A pyridine zinc(II) complex modified upconversion fluorescent material, its preparation method and application

Abstract

This invention relates to a zinc pyridine (II) complex-modified upconversion fluorescent material, its preparation method, and its application. This material is a functionalized material with dual-mode fluorescence emission. Its structure includes a zinc pyridine (II) complex and an upconversion fluorescent material. The method modifies the zinc pyridine (II) complex with the upconversion fluorescent material. The zinc pyridine (II) complex-modified upconversion fluorescent material obtained by this invention is applied in latent fingerprint development and identification. Under excitation by 365 nm and 980 nm light sources, it can display bright blue and green fingerprint imprints. The zinc pyridine (II) complex can coordinate with latent fingerprint secretions, enhancing the interaction between the developing material and the fingerprint ridges. The NaYF4:Yb,Er upconversion fluorescent material can reduce background interference during latent fingerprint development. It has the advantages of dual-mode development, resistance to background interference, simple operation, and high contrast. It can be used for criminal investigation evidence, individual identification, and forensic identification.

Description

Technical Field

[0001] This invention belongs to the field of fingerprint detection and identification in criminal science, specifically relating to a zinc pyridine (II) complex modified upconversion fluorescent material, its preparation method, and its application. Background Technology

[0002] Fingerprints are unique patterns formed by raised bumps on the fingers. Each person is born with fingerprints, which are unique and permanent. They are one of the most important forms of human identification and can serve as important physical evidence in forensic identification.

[0003] When fingerprints come into contact with a surface, endogenous substances secreted by sweat pores and exogenous substances from the environment form imprints on the surface. In most cases, these imprints cannot be directly observed with the naked eye, thus requiring technical means to visualize them. Currently, the main methods for visualizing latent fingerprints are physical and chemical methods. Physical methods primarily utilize electrostatic adsorption between the developing material and fingerprint secretions, but the contrast is low. Chemical methods may destroy the biological information carried by the latent fingerprint. Furthermore, some developing materials have colors or fluorescence that are the same or similar to the color or fluorescence of the object, further reducing the contrast of the latent fingerprint. Currently, fluorescent developing materials are rapidly developing in the field of latent fingerprint visualization due to their advantages such as high sensitivity, high contrast, speed, and ease of operation. However, most fluorescent display materials, such as organic fluorophores, quantum dots, metal-organic frameworks, aggregation-induced emission materials, and metal nanoparticles, may have the following problems in the latent fingerprint display process: (1) the fluorescence color of the display material is in the same color system as the fluorescence color of the object itself or the interfering substance, resulting in large background interference and reduced display contrast; (2) organic solvents are required for dissolution, and most organic solvents are toxic and will destroy the information of the latent fingerprint; (3) the synthesis process of the display material is cumbersome. Therefore, it is of great significance to develop a latent fingerprint fluorescent display material that is resistant to background interference, environmentally friendly, and easy to synthesize.

[0004] To address the above shortcomings, this invention provides a zinc pyridine (II) complex-modified upconversion fluorescent material, its preparation method, and its application. The functionalized upconversion fluorescent material obtained by this method enables dual-mode fluorescence display of latent fingerprints, namely, a blue fingerprint pattern is displayed under ultraviolet light irradiation and a green fingerprint pattern is displayed under 980nm near-infrared light irradiation. Furthermore, the tertiary detail features of the fingerprint can be clearly observed, exhibiting excellent resistance to background fluorescence and color interference. Summary of the Invention

[0005] The purpose of this invention is to provide a pyridine zinc(II) complex-modified upconversion fluorescent material, its preparation method, and its application. This material is a functionalized material with dual-mode fluorescence emission, and its structure consists of a pyridine zinc(II) complex and an upconversion fluorescent material. The method involves modifying the upconversion fluorescent material with a pyridine zinc(II) complex. The application of this pyridine zinc(II) complex-modified upconversion fluorescent material in latent fingerprint development and identification allows for high-contrast, high-resolution development of latent fingerprints under fluorescent light excitation. This fluorescent development material specifically interacts with latent fingerprint secretions and exhibits anti-interference properties. Under 365nm and 980nm light source excitation, it can display bright blue and green fingerprint imprints. The pyridine zinc(II) complex coordinates with latent fingerprint secretions, enhancing the interaction between the development material and the fingerprint ridges. The NaYF4:Yb,Er upconversion fluorescent material reduces background interference during latent fingerprint development. It has the advantages of dual-mode development, anti-background interference, simple operation, and high contrast. It can be used for criminal investigation evidence, individual identification, and forensic identification.

[0006] The present invention discloses a pyridine zinc(II) complex modified upconversion fluorescent material, which is made of pyridine zinc(II) complex and upconversion fluorescent material, and has the following structural formula (1):

[0007]

[0008] Where L represents acetate or chloride ions.

[0009] The method for preparing the pyridine zinc(II) complex modified upconversion fluorescent material comprises the following steps:

[0010] a. Mix dimethyl sulfoxide with water, heat to 50-70℃, add 2,6-bis(2-benzimidazolyl)pyridine, KOH and tetrabutylammonium bromide, then add 1,3-propanesulfonate lactone dropwise, stir overnight at 150℃, remove water under reduced pressure, add acetone, precipitate, dry under vacuum to obtain precipitate, then add precipitate and Zn(OAc)2 or ZnCl2 to methanol, stir at room temperature for 6 hours, filter, wash 3 times with acetone, dry under vacuum to obtain zinc pyridine (II) complex;

[0011] b. Dissolve the NaYF4:Yb,Er upconversion fluorescent material in dimethyl sulfoxide to form a transparent solution, and then slowly add the zinc pyridine (II) complex obtained in step a. Reflux at 95℃ for 24 hours, cool to room temperature to obtain a crude product. Wash the crude product three times and vacuum dry to obtain zinc pyridine (II) complex modified upconversion fluorescent material with a particle size of 20nm-3μm.

[0012] The application of the zinc pyridine (II) complex modified upconversion fluorescent material in latent fingerprint development and recognition involves depositing the zinc pyridine (II) complex modified upconversion fluorescent material onto the surface of a fingerprint-bearing object, removing excess powder with a blower, and irradiating the object with excitation light sources of 365nm and 980nm respectively to develop and photograph the fingerprint. The fingerprint emits bright blue fluorescence under 365nm light source irradiation and bright green fluorescence under 980nm light source irradiation.

[0013] The objects containing latent fingerprints can be glass, aluminum foil, stainless steel, ceramics, silicone sheets, paper, aluminum cans, coins, or commemorative medals.

[0014] Patent CN115466275A discloses a latent fingerprint fluorescence visualization probe and method on a substrate. This method uses a five-coordinate clamp-on Zn(II) metal-organic complex. The lipophilic R group at the para-position of the pyridine nitrogen in the middle of the complex in aqueous solution binds to the grease in the fingerprint component, increasing molecular aggregation and leading to aggregation-induced emission to reveal the latent fingerprint. This invention describes a pyridine zinc(II) complex modified upconversion fluorescent material, its preparation method, and its application. The prepared pyridine zinc(II) complex is a four-coordinate compound. The design of this complex considers two aspects: 1) introducing sulfonated alkyl chains onto its two pyridine rings, utilizing their bidentate ligand interaction with rare earth elements to obtain a robust functionalized upconversion material; 2) utilizing the coordination interaction between this pyridine zinc(II) complex and oleic acid, a latent fingerprint secretion, to immobilize upconversion nanomaterials, obtaining a high-contrast, highly interference-resistant dual-mode latent fingerprint revealing material that achieves blue fluorescence emission under 365nm excitation and green fluorescence emission under 980nm excitation in powder form.

[0015] The present invention relates to a zinc pyridine (II) complex modified upconversion fluorescent material, its preparation method, and its application. The zinc pyridine (II) complex modified upconversion fluorescent material is a functionalized upconversion nanoparticle with a particle size of 20 nm-3 μm.

[0016] This invention relates to a zinc pyridine (II) complex modified upconversion fluorescent material, its preparation method, and its application. The fluorescent display material is used for latent fingerprint visualization on a host, wherein the latent fingerprint is 0-70 days.

[0017] The pyridine zinc(II) complex modified upconversion fluorescent material, its preparation method, and its application, as described in this invention, have the following advantages compared to existing technologies:

[0018] 1. This invention uses fluorescence method for latent fingerprint development, which has the advantages of simple operation, speed, high fingerprint development sensitivity, and high contrast.

[0019] 2. The latent fingerprint display provided by this invention is a fluorescent dual-mode, that is, it can display clear fingerprint patterns under both 365nm and 980nm light source excitation, effectively avoiding interference from the color of the object or its own fluorescence on fingerprint display.

[0020] 3. When the pyridine zinc (II) complex modified upconversion fluorescent material of the present invention is used for latent fingerprint development, clear fingerprint outlines and even the tertiary fingerprint feature sweat pores can be observed on various objects. Attached Figure Description

[0021] Figure 1 Fluorescent images of latent fingerprints on different guests, showing the development of the pyridine zinc(II) complex-modified upconversion fluorescent material of the present invention;

[0022] Figure 2 These are detailed feature images of latent fingerprints on glass obtained by the pyridine zinc(II) complex modified upconversion fluorescent material of the present invention under illumination of 365nm and 980nm light sources;

[0023] Figure 3 The images show latent fingerprints appearing on objects in a real-world scenario using the pyridine zinc(II) complex-modified upconversion fluorescent material of the present invention.

[0024] Figure 4 The present invention relates to a method for revealing aged latent fingerprints on a glass object after aging, and fluorescent images obtained under illumination of 365nm and 980nm light sources. Detailed Implementation

[0025] Example 1

[0026] Preparation of upconversion fluorescent materials modified with pyridine zinc(II) complexes:

[0027] a. Mix 10 mL of dimethyl sulfoxide with 10 mL of water, heat to 50 °C, add 6.4 mmol of 2,6-bis(2-benzimidazolyl)pyridine, 25.7 mmol of KOH and 0.43 mmol of tetrabutylammonium bromide, then add 25.7 mmol of 1,3-propanesulfonate lactone dropwise. Stir overnight at 150 °C, remove water under reduced pressure, add acetone, precipitate, and dry under vacuum to obtain the precipitate. Add 3.0 mmol of the precipitate and 3.0 mmol of Zn(OAc)2 to methanol, stir at room temperature for 6 h, filter, wash 3 times with acetone, and dry under vacuum to obtain the zinc pyridine (II) complex.

[0028] b. Dissolve 50 mg of NaYF4:Yb,Er upconversion fluorescent material in 10 mL of dimethyl sulfoxide to form a transparent solution, then slowly add 500 mg of the zinc pyridine (II) complex obtained in step a, reflux at 95 °C for 24 h, cool to room temperature to obtain crude product, wash the crude product 3 times, and vacuum dry to obtain zinc pyridine (II) complex modified upconversion fluorescent material with a particle size of 20 nm.

[0029] Example 2

[0030] Preparation of upconversion fluorescent materials modified with pyridine zinc(II) complexes:

[0031] a. Mix 10 mL of dimethyl sulfoxide with 10 mL of water, heat to 60 °C, add 6.4 mmol of 2,6-bis(2-benzimidazolyl)pyridine, 25.7 mmol of KOH and 0.43 mmol of tetrabutylammonium bromide, then add 25.7 mmol of 1,3-propanesulfonate lactone dropwise. Stir overnight at 150 °C, remove water under reduced pressure, add acetone, precipitate, and dry under vacuum to obtain the precipitate. Add 3.0 mmol of the precipitate and 3.0 mmol of ZnCl2 to methanol, stir at room temperature for 6 h, filter, wash 3 times with acetone, and dry under vacuum to obtain the zinc pyridine (II) complex.

[0032] b. Dissolve 50 mg of NaYF4:Yb,Er upconversion fluorescent material in 10 mL of dimethyl sulfoxide to form a transparent solution, then slowly add 500 mg of the zinc pyridine (II) complex obtained in step a, reflux at 95 °C for 24 h, cool to room temperature to obtain crude product, wash the crude product 3 times, and vacuum dry to obtain zinc pyridine (II) complex modified upconversion fluorescent material with a particle size of 1 μm.

[0033] Example 3

[0034] Preparation of upconversion fluorescent materials modified with pyridine zinc(II) complexes:

[0035] a. Mix 10 mL of dimethyl sulfoxide with 10 mL of water, heat to 70 °C, add 6.4 mmol of 2,6-bis(2-benzimidazolyl)pyridine, 25.7 mmol of KOH and 0.43 mmol of tetrabutylammonium bromide, then add 25.7 mmol of 1,3-propanesulfonate lactone dropwise. Stir overnight at 150 °C, remove water under reduced pressure, add acetone, precipitate, and dry under vacuum to obtain the precipitate. Add 3.0 mmol of the precipitate and 3.0 mmol of Zn(OAc)2 to methanol, stir at room temperature for 6 h, filter, wash 3 times with acetone, and dry under vacuum to obtain the zinc pyridine (II) complex.

[0036] b. Dissolve 50 mg of NaYF4:Yb,Er upconversion fluorescent material in 10 mL of dimethyl sulfoxide to form a transparent solution, then slowly add 500 mg of the zinc pyridine (II) complex obtained in step a, reflux at 95 °C for 24 h, cool to room temperature to obtain crude product, wash the crude product 3 times, and vacuum dry to obtain zinc pyridine (II) complex modified upconversion fluorescent material with a particle size of 3 μm.

[0037] Example 4

[0038] Preparation of upconversion fluorescent materials modified with pyridine zinc(II) complexes:

[0039] a. Mix 10 mL of dimethyl sulfoxide with 10 mL of water, heat to 55 °C, add 6.4 mmol of 2,6-bis(2-benzimidazolyl)pyridine, 25.7 mmol of KOH and 0.43 mmol of tetrabutylammonium bromide, then add 25.7 mmol of 1,3-propanesulfonate lactone dropwise. Stir overnight at 150 °C, remove water under reduced pressure, add acetone, precipitate, and dry under vacuum to obtain the precipitate. Add 3.0 mmol of the precipitate and 3.0 mmol of ZnCl2 to methanol, stir at room temperature for 6 h, filter, wash 3 times with acetone, and dry under vacuum to obtain the zinc pyridine (II) complex.

[0040] b. Dissolve 50 mg of NaYF4:Yb,Er upconversion fluorescent material in 10 mL of dimethyl sulfoxide to form a transparent solution, then slowly add 500 mg of the zinc pyridine (II) complex obtained in step a, reflux at 95 °C for 24 h, cool to room temperature to obtain crude product, wash the crude product 3 times, and vacuum dry to obtain zinc pyridine (II) complex modified upconversion fluorescent material with a particle size of 80 nm.

[0041] Example 5

[0042] Any of the pyridine zinc(II) complexes obtained in Examples 1-4 were used to modify upconversion fluorescent materials, which were then deposited on a glass surface bearing fingerprints. Excess powder was removed with a blower, and the surfaces were irradiated with excitation sources of 365 nm and 980 nm, respectively, to reveal the fingerprints. The fingerprints were then photographed. Figure 1 It can be seen that fingerprints emitting bright blue fluorescence are obtained under 365nm light source illumination, and fingerprints emitting bright green fluorescence are obtained under 980nm light source illumination, and the fingerprint feature information in both modes is clearly distinguishable.

[0043] Example 6

[0044] Any of the pyridine zinc(II) complexes obtained in Examples 1-4 were used to modify upconversion fluorescent materials, which were then deposited on the surface of aluminum foil with fingerprints. Excess powder was removed with a blower, and the fingerprint patterns were observed and photographed using 365nm and 980nm light sources. Figure 1 It can be seen that under 365nm light source illumination, fingerprints emitting bright blue fluorescence can be obtained, while under 980nm light source illumination, fingerprints emitting bright green fluorescence can be obtained, and the fingerprint feature information in both modes is clearly distinguishable; from Figure 2 As can be seen, the fluorescence intensity of fingerprint ridges and grooves differs significantly between the two modes. Furthermore, the magnified image of the detailed features reveals information on secondary detailed features such as terminations, lakes, bifurcations, scars, and tertiary details such as sweat pores.

[0045] Example 7

[0046] Any of the pyridine zinc(II) complexes obtained in Examples 1-4 were used to modify upconversion fluorescent materials, which were then deposited on a stainless steel surface bearing fingerprints. Excess powder was removed with a blower, and the fingerprints were observed and photographed using 365nm and 980nm light sources. Figure 1 It can be seen that fingerprints emitting bright blue fluorescence are obtained under 365nm light source illumination, and fingerprints emitting bright green fluorescence are obtained under 980nm light source illumination, and the fingerprint feature information in both modes is clearly distinguishable.

[0047] Example 8

[0048] Any of the pyridine zinc(II) complexes obtained in Examples 1-4 were used to modify upconversion fluorescent materials, which were then deposited on the surface of a ceramic bearing fingerprints. Excess powder was removed with a blower, and the fingerprints were observed and photographed using 365nm and 980nm light sources. Figure 1 It can be seen that under 365nm light source illumination, even if the ceramic emits blue fluorescence and causes fluorescence interference, fingerprints emitting bright blue fluorescence can still be obtained. Under 980nm light source illumination, fingerprints emitting bright green fluorescence can be obtained, and the fingerprint feature information in both modes is clearly distinguishable.

[0049] Example 9

[0050] Any of the pyridine zinc(II) complexes obtained in Examples 1-4 were used to modify upconversion fluorescent materials, which were then deposited on the surface of a silicone plate with fingerprints. Excess powder was removed with a blower, and the fingerprints were observed and photographed using 365nm and 980nm light sources. Figure 1It can be seen that under 365nm light source illumination, even if the silicone plate emits blue fluorescence and causes fluorescence interference, fingerprints emitting bright blue fluorescence can still be obtained. Under 980nm light source illumination, fingerprints emitting bright green fluorescence are obtained, and the fingerprint feature information in both modes is clearly distinguishable.

[0051] Example 10

[0052] Any of the pyridine zinc(II) complexes obtained in Examples 1-4 were used to modify upconversion fluorescent materials, which were then deposited on the surface of paper with fingerprints. Excess powder was removed with a blower, and the paper was irradiated with 365nm and 980nm light sources to observe and photograph the fingerprint patterns. Figure 1 It can be seen that under 365nm light source illumination, the paper emits blue fluorescence, producing severe fluorescence interference, and fingerprints emitting bright blue fluorescence can be obtained. However, under 980nm light source illumination, fingerprints emitting bright green fluorescence are obtained, and the fingerprint feature information is clearly distinguishable.

[0053] Example 11

[0054] Any of the pyridine zinc(II) complexes obtained in Examples 1-4 were used to modify upconversion fluorescent materials, which were then deposited on the surface of a fingerprint-printed aluminum can. Excess powder was removed with a blower, and the cans were irradiated with 365nm and 980nm light sources to observe and photograph the fingerprint patterns. Figure 3 It can be seen that even with color interference on the surface of the can, a fingerprint emitting bright blue fluorescence can still be obtained under 365nm light source illumination, and a fingerprint emitting bright green fluorescence can be obtained under 980nm light source illumination, and the fingerprint feature information in both modes is clearly distinguishable.

[0055] Example 12

[0056] Any of the pyridine zinc(II) complexes obtained in Examples 1-4 were used to modify upconversion fluorescent materials, which were then deposited on the surface of coins bearing fingerprints. Excess powder was removed with a blower, and the fingerprints were observed and photographed using 365nm and 980nm light sources. Figure 3 It can be seen that even with an uneven coin surface, a fingerprint emitting bright blue fluorescence can still be obtained under 365nm light source illumination, and a fingerprint emitting bright green fluorescence can be obtained under 980nm light source illumination, and the fingerprint feature information in both modes is clearly distinguishable.

[0057] Example 13

[0058] Any of the pyridine zinc(II) complexes obtained in Examples 1-4 were used to modify upconversion fluorescent materials, which were then deposited on the surface of a commemorative badge bearing fingerprints. Excess powder was removed with a blower, and the fingerprints were irradiated with 365nm and 980nm light sources to observe and photograph the patterns. Figure 3It can be seen that even with color and pattern interference on the commemorative medal, and severe blue fluorescence interference under 365nm light source, fingerprints emitting blue fluorescence can still be obtained under this mode. Under 980nm light source, fingerprints emitting bright green fluorescence are obtained. The fingerprint feature information under this mode is clearly distinguishable.

[0059] Example 14

[0060] Wash your hands thoroughly and let them air dry. Rub your fingers on your forehead and gently press them onto a glass surface. Leave them for 1-70 days. Then, modify the upconversion fluorescent material with a zinc pyridine (II) complex and deposit it on the glass surface. Remove excess powder with a hairdryer. Irradiate the surface with 365nm and 980nm light sources to observe the fingerprint pattern and take pictures. Figure 4 It can be seen that even after 70 days of latent fingerprint storage, fingerprints emitting bright blue fluorescence can still be obtained under 365nm light source illumination, and fingerprints emitting bright green fluorescence can still be obtained under 980nm light source illumination, and the fingerprint feature information in both modes is clearly distinguishable.

Claims

1. A pyridine zinc(II) complex modified upconversion fluorescent material, characterized in that, This material is made from a zinc pyridine (II) complex and a NaYF4:Yb,Er upconversion fluorescent material. The structural formula of the zinc pyridine (II) complex is shown below: Where L represents acetate or chloride ions.

2. The method for preparing a pyridine zinc(II) complex modified upconversion fluorescent material according to claim 1, characterized in that, Prepare according to the following steps: a. Mix dimethyl sulfoxide with water, heat to 50-70℃, add 2,6-bis(2-benzimidazolyl)pyridine, KOH and tetrabutylammonium bromide, then add 1,3-propanesulfonate lactone dropwise, stir overnight at 150℃, remove water under reduced pressure, add acetone, precipitate, dry under vacuum to obtain precipitate, then add precipitate and Zn(OAc)2 or ZnCl2 to methanol, stir at room temperature for 6 hours, filter, wash 3 times with acetone, dry under vacuum to obtain zinc pyridine (II) complex; b. Dissolve the NaYF4:Yb,Er upconversion fluorescent material in dimethyl sulfoxide to form a transparent solution, and then slowly add the zinc pyridine (II) complex obtained in step a. Reflux at 95℃ for 24 hours, cool to room temperature to obtain a crude product. Wash the crude product three times and vacuum dry to obtain zinc pyridine (II) complex modified upconversion fluorescent material with a particle size of 20nm-3μm.

3. The application of the pyridine zinc(II) complex modified upconversion fluorescent material according to claim 1 in latent fingerprint development and recognition, characterized in that, Upconversion fluorescent material modified with zinc pyridine (II) complex was deposited on the surface of a fingerprint-bearing object. Excess powder was removed with a blower. The fingerprint was then irradiated with excitation light sources of 365 nm and 980 nm, respectively, to reveal the fingerprint and photograph it. The fingerprint emitted bright blue fluorescence under 365 nm light and bright green fluorescence under 980 nm light.

4. The application according to claim 3, characterized in that, The object containing the latent fingerprint can be glass, aluminum foil, stainless steel, ceramic, silicone plate, or paper.

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