A trace visualizing azine fluorescent dye, and a preparation method and application thereof

Abstract

The application discloses a trace developing xanthene fluorescent dye and a preparation method and application thereof, and belongs to the technical field of criminal investigation. The compound provided by the application has a structural formula as shown in the formula A: wherein R is independently selected from C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl or C2-C5 epoxyalkyl. The trace developing dye compound has the advantages of low cost, small dosage, rapid development, high development quality and simple operation. Compared with similar products, the compound has further improved comprehensive performance and is more convenient to use.

Description

Technical Field

[0001] This invention relates to the field of criminal investigation technology, specifically to a azine-based fluorescent dye that reveals traces, its preparation method, and its application. Background Technology

[0002] Fingerprints possess unique physiological structures and biological characteristics, making them one of the most convenient and reliable methods for personal identification. They are also characterized by their lifelong immutability and ability to leave a trace upon contact with objects. The scientific and accurate discovery, extraction, and visualization of fingerprints play a crucial role in investigative work and crime prevention. Fingerprints are recognized in the legal field as the "primary form of evidence," accounting for approximately 70% of cases solved by police using forensic techniques. Furthermore, in civil cases, fingerprints are often crucial for accurate identification of victims or deceased individuals in accidents or natural disasters who are unidentifiable by the naked eye due to injuries or other reasons. Inputting personal fingerprint data into ID cards, credit cards, and passports can verify the identity of the registered holder. In security, security checks, and business activities (such as automatic door locks, access control, and seal management), fingerprint information serves as an efficient basis for authorization. In clinical medicine, dermatoglyphics can provide information and evidence for disease screening and diagnosis. With the popularization of AI technology and CNC systems, fingerprints will find increasingly widespread applications in modern life.

[0003] Since French physician Auhert first used silver nitrate solution to reveal fingerprints from sweat in 1877, latent fingerprint development technology has a history of over a century. From its initial simple solution-based method, fingerprint development has evolved into a specialized technique integrating knowledge and technology from multiple disciplines, including physics, chemistry, and biology, with significant impacts in forensic identification, individual identification, daily life, and access control. In recent years, with the development of modern analytical instruments and techniques, fingerprint research has moved beyond simply observing its morphology using traditional physical or chemical methods. Efforts are also underway to develop various emerging technologies (such as mass spectrometry, infrared / Raman imaging, electrochemical imaging, and fluorescence immunoassay) to analyze and detect the components in fingerprints, thereby uncovering more valuable biological and medical information.

[0004] In the field of criminal investigation, fingerprints are the most direct physical evidence left by criminals at the scene. Based on the object of contact and the manner of residue formation, fingerprints can be divided into three categories: (1) visible fingerprints, which are fingerprints that can be seen with the naked eye, formed by the transfer of substances such as paint, blood, and ink from the fingers; (2) latent fingerprints, which are fingerprints that cannot be directly observed by sight or instruments, usually caused by unconscious contact between the fingers and the substrate; and (3) malleable fingerprints, such as indented fingerprints formed by the fingers pressing on candles or clay. Latent fingerprints are the most common type found at crime scenes, and their manifestation is a crucial step in solving the case. If latent fingerprints cannot be effectively manifested, subsequent sampling, analysis, and identification are impossible. The basic principle of fingerprint manifestation is to use light or substances to act on the fingerprint residue, creating a significant difference between the faint trace and the substrate that can be detected by instruments or the naked eye.

[0005] The material basis for revealing latent fingerprints lies in the chemical composition of fingerprint residue. After an object is touched, the amount of fingerprint material left on the surface is extremely limited, generally only 0.1–1 mg, and 99% of it is water, which evaporates rapidly. Of the remaining material, about 50% is inorganic, such as NaCl and KCl, which have almost no value for fingerprint development. Other organic components, such as oils, amino acids, nucleic acids, and vitamins, are needed to achieve fingerprint development. The identification and quantification of amino acids and fatty acids are relatively well-established, while research on proteins and polypeptides, although important components of the residue, is still largely lacking.

[0006] Traditional methods for developing latent fingerprints are mainly classified into three categories based on their development principles: optical development, chemical development, and physical adsorption (Table 1). Currently, commonly used methods include fumigation, super glue ("502"), silver nitrate, ninhydrin, and DFO. These methods have their own applicable conditions, and in practice, the correct technique must be used according to different factors (such as the type of fingerprint residue and the type of object on which it was left) to obtain effective development results. After over a century of research and practice, fingerprint development technology has made significant progress, but many unresolved problems remain. For example, there are still no good development reagents and methods for fingerprints left on the surface of objects with special structures or materials; latent fingerprints on living skin are difficult to develop and extract; the dust from brushing and the harmful gases produced by fumigation can damage operators; some reagents and dyes, such as Rhodamine 6G, are toxic, and long-term exposure can affect health; the brushing and staining processes can cause irreversible damage to fingerprints and valuable evidence. Therefore, there is still a need to develop and establish various low-cost, non-toxic, easy-to-operate, and widely applicable latent fingerprint development technologies.

[0007] Table 1. Classification, Principles, and Characteristics of Fingerprint Display Technology

[0008]

[0009]

[0010] Among the aforementioned techniques, ethyl α-cyanoacrylate fingerprint fuming (i.e., "502" glue fuming) is the most commonly used and practical method. Due to the high volatility of "502" glue, it cures latent fingerprints in a gaseous state, making it highly advantageous for large-area, complex-shaped fingerprint substrates. This technique was first used by the Japanese Police Department's Criminal Identification Division in 1978. Since then, technological improvements have been slow, primarily focusing on the design and development of fuming equipment, with little attention paid to improving the properties of "502" glue itself. This is especially true for some difficult-to-develop fingerprint substrates, where simple "502" glue cannot meet these needs. Therefore, there is an urgent need in this field for fingerprint fuming enhancement dyes that offer good fingerprint development and are suitable for various substrates.

[0011] In 2019, the Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, and other institutions applied for Chinese invention patent ZL201910848920.1, which discloses a fluorescent dye based on a tetrazine structure (named LUM in this paper), using the structure shown in Formula I below:

[0012]

[0013] Wherein, X and R are each independently selected from the group consisting of: halogen, azide, cyano, substituted or unsubstituted aziridine group, or OA-R1, wherein A represents a single bond or C1-C4 alkylene, and R1 is selected from the group consisting of: C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl, or C2-C5 epoxyalkyl; preferably, R1 is C1-C4 alkyl; X is selected from the group consisting of: F, Cl, Br; the colloidal solvent includes: cyanoacrylate (C1-4 alkyl) ester, polymerization inhibitor, and phosphate ester reagent; and the phosphate ester reagent is selected from the group consisting of: triphosphate (substituted or unsubstituted C1-C6 alkyl) ester, triphosphate (substituted or unsubstituted C6-C10 aryl) ester, or a combination thereof; the substitution refers to one or more hydrogen atoms on the group being replaced by a substituent selected from the group consisting of: C1-C4 alkyl, phenyl. LUM is not only applicable to non-permeable and semi-permeable objects, but also has obvious excitation and emission regions in the visible light band, making it relatively easy for observers to observe. Summary of the Invention

[0014] This invention provides a azine fluorescent dye for fingerprint development, its preparation method, and its application. The azine fluorescent dye of this invention has good fingerprint development effect and is suitable for fluorescent fuming development of different trace-bearing objects.

[0015] This invention first provides a compound with the structural formula shown in Formula A:

[0016]

[0017] Wherein, R is independently selected from C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl or C2-C5 epoxyalkyl; preferably, R is methyl.

[0018] The preparation method of the above compound includes the following steps:

[0019] (1) Using 3,6-dichloro-1,2,4,5-tetraazine as a raw material, 3,6-dimethoxy-1,2,4,5-tetraazine was synthesized;

[0020] (2) 3-hydroxy-6-methoxy-1,2,4,5-tetraazine was synthesized from 3,6-dimethoxy-1,2,4,5-tetraazine.

[0021] The preparation method of the above-mentioned compound includes the following steps:

[0022] (1) 3,6-dichloro-1,2,4,5-tetraazine, R-OH and 4-dimethylaminopyridine were mixed and reacted under an inert atmosphere to synthesize 3,6-dialkoxy-1,2,4,5-tetraazine;

[0023] In R-OH, R is defined in the same way as R above;

[0024] (2) 3,6-dialkoxy-1,2,4,5-tetraazine, aluminum trichloride and sodium iodide were mixed, ground and softened, and then heated under an inert atmosphere to react and synthesize the compound shown in Formula A.

[0025] In one embodiment of the present invention, the method for preparing the above-mentioned compound includes the following steps:

[0026] (1) 3,6-dichloro-1,2,4,5-tetraazine, anhydrous methanol and 4-dimethylaminopyridine were mixed and reacted under an inert atmosphere to synthesize 3,6-dimethoxy-1,2,4,5-tetraazine.

[0027] (2) 3,6-dimethoxy-1,2,4,5-tetraazine, aluminum trichloride and sodium iodide were mixed, ground and softened, and then heated under an inert atmosphere to react and synthesize 3-hydroxy-6-methoxy-1,2,4,5-tetraazine.

[0028] Specifically, the inert atmosphere is a nitrogen atmosphere;

[0029] In step (2), the temperature for heating the reaction is 60-100°C and the time is 1-3 hours.

[0030] In step (1), the reaction is carried out in an organic solvent; specifically, the organic solvent is dichloromethane.

[0031] Since tetrazine intermediates are extremely unstable, the synthetic route of this invention is currently a relatively safe and cost-effective route.

[0032] Second, the present invention provides a fluorescent fuming agent comprising the above-mentioned compound and a colloidal solvent.

[0033] The fluorescent developer is a fingerprint fluorescent developer.

[0034] In the aforementioned fluorescent fuming agent, the colloidal solvent is at least one of cyanoacrylate (C1-4 alkyl) ester, polymerization inhibitor, and phosphate ester reagent.

[0035] In the above-mentioned fluorescent fuming agents, the phosphate ester reagent is selected from tris(substituted or unsubstituted C1-C6 alkyl) phosphate, tris(substituted or unsubstituted C6-C10 aryl) phosphate, or a combination thereof;

[0036] The cyanoacrylate is methyl cyanoacrylate, ethyl cyanoacrylate, propyl cyanoacrylate or butyl cyanoacrylate;

[0037] The phosphate ester is at least one of trimethyl phosphate, triethyl phosphate, tripropyl phosphate, and tricyclopropyl phosphate.

[0038] Preferably, the adhesive solvent is ethyl cyanoacrylate.

[0039] In the above-mentioned fluorescent fuming agent, the mass-to-volume ratio of the compound and the colloidal solvent is 1g:10-100mL; specifically, it can be 1g:20mL or 1g:40mL.

[0040] Third, the present invention provides a fingerprint fluorescence development method, comprising the following steps: using the fluorescent fumigation agent as a fumigation reagent to develop fingerprints on the sample, thereby obtaining the developed sample.

[0041] The above-mentioned fingerprint fluorescence development method specifically includes the following steps:

[0042] (1) Dissolve the compound in a peptide to obtain a fluorescent fuming agent;

[0043] (2) The fluorescent fumigation agent is placed in an evaporation container as a fluorescent fumigation solution, and the evaporation container and the sample are placed in a fumigation cabinet for fumigation to obtain the developed sample.

[0044] In the above-mentioned fingerprint fluorescence development method, the fumigation temperature is 80-300℃, specifically 120℃; the fumigation time is 10-100min, specifically 30min.

[0045] Finally, the present invention provides a fingerprint detection method, comprising the following steps: after fingerprint development using the above-mentioned fingerprint fluorescence development method, the sample is irradiated with blue-green light (450-510nm) or blue light (420-470nm), and photographed for extraction and fixation.

[0046] The method also includes developing the image using an orange (500-600nm) filter before photographic extraction.

[0047] Compared to LUM, the fluorescent dye described in this invention exhibits significantly lower fluorescence excitation intensity in the 600 nm region, yet it possesses similar or even superior fluorescence development effects. The molecular mechanism lies in the stronger protein-protein interaction of the fluorescent dye, leading to its abundant accumulation on the trace surface during staining and resulting in strong fluorescence. Therefore, even without the optimal (fluorescence excitation) functional group combination of the LUM molecule, the fluorescent dye described in this invention still demonstrates excellent development performance.

[0048] The trace development dye compound of this invention is low in cost, requires minimal dosage, develops rapidly, produces high-quality results, and is easy to operate. Compared with excellent fluorescent fuming dyes such as LUM, the trace development dye of this invention is a rare high-definition fluorescent developing material existing in liquid form. It is not only directly miscible with carrier solvents such as water and cyanoacrylate for faster development, but it can also be applied directly to the object by spraying, thus greatly expanding the application conditions of fluorescent fuming and laying the foundation for the development of new fuming equipment. Attached Figure Description

[0049] Figure 1 The 3,6-dimethoxy-1,2,4,5-tetraazine prepared in Example 1 1 HNMR image.

[0050] Figure 2 The absorption spectra of 3-hydroxy-6-methoxy-1,2,4,5-tetraazine and LUM are shown.

[0051] Figure 3 The fluorescence spectra of 3-hydroxy-6-methoxy-1,2,4,5-tetraazine and LUM are shown.

[0052] Figure 4 The affinity of 3-hydroxy-6-methoxy-1,2,4,5-tetraazine and LUM for HAS.

[0053] Figure 5 Comparison of development effects of 3-hydroxy-6-methoxy-1,2,4,5-tetraazine and LUM.

[0054] Figure 6 The developing effect of half-3-hydroxy-6-methoxy-1,2,4,5-tetraazine.

[0055] Figure 7 Comparison of development effects between 3-hydroxy-6-methoxy-1,2,4,5-tetraazine and PHTFT. Detailed Implementation

[0056] The present invention will be further described in detail below with reference to specific embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.

[0057] Unless otherwise specified, the experimental methods described in the following examples are conventional methods.

[0058] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0059] Example 1: Synthesis of methoxy-p-hydroxytetrazine

[0060] The synthesis flowchart is as follows:

[0061]

[0062] (1) Synthesis of 3,6-dimethoxy-1,2,4,5-tetraazine

[0063]

[0064] Under nitrogen protection, 10.3 g (68.2 mmol) of 3,6-dichloro-1,2,4,5-tetraazine was weighed and dissolved in 800 mL of anhydrous dichloromethane. Then, 27 mL of anhydrous methanol (667 mmol) and 32.3 g of 4-dimethylaminopyridine (265 mmol) were added. Upon addition of 4-dimethylaminopyridine, the color immediately turned a bright milky orange. After 10 minutes, the solution turned a deep reddish-purple. After 20 minutes, TLC (20:80 ethyl acetate:petroleum ether, v / v) showed a small amount of the starting material remaining. After 45 minutes, the dichloromethane solvent was evaporated to dryness. The remaining solid was dissolved in a mixed solvent (40 mL ethyl acetate + 160 mL petroleum ether) and passed through a silica gel pad. The solution was washed with 600 mL of petroleum ether, and the filtrates were combined and evaporated to dryness. The solution was then purified by silica gel column chromatography (ethyl acetate:petroleum ether = 0%–60%) to obtain an orange crystalline solid (8.87 g, 92% yield).

[0065] The structural verification data is as follows: 1 H NMR (400MHz, CDCl3) δ4.25 (s, 6H).

[0066] (2) Synthesis of 3-hydroxy-6-methoxy-1,2,4,5-tetraazine

[0067]

[0068] Weigh 2 g (14.07 mmol) of 3,6-dimethoxy-1,2,4,5-tetraazine, 1.88 g (14.07 mmol) of aluminum trichloride, and 1.05 g (7.04 mmol) of sodium iodide and grind them vigorously in an agate mortar for several minutes. Under nitrogen protection, heat the softened mixture to 80 °C for two hours. After the reaction is complete, dissolve the reaction mixture in 30 mL of 5% sodium thiosulfate aqueous solution and extract with methyl ether (30 mL x 2). Dry the organic phase to obtain a red solution (1.53 g, 85% yield).

[0069] The structural verification data is as follows: 1 H NMR(500MHz,DMSO-d6)δ3.98(brs,1H),3.16(s,3H). 1 HNMR image see Figure 1 .

[0070] Example 2: Absorption and fluorescence spectra of methoxy-p-hydroxytetraazine

[0071] TU-1950 UV / Vis spectrophotometer (Beijing Purkinje General Instrument Co., Ltd.); Edinburgh FLS920 fluorescence spectrometer (brand: URG, model: FLS920, Edinburgh Instruments, UK); anhydrous ethanol (G00004-20KG, Lot#: KDHFN04, Beijing Innocare Technology Co., Ltd.); quartz cuvette (Allrenta, 10mm four-channel (export grade), Delmon Technologies). Sample concentration: 0.4 mg / mL; scanning range: 300–1000 nm.

[0072] The 3-hydroxy-6-methoxy-1,2,4,5-tetraazine prepared in Example 1 and LUM were mixed to prepare a 0.4 mg / mL 50% (v / v) methanol / water solution. The absorption spectrum was observed in the UV-VIS band (see [link to UV-VIS]). Figure 2 ).

[0073] The specific structure of LUM is as follows:

[0074]

[0075] The 3-hydroxy-6-methoxy-1,2,4,5-tetraazine prepared in Example 1 and LUM were mixed to prepare a 0.4 mg / mL 50% (v / v) methanol / water solution. The fluorescence spectrum was observed in the optimal excitation region using an FLS920 spectrometer (see [link to FLS920]). Figure 3 ).

[0076] Depend on Figure 3It is known that 3-hydroxy-6-methoxy-1,2,4,5-tetraazine has two large emission regions in the 300-800 nm region, which gives it a wider observation range than LUM.

[0077] Example 3: Determination of the affinity between methoxy-p-hydroxytetrazine and bovine serum albumin (BSA) using Biacore I. Solution Preparation

[0078] 1) Preparation of phosphate-buffered saline (PBS): Weigh 22.5g NaCl, 7.32g Na2HPO4·12H2O, and 0.97g NaH2PO4·2H2O into the same beaker, add 400mL of deionized water and sonicate to dissolve. Then add 250μL of Tween 20 and bring the volume to 500mL. Filter the resulting solution through a 0.2μM filter membrane and transfer it to a new bottle to obtain PBS buffer containing 0.05% surfactant Tween 20. Prepare multiple portions for later use.

[0079] 2) Preparation of running buffer: Measure 0.45 mL, 0.58 mL, and 25 mL of DMSO respectively, and add 9.5 mL, 9.5 mL, and 475 mL of PBS buffer containing 0.05% Tween 20 to prepare running buffers containing 4.5%, 5.8%, and 5% DMSO respectively; transfer 0, 200, 400, 800, 1000, 1200, and 1400 μL of 5.8% running buffer into EP tubes 1-8 respectively, and then add 0, 200, 400, 800, 1000, 1200, and 1400 mL of 4.5% running buffer sequentially from tube 8 to tube 1 to obtain solvent correction solutions.

[0080] 3) Preparation of test sample solutions: Weigh 5.5, 5.0, 5.0, 9.0, 5.0, and 5.0 mg of 3-hydroxy-6-methoxy-1,2,4,5-tetraazine and LUM prepared in Example 1 into 1.5 mL EP tubes, respectively. Add 59, 55, 36, 85, 57, and 61 μL of LDMSO, respectively. After shaking to dissolve, add 1114, 1044, 681, 1608, 1019, and 1154 μL of filtered PBS buffer containing 0.05% surfactant Tween 20, respectively, to obtain the sample stock solution. 200, 100, 50, and 25 μL of sample stock solution were transferred into EP tubes, respectively. Then, 200, 300, 350, and 375 μL of filtered PBS containing 0.05% Tween 20 surfactant and 5% DMSO were added, respectively, to obtain sample solutions with concentrations of 16000 μM, 8000 μM, 4000 μM, and 2000 μM. The 1000 μM and 500 μM solutions used the 2000 μM sample as the stock solution, and the procedure was as described above. Finally, sample solutions with concentration gradients of 16000, 8000, 4000, 2000, 1000, and 500 μM were obtained.

[0081] 4) Preparation of human serum albumin HSA solution: Accurately weigh 10.0 mg of human serum albumin into a beaker, add phosphate buffer to dissolve, and bring the volume to 10 mL to obtain a 1 mg / mL human serum albumin stock solution. Dilute the stock solution with acetic acid at pH 4.0 to a concentration of 20 μg / mL for later use.

[0082] II. Using Biacore T100 to analyze molecular binding processes

[0083] 1) Start the Biacore T100: Log in to the system, replace the buffer bottle on the left side of the instrument with a PBS buffer containing 0.05% Tween 20 and insert the buffer tube into the bottle; insert the waste liquid tube on the right side into the waste liquid bottle.

[0084] 2) pH screening: Set process parameters, select chip channel, and use acetic acid solutions with pH values ​​of 3.6, 3.8, 4.0, 4.2, 4.4, and 4.6 to screen for suitable ligand buffer pH values.

[0085] 3) Ligand (human serum albumin) immobilization: Channel 1 is used as the reference channel, and channel 2 is coupled with the ligand. An activation-blocking ligand-free immobilization method is used. First, NHS is used for activation to immobilize the ligand, followed by blocking with ethanolamine.

[0086] 4) Set the chip, start-up and injection parameters, and load the sample. Use a 96-well plate for sample assembly. Add 3-hydroxy-6-methoxy-1,2,4,5-tetraazine and LUM sample solutions to wells 1-7 in the first and second columns, respectively, with concentration gradients of 0, 500, 1000, 2000, 4000, 8000, and 16000 μM, 240 μL for each. Add solvent correction solutions 1-8 to wells 1-8 in the sixth column.

[0087] 5) Start the instrument and observe the binding process of serum proteins with small molecule samples.

[0088] 6) Collect data and process and analyze it.

[0089] The results are shown in Figure 4 Affinity analysis showed that 3-hydroxy-6-methoxy-1,2,4,5-tetraazine has approximately three times the affinity for HSA compared to LUM. Even at smaller doses, 3-hydroxy-6-methoxy-1,2,4,5-tetraazine can achieve similar developing effects to LUM. In terms of physical properties, LUM is a red powder that requires thorough shaking to dissolve in carrier 502. In contrast, 3-hydroxy-6-methoxy-1,2,4,5-tetraazine is a red liquid at room temperature and is highly miscible with carrier 502, making it more convenient for practical use.

[0090] Example 4: Application conditions and effects of fluorescent fuming agent

[0091] 1. Materials: Lumicyano (CST, Lot: NO40320), matching 502 glue (Lot: 01005C), FENGE fumigation cabinet (50L), BYA BY1010 intelligent constant temperature heating table (400℃ digital display adjustable heating plate), 400℃ range thermometer (Hengxinda Instruments), multi-functional dotted line paper cutter (KW-TRIO model: 139394In1), Doppler multi-band light source (portable for criminal investigation, serial number: 001000772, 85-264V, 50-60Hz, 4-8A, Fuse 8A F, POLI LIGHT, PL500), aluminum bowls (SIGMA-ALDRICH, Z154857-1PAK, Lot#3110, Disposable aluminum dishes, crimped sides with finger-grip). Handle, capacity 50ml, top ID 60mm), microscope camera (Canon), photographic table (BULANT, microdrive), filter eyepiece (NOIR, UVShield-NoIR-GlareShield-LaserShield), BTSS-I type LED uniform light survey lamp, pipette system (Eppendorf, 1ml), TU-1950 UV / Vis spectrophotometer (Beijing Purkinje General Machinery Co., Ltd.); F-7000FL Spectrophotometer.

[0092] 2. Comparison of development effects between 3-hydroxy-6-methoxy-1,2,4,5-tetraazine and LUM

[0093] Dotted lines are drawn on a polyethylene film, and fingerprints are pressed directly onto the dotted lines with random pressure to form a sample.

[0094] The FENGE fumigation and development cabinet was started with a humidification program, maintaining a constant humidity of 75% and a temperature of 120°C. 40 mg of 3-hydroxy-6-methoxy-1,2,4,5-tetraazine was injected into 0.8 mL of 502 to form a homogeneous, transparent solution. After maintaining the temperature and humidity in the fumigation and development cabinet for 20 minutes, the sample was hung on the cabinet. The aluminum bowl (with the sample) was placed on the heating plate, and the temperature was linearly increased to the target value under program control. After 30 minutes of fumigation and development, a 20-minute purification program was initiated. The sample was removed, and the object was excited at 450 nm using a Doppler multi-band light source. Microscopic imaging was performed using a 565 nm filter for development. The fingerprint development was observed.

[0095] As a control, LUM was used for fumigation and development under the same conditions (dose 40 mg), with the subject excited by a Doppler multi-band light source at 450 nm and developed by microscopy using a 565 nm filter. Fingerprint development was observed. The results showed that the development effect of 3-hydroxy-6-methoxy-1,2,4,5-tetraazine was comparable to that of LUM (see...). Figure 5 ).

[0096] 3. Comparison of imaging effects between half-maximal dose 3-hydroxy-6-methoxy-1,2,4,5-tetraazine and LUM

[0097] Dotted lines are drawn on a polyethylene film, and fingerprints are pressed directly onto the dotted lines with random pressure to form a sample.

[0098] The FENGE fumigation and development cabinet was started with a humidification program, maintaining a constant humidity of 75% and a constant temperature of 120°C. 20 mg of 3-hydroxy-6-methoxy-1,2,4,5-tetraazine was dissolved in 0.8 mL of 502 to form a homogeneous, transparent solution. After maintaining the temperature and humidity in the fumigation and development cabinet for 20 minutes, the sample was placed in the cabinet. The aluminum bowl (with the sample) was placed on the heating plate, and the temperature was linearly increased to the target value under program control. After 30 minutes of fumigation and development, a 20-minute purification program was initiated. The sample was removed, and the object was excited at 450 nm using a Doppler multi-band light source. Microscopic imaging was performed using a 535 nm filter for development. The fingerprint development was observed.

[0099] As a control, LUM was used for fumigation and development under the same conditions (dose 40mg). The subject was excited by a Doppler multi-band light source at 450nm and developed by microscopy with a 565nm filter. The fingerprint development was observed.

[0100] Comparative results show that, under identical fumigation and development conditions, even half-dose of 3-hydroxy-6-methoxy-1,2,4,5-tetraazine can produce development results comparable to LUM. Figure 6 It can also provide valuable imaging for blurry fingerprints.

[0101] 4. Comparison of development effects of 3-hydroxy-6-methoxy-1,2,4,5-tetraazine with other derivatives

[0102] Under the same fumigation and development conditions as described above, many derivatives of 3-hydroxy-6-methoxy-1,2,4,5-tetraazine failed to develop clearly. For example, p-hydroxytrifluoromethyltetraazine (PHTFT), obtained by methoxy substitution modification of 3-hydroxy-6-methoxy-1,2,4,5-tetraazine, showed almost no development and was completely incomparable to 3-hydroxy-6-methoxy-1,2,4,5-tetraazine. Figure 7 ).

Claims

1. A compound having the structural formula shown in Formula A: Formula A in, R is independently selected from C1 C6 alkyl group.

2. The compound according to claim 1, characterized in that: R is a methyl group.

3. A method for preparing the compound according to claim 1 or 2, comprising the following steps: (1) 3,6-dialkoxy-1,2,4,5-tetraazine, R-OH and 4-dimethylaminopyridine were reacted under an inert atmosphere to synthesize 3,6-dialkoxy-1,2,4,5-tetraazine; In R-OH, R is the same as the definition of R in claim 1 or 2; (2) Mix and grind 3,6-dialkoxy-1,2,4,5-tetraazine, aluminum trichloride and sodium iodide to soften them, and then heat them under an inert atmosphere to react and synthesize the compound of claim 1 or 2.

4. A fluorescent fuming agent comprising the compound of claim 1 or 2 and a colloidal solvent.

5. The fluorescent developing agent according to claim 4, characterized in that: The fluorescent developer is a fingerprint fluorescent developer.

6. The fluorescent developing agent according to claim 4 or 5, characterized in that: The adhesive solvent is at least one of methyl cyanoacrylate, ethyl cyanoacrylate, propyl cyanoacrylate, butyl cyanoacrylate, a polymerization inhibitor, and a phosphate ester reagent.

7. The fluorescent developing agent according to claim 6, characterized in that: The phosphate ester reagent is selected from at least one of trimethyl phosphate, triethyl phosphate, tripropyl phosphate, and tricyclopropyl phosphate.

8. The fluorescent developing agent according to claim 4 or 5, characterized in that: The adhesive solvent is ethyl cyanoacrylate.

9. The fluorescent developing agent according to claim 4 or 5, characterized in that: The mass-to-volume ratio of the compound and the adhesive solvent according to claim 1 or 2 is 1 g: 10~100 mL.

10. A fingerprint fluorescence development method, comprising the following steps: using the fluorescent fuming agent as described in any one of claims 4-9 as the fuming agent to develop the fingerprint of the sample, thereby obtaining the developed sample.

11. The fingerprint fluorescence development method according to claim 10, characterized in that: The method includes the following steps: (1) Dissolve the compound of claim 1 or 2 in a colloidal solvent to obtain a fluorescent fuming agent; (2) The fluorescent fumigation agent is placed in an evaporation container as a fluorescent fumigation solution, and the evaporation container and the sample are placed in a fumigation cabinet for fumigation to obtain the developed sample.

12. The fingerprint fluorescence development method according to claim 11, characterized in that: The fumigation temperature is 80~300℃; the fumigation time is 10~100min.

13. A fingerprint detection method, comprising the following steps: after fingerprint development using the fingerprint fluorescence development method according to any one of claims 10-12, irradiating the sample with blue-green light or blue light, and photographing and extracting the sample for fixation.

Images