Pyridine zinc (II) complex modified up-conversion fluorescent material as well as preparation method and application thereof

Abstract

The invention relates to a pyridine zinc (II) complex modified up-conversion fluorescent material and a preparation method and application thereof.The material is a functional material with dual-mode fluorescence emission and structurally comprises a pyridine zinc (II) complex and an up-conversion fluorescent material.According to the method, the pyridine zinc (II) complex modified up-conversion fluorescent material is used for preparing the up-conversion fluorescent material with the dual-mode fluorescence emission function. The zinc pyridine (II) complex modified up-conversion fluorescent material obtained through the method is applied to latent fingerprint development and recognition, bright blue and green fingerprint prints can be developed under excitation of 365 nm and 980 nm light sources, the zinc pyridine (II) complex can be coordinated with latent fingerprint secretions, and therefore the potential fingerprint development and recognition can be achieved. The action force between the development material and the fingerprint ridge of the latent fingerprint is enhanced, and the NaYF4: Yb, Er up-conversion fluorescent material can reduce background interference in the latent fingerprint development process. The method has the advantages of dual-mode display, background interference resistance, simplicity and convenience in operation and high contrast ratio. The method can be used for criminal investigation evidence, individual identification, judicial expertise and the like.

Description

Technical Field

[0001] The invention belongs to the field of criminal science fingerprint detection and identification, and specifically relates to a pyridine zinc (II) complex modified up-conversion fluorescent material and a preparation method and application thereof. Background Art

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

[0003] When fingerprints come into contact with the surface of an object, they will form marks on the surface of the object due to the endogenous substances secreted by the sweat pores and the exogenous substances in the environment. In most cases, these marks cannot be directly observed by the eyes, so technical means are needed to visualize them. At present, there are mainly physical visualization methods and chemical visualization methods for latent fingerprints. The physical visualization method mainly visualizes fingerprints through electrostatic adsorption between the visualization material and the fingerprint secretions, but the visualization contrast is low, and the chemical visualization method may destroy the biological information carried by the latent fingerprint. The color or fluorescent color of some visualization materials themselves is the same or similar to the color or fluorescent color of the object, resulting in a decrease in the visualization contrast of the latent fingerprint. At present, fluorescent visualization materials are rapidly developing in the field of latent fingerprint visualization due to their advantages such as high sensitivity, high contrast, fast speed, and simple operation. However, most fluorescent materials such as organic fluorophores, quantum dots, metal organic framework materials, aggregation induced emission materials, metal nanoparticles, etc. may have the following problems in the latent fingerprint development process: (1) The fluorescent color of the development material is in the same color system as the fluorescent color of the object itself or the interferent, and the background interference is large, resulting in reduced contrast; (2) Organic solvents are required for dissolution, and most organic solvents are toxic and will destroy the information of latent fingerprints; (3) The synthesis process of the development material is cumbersome. Therefore, it is of great significance to develop a latent fingerprint fluorescent development material that is resistant to background interference, environmentally friendly, and simple to synthesize.

[0004] In view of the above shortcomings, the present invention provides a pyridine zinc (II) complex modified upconversion fluorescent material and a preparation method and application thereof. The functionalized upconversion fluorescent material obtained by the method performs dual-mode fluorescence visualization on latent fingerprints, that is, under ultraviolet light irradiation, a blue fingerprint pattern is visualized, and under 980nm near-infrared light irradiation, a green fingerprint pattern is visualized, and the three-level detail features of the fingerprint can be clearly observed, and the material has excellent resistance to background fluorescence and color interference. Summary of the invention

[0005] The purpose of the present invention is to provide a pyridine zinc (II) complex modified up-conversion fluorescent material and a preparation method and application thereof. The material is a functionalized material with dual-mode fluorescence emission, and its structure is made of a pyridine zinc (II) complex and an up-conversion fluorescent material. The method adopts a pyridine zinc (II) complex to modify the up-conversion fluorescent material. The pyridine zinc (II) complex modified up-conversion fluorescent material obtained by the method of the present invention is used in latent fingerprint visualization and identification. Under the excitation of a fluorescent light source, the latent fingerprint is visualized with high contrast and high resolution. The fluorescent visualization material can specifically interact with the latent fingerprint secretion and has anti-interference performance. Under the excitation of 365nm and 980nm light sources, bright blue and green fingerprint imprints can be visualized, wherein the pyridine zinc (II) complex can coordinate with the latent fingerprint secretion to enhance the interaction between the visualization material and the fingerprint ridge of the latent fingerprint, and NaYF 4 :Yb, Er upconversion fluorescent materials can reduce background interference in the process of latent fingerprint display. It has the advantages of dual-mode display, anti-background interference, simple operation and high contrast. It can be used for criminal investigation evidence, individual identification, forensic identification, etc.

[0006] The invention discloses a zinc pyridine (II) complex modified up-conversion fluorescent material, which is made of a zinc pyridine (II) complex and an up-conversion fluorescent material, and has a structural formula (1) as follows:

[0007]

[0008] Wherein, L is acetate or chloride ion.

[0009] The method for preparing a pyridine zinc (II) complex modified upconversion fluorescent material is prepared according to the following steps:

[0010] a. Mix dimethyl sulfoxide with water, heat to 50-70°C, add 2,6-bis(2-benzimidazolyl)pyridine, KOH and tetrabutylammonium bromide, then drop 1,3-propane sultone, stir overnight at 150°C, remove water under reduced pressure, add acetone, precipitate, vacuum dry to obtain a precipitate, and then mix the precipitate with Zn(OAc) 2 or ZnCl 2 Add methanol, stir at room temperature for 6 h, filter, wash with acetone three times, and dry in vacuum to obtain pyridine zinc (II) complex;

[0011] b. NaYF 4 :Yb, Er upconversion fluorescent material is dissolved in dimethyl sulfoxide to form a transparent solution, and then the pyridine zinc (II) complex obtained in step a is slowly added dropwise, refluxed at 95°C for 24 hours, cooled to room temperature to obtain a crude product, and then the crude product is washed 3 times and vacuum dried to obtain a pyridine zinc (II) complex modified upconversion fluorescent material with a particle size of 20nm-3μm.

[0012] The invention discloses an application of the zinc pyridine (II) complex modified up-conversion fluorescent material in latent fingerprint visualization and identification. The zinc pyridine (II) complex modified up-conversion fluorescent material is deposited on the surface of an object with fingerprints, and excess powder is removed by a hair dryer. The fingerprints are illuminated by excitation light sources of 365 nm and 980 nm, respectively, to visualize the fingerprints, and photographed. Bright blue fluorescence is emitted under the 365 nm light source, and bright green fluorescence is emitted under the 980 nm light source.

[0013] The latent fingerprint object is glass, aluminum foil, stainless steel, ceramic, silica gel plate, paper, can, coin or commemorative medal.

[0014] Patent CN115466275A discloses a fluorescent visualization identification probe and method for latent fingerprints on a substrate. In this method, a five-coordinate clamp-type Zn (II) metal organic complex is used to combine the lipophilic R group on the para position of the pyridine nitrogen in the complex in an aqueous solution with the grease in the fingerprint component to increase the molecular aggregation, resulting in aggregation-induced luminescence to realize latent fingerprint visualization. The invention discloses a pyridine zinc (II) complex modified upconversion fluorescent material and preparation method and application. The prepared pyridine zinc (II) complex is a tetracoordinate compound. The design of the complex considers two aspects: 1) introducing a sulfonated alkyl chain on its bilateral pyridine ring, and utilizing its bidentate ligand effect with rare earth elements to obtain a firm functionalized upconversion material; 2) utilizing the coordination effect of the pyridine zinc (II) complex with oleic acid in latent fingerprint secretions to fix the upconversion nanomaterial, and obtaining a high-contrast, strong anti-interference dual-mode latent fingerprint visualization material that can achieve blue fluorescence emission under 365nm excitation and green fluorescence emission under 980nm excitation in a powder state.

[0015] The invention discloses a pyridine zinc (II) complex modified up-conversion fluorescent material, a preparation method and an application thereof. The pyridine zinc (II) complex modified up-conversion fluorescent material is a functionalized up-conversion nanoparticle with a particle size of 20nm-3μm.

[0016] The invention discloses a pyridine zinc (II) complex modified up-conversion fluorescent material, a preparation method and an application thereof, and an application of the fluorescent visualization material to visualize latent fingerprints on an object, wherein the latent fingerprints are 0-70 days.

[0017] The zinc (II) pyridine complex modified up-conversion fluorescent material, preparation method and application of the present invention have the following beneficial effects compared with the prior art:

[0018] 1. The present invention adopts the fluorescence method to reveal latent fingerprints, which has the advantages of simple and rapid operation, high sensitivity and high contrast of fingerprint revealing;

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

[0020] 3. When the up-conversion fluorescent material modified with the zinc (II) pyridine complex of the present invention is used for latent fingerprint visualization, clear fingerprint contours and even the third-level characteristic sweat pores of fingerprints can be observed on various objects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The fluorescent pictures are of latent fingerprints of the up-conversion fluorescent material modified with the zinc (II) pyridine complex of the present invention on different objects;

[0022] Figure 2 It is a detailed characteristic picture obtained by irradiating the latent fingerprint on glass with the up-conversion fluorescent material modified with the zinc pyridine (II) complex of the present invention under 365nm and 980nm light sources;

[0023] Figure 3 This is a picture of the latent fingerprints appearing on an object in an actual scene using the up-conversion fluorescent material modified with the zinc pyridine (II) complex of the present invention;

[0024] Figure 4 After the latent fingerprint on the glass object of the present invention is aged, the aged latent fingerprint is visualized and the fluorescent images are obtained under the irradiation of 365nm and 980nm light sources. DETAILED DESCRIPTION

[0025] Example 1

[0026] Preparation of upconversion fluorescent materials modified by 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 drop 25.7 mmol of 1,3-propane sultone, stir overnight at 150°C, remove water under reduced pressure, add acetone, precipitate, and vacuum dry to obtain a precipitate. Then, mix 3.0 mmol of the precipitate with 3.0 mmol of Zn(OAc) 2 Add methanol, stir at room temperature for 6 h, filter, wash with acetone three times, and dry in vacuum to obtain pyridine zinc (II) complex;

[0028] b. NaYF 4: 50 mg of Yb, Er upconversion fluorescent material was dissolved in 10 mL of dimethyl sulfoxide to form a transparent solution, and then 500 mg of pyridine zinc (II) complex obtained in step a was slowly added dropwise, refluxed at 95°C for 24 hours, cooled to room temperature to obtain a crude product, and then the crude product was washed 3 times and vacuum dried to obtain a pyridine zinc (II) complex modified upconversion fluorescent material with a particle size of 20 nm.

[0029] Example 2

[0030] Preparation of upconversion fluorescent materials modified by 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 drop 25.7 mmol of 1,3-propane sultone, stir overnight at 150°C, remove water under reduced pressure, add acetone, precipitate, and vacuum dry to obtain a precipitate. Then, mix 3.0 mmol of the precipitate with 3.0 mmol of ZnCl 2 Add methanol, stir at room temperature for 6 h, filter, wash with acetone three times, and dry in vacuum to obtain pyridine zinc (II) complex;

[0032] b. NaYF 4 : 50 mg of Yb, Er upconversion fluorescent material was dissolved in 10 mL of dimethyl sulfoxide to form a transparent solution, and then 500 mg of pyridine zinc (II) complex obtained in step a was slowly added dropwise, refluxed at 95°C for 24 hours, cooled to room temperature to obtain a crude product, and then the crude product was washed 3 times and vacuum dried to obtain a pyridine zinc (II) complex modified upconversion fluorescent material with a particle size of 1 μm.

[0033] Example 3

[0034] Preparation of upconversion fluorescent materials modified by 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 drop 25.7 mmol of 1,3-propane sultone, stir overnight at 150°C, remove water under reduced pressure, add acetone, precipitate, and vacuum dry to obtain a precipitate. Then, mix 3.0 mmol of the precipitate with 3.0 mmol of Zn(OAc) 2 Add methanol, stir at room temperature for 6 h, filter, wash with acetone three times, and dry in vacuum to obtain pyridine zinc (II) complex;

[0036] b. NaYF4 : 50 mg of Yb, Er upconversion fluorescent material was dissolved in 10 mL of dimethyl sulfoxide to form a transparent solution, and then 500 mg of pyridine zinc (II) complex obtained in step a was slowly added dropwise, refluxed at 95°C for 24 hours, cooled to room temperature to obtain a crude product, and then the crude product was washed 3 times and vacuum dried to obtain a pyridine zinc (II) complex modified upconversion fluorescent material with a particle size of 3 μm.

[0037] Example 4

[0038] Preparation of upconversion fluorescent materials modified by 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 drop 25.7 mmol of 1,3-propane sultone, stir overnight at 150°C, remove water under reduced pressure, add acetone, precipitate, and vacuum dry to obtain a precipitate. Then, mix 3.0 mmol of the precipitate with 3.0 mmol of ZnCl 2 Add methanol, stir at room temperature for 6 h, filter, wash with acetone three times, and dry in vacuum to obtain pyridine zinc (II) complex;

[0040] b. NaYF 4 : 50 mg of Yb, Er upconversion fluorescent material was dissolved in 10 mL of dimethyl sulfoxide to form a transparent solution, and then 500 mg of pyridine zinc (II) complex obtained in step a was slowly added dropwise, refluxed at 95 ° C for 24 h, cooled to room temperature to obtain a crude product, and then the crude product was washed 3 times and vacuum dried to obtain a pyridine zinc (II) complex modified upconversion fluorescent material with a particle size of 80 nm.

[0041] Example 5

[0042] Deposit any of the pyridine zinc (II) complex modified upconversion fluorescent materials obtained in Examples 1-4 on a glass surface with fingerprints, remove excess powder with a hair dryer, irradiate with excitation light sources of 365nm and 980nm, respectively, to visualize fingerprints, and take photos. Figure 1 It can be seen that under the irradiation of 365nm light source, the fingerprint emitting bright blue fluorescence can be obtained, and under the irradiation of 980nm light source, the fingerprint emitting bright green fluorescence can be obtained, and the fingerprint feature information in both modes is clearly discernible.

[0043] Example 6

[0044] Deposit any of the zinc (II) pyridine complexes obtained in Examples 1-4 on the surface of the aluminum foil with fingerprints, remove excess powder with a hair dryer, irradiate with 365nm and 980nm light sources, observe the fingerprint pattern, and take a photo. Figure 1 It can be seen that under the irradiation of 365nm light source, a fingerprint emitting bright blue fluorescence can be obtained, and under the irradiation of 980nm light source, a fingerprint emitting bright green fluorescence can be obtained, and the fingerprint feature information in both modes is clearly discernible; Figure 2 It can be seen that the fluorescence intensity of fingerprint ridges and grooves in the two modes is quite different, and the information of secondary detail features such as termination, lakes, bifurcations, scars and tertiary details such as sweat pores can be obtained from the enlarged image of the detail features.

[0045] Example 7

[0046] Deposit any of the zinc (II) pyridine complexes obtained in Examples 1-4 on a stainless steel surface with fingerprints, remove excess powder with a hair dryer, irradiate with 365nm and 980nm light sources, observe the fingerprint pattern, and take a photo. Figure 1 It can be seen that under the irradiation of 365nm light source, the fingerprint emitting bright blue fluorescence can be obtained, and under the irradiation of 980nm light source, the fingerprint emitting bright green fluorescence can be obtained, and the fingerprint feature information in both modes is clearly discernible.

[0047] Example 8

[0048] Deposit any of the zinc (II) pyridine complexes obtained in Examples 1-4 on the ceramic surface with fingerprints, remove excess powder with a hair dryer, irradiate with 365nm and 980nm light sources, observe the fingerprint pattern, and take pictures. Figure 1 It can be seen that under the irradiation of 365nm light source, even if the ceramic emits blue fluorescence and produces fluorescence interference, a fingerprint emitting bright blue fluorescence can still be obtained. Under the irradiation of 980nm light source, a fingerprint emitting bright green fluorescence can be obtained, and the fingerprint feature information in both modes is clearly discernible.

[0049] Example 9

[0050] Deposit any of the zinc (II) pyridine complexes obtained in Examples 1-4 on the surface of a silica gel plate with fingerprints, remove excess powder with a hair dryer, irradiate with 365nm and 980nm light sources, observe the fingerprint pattern, and take a photo. Figure 1It can be seen that under the irradiation of 365nm light source, even if the silicone plate emits blue fluorescence and produces fluorescence interference, a fingerprint emitting bright blue fluorescence can still be obtained. Under the irradiation of 980nm light source, a fingerprint emitting bright green fluorescence can be obtained, and the fingerprint feature information in both modes is clearly discernible.

[0051] Example 10

[0052] Deposit any of the zinc (II) pyridine complexes obtained in Examples 1-4 on the surface of the paper with fingerprints, remove excess powder with a hair dryer, irradiate with 365nm and 980nm light sources, observe the fingerprint pattern, and take a photo. Figure 1 It can be seen that under the irradiation of 365nm light source, the paper emits blue fluorescence, resulting in serious fluorescence interference, and a fingerprint emitting bright blue fluorescence can be obtained. However, under the irradiation of 980nm light source, a fingerprint emitting bright green fluorescence is obtained, and the fingerprint feature information is clearly discernible.

[0053] Embodiment 11

[0054] Deposit any of the zinc pyridine (II) complex-modified upconversion fluorescent materials obtained in Examples 1-4 on the surface of a can with fingerprints, remove excess powder with a hair dryer, irradiate with 365nm and 980nm light sources, observe the fingerprint pattern, and take a photo. Figure 3 It can be seen that even if there is color interference on the surface of the can, a fingerprint emitting bright blue fluorescence can still be obtained under irradiation with a 365nm light source, and a fingerprint emitting bright green fluorescence can be obtained under irradiation with a 980nm light source, and the fingerprint feature information in both modes is clearly discernible.

[0055] Example 12

[0056] Deposit any of the zinc (II) pyridine complexes obtained in Examples 1-4 on the surface of a coin with fingerprints, remove excess powder with a hair dryer, irradiate with 365nm and 980nm light sources, observe the fingerprint pattern, and take a photo. Figure 3 It can be seen that even if the surface of the coin is uneven, a fingerprint emitting bright blue fluorescence can still be obtained under 365nm light source, and a fingerprint emitting bright green fluorescence can be obtained under 980nm light source, and the fingerprint feature information in both modes is clearly discernible.

[0057] Embodiment 13

[0058] Deposit any of the zinc (II) pyridine complexes obtained in Examples 1-4 on the surface of a commemorative badge with fingerprints, remove excess powder with a hair dryer, irradiate with 365nm and 980nm light sources, observe the fingerprint pattern, and take a photo. Figure 3It can be seen that even though the commemorative badge has color and pattern interference, and under the irradiation of the 365nm light source, it will produce serious blue fluorescence interference, but in this mode, fingerprints emitting blue fluorescence can still be obtained, and under the irradiation of the 980nm light source, fingerprints emitting bright green fluorescence can be obtained. The fingerprint feature information in this mode is clearly discernible.

[0059] Embodiment 14

[0060] Wash your hands, dry them naturally, wipe your forehead with your fingers, press gently on the glass surface, leave it for 1-70 days, then deposit the upconversion fluorescent material modified with pyridine zinc (II) complex on the glass surface, remove excess powder with a hair dryer, irradiate with 365nm and 980nm light sources, observe the fingerprint pattern, and take pictures. Figure 4 It can be seen that even after the latent fingerprint has been stored for 70 days, a fingerprint emitting bright blue fluorescence can still be obtained under 365nm light source, and a fingerprint emitting bright green fluorescence can still be obtained under 980nm light source, and the fingerprint feature information in both modes is clearly discernible.

Claims

1. A zinc pyridine (II) complex modified upconversion fluorescent material, characterized in that: The material is made of pyridine zinc (II) complex and up-conversion fluorescent material, and the structural formula (1) is: Wherein, L is acetate or chloride ion.

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

3. The use of the zinc (II) pyridine complex modified upconversion fluorescent material in latent fingerprint identification according to claim 1, characterized in that: The upconversion fluorescent material modified with zinc pyridine (II) complex was deposited on the surface of the object with fingerprints, and the excess powder was removed with a hair dryer. The fingerprints were irradiated with excitation light sources of 365nm and 980nm respectively to visualize the fingerprints and take pictures. Bright blue fluorescence was emitted under irradiation with a 365nm light source, and bright green fluorescence was emitted under irradiation with a 980nm light source.

4. The use according to claim 3, characterized in that: The latent fingerprint object is glass, aluminum foil, stainless steel, ceramic, silica gel plate, paper, can, coin or commemorative medal.

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