 20%. The yield of Compound B1 increased when 1.2 equivalents of Compound A1 were added.

[0035] Example 3

[0036] 1,8-Naphtholactimide (169.0 mg, 1.0 mmol) and Compound A1 (498 mg, 2 mmol) were weighed and dissolved in 15 mL of toluene. The mixture was heated and stirred. When the temperature reached 100°C, POCl3 (93 μL, 1.0 mmol) was added and refluxed for 2 h. After completion of the reaction as monitored by TLC, the mixture was neutralized with NaOH to pH 7-8, extracted with dichloromethane, dried by spin drying, and purified by silica gel column chromatography to obtain an orange solid Compound B1 with a yield of 21%. The yield of Compound B1 did not change significantly when 2 equivalents of Compound A1 were added.

[0037] Example 4

[0038] 1,8-Naphtholactimide (169.0 mg, 1.0 mmol) and compound A1 (299 mg, 1.2 mmol) were weighed and 15 mL of toluene was added. The mixture was dissolved and heated with stirring. When the temperature rose to 100°C, POCl3 (280 μL, 3.0 mmol) was added and refluxed for 2 h. After the reaction was completed by TLC monitoring, the mixture was neutralized with NaOH to pH = 7-8, extracted with dichloromethane, dried by spin drying, and purified by silica gel column chromatography to obtain an orange solid compound B1 with a yield of 29%. When 3 equivalents of POCl3 were added, the yield of compound B1 increased significantly.

[0039] Example 5

[0040] 1,8-naphtholactimide (169.0 mg, 1.0 mmol) and compound A1 (299 mg, 1.2 mmol) were weighed, and 15 mL of toluene was added. The mixture was dissolved and heated with stirring. When the temperature rose to 100°C, POCl3 (465 μL, 5.0 mmol) was added and refluxed for 4 h. After the reaction was completed by TLC monitoring, the mixture was neutralized with NaOH to pH = 7-8, extracted with dichloromethane, dried by spin drying, and purified by silica gel column chromatography to obtain an orange solid compound B1 with a yield of 30%. When 5 equivalents of POCl3 were added, the yield of compound B1 did not change much from that of Example 4.

[0041] Example 6

[0042] 1,8-Naphtholactimide (169.0 mg, 1.0 mmol) and Compound A1 (299 mg, 1.2 mmol) were weighed and dissolved in 15 mL of toluene. The mixture was heated and stirred. When the temperature rose to 120°C, POCl3 (280 μL, 3.0 mmol) was added and refluxed for 2 h. After the reaction was complete as monitored by TLC, the mixture was neutralized with NaOH to pH 7-8, extracted with dichloromethane, dried by spin drying, and purified by silica gel column chromatography to obtain an orange solid Compound B1 with a yield of 41%. Increasing the reaction temperature significantly increased the yield of Compound B1.

[0043] Example 7

[0044] 1,8-Naphtholactimide (169.0 mg, 1.0 mmol) and Compound A1 (299 mg, 1.2 mmol) were weighed and dissolved in 15 mL of toluene. The mixture was heated and stirred. When the temperature rose to 140°C, POCl3 (280 μL, 3.0 mmol) was added and refluxed for 2 h. After the reaction was completed as monitored by TLC, the mixture was neutralized with NaOH to pH 7-8, extracted with dichloromethane, dried by spin drying, and purified by silica gel column chromatography to obtain an orange solid Compound B1 with a yield of 41%. Increasing the reaction temperature had little effect on the reaction, and 120°C was considered the optimal reaction temperature.

[0045] Example 8

[0046] 1,8-Naphtholactimide (169.0 mg, 1.0 mmol) and Compound A1 (299 mg, 1.2 mmol) were weighed and dissolved in 15 mL of toluene. The mixture was heated and stirred. When the temperature rose to 140°C, POCl3 (280 μL, 3.0 mmol) was added and refluxed for 4 h. After completion of the reaction as monitored by TLC, the mixture was neutralized with NaOH to pH 7-8, extracted with dichloromethane, dried by spin drying, and purified by silica gel column chromatography to obtain an orange solid Compound B1 with a yield of 57%. Prolonging the reaction time significantly increased the yield of Compound B1.

[0047] Example 9

[0048] 1,8-naphtholactimide (169.0 mg, 1.0 mmol) and compound A1 (299 mg, 1.2 mmol) were weighed, and 15 mL of toluene was added. The mixture was dissolved and heated with stirring. When the temperature rose to 140°C, POCl3 (280 μL, 3.0 mmol) was added and refluxed for 5 h. After the reaction was completed as monitored by TLC, the mixture was neutralized with NaOH to pH = 7-8, extracted with dichloromethane, dried by spin drying, and purified by silica gel column chromatography to obtain an orange solid compound B1 with a yield of 54%. With the extension of the reaction time, the yield of compound B1 did not change much from that of Example 8.

[0049] Example 10

[0050] 1,8-naphtholactimide (169.0 mg, 1.0 mmol) and compound A2 (335 mg, 1.2 mmol) were weighed and dissolved in 15 mL of toluene. The mixture was heated and stirred. When the temperature reached 120°C, POCl3 (280 μL, 3.0 mmol) was added and refluxed for 4 h. After the reaction was complete as monitored by TLC, the mixture was neutralized with NaOH to a pH of 7-8, extracted with dichloromethane, dried by spin drying, and purified by silica gel column chromatography to obtain an orange solid compound B2 with a yield of 52%. The reaction process was as follows:

[0051] .

[0052] Example 11

[0053] 1,8-naphtholactimide (169.0 mg, 1.0 mmol) and compound A3 (368 mg, 1.2 mmol) were weighed and dissolved in 15 mL of toluene. The mixture was heated and stirred. When the temperature reached 120°C, POCl3 (280 μL, 3.0 mmol) was added and refluxed for 4 h. After the reaction was complete as monitored by TLC, the mixture was neutralized with NaOH to pH 7-8, extracted with dichloromethane, dried by spin drying, and purified by silica gel column chromatography to obtain an orange solid compound B3 with a yield of 33%. The reaction process was as follows:

[0054] .

[0055] Example 12

[0056] 1,8-Naphtholactimide (169.0 mg, 1.0 mmol) and Compound A4 (335 mg, 1.2 mmol) were weighed and dissolved in 15 mL of toluene. The mixture was heated and stirred. When the temperature reached 120°C, POCl3 (280 μL, 3.0 mmol) was added and refluxed for 4 h. After completion of the reaction as monitored by TLC, the mixture was neutralized with NaOH to a pH of 7-8, extracted with dichloromethane, dried by spin drying, and purified by silica gel column chromatography to obtain an orange solid Compound B4 with a yield of 62%. The reaction process was as follows:

[0057] .

[0058] Example 13

[0059] 1,8-Naphtholactimide (169.0 mg, 1.0 mmol) and Compound A5 (335 mg, 1.2 mmol) were weighed and dissolved in 15 mL of toluene. The mixture was heated and stirred. When the temperature reached 120°C, POCl3 (280 μL, 3.0 mmol) was added and refluxed for 4 h. After completion of the reaction as monitored by TLC, the mixture was neutralized with NaOH to a pH of 7-8, extracted with dichloromethane, dried by spin drying, and purified by silica gel column chromatography to obtain an orange solid Compound B5 with a yield of 57%. The reaction process was as follows:

[0060] .

[0061] Example 14

[0062] Weigh the compound B1 (4.0 mg, 0.01 mmol), compound B2 (4.3 mg, 0.01 mmol), compound B3 (4.6 mg, 0.01 mmol), compound B4 (4.8 mg, 0.01 mmol), and compound B5 (4.3 mg, 0.01 mmol) in Example 9, Example 10, Example 11, Example 12, and Example 13, respectively, and dissolve them in 0.1 mL of dichloromethane to a concentration of 10 -1 3 μL of each of the five mother solutions were dissolved in 3 mL of toluene, dichloromethane, acetone, acetonitrile and dimethyl sulfoxide to a concentration of 1×10 -4 M test solutions, the test solutions corresponding to the four compounds are numbered as (a), (b), (c), (d), and (e) in sequence, and all the test solutions are tested by UV and fluorescence tests, such as Figure 7-11 As shown in the figure, it can be observed that the excitation and emission wavelengths of the five compounds are very close, and the red-shift and blue-shift phenomena in different solvents are not obvious. The test results show that the optical properties of this series of substances are basically unaffected by different substituents and solvents.

[0063] Example 15

[0064] Take 5 groups of 10 μL of the mother liquor of compound B1 in Example 14, and mix them evenly with 10 μL, 20 μL, 30 μL, 40 μL, and 50 μL of acrylic resin in a ratio of 1:1, 1:2, 1:3, 1:4:, and 1:5, respectively. Apply it evenly on the glass plate, dry it in an oven at 30 degrees Celsius, place the glass plate under natural light, and take pictures with Xiaomi 12 mobile phone to obtain a clear picture, as shown below. Figure 12 It can be found that bubbles exist in the 1:2, 1:3, 1:4, and 1:5 groups of experiments after film formation, and the film formation time is relatively long. Based on the above five groups of experiments, the best film formation effect is in the 1:1 group, and the volume ratio of the compound solution to the acrylic resin is 1:1, which is the best.

[0065] Example 16

[0066] 100 μL of the mother solution of compound B1 in Example 9 was taken respectively and diluted 0-4 times (numbered as 0, 1, 2, 3, and 4), 20 μL of each solution of different dilution concentrations was dissolved in 40 μL of acrylic resin, and coated on the surface of a glass slide, dried in an oven at 30°C, placed under a 365nm ultraviolet lamp, and photographed with a Xiaomi 12 mobile phone to obtain a clear fluorescence image, as shown below. Figure 13-14 It can be clearly observed that the membrane fluorescence imaging effect is best when the mother solution of compound B1 is diluted 1-fold.

[0067] The above embodiments are merely preferred technical solutions of the present invention and should not be construed as limiting the present invention. The embodiments and features in the embodiments of this application may be arbitrarily combined with each other unless they conflict. The scope of protection of the present invention shall be the technical solutions described in the claims, including equivalent alternatives to the technical features of the technical solutions described in the claims. Equivalent alternatives and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A nitrogen-containing heterocyclic dye, characterized in that The structural formula of the compound is shown in formula (II), wherein R is any one of H, OMe, COOMe, Br or Cl. Formula (II).

2. The method for synthesizing a nitrogen-containing heterocyclic dye according to claim 1, wherein Its synthesis method comprises the following steps: 1,8-naphtholactimide (1) and the compound represented by formula (I) were dissolved in toluene. After heating, the catalyst POCl3 was added. After TLC monitoring, the reaction solution was evaporated to remove the solvent under reduced pressure. Finally, the orange solid compound II was obtained by silica gel column chromatography. The reaction equation is as follows: The compound represented by formula (I) is one of the compounds represented by formulas A1-A5; 。 3. The synthetic method of nitrogen-containing heterocyclic dye according to claim 2, wherein In the synthesis step, the molar ratio of 1,8-naphtholactimide, the compound represented by formula (I) and POCl3 is 1:1-2:1-5.

4. The synthetic method of nitrogen-containing heterocyclic dye according to claim 2, wherein The reflux temperature of the synthesis step is 100-140° C., and the reflux time is 2-4 hours.

5. The method for synthesizing a nitrogen-containing heterocyclic dye and a ligand thereof according to claim 3, wherein: In the synthesis step, the order of adding materials is the compound represented by formula (I), 1,8-naphtholactimide, toluene, and POCl3.

6. Use of the synthesis method of the nitrogen-containing heterocyclic dye according to claim 1 in a fluorescent holographic anti-counterfeiting film, wherein the structural formula of the nitrogen-containing heterocyclic dye is selected from any one of the following: 。

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