BODIPY dye as well as preparation method and latent fingerprint identification application thereof

Abstract

The invention discloses BODIPY dyes and a preparation method and latent fingerprint identification application thereof.The BODIPY dyes of four structures and different light-emitting colors are prepared and all have the high fluorescence quantum yield, the absolute fluorescence quantum yield of the four dyes exceeds 55%, and the lipophilicity is excellent; the latent fingerprints on different substrates can be efficiently and conveniently detected within 10 seconds through a spraying method; the detection solution has excellent stability and can be stored for up to 30 days, the color change from green to red is realized through regulation and control, and the regulation and control can effectively cope with complex background colors and ensure that the best latent fingerprint detection effect can be achieved under different color backgrounds.

Description

Technical Field

[0001] The invention belongs to the field of detection technology, and specifically relates to a BODIPY dye and a preparation method thereof and latent fingerprint identification application. Background Art

[0002] Fingerprints are part of the skin, formed by the protrusions of the dermis into the epidermis. Latent fingerprints refer to the subtle marks left by the skin when it touches the surface of an object. Fingerprints can not only be used to identify identity but also serve as important evidence in court. Traditional fingerprint detection methods, such as powder blowing method, chemical reagent fumigation method, multi-metal deposition method and fluorescent staining method, are usually unreliable and have high environmental pollution, which is not conducive to practical application. In practical applications, the spray method is widely used because it is not restricted by the shape of the base material and does not directly contact the fingerprint. It has the advantages of simplicity, speed, high sensitivity, economy and large-area operation. It is considered to be one of the most promising methods for latent fingerprint detection.

[0003] The raw materials used in the spray method are mostly organic fluorescent dyes. Organic fluorescent dyes are widely used in the field of latent fingerprint detection due to their good chemical stability, excellent luminescence performance, and easy detection. Therefore, it is particularly necessary to develop efficient, fast, and universal organic fluorescent dyes as latent fingerprint developers. BODIPY dyes have outstanding advantages among many dyes due to their high fluorescence quantum yield, narrow absorption and emission spectra, good chemical and light stability, and abundant modification sites. In recent years, BODIPY has been widely used in detection, imaging, photodynamic therapy, photothermal therapy, and other fields. Due to the excellent lipophilicity of BODIPY dyes, they have good affinity for fingerprint residues, which makes BODIPY widely studied in the field of fingerprint detection.

[0004] Traditional latent fingerprint detection molecules have a single color, a difficult structure to change, and it is difficult to significantly improve their properties. However, BODIPY dyes have many modification sites, and their photophysical properties can be easily adjusted by modifying organic groups. The Knoevenagel condensation reaction of the BODIPY parent nucleus with aromatic aldehydes is one of the effective methods to expand the conjugated structure of BODIPY, thereby achieving a gradient change in the emission color to better cope with complex background colors. Summary of the invention

[0005] The present invention provides a BODIPY dye and a preparation method thereof and an application in latent fingerprint identification. The prepared BODIPY dye has a high fluorescence quantum yield and excellent lipophilicity, and can realize efficient and convenient detection of latent fingerprints on different substrates within 10 seconds by a spray method; and the color is adjustable, and the best latent fingerprint detection effect can be achieved under different color backgrounds.

[0006] To achieve the above objectives, the present invention adopts the following technical solutions: Four BODIPY dyes with high fluorescence yields of different luminescent colors are named BDP-G, BDP-Y, BDP-O, and BDP-R, and their chemical structures are as follows:

[0007] The preparation method of the above four BODIPY dyes comprises the following steps: (1) Dissolve 2,4-dimethylpyrrole and 4-hydroxybenzaldehyde in tetrahydrofuran in a reaction flask, keep the reaction system oxygen-free, then add a few drops of TFA (trifluoroacetic acid) and stir overnight, then add DDQ (2,3-dichloro-5,6-dicyanobenzoquinone), and stir at room temperature for 5 hours, add triethylamine dropwise to the solution, and then stir at room temperature for 30 minutes, then cool the reaction mixture in an ice bath, add boron trifluoride-ether solution dropwise, and stir the reaction mixture at room temperature for 12 hours to obtain BDP-G; (2) BDP-G, benzaldehyde, glacial acetic acid, and piperidine were dissolved in toluene and refluxed for 12 h. The water formed during the reaction was azeotropically removed using a Dean-Stark apparatus. The mixture was concentrated under reduced pressure to obtain BDP-Y. (3) BDP-G, 4-methoxybenzaldehyde, glacial acetic acid, and piperidine were dissolved in toluene and refluxed for 12 h. The water formed during the reaction was azeotropically removed using a Dean-Stark apparatus. The mixture was concentrated under reduced pressure to obtain BDP-O. (4) BDP-G, 4-(N,N-diphenylamino)benzaldehyde, glacial acetic acid, and piperidine were dissolved in toluene and refluxed for 12 h. The water formed during the reaction was azeotropically removed using a Dean-Stark apparatus, and the mixture was concentrated under reduced pressure to obtain BDP-R.

[0008] In the above steps, the reaction system is oxygen-free, specifically carried out under a nitrogen atmosphere; In step (1), the molar ratio of 2,4-dimethylpyrrole to 4-hydroxybenzaldehyde is 2.5:1; the molar ratio of DDQ to 4-hydroxybenzaldehyde is 1.1:1; the molar ratio of triethylamine to 4-hydroxybenzaldehyde is 5-10:1; the molar ratio of boron trifluoride-ether solution to 4-hydroxybenzaldehyde is 10-20:1, and the TFA is slowly added in the dark, with the amount of 0.1 ml added; The mixing method of the 2,4-dimethylpyrrole and 4-hydroxybenzaldehyde is as follows: firstly, 4-hydroxybenzaldehyde is dissolved in THF in a round-bottom flask, and the reaction bottle is kept in an argon atmosphere, and 2,4-dimethylpyrrole is added to the reaction bottle under continuous stirring; The DDQ dissolved in THF should be slowly added dropwise and the addition should be completed within one hour; the boron trifluoride-ether solution should be added dropwise in an ice-water bath.

[0009] The molar ratio of BDP-G to benzaldehyde, 4-methoxybenzaldehyde and 4-(N,N-diphenylamino)benzaldehyde in steps (2), (3) and (4) is 1:1; The volume ratio of glacial acetic acid to piperidine in steps (2), (3) and (4) is 1:1.

[0010] The above four BODIPY dyes can all be used in latent fingerprint detection.

[0011] Beneficial effects: The present invention provides BODIPY dye and its preparation method and latent fingerprint recognition application, which has the following advantages over the prior art: 1. The BODIPY dye synthesis method prepared by the present invention is simple, the raw materials are easily available, and the purification is convenient and easy to operate; 2. The four BODIPY dyes prepared by the present invention have high quantum yields, and the absolute fluorescence quantum yields of the four dyes are all over 55%; 3. The BODIPY dye prepared by the present invention can be used in a low concentration (10 μM) detection solution to efficiently and conveniently detect latent fingerprints on different substrates (tin foil, coins, glass, cardboard, desktop, steel) within 10 seconds by spraying. The detection solution has excellent stability and can be stored for up to 30 days. 4. The four BODIPY dyes prepared by the present invention realize color regulation from green to red. This regulation can effectively cope with complex background colors and ensure that the best latent fingerprint detection effect can be achieved under different color backgrounds. This will greatly improve the work efficiency of investigators and significantly improve the success rate of case solving. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The structural formulas of four BODIPY dyes in the embodiments of the present invention are shown in FIG. Figure 2 is a flow chart for preparing BODIPY dye in an embodiment of the present invention; Figure 3 The latent fingerprint detection effect of four BODIPY dyes on tin foil and the gray value change diagram in yellow or blue in the embodiment of the present invention; Figure 4 This is a latent fingerprint detection effect diagram of four BODIPY dyes on different substrate materials in the embodiment of the present invention; Figure 5In the embodiment of the present invention, (a) the state and detection effect of the BDP-G detection solution after being placed for 30 days, and the fluorescence change diagram; (b) the state and detection effect of the BDP-G detection solution after being irradiated with an 80W 365nm ultraviolet lamp for 30 minutes, and the fluorescence change diagram; Figure 6 In the embodiment of the present invention, (a) BDP-G is used to detect latent fingerprints on tin foil and the fingerprint status is placed in a natural space for 1 day, 15 days and 30 days, and the gray value change diagram within the yellow line; (b) three fresh fingerprints are made on tin foil and placed in a drawer to obtain latent fingerprints aged for 1 day, 4 days and 7 days, and the BDP-G detection solution is used to detect the latent fingerprint effect and the gray value change diagram within the yellow line; Figure 7 The following are the comparison diagrams of (a) detecting latent fingerprints on glass using BDP-O and placing them on tin foil of different colors (green, blue, red, and orange) in the embodiments of the present invention; (b) detecting latent fingerprints on a 50-yuan bill using BDP-G and detecting latent fingerprints on a 50-yuan bill using BDP-R, and detecting latent fingerprints on a 100-yuan bill using BDP-G and detecting latent fingerprints on a 100-yuan bill using BDP-R. DETAILED DESCRIPTION

[0013] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments: Example 1

[0014] The preparation method of BDP-G comprises the following steps: In a 500 mL round-bottom flask, take 2, 4-dimethylpyrrole (1.94 g, 20.47 mmol) and 150 mLTHF, degas with argon for 30 minutes, then add 4-hydroxybenzaldehyde (1.00 g, 8.19 mmol), purge with argon again for 30 minutes, then add 0.1 mL TFA and stir overnight, dissolve DDQ (2.08 g, 9.171 mmol) in 10 mLTHF, add dropwise within 1 hour, and stir at room temperature for 5 hours, the color changes from orange to dark red and then to black, add triethylamine (8.5 mL, 61.13 mmol) dropwise to the solution, add it dropwise within 40 minutes, stir at room temperature for 30 minutes, then cool the reaction mixture in an ice bath, add boron trifluoride-ether solution (17.3 mL, 137.33 mmol), stir the reaction mixture at room temperature for 12 h, remove THF under reduced pressure, dissolve the crude product in dichloromethane, and use 0.5M NaHCO 3 The solution was washed, and then washed with water several times. The organic solvent was washed with Na 2 SO 4The residue was dried on a silica gel column and evaporated to dryness, and BDP-G was obtained by silica gel column chromatography using ethyl acetate:n-hexane (1:4) as the eluent. Example 2

[0015] The preparation method of BDP-Y comprises the following steps: A mixture of BDP-G (0.30 g, 0.88 mmol), benzaldehyde (0.09 g, 0.88 mmol), glacial acetic acid (0.6 mL), and piperidine (0.6 mL) in toluene (60 mL) was refluxed for 12 h. The water formed during the reaction was azeotropically removed using a Dean-Stark apparatus. The mixture was concentrated under reduced pressure, washed with distilled water three times, extracted with ethyl acetate, dried over anhydrous sodium sulfate, filtered, and the solvent was distilled off under reduced pressure to obtain a crude product. The product was purified by column chromatography using ethyl acetate / n-hexane (1:4) as the eluent. The residue was subjected to silica gel column chromatography, the pink fraction was collected, and the solvent was removed under reduced pressure to obtain a pink solid product BDP-Y. Example 3

[0016] The preparation method of BDP-O comprises the following steps: A mixture of BDP-G (0.30 g, 0.88 mmol), 4-methoxybenzaldehyde (0.12 g, 0.88 mmol), glacial acetic acid (0.6 mL), and piperidine (0.6 mL) in toluene (60 mL) was refluxed for 12 h. The water formed during the reaction was azeotropically removed using a Dean-Stark apparatus. The mixture was concentrated under reduced pressure, washed with distilled water three times, extracted with ethyl acetate, dried over anhydrous sodium sulfate, filtered, and purified by column chromatography. The mixture was concentrated under reduced pressure, and the residue was subjected to silica gel column chromatography using ethyl acetate / n-hexane (1:4) as the eluent. The pink fraction was collected, and the solvent was removed under reduced pressure to obtain a pink solid product BDP-O. Example 4

[0017] The preparation method of BDP-R comprises the following steps: A toluene solution (60 mL) of BDP-G (0.30 g, 0.88 mmol), 4-(N,N-diphenylamino)benzaldehyde (0.24 g, 0.88 mmol), glacial acetic acid (0.6 mL), and piperidine (0.6 mL) was refluxed for 12 h, and the water formed during the reaction was azeotropically removed using a Dean-Stark apparatus. The mixture was concentrated under reduced pressure, washed with distilled water three times, extracted with ethyl acetate, dried over anhydrous sodium sulfate, filtered, and purified by column chromatography. The mixture was concentrated under reduced pressure, and the residue was subjected to silica gel column chromatography using ethyl acetate / n-hexane (1:7) as the eluent. The red fraction was collected, and the solvent was removed under reduced pressure to obtain a black solid product BDP-R.

[0018] The NMR data are: BDP-G: 1 H NMR (400 MHz, DMSO- d 6 ) δ 9.90 (s, 1H), 7.08 (d, J = 8.5 Hz,2H), 6.93 (d, J = 8.5 Hz, 2H), 6.14 (s, 2H), 2.44 (s, 6H), 1.42 (s, 6H). 13 C NMR (101 MHz, DMSO) δ158.63,154.90,143.23,143.20,131.68,29.40,124.70,121.61,116.52,14.63, 14.59. BDP-Y: 1 H NMR (400 MHz, DMSO- d 6 ) δ 9.89 (s, 1H), 7.59 (d, J = 8.6 Hz,2H), 7.51 (s, 2H), 7.45 (t, J = 8.0 Hz, 2H), 7.40 – 7.34 (m, 1H), 7.14 (d, J =8.5 Hz, 2H), 6.94 (d, J = 8.5 Hz, 2H), 6.92 (s, 1H), 6.20 (s, 1H), 2.49 (s, 3H), 1.49 (s, 3H), 1.45 (s, 3H). 13 C NMR (101 MHz, DMSO) δ 158.66,155.38,151.95,143.37,142.59,142.08, 136.65,136.57,133.01,132.30,129.64,129.58,127.47,124.73,122.01,118.68,118.33, 116.52,14.83,14.68. BDP-O: 11H NMR (400 MHz, DMSO-d6) δ 9.85 (s, 1H), 7.58 – 7.51 (m, 2H),7.48 (s, 1H), 7.35 (d, J = 16.4 Hz, 1H), 7.14 (d, J = 8.5 Hz, 2H), 7.03 (d, J= 8.8 Hz, 2H), 6.94 (d, J = 8.5 Hz, 2H), 6.89 (s, 1H), 6.17 (s, 1H), 3.81 (s,3H), 2.48 (s, 3H), 1.49 (s, 3H), 1.44 (s, 3H). 13 13C NMR (101 MHz, DMSO) δ160.82, 158.61, 154.12, 153.04, 142.87, 142.39, 141.43, 137.06, 133.08,131.93, 129.70, 129.21, 124.85, 121.55, 118.30, 116.48, 116.33, 115.14,56.50, 55.79, 19.02, 14.88, 14.76, 14.61. BDP-R: 1 1H NMR (400 MHz, DMSO- d 6 ) δ 9.86 (s, 1H), 7.47 (d, J J = 8.8 Hz,3H), 7.38 – 7.31 (m, 6H), 7.14 – 7.07 (m, 9H), 6.99 – 6.88 (m, 7H), 6.16 (s,1H), 2.46 (s, 3H), 1.48 (s, 4H), 1.43 (s, 3H). 13 13C NMR (101 MHz, DMSO) δ158.60, 153.99, 153.03, 148.80, 146.98, 142.83, 142.24, 141.22, 136.93,133.19, 131.94, 130.19, 130.05, 129.70, 128.94, 125.39, 125.31, 124.87,124.44, 122.40, 121.50, 118.45, 116.48, 14.87, 14.76, 14.61. Test Example 1

[0019] The four BODIPY dyes prepared above were used to detect latent fingerprints on tinfoil. The specific experimental steps are as follows: Invite different volunteers to wash their hands, touch their foreheads with their fingers, and then press their fingers gently on the tin foil to leave fingerprints. Then prepare 1×10 -5 M ethanol solution is used as the detection solution; 0.5 ml of the four detection reagents are put into the purchased (KF-WHQ-601B) spray tank, and the start button is pressed to spray the latent fingerprint. Then, a 365 nm ultraviolet lamp is used for irradiation. Within 10 seconds, the obvious latent fingerprint development effect can be observed, and the secondary structure (bifurcation, encirclement, end point) and tertiary structure (sweat pores, scars, edges) of the latent fingerprint can be clearly seen. Figure 3 As shown in the figure, the gray value within the yellow or blue line is measured. These latent fingerprints have good fluorescence contrast, and the minimum gray value is recorded as G. 0 , G / G 0 As an important parameter for analyzing image resolution, the large gap between the maximum and minimum grayscale values ​​indicates that the captured latent fingerprint image has excellent resolution; it is worth noting that BDP-O and BDP-R detect latent fingerprints of female volunteers on tin foil. Since female fingers are relatively slender and more easily exposed to various cosmetics, it is difficult to detect the tertiary structure in practical applications. However, the four BODIPY dyes prepared above all successfully detected the tertiary structure, indicating that the four BODIPY dyes prepared above have strong practicality.

[0020] Test Example 2

[0021] The latent fingerprints on different substrates were detected by four BODIPY dyes. The specific experimental steps are as follows: Different volunteers were asked to wash their hands, touch their foreheads lightly with their fingers, and then press their fingers gently on different substrates to leave fingerprints. Latent fingerprint detection was performed on tin foil, coins, glass, cardboard, desktops, and steel surfaces. Figure 4 As shown, these detection reagents can clearly reveal latent fingerprints on different substrates.

[0022] Test Example 3

[0023] The stability of the BDP-G test solution was tested by placement and illumination. The specific test steps are as follows: The prepared BDP-G detection solution was stored for 1 month and used for latent fingerprint detection to determine the stability of the detection solution. Figure 5As shown in (a), the detection reagent stored for one month did not show obvious precipitation, and there was no significant difference in fluorescence intensity. In addition, the tertiary structure of the fingerprint can be clearly detected using this solution, which shows that the detection solution can maintain stability for a long time. In addition, the photostability of the BDP-G detection solution was tested. After continuous irradiation with an 80 W strong ultraviolet lamp for 30 min, Figure 5 As shown in (b), no obvious fluorescence decay was observed, and the fluorescence intensity remained almost constant. Continuing to use the solvent can still effectively detect the tertiary structure of the latent fingerprint, indicating that the detection solution has good photostability.

[0024] Test Example 4

[0025] The stability of BDP-G detection molecules and the aging fingerprint detection effect were determined by aging fingerprint. The specific test steps are as follows: Use BDP-G detection solution to detect latent fingerprints on tin foil, and place the detected latent fingerprints in natural space for 1 day, 15 days and 30 days. Figure 6 As shown in (a), a clear fingerprint image can still be obtained, and it is almost exactly the same. By measuring the grayscale value within the yellow line, it is found that the grayscale value after 30 days still has obvious fluorescence signal changes, which also shows that the detection molecule has excellent stability.

[0026] The volunteers made three fresh fingerprints on tin foil and placed them in a drawer to obtain latent fingerprints aged for 1 day, 4 days, and 7 days. These latent fingerprints were then tested using BDP-G. Figure 6 As shown in (b), clear fingerprint images were obtained and the grayscale value within the yellow line was measured. Obvious changes in the fluorescence signal were also observed, which means that the detection molecules still have a good detection effect on aged fingerprints.

[0027] Test Example 5

[0028] The detection effect under different color backgrounds was measured by fingerprints on glass. The specific test steps are as follows: After soaking the glass in an ethanol solution and letting it dry naturally, the volunteers washed their hands, gently touched their foreheads with their fingers, and then gently pressed their fingers on the glass surface. Taking BDP-O as an example, it was used to detect latent fingerprints on the glass surface and easily obtain the characteristics of its tertiary structure. Subsequently, different colored tin foils were placed behind the glass substrate to simulate different background colors. Figure 7 As shown in (a), the tertiary structure of the orange latent fingerprint can be more clearly observed against the green and blue backgrounds, while against the red and orange backgrounds, although the tertiary structure is still visible, it is not as clear as against the green and blue backgrounds.

[0029] The volunteers also left their fingerprints on a red background of 100 yuan, and used red detection reagents and green detection reagents to detect latent fingerprints. It was found that there was a significant difference in the detection effect. Similarly, when using a green background of 50 yuan to detect fingerprints, such as Figure 7 As shown in (b), the effect of the green detection reagent is far inferior to that of the red detection reagent. The detection reagent with high contrast color can more effectively cope with the challenge of different background colors. At the same time, it also verifies that the four detection molecules synthesized above have high practicality.

[0030] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. BODIPY dye, characterized in that There are four types of BODIPY dyes, named BDP-G, BDP-Y, BDP-O, and BDP-R, and their chemical structures are as follows: 。 2. The BODIPY dye according to claim 1, characterized in that The four BODIPY dyes have different emission colors.

3. The method for preparing the BODIPY dye according to any one of claims 1 to 2, characterized in that: The following steps are involved: 2,4-Dimethylpyrrole and 4-hydroxybenzaldehyde were dissolved in tetrahydrofuran, and the reaction system was kept oxygen-free. 0.1 ml of trifluoroacetic acid was added and stirred overnight, and then 2,3-dichloro-5,6-dicyanobenzoquinone was added and stirred at room temperature for 5 hours. Triethylamine was added dropwise to the solution, and then stirred at room temperature for 30 minutes. The reaction mixture was cooled in an ice bath, and a boron trifluoride-ether solution was added dropwise. The reaction mixture was stirred at room temperature for 12 hours to obtain BDP-G; BDP-G, benzaldehyde, glacial acetic acid, and piperidine were dissolved in toluene and refluxed for 12 h. The water formed during the reaction was azeotropically removed using a Dean-Stark apparatus, and the mixture was concentrated under reduced pressure to obtain BDP-Y; BDP-G, 4-methoxybenzaldehyde, glacial acetic acid, and piperidine were dissolved in toluene and refluxed for 12 h. The water formed during the reaction was azeotropically removed using a Dean-Stark apparatus, and the mixture was concentrated under reduced pressure to obtain BDP-O; BDP-G, 4-(N,N-diphenylamino)benzaldehyde, glacial acetic acid, and piperidine were dissolved in toluene and refluxed for 12 h. The water formed during the reaction was azeotropically removed using a Dean-Stark apparatus, and the mixture was concentrated under reduced pressure to obtain BDP-R.

4. The method for preparing BODIPY dye according to claim 3, characterized in that: The reaction system is oxygen-free and is carried out under a nitrogen atmosphere.

5. The method for preparing BODIPY dye according to claim 3, characterized in that: The molar ratio of the 2,4-dimethylpyrrole to 4-hydroxybenzaldehyde is 2.5:1; the molar ratio of the 2,3-dichloro-5,6-dicyanobenzoquinone to 4-hydroxybenzaldehyde is 1.1:1; the molar ratio of the triethylamine to 4-hydroxybenzaldehyde is 5-10:1; and the molar ratio of the boron trifluoride-ether solution to 4-hydroxybenzaldehyde is 10-20:

1.

6. The method for preparing the BODIPY dye according to claim 3 or 4, characterized in that: The trifluoroacetic acid was added in a dark environment, and the amount added was 0.1 ml.

7. The method for preparing the BODIPY dye according to claim 3 or 5, characterized in that: The mixing method of the 2,4-dimethylpyrrole and 4-hydroxybenzaldehyde is as follows: firstly, 4-hydroxybenzaldehyde is dissolved in tetrahydrofuran in a round-bottom flask, and the reaction bottle is kept in an argon atmosphere, and 2,4-dimethylpyrrole is added to the reaction bottle under continuous stirring.

8. The method for preparing the BODIPY dye according to claim 3 or 5, characterized in that: The 2,3-dichloro-5,6-dicyanobenzoquinone was dissolved in tetrahydrofuran and slowly added dropwise and the addition was completed within one hour.

9. The method for preparing BODIPY dye according to claim 3, characterized in that: The molar ratio of BDP-G to benzaldehyde, 4-methoxybenzaldehyde and 4-(N,N-diphenylamino)benzaldehyde is 1:1; the volume ratio of glacial acetic acid to piperidine is 1:

1.

10. Use of the BODIPY dye according to any one of claims 1 to 2 in latent fingerprint detection.

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