A responsive color-changing fluorescent dye and its preparation method and application

Abstract

The present invention provides a grease-responsive color-changing fluorescent dye, which is synthesized using 4-formyltriphenylamine and an indone compound as raw materials. The structure of the fluorescent dye is different from that of existing fluorescent dyes, and the fluorescent dye is a novel grease-responsive fluorescent dye. The preparation method provided by the present invention is simple, the product yield is high, the stability is good, and the biological toxicity is low. When applied to fluorescent fingerprint powder, the fluorescent dye can respond to latent fingerprints and cause color change, changing the orange-red fluorescent color of the fluorescent fingerprint powder itself to bright yellow fluorescent color. Therefore, compared with other fluorescent dyes, the fluorescent dye has higher contrast, anti-interference and biocompatibility, can achieve imaging effects with high resolution, high contrast, strong anti-interference and real-time development, and has broad application prospects in latent fingerprint recognition in complex criminal investigation environments.

Description

Technical Field

[0001] The present invention belongs to the technical field of color-changing fluorescent dyes, and in particular relates to a responsive color-changing fluorescent dye and a preparation method and application thereof. Background Art

[0002] Latent fingerprint visualization technologies can be categorized into chemical and physical methods. Chemical methods, including the cyanoacrylate fuming method, silver nitrate method, and ninhydrin method, primarily rely on the reaction of a developer with residual organic matter in the fingerprint. While these methods are typically stable, they suffer from drawbacks such as the lack of real-time detection, low contrast, and high toxicity. Physical methods, primarily involving powder coating or metal deposition, utilize electrostatic attraction between fluorescent or magnetic powders and finger secretions such as skin oils, amino acids, or other chemicals. These methods are convenient and enable real-time visualization of latent fingerprints. However, traditional commercial magnetic powder developers are typically micron-sized, resulting in poor dispersibility and the tendency to form large aggregates. Therefore, both physical and chemical methods have their own advantages and disadvantages.

[0003] Fluorescent fingerprint powder development has emerged as a popular method for latent fingerprint development in criminal investigations. However, currently available fluorescent fingerprint powders lack color-changing properties and fluoresce wherever they adhere. Therefore, fingerprints left on uneven surfaces or those subject to static electricity are difficult to develop at high resolution, failing to meet the requirements for fingerprint extraction in criminal investigations. Summary of the Invention

[0004] The embodiments of the present application provide a responsive color-changing fluorescent dye, a preparation method thereof, and an application thereof. The structure of the responsive fluorescent dye is different from that of existing fluorescent dyes, and the responsive fluorescent dye is a new type. The preparation method provided by the present invention is simple and the product yield is high. When the responsive fluorescent dye is applied to fluorescent fingerprint powder for latent fingerprint identification, it can achieve imaging effects with high resolution, high contrast, strong anti-interference ability, and real-time development. The responsive fluorescent dye has broad application prospects in latent fingerprint identification in complex criminal investigation environments.

[0005] The technical solution of the present invention is:

[0006] In a first aspect, the present invention provides a responsive color-changing fluorescent dye having a structure of Formula I:

[0007]

[0008] Wherein, R is at least one of hydrogen, bromine, fluorine, hydroxyl, nitro, amino, methoxy or methyl.

[0009] In a second aspect, the present invention further provides a method for preparing a responsive color-changing fluorescent dye, which specifically comprises the following steps:

[0010] Step 1: Weigh 4-formyltriphenylamine, an indone compound, and NaOH in a certain molar ratio, place them in a flask, add a certain amount of anhydrous ethanol, heat and stir to react, and after TLC monitoring, cool to room temperature;

[0011] In step 2, the pH value is adjusted to 6-7 with a saturated potassium carbonate solution, extracted with ethyl acetate and then dried in vacuo, and the product is separated by column chromatography to obtain an orange-red solid powder, which is a responsive color-changing fluorescent dye.

[0012] The reaction process is shown in Formula II:

[0013]

[0014] Specifically, the molar ratio of 4-formyltriphenylamine, indanone compound and NaOH is 1:1:1.5.

[0015] Specifically, the heating temperature is 40° C.-50° C., and the stirring time is 10 h-14 h.

[0016] In a second aspect, the present invention also provides an application of a responsive color-changing fluorescent dye, which is prepared into fluorescent fingerprint powder and applied to latent fingerprint recognition.

[0017] Specifically, the preparation of fluorescent fingerprint powder includes the following steps:

[0018] A certain amount of responsive color-changing fluorescent dye is weighed and dissolved in an organic solvent, a carrier is added, and the mixture is uniformly mixed by ultrasonication. The solvent is evaporated by a rotary evaporator, and then the mixture is ground and dried to obtain fluorescent fingerprint powder.

[0019] Specifically, in the preparation of the fluorescent fingerprint powder, the mass ratio of the responsive color-changing fluorescent dye to the carrier is 0.001:1 to 0.02:1.

[0020] Specifically, the carrier is selected from at least one of montmorillonite, silica, or magnetic powder.

[0021] Specifically, the application in latent fingerprint recognition includes the following steps:

[0022] Step 1: Apply the prepared fluorescent fingerprint powder to the surface area where the latent fingerprint is located, and remove the unadsorbed fluorescent fingerprint powder;

[0023] In step 2, an ultraviolet light source is used to illuminate the surface area where the latent fingerprint is located. The fluorescent fingerprint powder appears orange-red in the area without fingerprints and bright yellow in the area with fingerprints, thereby obtaining a responsive color-changing fluorescent imaging of the latent fingerprint.

[0024] Specifically, the ultraviolet light source irradiation is performed under the condition of light with a wavelength of 350 to 430 nm.

[0025] Specifically, the substrate is at least one of glass, tin foil, apple, leather, and coins.

[0026] Using 4-formyltriphenylamine and indanone compounds as raw materials, a responsive color-changing fluorescent dye is obtained through a condensation reaction. When prepared as fluorescent fingerprint powder, the dye exhibits photoinduced fluorescence color-changing properties. The color-changing response principle is that the prepared fluorescent dye interacts with oily secretions from the fingers, such as oleic acid and cholesterol, causing a color change from the fluorescent dye's inherent orange-red color to bright yellow. The fluorescent dye's chemical molecular structure contains both triphenylamine structural units and indanone units as fluorophores, connected by a carbon-carbon double bond. This results in a simple crystal structure, excellent photostability, enhanced photosensitivity, high fluorescence efficiency, good biocompatibility, and low toxicity. Due to its good fat solubility, it can bind to trace amounts of oil in finger secretions and induce a fluorescence color change through changes in the dissolution environment, thereby revealing latent fingerprints and improving the efficiency and validity of fingerprint identification results.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The responsive color-changing fluorescent dye prepared by the present invention has a structure different from that of existing fluorescent dyes and is a new type of responsive fluorescent dye. The raw materials required for its preparation are readily available, the preparation process is simple, the production cost is low, and the target product can be obtained in only two steps with high yield, good product stability, and low biological toxicity. At the same time, the fluorescent dye has color-changing properties and can be applied to latent fingerprint recognition;

[0029] (2) The fluorescent fingerprint powder prepared by the present invention is used in latent fingerprint recognition. After responding to the fingerprint, the color changes, combining the advantages of physical development method and chemical development method, with strong anti-interference, high resolution, high contrast, high fingerprint display accuracy, no damage to the DNA information in the fingerprint and real-time development and other excellent imaging effects;

[0030] (3) The fluorescent fingerprint powder prepared by the present invention is not limited by the substrate material in latent fingerprint recognition. It can show the latent fingerprint development effect in the area where fingerprints are left on various substrates such as leather, coins, and apples, thereby broadening the applicability of fingerprint powder and reducing the interference caused by the signal of the fluorescent fingerprint powder itself. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 The changes in fluorescence spectra and photos of the a-fluorescent fingerprint powder prepared in Example 1 before and after the latent fingerprint is irradiated with ultraviolet light;

[0033] Figure 2 This is the H NMR spectrum of the α-responsive color-changing fluorescent dye prepared in Example 1;

[0034] Figure 3 This is the H NMR spectrum of the b-responsive color-changing fluorescent dye prepared in Example 2;

[0035] Figure 4 This is the H NMR spectrum of the c-responsive color-changing fluorescent dye prepared in Example 3;

[0036] Figure 5 This is the H NMR spectrum of the d-responsive color-changing fluorescent dye prepared in Example 4;

[0037] Figure 6 This is the H NMR spectrum of the e-responsive color-changing fluorescent dye prepared in Example 5;

[0038] Figure 7 This is the H NMR spectrum of the f-responsive color-changing fluorescent dye prepared in Example 6;

[0039] Figure 8 This is the H NMR spectrum of the g-responsive color-changing fluorescent dye prepared in Example 7;

[0040] Figure 9 This is the H NMR spectrum of the h-responsive color-changing fluorescent dye prepared in Example 8;

[0041] Figure 10a The a-fluorescent fingerprint powder prepared in Example 1 was used to develop latent fingerprints on glass and the effect after storage for 15 days;

[0042] Figure 10b The a-fluorescent fingerprint powder prepared in Example 1 was used to image the latent fingerprint on glass 15 days ago;

[0043] Figure 10c This is a detailed analysis diagram of latent fingerprint imaging on glass using the α-fluorescent fingerprint powder prepared in Example 1;

[0044] Figure 10d The image and grayscale comparison of the latent fingerprint developed on glass using the α-fluorescent fingerprint powder prepared in Example 1 and then rubbing it with black tape;

[0045] Figure 11a The image and grayscale value comparison of the latent fingerprint developed on tin foil using the α-fluorescent fingerprint powder prepared in Example 1 and then rubbing it with transparent tape;

[0046] Figure 11b This is a comparison chart of the fingerprint information before and after the latent fingerprint on tin foil was developed with the a-fluorescent fingerprint powder prepared in Example 1 and then rubbed with transparent tape;

[0047] Figure 11c This is an electron microscope image of latent fingerprint imaging on tinfoil using the α-fluorescent fingerprint powder prepared in Example 1;

[0048] Figure 12 The α-fluorescent fingerprint powder prepared in Example 1 was used for latent fingerprint imaging and grayscale contrast analysis on an apple;

[0049] Figure 13 The α-fluorescent fingerprint powder prepared in Example 1 was used for latent fingerprint imaging and grayscale contrast analysis on leather;

[0050] Figure 14 The α-fluorescent fingerprint powder prepared in Example 1 was used for latent fingerprint imaging and grayscale contrast analysis on coins;

[0051] Figure 15 The graph of DNA fragment changes of d-responsive color-changing fluorescent dye at different molar ratios; DETAILED DESCRIPTION

[0052] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention are within the scope of protection of the present invention.

[0053] Example 1

[0054] Preparation of a-responsive color-changing fluorescent dye:

[0055] Place 2 mmol of 4-formyltriphenylamine, 2 mmol of 1-indanone, and 3 mmol of NaOH in a 50 ml flask, add 20 ml of ethanol, heat to 50 ° C and stir for 12 h, check the reaction by TLC until the reaction is complete, and cool to room temperature;

[0056] The pH value was adjusted to 7 with saturated potassium carbonate solution, extracted with ethyl acetate and dried in vacuo, and the product was separated by column chromatography to obtain an orange-red solid powder, namely, an a-responsive color-changing fluorescent dye, with a yield of 88.43%.

[0057] The structure of the a-responsive color-changing fluorescent dye is shown in Formula Ia, namely (E)-2-(4-(diphenylamino)benzyl)-1-indanone:

[0058]

[0059] The synthetic route of the a-responsive color-changing fluorescent dye prepared in Example 1 is shown in Formula IIa:

[0060]

[0061] Preparation of a-fluorescent fingerprint powder:

[0062] 20 mg of the α-fluorescent dye prepared in Example 1 was dissolved in an ethanol solution, 3 g of montmorillonite was added, and the mixture was uniformly mixed by ultrasonication. The solvent was evaporated by a rotary evaporator, and then ground and dried to obtain α-fluorescent fingerprint powder.

[0063] Color change response:

[0064] Figure 1 The fluorescence spectrum and photo of the a-fluorescent fingerprint powder prepared in Example 1 before and after the latent fingerprint is irradiated with ultraviolet light. The fluorescent fingerprint powder itself is an orange powder that emits orange-red fluorescence. After the fingerprint is developed, the fingerprint area appears bright yellow. Figure 1 As shown, the maximum fluorescence emission wavelength before response is 605 nm, and the CIE coordinates are (0.519, 0.468). The maximum emission wavelength after response is 560 nm, and the CIE coordinates are (0.376, 0.442). An obvious fluorescence color change can be observed.

[0065] MRI test results:

[0066] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of the α-responsive color-changing fluorescent dye prepared in Example 1.

[0067] The NMR information is:

[0068] 1 H NMR(500MHz,Chloroform-d)δ7.94(d,J=7.6Hz,1H),7.69-7.59(m,2H),7.60-7.54(m ,3H),7.45(t,J=7.4Hz,1H),7.38-7.27(m,3H),7.22-7.08(m,9H),4.06-4.01(m,2H).

[0069] The results showed that the compound prepared in this example had the structure shown in Formula Ia.

[0070] Example 2

[0071] Preparation of b-responsive color-changing fluorescent dye:

[0072] Place 4 mmol of 4-formyltriphenylamine, 4 mmol of 5-bromo-1-indanone, and 6 mmol of NaOH in a 90 ml flask, add 40 ml of ethanol, heat to 50 ° C and stir for 14 h, check the reaction by TLC until the reaction is complete, and cool to room temperature;

[0073] The pH value was adjusted to 7 with saturated potassium carbonate solution, extracted with ethyl acetate and dried in vacuo, and the product was separated by column chromatography to obtain an orange-red solid powder, namely, the b-responsive color-changing fluorescent dye, with a yield of 87.81%.

[0074] The structure of the b-responsive color-changing fluorescent dye, i.e., (E)-2-(4-(diphenylamino)benzyl)-5-bromo-1-indanone, is shown in Formula Ib:

[0075]

[0076] The synthesis route of the b-responsive color-changing fluorescent dye is shown in Formula IIb:

[0077]

[0078] Preparation of b-fluorescent fingerprint powder:

[0079] 20 mg of the b-fluorescent dye prepared in Example 2 was dissolved in an ethanol solution, 3 g of silicon dioxide was added, and the mixture was ultrasonically mixed. The solvent was evaporated by a rotary evaporator, and the mixture was ground and dried to obtain b-fluorescent fingerprint powder.

[0080] MRI test results:

[0081] Figure 3 This is the hydrogen nuclear magnetic resonance spectrum of the b-responsive color-changing fluorescent dye prepared in Example 2.

[0082] The NMR information is:

[0083] 1 H NMR(500MHz,Chloroform-d)δ7.79(d,J=8.1Hz,1H),7.73(s,1H),7.67(s,1H),7.59(d,J=8.0Hz,1H),7.55(d,J=8 .8Hz,2H),7.35(t,J=7.9Hz,4H),7.20(d,J=7.9Hz,4H),7.16(t,J=7.4Hz,2H),7.10(d,J=8.8Hz,2H),4.01(s,2H).

[0084] The results showed that the compound prepared in this example had the structure shown in Formula Ib.

[0085] Example 3

[0086] Preparation of c-responsive color-changing fluorescent dye:

[0087] Place 1.5 mmol of 4-formyltriphenylamine, 1.5 mmol of 5-fluoro-1-hydroxyindanone, and 2.25 mmol of NaOH in a 35 ml flask, add 15 ml of ethanol, heat to 45 ° C and stir for 10 hours, check the reaction by TLC until the reaction is complete, and cool to room temperature;

[0088] The pH value was adjusted to 7 with saturated potassium carbonate solution, extracted with ethyl acetate and dried in vacuo, and the product was separated by column chromatography to obtain an orange-red solid powder, namely, the c-responsive color-changing fluorescent dye, with a yield of 84.98%.

[0089] The structure of the c-responsive color-changing fluorescent dye, i.e., (E)-2-(4-(diphenylamino)benzyl)-5-fluoro-1-indanone, is shown in Formula Ic:

[0090]

[0091] The synthesis route of the c-responsive color-changing fluorescent dye is shown in Formula IIc:

[0092]

[0093] Preparation of c-light fingerprint powder:

[0094] 15 mg of the c-fluorescent dye prepared in Example 3 was dissolved in an ethanol solution, 2 g of magnetic powder was added, and the mixture was ultrasonically mixed. The solvent was evaporated by a rotary evaporator, and the mixture was ground and dried to obtain c-fluorescent fingerprint powder.

[0095] MRI test results:

[0096] Figure 4 This is the hydrogen nuclear magnetic resonance spectrum of the c-responsive color-changing fluorescent dye prepared in Example 3.

[0097] The NMR information is:

[0098] 1 H NMR(500MHz,Chloroform-d)δ7.94(dd,J=8.5,5.3Hz,1H),7.63(d,J=2.2Hz,1H),7.55( d,J=8.7Hz,2H),7.35(d,J=15.7Hz,2H),7.29(s,1H),7.26-7.07(m,11H),4.02(s,2H).

[0099] The results showed that the compound prepared in this example had the structure shown in Formula Ic.

[0100] Example 4

[0101] Preparation of d-responsive color-changing fluorescent dye:

[0102] Place 1.5 mmol of 4-formyltriphenylamine, 1.5 mmol of 5-hydroxy-1-indanone, and 2.25 mmol of NaOH in a 35 ml flask, add 15 ml of ethanol, heat to 45 ° C and stir for 10 hours, check the reaction by TLC until the reaction is complete, and cool to room temperature;

[0103] The pH value was adjusted to 7 with saturated potassium carbonate solution, extracted with ethyl acetate and dried in vacuo, and the product was separated by column chromatography to obtain an orange-red solid powder, i.e., a d-responsive color-changing fluorescent dye, with a yield of 84.98%.

[0104] The structure of the d-responsive color-changing fluorescent dye, namely 2-(4-(diphenylamino)benzyl)-5-hydroxy-1-indanone, is shown in Formula Id:

[0105]

[0106] The synthetic route of the d-responsive color-changing fluorescent dye is shown in Formula IId:

[0107]

[0108] Preparation of d-light fingerprint powder:

[0109] 15 mg of the d-fluorescent dye prepared in Example 4 was dissolved in an ethanol solution, 2 g of magnetic powder was added, and the mixture was ultrasonically mixed. The solvent was evaporated by a rotary evaporator, and then ground and dried to obtain d-fluorescent fingerprint powder.

[0110] MRI test results:

[0111] Figure 5 This is the hydrogen nuclear magnetic resonance spectrum of the d-responsive color-changing fluorescent dye prepared in Example 4.

[0112] The NMR information is:

[0113] 1 H NMR(500MHz,DMSO-d6)δ10.55(s,1H),7.64(t,J=8.4Hz,3H),7.38(q,J=9.3,8.5Hz,5H),7 .15(dd,J=20.2,7.7Hz,6H),7.00–6.93(m,3H),6.86(dd,J=8.4,2.0Hz,1H),3.97(s,2H). 13C NMR (126MHz, DMSO-d6) δ191.68,164.79,153.17,148.81,146.80,134.06,132.38,131 .04,130.22,129.68,128.70,126.01,125.62,124.68,121.48,32.31.HRMS:m / z[M+H] + calcd for C 28 H 22 NO2 + .

[0114] The results showed that the compound prepared in this example had the structure shown in Formula Id.

[0115] Example 5

[0116] Preparation of e-responsive color-changing fluorescent dye:

[0117] Place 1.5 mmol of 4-formyltriphenylamine, 1.5 mmol of 5-methoxy-1-indanone, and 2.25 mmol of NaOH in a 35 ml flask, add 15 ml of ethanol, heat to 40 ° C and stir for 12 h, check the reaction by TLC until the reaction is complete, and cool to room temperature;

[0118] The pH value was adjusted to 7 with saturated potassium carbonate solution, extracted with ethyl acetate and dried in vacuo, and the product was separated by column chromatography to obtain an orange-red solid powder, i.e., the e-responsive color-changing fluorescent dye, with a yield of 81.28%.

[0119] The structure of the e-responsive color-changing fluorescent dye, i.e., (E)-2-(4-(diphenylamino)benzyl)-5-methoxy-1-indanone, is shown in Formula 1e:

[0120]

[0121] The synthetic route of the e-responsive color-changing fluorescent dye is shown in Formula IIe:

[0122]

[0123] Preparation of e-light fingerprint powder:

[0124] 15 mg of the e-fluorescent dye prepared in Example 5 was dissolved in an ethanol solution, 2 g of magnetic powder was added, and the mixture was ultrasonically mixed. The solvent was evaporated by a rotary evaporator, and then ground and dried to obtain e-fluorescent fingerprint powder.

[0125] MRI test results:

[0126] Figure 6 This is the hydrogen nuclear magnetic resonance spectrum of the e-responsive color-changing fluorescent dye prepared in Example 5.

[0127] The NMR information is:

[0128] 1 H NMR(500MHz,Chloroform-d)δ7.88(d,J=8.5Hz,1H),7.69–7.48(m,2H),7.39–7.32(m,4H), 7.19(d,J=7.5Hz,4H),7.16–7.07(m,3H),7.02–6.98(m,1H),3.99(s,2H),3.94(s,3H).13C NMR (126MHz, Chloroform-d) δ 192.81, 164.98, 152.25, 149.05, 146.88, 132.66 (d, J = 27.8Hz), 131. 84,129.49,128.61,125.98,125.44,124.05,121.64,115.05,109.74,55.66,32.65.HRMS:m / z[M+H] + calcd for C 29 H 24 NO2 + ,Theory:418.1807,Found:418.1802.

[0129] The results showed that the compound prepared in this example had the structure shown in Formula Ie.

[0130] Example 6

[0131] Preparation of f-responsive color-changing fluorescent dye:

[0132] Place 4 mmol of 4-formyltriphenylamine, 4 mmol of 6-nitro-1-indanone, and 6 mmol of NaOH in a 90 ml flask, add 40 ml of ethanol, heat to 50 ° C and stir for 14 h, check the reaction by TLC until the reaction is complete, and cool to room temperature;

[0133] The pH value was adjusted to 7 with saturated potassium carbonate solution, extracted with ethyl acetate and dried in vacuo, and the product was separated by column chromatography to obtain an orange-red solid powder, i.e., f-responsive color-changing fluorescent dye, with a yield of 87.81%.

[0134] The structure of the f-responsive color-changing fluorescent dye, i.e., (E)-2-(4-(diphenylamino)benzyl)-6-nitro-1-indanone, is shown in Formula If:

[0135]

[0136] The synthetic route of f-responsive color-changing fluorescent dye is shown in Formula IIf:

[0137]

[0138] Preparation of f-fluorescent fingerprint powder:

[0139] 20 mg of the f-fluorescent dye prepared in Example 6 was dissolved in an ethanol solution, 3 g of silicon dioxide was added, and the mixture was ultrasonically mixed. The solvent was evaporated by a rotary evaporator, and then ground and dried to obtain f-fluorescent fingerprint powder.

[0140] MRI test results:

[0141] Figure 7 This is the hydrogen nuclear magnetic resonance spectrum of the f-responsive color-changing fluorescent dye prepared in Example 6.

[0142] The NMR information is:

[0143] 1 H NMR (500MHz, DMSO-d6) δ8.53(dd,J=8.4,2.3Hz,1H),8.43(d,J=2.3Hz,1H),7.93(d,J=8.4Hz,1H),7.72(d,J=8.7Hz,2 H),7.58(s,1H),7.41(t,J=7.8Hz,4H),7.19(dd,J=20.6,7.6Hz,6H),6.97(d,J=8.7Hz,2H),4.24(d,J=2.1Hz,2H).13C NMR(126MHz,Chloroform-d)δ192.01,154.95,150.05,148.04,146.46,139.61,136.09,132.44,130.52 ,129.62,128.28,127.11(d,J=21.1Hz),125.84,124.61,120.87,119.43,32.86,29.70.HRMS:m / z[M+H] + calcd for C 29 H 24 NO2 + ,Theory:433.1547,Found:433.1555.

[0144] The results show that the compound prepared in this example has the structure shown in Formula If.

[0145] Example 7

[0146] Preparation of g-responsive color-changing fluorescent dye:

[0147] Place 2 mmol of 4-formyltriphenylamine, 2 mmol of 4-nitro-1-indanone, and 3 mmol of NaOH in a 50 ml flask, add 20 ml of ethanol, heat to 50 ° C and stir for 12 hours, check the reaction by TLC until the reaction is complete, and cool to room temperature;

[0148] The pH value was adjusted to 7 with saturated potassium carbonate solution, extracted with ethyl acetate and dried in vacuo, and the product was separated by column chromatography to obtain an orange-red solid powder, i.e., g-responsive color-changing fluorescent dye, with a yield of 84.15%.

[0149] The structure of the g-responsive color-changing fluorescent dye is shown in Formula Ia, namely (E)-2-(4-(diphenylamino)benzyl)-4-nitro-1-indanone:

[0150]

[0151] The synthesis route of the g-responsive color-changing fluorescent dye prepared in Example 7 is shown in Formula IIg:

[0152]

[0153] Preparation of g-fluorescent fingerprint powder:

[0154] 20 mg of the g-fluorescent dye prepared in Example 7 was dissolved in an ethanol solution, 3 g of montmorillonite was added, and the mixture was uniformly mixed by ultrasonication. The solvent was evaporated by a rotary evaporator, and the mixture was ground and dried to obtain g-fluorescent fingerprint powder.

[0155] MRI test results:

[0156] Figure 8 This is the hydrogen nuclear magnetic resonance spectrum of the g-responsive color-changing fluorescent dye prepared in Example 7.

[0157] The NMR information is:

[0158] 1H NMR (500MHz, DMSO-d6) δ8.50(d,J=8.0Hz,1H),8.26(d,J=7.5Hz,1H),7.74(s,1H),7.69(t,J=7.8Hz,1H),7.64( d,J=8.8Hz,1H),7.37(t,J=7.9Hz,4H),7.29(s,1H),7.26–7.15(m,6H),7.13(d,J=8.8Hz,2H),4.50(s,2H).13C NMR(126MHz,Chloroform-d)δ191.79,150.11,146.48,145.79,144.14,141.57,136.17,132.63, 130.00,129.79,129.63,129.19,128.86,127.18,125.88,124.61,120.88,33.66.HRMS:m / z[M+H] + calcd for C 29 H 24 NO2 + ,Theory:433.1547,Found:433.1561.

[0159] The results showed that the compound prepared in this example had the structure shown in Formula Ig.

[0160] Example 8

[0161] Preparation of h-responsive color-changing fluorescent dye:

[0162] Place 4 mmol of 4-formyltriphenylamine, 4 mmol of 6-amino-1-indanone, and 6 mmol of NaOH in a 90 ml flask, add 40 ml of ethanol, heat to 50 ° C and stir for 14 h, check the reaction by TLC until the reaction is complete, and cool to room temperature;

[0163] The pH value was adjusted to 7 with saturated potassium carbonate solution, extracted with ethyl acetate and dried in vacuo, and the product was separated by column chromatography to obtain an orange-red solid powder, i.e., the h-responsive color-changing fluorescent dye, with a yield of 87.81%.

[0164] The structure of the h-responsive color-changing fluorescent dye, i.e., (E)-2-(4-(diphenylamino)benzyl)-6-amino-1-indanone, is shown in Formula Ih:

[0165]

[0166] The synthesis route of h-responsive color-changing fluorescent dye is shown in Formula IIh:

[0167]

[0168] Preparation of h-fluorescent fingerprint powder:

[0169] 20 mg of the h-fluorescent dye prepared in Example 8 was dissolved in an ethanol solution, 3 g of silicon dioxide was added, and the mixture was ultrasonically mixed. The solvent was evaporated by a rotary evaporator, and then ground and dried to obtain h-fluorescent fingerprint powder.

[0170] MRI test results:

[0171] Figure 9 This is the hydrogen nuclear magnetic resonance spectrum of the h-responsive color-changing fluorescent dye prepared in Example 8.

[0172] The NMR information is:

[0173] 1 H NMR(500MHz,Chloroform-d)δ7.60(d,J=2.1Hz,1H),7.58–7.51(m,2H),7.38–7.31(m,5H),7.22–7.16(m,5H),7.14(t d,J=7.3,1.4Hz,2H),7.09(dd,J=9.0,2.1Hz,2H),6.98(dd,J=8.0,2.4Hz,1H),3.92(d,J=2.0Hz,2H),3.84(s,2H).13C NMR(126MHz,Chloroform-d)δ193.57,148.27,145.96,145.27,139.08,138.57,132.49,132.41,131 .09,128.61,127.68,125.71,124.59,123.20,121.48,120.66,107.77,31.00,28.81.HRMS:m / z[M+H] + calcd for C 29 H 24 NO2 + ,Theory:403.1805,Found:403.1809.

[0174] The results showed that the compound prepared in this example had the structure shown in Formula Ih.

[0175] Example 9

[0176] The α-fluorescent fingerprint powder prepared in Example 1 was applied to the latent fingerprint on the glass surface.

[0177] Dip a brush in a small amount of prepared fluorescent fingerprint powder and apply it to the surface area of the glass where the latent fingerprint is located. Use an ear cleaner to remove the unabsorbed fluorescent fingerprint powder. After leaving it for 1 minute, irradiate it with a 365m ultraviolet lamp. The part with the fingerprint will appear bright yellow. Use a camera to take a picture to obtain the fingerprint image.

[0178] Obtain a copy of your latent fingerprint:

[0179] Use black tape to evenly cover the developed fingerprint surface, press it to fit, and then remove the tape to get a copy.

[0180] Fluorescent fingerprint powder itself is an orange powder that emits orange-red fluorescence. After developing with a fingerprint, the fingerprinted area appears bright yellow. Under ultraviolet light, the bright yellow color change can be observed in the fingerprinted area. A camera can capture a clear fingerprint image. The fingerprint image can be used to extract various fingerprint feature information, including level 2 and level 3 features.

[0181] Figure 10a The a-fluorescent fingerprint powder prepared in Example 1 was used to develop latent fingerprints on glass and the effect after storage for 15 days; Figure 10a It can be seen that the fingerprint display information is complete, the glass after fingerprint development has not changed after being stored for 15 days, and the fingerprint details are still clearly visible.

[0182] Figure 10b The a-fluorescent fingerprint powder prepared in Example 1 was used for latent fingerprint imaging on glass 15 days ago; Figure 10b It can be seen that the latent fingerprint image on the glass 15 days ago using a-fluorescent fingerprint powder is still clearly visible;

[0183] Figure 10c This is a detailed analysis of the latent fingerprint imaging of the α-fluorescent fingerprint powder prepared in Example 1 on glass; Figure 10c It can be seen that the fingerprint display accuracy is high, and the 3-level features including sweat pores are also fully visible.

[0184] Figure 10d The effect picture and gray value comparison of the latent fingerprint developed on glass by the α-fluorescent fingerprint powder prepared in Example 1 and then printed with black tape; Figure 10d It can be seen that the developed fingerprint is copied with black tape. The copy information is complete, and the high grayscale contrast value proves that it has high contrast to highlight the latent fingerprint.

[0185] Example 10

[0186] The α-fluorescent fingerprint powder prepared in Example 1 was applied to the latent fingerprint on the tin foil surface.

[0187] Dip a brush in a small amount of prepared fluorescent fingerprint powder and apply it to the surface area of the latent fingerprint on the tin foil. Use an ear bulb to remove the unabsorbed fluorescent fingerprint powder. After leaving it for 30 seconds, irradiate it with a 365nm ultraviolet lamp. The part with the fingerprint will appear bright yellow. Use a camera to take a picture to obtain a clear fingerprint image.

[0188] Obtain a copy of your latent fingerprint:

[0189] Use transparent tape to evenly cover the developed fingerprint surface, press it to fit, and then remove the tape to get a copy.

[0190] Figure 11a The effect diagram and grayscale value comparison of the latent fingerprint developed on tin foil by the α-fluorescent fingerprint powder prepared in Example 1 and then printed with transparent tape; Figure 11a It can be seen that the developed fingerprint is copied with transparent tape, and the copy information is complete. The grayscale contrast value proves that it has high contrast, and the latent fingerprint and its information can be clearly observed.

[0191] Figure 11b The a-fluorescent fingerprint powder prepared in Example 1 is used to develop the latent fingerprint on the tin foil and then use transparent tape to rub the fingerprint information before and after comparison chart; Figure 11b It can be seen that the fingerprint display accuracy is high, and detailed information such as the displayed three-level feature effect (sweat pore distribution) can be observed with the naked eye.

[0192] Figure 11c This is an electron microscope image of the latent fingerprint imaging of the α-fluorescent fingerprint powder prepared in Example 1 on tinfoil; Figure 11c It can be seen that the scanning electron microscope can be used to obtain the fingerprint ridge width, gap, sweat pore diameter and other fine information.

[0193] Example 11

[0194] The α-fluorescent fingerprint powder prepared in Example 1 was applied to the surface of apples to reveal latent fingerprints.

[0195] Dip a brush in a small amount of prepared a-fluorescent fingerprint powder and apply it to the surface area of the apple where the latent fingerprint is located. Use an ear cleaner to remove the unabsorbed fluorescent fingerprint powder. After leaving it for 50 seconds, irradiate it with a 380nm ultraviolet lamp. The part with the fingerprint will appear bright yellow. Use a camera to take a picture to obtain a clear fingerprint image.

[0196] Figure 12 The α-fluorescent fingerprint powder prepared in Example 1 was used for latent fingerprint imaging and grayscale contrast analysis on apples; Figure 12 It can be seen that on the surface of the apple, the fingerprint is displayed with high accuracy and the fingerprint information is complete. The grayscale contrast value proves that it has high contrast and the latent fingerprint and its information can be clearly observed.

[0197] Example 12

[0198] The α-fluorescent fingerprint powder prepared in Example 1 was applied to the latent fingerprint on the leather surface.

[0199] Dip a brush in a small amount of the prepared fluorescent fingerprint powder and apply it to the surface of the leather where the latent fingerprint is located. Remove any unabsorbed fluorescent fingerprint powder with an ear bulb. Leave it on for 30 seconds before irradiating with a 365nm UV lamp. The area where the fingerprint is located will appear bright yellow, resulting in a color-shifting fluorescence image of the latent fingerprint. The fluorescent fingerprint powder itself is orange and emits orange-red fluorescence, which appears bright yellow in the area where the fingerprint is located. A camera captures the fingerprint, producing a clear image.

[0200] Figure 13 The α-fluorescent fingerprint powder prepared in Example 1 was used for latent fingerprint imaging and grayscale contrast analysis on leather; Figure 13 It can be seen that on the leather surface, the fingerprint is displayed with high accuracy and the fingerprint information is complete. The grayscale contrast value proves that it has high contrast and the latent fingerprint and its information can be clearly observed.

[0201] Example 13

[0202] The fluorescent fingerprint powder prepared in Example 1 was applied to the latent fingerprint on the coin surface.

[0203] Dip a brush in a small amount of the prepared fluorescent fingerprint powder and apply it to the surface area of the coin where the latent fingerprint is located. Remove any unabsorbed fluorescent fingerprint powder with an ear bulb. Leave it for 10 seconds before irradiating with a 410nm UV lamp. The area where the fingerprint is located will appear bright yellow, resulting in a color-shifting fluorescence image of the latent fingerprint. The fluorescent fingerprint powder itself is orange and emits orange-red fluorescence, which appears bright yellow in the area where the fingerprint is located. A camera captures the image, producing a clear fingerprint image.

[0204] Figure 14 The α-fluorescent fingerprint powder prepared in Example 1 was used for latent fingerprint imaging and grayscale contrast analysis on coins; Figure 14 It can be seen from the figure that on the surface of the coin, the fingerprint is displayed with high accuracy and the fingerprint information is complete. The grayscale contrast value proves that it has high contrast and the latent fingerprint and its information can be clearly observed.

[0205] DNA gel electrophoresis experiment:

[0206] DNA gel electrophoresis experiments demonstrated that the d-responsive color-changing fluorescent dyes did not induce DNA hydrolysis or breakage into smaller fragments. Figure 15 The graph of DNA fragment changes of d-responsive color-changing fluorescent dye at different molar ratios;

[0207] Figure 15Channel 1 in the middle is a marker (for reference of DNA fragment size); Channel 2 is pure DNA, Channel 3 is pure d-responsive color-changing fluorescent dye, and Channels 4-7 are DNA:d-responsive color-changing fluorescent dye at a molar ratio of 1:1, 1:10, 1:100, and 1:1000, respectively. The experimental process is to react the fluorescent dye with double-stranded DNA in accordance with the ratio at 37°C for 1 hour, and then perform the DNA gel experiment with the d-responsive color-changing fluorescent dye. Figure 15 It can be clearly seen that the double-stranded DNA was not hydrolyzed into single-stranded DNA or cut into smaller fragments by the dye.

[0208] Therefore, during the criminal investigation process, even if the fingerprint matching fails, the suspect can be further tracked by extracting the residual DNA in the fingerprint.

[0209] 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 these will fall within the scope of protection of the present invention.

Claims

1. An application of a responsive color-changing fluorescent dye, characterized in that: It is prepared into fluorescent fingerprint powder and applied to latent fingerprint recognition; the responsive color-changing fluorescent dye has a structure of formula I: wherein R is at least one of hydrogen, bromine, fluorine, hydroxyl, nitro, amino, methoxy or methyl; The preparation method of the responsive color-changing fluorescent dye specifically comprises the following steps: Step 1: Weigh 4-formyltriphenylamine, an indone compound, and NaOH in a certain molar ratio, place them in a flask, add a certain amount of anhydrous ethanol, heat and stir to react, and after TLC monitoring, cool to room temperature; Step 2: adjusting the pH value to 6-7 with a saturated potassium carbonate solution, extracting with ethyl acetate, and vacuum drying. The product is separated by column chromatography to obtain an orange-red solid powder, i.e., a responsive color-changing fluorescent dye; The molar ratio of 4-formyltriphenylamine, indanone compound and NaOH is 1:1:1.

5.

2. The use of the responsive color-changing fluorescent dye according to claim 1, characterized in that: In step 1, the heating temperature is 40° C.-50° C., and the stirring time is 10 h-14 h.

3. The use of the responsive color-changing fluorescent dye according to claim 1, characterized in that: The preparation of fluorescent fingerprint powder specifically includes the following steps: A certain amount of responsive color-changing fluorescent dye is weighed and dissolved in an organic solvent, a carrier is added, and the mixture is ultrasonically mixed. The solvent is evaporated by a rotary evaporator, and the mixture is ground and dried to obtain fluorescent fingerprint powder. Wherein, in the preparation of the fluorescent fingerprint powder, the mass ratio of the responsive color-changing fluorescent dye to the carrier is 0.001:1 to 0.02:

1.

4. The use of the responsive color-changing fluorescent dye according to claim 3, characterized in that: Applied to latent fingerprint recognition, it specifically includes the following steps: Step 1: Coat the prepared fluorescent fingerprint powder on the substrate where the latent fingerprint is located, and remove the unadsorbed fluorescent fingerprint powder; In step 2, an ultraviolet light source is used to illuminate the substrate where the latent fingerprint is located. The fluorescent fingerprint powder appears bright yellow at the part where the fingerprint is located, thereby obtaining a responsive color-changing fluorescent imaging of the latent fingerprint. The ultraviolet light source irradiation is carried out under the condition of light with a wavelength of 350 to 430 nm.

5. The use of the responsive color-changing fluorescent dye according to claim 4, characterized in that: The substrate is at least one of glass, tinfoil, apple, leather, and coins.

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