Fingerprint extraction method based on mechanochromic pyrenyl derivative

Abstract

The invention belongs to the technical field of novel fluorescent materials, and particularly discloses application of a mechanical color change pyrenyl derivative in latent fingerprint fluorescence imaging and extraction. The mechanical color-changing pyrenyl derivative can be selectively combined with fingerprint residual substances under the excitation of ultraviolet light through the unique fluorescence response characteristic, so that potential fingerprints form high-contrast fluorescence imaging on smooth or rough surfaces (such as glass, metal, plastic and the like), and the mechanical color-changing pyrenyl derivative is compatible with conventional camera equipment to realize rapid acquisition. The compound design is based on a modular synthesis route, and has the advantages of simple and convenient synthesis process, controllable raw material cost, high reaction yield and the like. The product has excellent thermal stability and chemical stability, can be stored at normal temperature and does not need special treatment, and the practical application threshold is greatly reduced. Compared with a traditional fingerprint developing technology, the method has remarkable breakthroughs in the aspects of sensitivity, substrate adaptability and operation convenience, and an efficient, economical and environment-friendly novel solution is provided for the fields of criminal investigation, forensic identification and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of luminescent materials, and in particular relates to an application of a mechanically color-changing pyrene-based derivative in fingerprint extraction. Background Art

[0002] Latent fingerprints refer to marks with unique patterns (such as loops, whorls, and arches) left when a finger touches the surface of an object. Due to its highly individual characteristics and uniqueness, fingerprints are regarded as one of the most reliable biometrics and are widely used in fields such as identity verification, criminal investigation, and forensic analysis. At the crime scene, latent fingerprints are often important traces left unintentionally. They have extremely high forensic value and have become one of the key evidences for conviction by law enforcement and judicial agencies. For a long time, fingerprints have played an irreplaceable role as core physical evidence in criminal investigations. With the advancement of science and technology, evidence collection and analysis methods have been significantly improved, and the accuracy of fingerprint extraction and identification has also been greatly improved.

[0003] Features extracted from latent fingerprints are usually divided into three levels: primary features, secondary features, and tertiary features. Primary features include macroscopic structures such as arches, left loops, right loops, and spirals, which are visible to the naked eye and can be used for preliminary visual inspection and manual matching. Secondary features are more sophisticated, including microscopic details such as ridge ends, bifurcations, and hooks, which have higher identification value in fingerprint matching. However, since fingerprint quality may be affected by factors such as contamination, blurring, or substrate interference, the extraction of ridge details may be challenging and requires reconstruction and enhancement through technical means to eliminate false features and improve recognition accuracy. Tertiary features are the most decisive details in fingerprints, including permanent features such as sweat pore distribution, ridge morphology, and scars, which can provide a higher level of individualized information. However, due to the limitations of resolution and extraction technology, the acquisition and analysis of tertiary features are still difficult.

[0004] Therefore, developing an efficient, non-destructive latent fingerprint visualization reagent that is applicable to a variety of substrates is of great practical significance for improving the success rate of fingerprint extraction and enhancing the accuracy of criminal investigation. This reagent should not only have high sensitivity and selectivity, but also be environmentally friendly and easy to operate to meet the needs of modern forensic medicine and law enforcement practice. Summary of the invention

[0005] The purpose of the present invention is to provide a fluorescence imaging method based on a mechanochromic pyrene derivative for efficiently and non-destructively extracting latent fingerprints on the surfaces of various materials in view of the shortcomings of the latent fingerprint visualization reagents in the prior art in terms of efficiency, environmental friendliness and applicability. The probe can form high-definition and highly recognizable fluorescence imaging on different substrates, significantly improving the effect of fingerprint extraction. Compared with traditional methods, the present invention solves the technical problems of complex operation, low efficiency and high requirements for background materials in traditional fingerprint collection technology, and provides a more convenient and reliable solution for criminal investigation and forensic analysis.

[0006] Another object of the present invention is to provide a method for preparing the above compound.

[0007] The purpose of the present invention can be achieved by the following measures: Using 4-pyrenyl-2-hydroxybenzaldehyde and 4-(trifluoromethyl)benzyl acetonitrile as raw materials, a mechanically color-changing pyrenyl derivative was prepared by Knoevenagel condensation reaction. The reaction formula is:

[0008] Step 2: Extraction: After the reaction is completed, the cooled reaction product is extracted with a good solvent for 2 to 3 times, and the organic phase solution is collected. The collected organic phase solution is washed with saturated brine for 2 to 3 times, and then dried with anhydrous magnesium sulfate to obtain a mixture of the crude reaction product and the good solvent; Step 3: Purification: distill the mixture of the crude reaction product and the good solvent until a small amount of solvent remains, separate by column chromatography, and then rotary evaporate to obtain the pure target product.

[0009] The various raw materials used in the present invention are all commercial reagents with low prices. The intermediates are relatively simple to prepare and have good thermal stability without requiring special storage conditions. The overall synthetic route is simple, the yield is high, and the pollution is low.

[0010] In order to better prepare the mechanical color-changing pyrene derivative, the preferred technical scheme is that in the first step, the molar ratio of 4-pyrene-2-hydroxybenzaldehyde and 4-(trifluoromethyl)benzyl acetonitrile is 1:1.5, the solvent is methanol and tetrahydrofuran, the reaction temperature is 90°C, and the reaction time is 24h.

[0011] In order to improve the purification efficiency, the preferred technical solution is that the solvents used for column chromatography are dichloromethane and petroleum ether, and the ratio of dichloromethane to petroleum ether is 1:1.

[0012] In order to better promote the application of this type of pyrene derivatives with fingerprint development properties, the application of the mechanical color-changing pyrene derivatives in fingerprint extraction is proposed.

[0013] The advantages and beneficial effects of the present invention are: 1. The present invention proposes a mechanically color-changing pyrene derivative, which expands the types of substances for traditional fingerprint development; the compound has great development potential in fingerprint fluorescence imaging.

[0014] 2. The present invention uses 4-pyrenyl-2-hydroxybenzaldehyde and 4-(trifluoromethyl)phenylacetonitrile as raw materials, and the reaction conditions are relatively mild. The mechanical color-changing pyrenyl derivative is prepared by Knoevenagel condensation reaction, and a new substance is extracted for fingerprints.

[0015] 3. The various raw materials used in the synthesis of the present invention are cheap and easy to obtain, the intermediates are simple to prepare and have stable performance, and do not require special storage conditions; the relevant reagents and solvents are commonly used commercial reagents with low cost; the overall synthesis route is simple, the yield is high, and the pollution is small; the synthesis method includes three steps of synthesis, extraction and purification, which simplifies the synthesis steps compared to other synthetic mechanical color-changing pyrene derivatives, making the method easier to promote industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The structure diagram of the substance synthesized by the present invention; Figure 2 This is the fingerprint display effect and grayscale image on non-fluorescent paper; Figure 3 This is a fingerprint display effect diagram without different substrates; DETAILED DESCRIPTION

[0017] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical scheme of the present invention, and cannot be used to limit the scope of protection of the present invention. The process, conditions, reagents, experimental methods, test methods, etc. of implementing the present invention, except for the contents specifically mentioned below, are all common knowledge and common common sense in the art, and the present invention has no special restrictions. The data given in the following examples include specific operations and reaction conditions and products. The product purity is identified by nuclear magnetic resonance and high-resolution mass spectrometry, and the structure is accurately characterized.

[0018] A mechanically color-changing pyrene derivative, the structural formula of which is Figure 1 As shown:

[0019] The synthesis method of the above-mentioned mechanically color-changing pyrene derivative comprises the following steps: Step 1: Synthesis: Using 4-pyrenyl-2-hydroxybenzaldehyde and 4-(trifluoromethyl)benzyl acetonitrile as raw materials, a 1-substituted pyrenyl derivative is prepared by Knoevenagel condensation reaction. The reaction formula is:

[0020] Step 2: Extraction: After the reaction is completed, the cooled reaction product is extracted with a good solvent for 2 to 3 times, and the organic phase solution is collected. The collected organic phase solution is washed with saturated brine for 2 to 3 times, and then dried with anhydrous magnesium sulfate to obtain a mixture of the crude reaction product and the good solvent; Step 3: Purification: distill the mixture of the crude reaction product and the good solvent until a small amount of solvent remains, separate by column chromatography, and then rotary evaporate to obtain the pure target product.

[0021] In order to better prepare the mechanical color-changing pyrene derivative, the preferred technical scheme is that in the first step, the molar ratio of 4-pyrene-2-hydroxybenzaldehyde and 4-(trifluoromethyl)benzyl acetonitrile is 1:1.5, the solvent is methanol and tetrahydrofuran, the reaction temperature is 90°C, and the reaction time is 24h.

[0022] In order to improve the purification efficiency, the preferred technical solution is that the solvents used for column chromatography are dichloromethane and petroleum ether, and the ratio of dichloromethane to petroleum ether is 1:1.

[0023] In order to better promote the application of this type of pyrene derivatives that can be used in fingerprint fluorescence imaging, it is proposed that the mechanical color-changing pyrene derivatives have great development potential in fingerprint extraction. Example

[0024] Taking the synthesis of 4-pyrenyl-2-hydroxybenzaldehyde as an example, 4-(Trifluoromethyl)benzylacetonitrile (277.6 mg, 1.5 mmol) was added to a mixture of 4-pyrenyl-2-hydroxybenzaldehyde (489.5 mg, 1 mmol), MeOH (50 mL) and THF (15 mL), sodium tert-butoxide (480 mg, 5 mmol) at room temperature under nitrogen atmosphere. The mixture was heated to 90 °C for 12 h while stirring. After the reaction was cooled, H 2 O and saline. The organic matter was washed with Na 2 SO 4 Dry and evaporate. 2 Cl 2 =1:1 column chromatography to obtain the product with a yield of 46%. Example

[0025] Taking the synthesis of 4-pyrenyl-2-hydroxybenzaldehyde as an example, 4-(Trifluoromethyl)benzylacetonitrile (277.6 mg, 1.5 mmol) was added to a mixture of 4-pyrenyl-2-hydroxybenzaldehyde (489.5 mg, 1 mmol), MeOH (50 mL) and THF (15 mL), sodium tert-butoxide (480 mg, 5 mmol) at room temperature under nitrogen atmosphere. The mixture was heated to 90 °C for 24 h while stirring. After the reaction was cooled, H 2 O and saline. The organic matter was washed with Na 2 SO 4 Dry and evaporate. 2 Cl 2 =1:1 column chromatography to obtain the product with a yield of 71%. Example

[0026] Taking the synthesis of 4-pyrenyl-2-hydroxybenzaldehyde as an example, 4-(Trifluoromethyl)benzylacetonitrile (277.6 mg, 1.5 mmol) was added to a mixture of 4-pyrenyl-2-hydroxybenzaldehyde (489.5 mg, 1 mmol), MeOH (50 mL) and THF (15 mL), sodium tert-butoxide (480 mg, 5 mmol) at room temperature under nitrogen atmosphere. The mixture was heated to 90 °C for 36 h while stirring. After the reaction was cooled, H 2 O and saline. The organic matter was washed with Na 2 SO 4 Dry and evaporate. 2 Cl 2 =1:1 column chromatography to obtain the product with a yield of 69%. Example

[0027] Taking the synthesis of 4-pyrenyl-2-hydroxybenzaldehyde as an example, 4-(Trifluoromethyl)benzylacetonitrile (277.6 mg, 1.5 mmol) was added to a mixture of 4-pyrenyl-2-hydroxybenzaldehyde (489.5 mg, 1 mmol), MeOH (50 mL) and THF (15 mL), sodium tert-butoxide (480 mg, 5 mmol) at room temperature under nitrogen atmosphere. The mixture was heated to 90 °C for 48 h while stirring. After the reaction was cooled, H 2 O and saline. The organic matter was washed with Na 2 SO 4 Dry and evaporate. 2 Cl 2 =1:1 column chromatography to obtain the product with a yield of 66%.

[0028] The NMR characterization results are as follows: 1 H NMR (400 MHz, CDCl 3 ): (δ= ppm): δ H = 7.39-7.41 (d, J = 8 Hz, 1H), 7.46-7.49 (d, J = 12 Hz, 1H), 7.57 (s, 1H), 7.62-7.67(t, J = 20 Hz,1H), 7.70-7.76(m,3H), 7.83-7.85(d, J = 8 Hz, 1H), 7.88-7.92(t, J = 24 Hz 2H), 8-8.02(d, J = 8 Hz, 1H), 8.06-8.12(m, 1H), 8.14-8.16(d, J = 8 Hz, 2H), 8.18-8.28(m,3H); FAB-MS: m / z calcd for C33H22F3N 487.5376 [M+]; found 487.5369 [M+] 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 technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

[0029] Fingerprint display effect Visualization on non-fluorescent paper; 2. Fluorescent agents used in the experiment The mechanochromic pyrene-based derivatives of the present invention are used.

[0030] 3. Display the camera fixed The latent fingerprints are revealed by doping with mechanically color-changing pyrene derivatives and neutral alumina, and then irradiated with ultraviolet light to excite fluorescence, which is then photographed and fixed.

[0031] Use a mobile phone with a high-definition camera to take pictures, select a 365 nm light source to excite fluorescence and take pictures, and the lighting angle is 30°~45°. The fingerprint effect is shown in the attached figure.

Claims

1. A fingerprint extraction method based on mechanical color-changing pyrene derivatives, characterized in that: The structural formula is: 。 2. The method for synthesizing the compound according to claim 1, characterized in that The preparation reaction equation is as follows: 。 3. The method according to claim 2, characterized in that The steps include: Step 1: Synthesis: Using 4-pyrenyl-2-hydroxybenzaldehyde and 4-(trifluoromethyl)phenylacetonitrile as raw materials, a mechanochromic pyrenyl derivative was prepared by Knoevenagel condensation reaction; Step 2: Extraction: After the reaction is completed, the cooled reaction product is extracted with a good solvent for 2 to 3 times, and the organic phase solution is collected. The collected organic phase solution is washed with saturated brine for 2 to 3 times, and then dried with anhydrous magnesium sulfate to obtain a mixture of the crude reaction product and the good solvent; Step 3: Purification: distill the mixture of the crude reaction product and the good solvent until a small amount of solvent remains, separate by column chromatography, and then rotary evaporate to obtain the pure target product.

4. The method for synthesizing a mechanochromic pyrene derivative according to claim 2, characterized in that: In the first step, the molar ratio of 4-pyrenyl-2-hydroxybenzaldehyde to 4-(trifluoromethyl)benzyl acetonitrile is 1:1.5, the solvent is methanol and tetrahydrofuran, the reaction temperature is reflux, and the reaction time is 12 to 48 hours.

5. The method for synthesizing a mechanochromic pyrene derivative according to claim 2, characterized in that: The optimized reaction conditions are: the molar ratio of 4-pyrenyl-2-hydroxybenzaldehyde to 4-(trifluoromethyl)benzyl acetonitrile is 1:1.5, the solvents are methanol and tetrahydrofuran, the reaction temperature is reflux, and the reaction time is 24h.

6. The use of a mechanically color-changing pyrene derivative as claimed in claim 1, characterized in that: The mechanically color-changing pyrene derivative as described in claim 1 has important applications in fingerprint extraction.

7. The use according to claim 6, characterized in that The fingerprint powder containing the fluorescent material is sprayed on the carrier containing the latent fingerprint, so that the fingerprint powder containing the fluorescent material is in contact with the carrier containing the latent fingerprint.

8. The use according to claim 7, characterized in that The ratio of the mass of the fluorescent material to the mass of the neutral alumina in the fingerprint powder containing the fluorescent material is 1:

20.

9. The fingerprint carrier according to claim 7, characterized in that: The carrier can be paper, metal, plastic, alloy, wood, glass, but is not limited to the above carriers.

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