A fluorescent powder material for latent fingerprint visualization and its application
By developing a fluorescent powder material with a simple structure, combining a combination of a specific compound of formula I and a carrier, the problem of existing fluorescent powder materials being susceptible to background interference is solved, and high definition and high contrast fingerprint display is achieved, providing multiple This feature information ensures the reliability of identity verification.
Patent Information
- Application Number
- CN202210432839.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-04-24
- Publication Date
- 2025-01-03
- Estimated Expiration
- 2042-04-24
AI Technical Summary
The existing fluorescent powder materials used for latent fingerprint display have short emission wavelengths and are easily disturbed by background, resulting in poor sharpness and contrast of fingerprint images, and complex synthesis routes and high cost.
Develop a fluorescent powder material with simple structure and easy to synthesize, including a combination of a specific compound of formula I, with montmorillonite, silica or magnetic powder, to prepare a fluorescent powder by ultrasound uniformly dispersing and evaporating organic solvents, and to display fingerprints using ultraviolet light sources.
It realizes high-definition and high-contrast fingerprint image display, provides a variety of feature information, provides a solid basis for identity verification, and is simple in preparation, low in cost and good stability.
Smart Images
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Abstract
Description
[Technical field]
[0001] The invention relates to a fluorescent powder material and application thereof, in particular to a fluorescent powder material for latent fingerprint visualization and application thereof, belonging to the field of organic fluorescent materials. [Background technology]
[0002] Fingerprints are unique patterns formed by ridges on the skin of the fingers. Human fingerprints are different and remain unchanged throughout life. People have long identified their identities by pressing fingerprints on paper or wood. Fingerprint identification is one of the most reliable methods for personal identification. Confirming the identity of criminal suspects through fingerprint technology has become a powerful means of investigating and cracking down on crimes. The most common fingerprints at the crime scene are latent fingerprints, which are fingerprints left by fingers with sweat or oil touching the surface of an object. They are not easy to detect with the naked eye. Special methods or chemical reagents are required to reveal this type of latent fingerprint. The methods for revealing latent fingerprints are mainly divided into optical, physical and chemical methods. Among them, the physical method mainly uses the hydrophobic and adsorption effects between the secretions on the latent fingerprints and the powder developer to make them imaged. It has the characteristics of simple operation and strong visualization ability. Traditional powder developers still have some urgent problems to be solved in practical applications. For example: magnetic fingerprint powder and metal fingerprint powder are easily interfered by the background color of the object, and the imaging contrast is relatively poor.
[0003] Organic solid-state fluorescent molecules have excellent fluorescence luminescence properties in the aggregated state, and their luminescence signals have high resolution. In the application of latent fingerprint development, solutions of organic solid-state fluorescent molecules are usually used to image fingerprints by utilizing their enhanced luminescence properties in the aggregated state. However, the solution method operation process is relatively complicated, and the development time of latent fingerprints is also relatively long. The application research of fluorescent powder materials based on organic solid-state fluorescent molecules in latent fingerprint development is still very limited. At present, the emission wavelength of such fluorescent powder materials that have been developed is generally short, the Stokes shift is small, and they are easily interfered by the background fluorescence of the object. The clarity and contrast of the obtained fingerprint image are poor, and the fingerprint feature information obtained is not complete enough. In addition, the developed red fluorescent powder materials require the use of organic solid-state fluorescent molecules with complex structures, and their synthesis route is long and the cost is high. Therefore, there is still a need to develop a type of fluorescent powder material that is easy to prepare, low in cost, has a long fluorescence emission wavelength, and can be used for high-definition and high-contrast imaging of latent fingerprints. [Summary of the invention]
[0004] The purpose of the present invention is to provide a fluorescent powder material for latent fingerprint visualization and its application in view of the above technical analysis and existing problems. The fluorescent compound described in the present invention has a simple structure, is easy to synthesize, has a large fluorescence emission wavelength and a high solid fluorescence quantum yield. The fluorescent powder material described in the present invention has the advantages of easy preparation, low cost, good stability, non-toxic and environmentally friendly, etc., and can be used for latent fingerprint visualization to obtain a fingerprint image with high definition and high contrast.
[0005] The present invention discloses the following technical solutions:
[0006] 1. A fluorescent powder material for latent fingerprint visualization, characterized in that the fluorescent powder material comprises a compound of formula I and a carrier for adsorbing the compound; the carrier is selected from at least one of montmorillonite, silicon dioxide, or magnetic powder; the structural formula of the compound of formula I is as follows:
[0007]
[0008] It is characterized by: R 1 is methyl, R 2 For hydrogen.
[0009] 2. A method for preparing the fluorescent powder material for latent fingerprint visualization as described above, the method comprising the following steps:
[0010] (1) Dissolve the compound of formula I in an organic solvent, add a carrier, and uniformly disperse it in the solution by ultrasonic or oscillation.
[0011] (2) The organic solvent in the solution is removed by evaporation, and the obtained solid is ground into powder to obtain a fluorescent powder material for latent fingerprint visualization.
[0012] Preferably, the organic solvent includes at least one of dichloromethane or chloroform.
[0013] 3. A method for applying the fluorescent powder material for latent fingerprint visualization as described above, the method comprising the following steps:
[0014] (1) coating the fluorescent powder material on the surface area where the latent fingerprint is located, and removing the fluorescent powder material that is not adsorbed.
[0015] (2) Use ultraviolet light to illuminate the surface area where the latent fingerprint is located, and use a camera or mobile phone to take a picture to obtain a fingerprint image.
[0016] Preferably, the wavelength range of the ultraviolet light source is 250-400 nm.
[0017] 4. A method for preparing a compound of formula I as described above, the method comprising the following steps:
[0018] In a reaction container, a benzyl cyanide compound, a 2-naphthaldehyde compound, an inorganic base and an appropriate amount of an organic solvent are added respectively, and a reflux reaction is carried out to generate a compound of formula I.
[0019] Preferably, the organic solvent is selected from at least one of tetrahydrofuran, chloroform, acetonitrile or ethanol.
[0020] Preferably, the inorganic base is selected from at least one of potassium carbonate, cesium carbonate, sodium tert-butoxide or potassium tert-butoxide.
[0021] The present invention has the following advantages:
[0022] (1) The fluorescent powder material provided by the present invention has a simple preparation method, excellent fluorescent properties, good stability, and is non-toxic and environmentally friendly.
[0023] (2) The latent fingerprint development method of the present invention is simple to operate and has high development efficiency.
[0024] (3) The fingerprint image obtained by the fluorescent powder material provided by the present invention in the latent fingerprint display has high definition and high contrast, and can provide a variety of characteristic information contained in the fingerprint, providing a solid basis for identity confirmation.
Brief Description of the Drawings
[0025] Figure 1 The fluorescent powder material prepared in Example 3 is used for the latent fingerprint revealing effect on the surface of a glass dish;
[0026] Figure 2 The fluorescent powder material prepared in Example 3 is used for the latent fingerprint visualization effect on the surface of a bank card;
[0027] Figure 3 The fluorescent powder material prepared in Example 3 is used for the latent fingerprint revealing effect on the marble surface. [Specific implementation method]
[0028] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood by those skilled in the art that the following embodiments are only used to illustrate the present invention and should not be used to limit the scope of protection of the present invention.
[0029] Embodiment 1:
[0030] Synthesis of fluorescent dye molecule 1 having a structure similar to that of compound I:
[0031]
[0032] Potassium tert-butoxide (79 mg, 0.71 mmol) was added to a solution of benzyl cyanide (60 mg, 0.51 mmol) in ethanol (10 ml). The reaction mixture was stirred at room temperature for 10 minutes. Then 6-(dimethylamino)-2-naphthaldehyde (70 mg, 0.35 mmol) was added. The solution was warmed to reflux and reacted for 4 hours. After the reaction was complete, the reaction solution was cooled to room temperature and the organic solvent was removed by rotary evaporation. The crude product was purified by silica gel column to obtain 73 mg of a yellow solid with a yield of 70%.
[0033] The product structure was characterized by H-NMR, C-NMR and high-resolution mass spectrometry.
[0034] 1 H NMR(500MHz, CDCl3)δ8.14(s,1H),8.05–8.01(m,1H),7.76(d,J=9.0Hz,1H),7.70–7.66(m,3H),7.59(s,1H), 7.44(t,J=7.6Hz,2H),7.36(t,J=7.3Hz,1H),7.16(dd,J=9.1,2.4Hz,1H),6.88(d,J=2.0Hz,1H),3.10(s,6H). 13 C NMR (126MHz, CDCl3) δ148.8,141.9,135.2,134.2,129.8,128.9,128.0,127.6,12 6.3,125.7,124.8,124.8,117.9,115.4,107.2,104.7,39.5.HRMS(ESI)calcd.for C 21 H 19 N2[M+H] + :299.1543,found:299.1548.
[0035] Embodiment 2:
[0036] The optical properties of the fluorescent dye molecule 1 prepared in Example 1, such as ultraviolet absorption and fluorescence emission, were studied.
[0037] Dissolve the fluorescent dye molecule 1 in DMSO solution to prepare a concentration of 10 -5M test solution. Through UV absorption and fluorescence tests, it was found that the maximum absorption wavelength of fluorescent dye molecule 1 in DMSO solution was 410nm, the maximum fluorescence emission wavelength was 578nm, and the Stokes shift could reach 171nm. The fluorescence quantum yield of fluorescent dye molecule 1 in DMSO solution was 0.05. In the solid state, fluorescent dye molecule 1 can emit bright yellow fluorescence after being excited, and its fluorescence emission wavelength is 566nm. The solid-state fluorescence quantum yield reaches 0.28, which is 5.4 times the fluorescence quantum yield in DMSO solution.
[0038] Embodiment 3:
[0039] Fluorescent dye molecule 1-preparation of montmorillonite fluorescent powder material.
[0040] The fluorescent dye molecule 1 is dissolved in dichloromethane, and then powdered montmorillonite is added. The mass ratio of the fluorescent dye molecule 1 to the montmorillonite is 1:99. Under ultrasonic conditions, the montmorillonite powder is evenly dispersed in the solvent. The resulting solution is poured into a round-bottom flask, and the dichloromethane solvent is removed by rotary evaporation to obtain a solid mixture. The resulting solid mixture is ground into powder to obtain a fluorescent dye molecule 1-montmorillonite fluorescent powder material.
[0041] Embodiment 4:
[0042] Fluorescent dye molecule 1- Preparation of silica fluorescent powder material.
[0043] Dissolve the fluorescent dye molecule 1 in dichloromethane, and then add powdered silica. The mass ratio of the fluorescent dye molecule 1 to the silica is 1:90. Under ultrasonic conditions, the silica powder is evenly dispersed in the solvent. Pour the resulting solution into a round-bottom flask, and remove the dichloromethane solvent by rotary evaporation to obtain a solid mixture. Grind the resulting solid mixture into powder to obtain a fluorescent dye molecule 1-silica fluorescent powder material.
[0044] Embodiment 5:
[0045] Fluorescent dye molecule 1- preparation of magnetic powder fluorescent powder material.
[0046] Dissolve the fluorescent dye molecule 1 in dichloromethane, and then add magnetic powder. The mass ratio of the fluorescent dye molecule 1 to the magnetic powder is 1:95. Under ultrasonic conditions, the magnetic powder is evenly dispersed in the solvent. Pour the resulting solution into a round-bottom flask, and remove the dichloromethane solvent by rotary evaporation to obtain a solid mixture. Grind the resulting solid mixture into powder to obtain a fluorescent dye molecule 1-magnetic powder fluorescent powder material.
[0047] Embodiment 6:
[0048] Fluorescent powder material is used to reveal latent fingerprints on glass surfaces
[0049] The person being tested washes his hands, touches his forehead with his fingers, and then presses the fingerprint on the surface of the glass dish. Gently apply the fluorescent powder material to the location of the latent fingerprint. Blow away the unabsorbed fluorescent powder material with a balloon. Illuminate the location of the latent fingerprint with a 365nm ultraviolet lamp, and the fingerprint emits bright yellow fluorescence. Take a photo with a mobile phone or camera to get a clear fingerprint image. From the fingerprint image, you can get a variety of feature information contained in the fingerprint, including level 2 and level 3 features.
[0050] Embodiment 7:
[0051] Fluorescent powder material is used to reveal latent fingerprints on bank card surfaces
[0052] The person being tested washes his hands, touches his forehead with his fingers, and then presses his fingerprint on the surface of the bank card. Gently apply the fluorescent powder material to the location of the latent fingerprint. Blow away the unabsorbed fluorescent powder material with a balloon. Illuminate the location of the latent fingerprint with a 365nm ultraviolet lamp, and the fingerprint emits bright yellow fluorescence. Take a photo with a mobile phone or camera to get a clear fingerprint image. From the fingerprint image, you can get a variety of feature information contained in the fingerprint, including level 2 and level 3 features.
[0053] Embodiment 8:
[0054] Fluorescent powder material is used to reveal latent fingerprints on marble surfaces
[0055] The person being tested washes his hands, touches his forehead with his fingers, and then presses his fingerprint on the marble surface. Gently apply the fluorescent powder material to the location of the latent fingerprint. Blow away the unabsorbed fluorescent powder material with a balloon. Illuminate the location of the latent fingerprint with a 365nm ultraviolet lamp, and the fingerprint emits bright yellow fluorescence. Take a photo with a mobile phone or camera to get a clear fingerprint image. From the fingerprint image, you can get a variety of feature information contained in the fingerprint, including level 2 and level 3 features.
[0056] The above description is only a preferred embodiment of the present invention, which is merely illustrative and not restrictive of the present invention. It is understood by those skilled in the art that many changes, modifications, and even equivalent changes may be made thereto within the scope defined by the patent claims of the present invention, but all of them will fall within the protection scope of the present invention.
Claims
1. A fluorescent powder material for latent fingerprint visualization, characterized in that The fluorescent powder material comprises a compound of formula I and a carrier for absorbing the compound; the carrier is selected from at least one of montmorillonite, silicon dioxide, or magnetic powder; the structural formula of the compound of formula I is as follows: It is characterized by: R 1 is methyl, R 2 For hydrogen.
2. The use of the fluorescent powder material according to claim 1 in latent fingerprint visualization, characterized in that: The application steps are as follows: (1) coating the fluorescent powder material on the surface area where the latent fingerprint is located, and removing the fluorescent powder material that is not adsorbed; (2) Use ultraviolet light to illuminate the surface area where the latent fingerprint is located, and use a camera or mobile phone to take a picture to obtain a fingerprint image.
3. The use of the fluorescent powder material according to claim 2 in latent fingerprint visualization, characterized in that: The wavelength range of the ultraviolet light source is 250-400nm.