CN113025325A

CN113025325A - Preparation method and application of room-temperature phosphorescent carbon-based composite material capable of changing color under single excitation source

Info

Publication number: CN113025325A
Application number: CN202110320107.4A
Authority: CN
Inventors: 瞿建; 张鑫; 陈新龙; 衡祥俊; 唐志远; 丁华俊
Original assignee: Yancheng Institute of Technology
Current assignee: Yancheng Institute of Technology
Priority date: 2021-03-25
Filing date: 2021-03-25
Publication date: 2021-06-25
Anticipated expiration: 2041-03-25
Also published as: CN113025325B

Abstract

The invention discloses a preparation method of a room temperature phosphorescent carbon-based composite material that changes color under a single excitation source. The carbon quantum dots and common room temperature-induced aromatic compounds are co-crystallized and compounded through hydrogen bonding to obtain the color changing room temperature phosphorescence performance under a single excitation source. The carbon-based composites were obtained with yields ranging from 75.3% to 90.7%. The invention effectively overcomes the limitation of the existing color-changing room temperature phosphorescent materials that need to be under the joint action of different excitation sources or the condition of blending of multiple compounds, and realizes that the carbon-based composite material is visible to the naked eye in the range of orange-yellow-yellow-green-green under a single excitation source Color-changing room temperature phosphorescence with a lifetime of 91 ms~582 ms. In addition, the preparation route of the invention is green, environmentally friendly, economical and convenient, the phosphorescence color change range and life are adjustable, and the invention has broad application prospects in the fields of advanced anti-counterfeiting and digital encryption.

Description

Preparation method and application of room-temperature phosphorescent carbon-based composite material capable of changing color under single excitation source

Technical Field

The invention belongs to the field of material preparation and luminescent materials, and particularly relates to a preparation method and application of a carbon-based composite material capable of realizing color change room temperature phosphorescent performance under a single excitation source.

Background

The long-life room temperature phosphorescent material is a light-storing luminescent material, can slowly emit macroscopic long-life phosphorescence after light source irradiation is stopped, and is widely applied to the fields of information safety, digital encryption, life science, photoelectric devices and the like. The long-life room temperature phosphorescent material reported at present mainly comprises sulfide doped lanthanide elements, oxides doped with heavy metal ions or heterocyclic conjugated organic matters doped with heteroatoms. It is expensive, has a certain biological toxicity, and is complex to prepare or purify. More importantly, the functional application of the compounds is almost based on the attenuation of single emission peak intensity along with time, so that the application of the compounds in the aspects of high-density information storage and high-grade multi-dimensional anti-counterfeiting is limited. Therefore, a new generation of green intelligent materials which are composed of multiple emission centers and have room temperature phosphorescence and continuously change color along with time are developed, and the green intelligent materials have important significance for the development of modern information technology materials.

CN201911304592.5 discloses the application of hydantoin and its derivatives as color-changing room temperature phosphorescent materials. The preparation method takes hydantoin and formaldehyde or acetaldehyde as raw materials, prepares organic non-aromatic micromolecule hydantoin derivatives under the acidic condition, and obtains crystal products with the excitation wavelength depending on room temperature phosphorescence performance through a method of cooling hot saturated aqueous solution. It shows different color long afterglow under different excitation sources, such as sky blue afterglow after the 312nm ultraviolet lamp is removed (tau is 1.54s), and yellow green afterglow after the 365nm ultraviolet lamp is removed (tau is 1.74 s).

CN202010522766.1 discloses an organic ultralong room temperature phosphorescent material, triple anti-counterfeiting organic ink and application, wherein three types of phosphonium salt crystals with the same luminescence color and different luminescence lives are dissolved by ethanol and then are used as safe ink to be respectively placed in three ink boxes of a printer for printing anti-counterfeiting patterns. Namely, the color-changing afterglow is realized by mixing three compounds.

The carbon nano material is a novel optical material developed in recent years, has the advantages of good light stability, photobleaching resistance, adjustable emission and excitation wavelength, low toxicity, easy preparation and the like, and has wide application prospect in the fields of biomedicine, photoelectric devices and the like. By embedding the carbon quantum dots into the outer substrate, the carbon quantum dots can not only isolate oxygen and block water, but also anchor the vibration or rotation of the sub-emitting groups on the surface, such as C (O/C) (N) and the like, so that the triplet excitons can be stabilized stably, the non-radiative energy dissipation can be inhibited, and the generation of long-life room-temperature phosphorescence can be promoted. The invention compounds the carbon quantum dots and the aromatic substance with crystallization induction through the hydrogen bond self-assembly function, adjusts and activates the optical performance of the dual-room-temperature phosphor center through crystallization, and realizes the color-changing afterglow characteristic of the composite material by utilizing different luminescent colors and different luminescent lives of the carbon quantum dots and the aromatic substance under the same excitation source.

Disclosure of Invention

The purpose of the invention is as follows: the invention provides a preparation method and application of a room temperature phosphorescent carbon-based composite material capable of changing color under a single excitation source, aiming at overcoming the phenomenon that the existing color-changing room temperature phosphorescent material needs to be realized under the combined action of different excitation sources or under the condition of blending of a plurality of compounds.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a preparation method of room temperature phosphorescent carbon-based composite material with color changing under a single excitation source comprises the following steps:

(1) uniformly stirring and dissolving melamine and amino acid containing sulfur or selenium in a solvent to obtain a solution; preferably, the concentration of the melamine is 0.01 mol/L-0.05 mol/L;

(2) transferring the solution obtained in the step (1) into a reaction kettle, sealing, then naturally cooling to room temperature after high-temperature reaction in an oven, centrifuging at high speed, refrigerating the obtained clear liquid, centrifuging at high speed, dialyzing, and freeze-drying to obtain powder, namely the yellow fluorescent emission carbon quantum dots; preferably, it is refrigerated at 4 ℃ and lyophilized at 55 ℃;

(3) and (3) dissolving the carbon quantum dots in the step (2) in a solvent, preferably, adding an aromatic compound with crystallization-induced room temperature phosphorescence performance into the solvent to perform heating reflux self-assembly and natural cooling cocrystallization precipitation, then filtering, washing with the solvent, performing vacuum drying, preferably, performing vacuum drying at 50 ℃, and obtaining the crystal, namely the room temperature phosphorescent carbon-based composite material.

Wherein, the amino acid containing sulfur or selenium in the step (1) is any one of cystine, cysteine, selenocysteine and selenocysteine.

The aromatic compound in the step (3) is any one of isophthalic acid, phthalic acid, terephthalic acid and melamine.

Preferably, the solvent in step (1) and step (3) is water or ethanol.

Preferably, the reaction kettle in the step (2) is a polytetrafluoroethylene-lined high-pressure reaction kettle.

Preferably, in the step (2), the reaction is carried out in an oven at 160-200 ℃ for 4-6 h.

Preferably, in the step (3), the temperature is raised to a reflux temperature of 80-130 ℃, and the self-assembly time under reflux is 0.5-2 hours.

More preferably, the molar ratio of the melamine to the amino acid containing sulfur or selenium is 1: 1-1: 5.

Further preferably, the mass ratio of the carbon quantum dots to the aromatic compound is 1:5 to 1: 20.

Preferably, the high-speed centrifugation rotating speed in the step (2) is 10000-16000 r/min, and the adopted dialysis bag is a ready-to-use dialysis bag 3500D.

The filter paper used in the filtering in the step (3) is medium-speed filter paper, and the aperture is 30-50 microns.

Wherein, the yield of the carbon-based compound prepared by the method is 75.3-90.7%, the color change range of the color-changing afterglow is orange-yellow-yellowish green-green, and the afterglow life is 91 ms-582 ms.

The invention further provides application of the room-temperature phosphorescent carbon-based composite material prepared by the preparation method in preparation of high-grade anti-counterfeiting icons.

Specifically, the prepared carbon-based composite material is dissolved according to a conventional method to prepare ink, and an anti-counterfeiting icon is prepared by using a printer for anti-counterfeiting application.

Has the advantages that: compared with the prior art, the invention has the following advantages and beneficial effects:

(1) the carbon quantum dots and common organic compounds are adopted to be combined by cocrystallization through hydrogen bond action, so that the method is green, environment-friendly, economical and convenient;

(2) the color-changing room temperature phosphorescent carbon-based composite material prepared by the invention can realize continuous luminescence under the condition of a single material and the same excitation source;

(3) the material can regulate and control the room temperature phosphorescence color change range and the duration time by adjusting the types of the carbon quantum dots or the aromatic substances.

Drawings

FIG. 1 is a transmission electron microscope image of the carbon quantum dots prepared in example 1;

FIG. 2 is a size distribution of carbon quantum dots prepared in example 1;

FIG. 3 is an XPS map of carbon quantum dots prepared in example 1, wherein (a) the XPS survey spectrum; (b) carbon, nitrogen, oxygen and sulfur element high resolution XPS energy spectrum;

FIG. 4 is a 3D fluorescence emission plot of the carbon quantum dots prepared in example 1;

FIG. 5 is a transmission electron microscope and elemental distribution plots of (a) a carbon-based composite prepared in example 1;

FIG. 6 is a color change room temperature phosphorescence photograph of the carbon-based composites prepared in examples 1-4;

FIG. 7 is a graph of room temperature phosphorescent emission of a carbon-based composite prepared in example 1 and its Gaussian fit;

FIG. 8 is a graph of the phosphorescence emission at room temperature for different time delays for the carbon-based composite prepared in example 1;

FIG. 9 is a CIE chromaticity diagram of color change room temperature phosphorescence of the carbon-based composite prepared in example 1;

FIG. 10 is a graph of the room temperature phosphorescence lifetime of the carbon-based composite prepared in example 1 at different peak positions;

FIG. 11 is a color-changing room temperature phosphorescence map of an anti-counterfeit icon made of the carbon-based composite prepared in examples 1-4;

FIG. 12 is a transmission electron micrograph of a carbon-based composite prepared according to example 2;

FIG. 13 is a graph of room temperature phosphorescent emission and Gaussian fit for the carbon-based composite prepared in example 2;

FIG. 14 is a graph of room temperature phosphorescence emission of the carbon-based composite prepared in example 2 at different time delays;

FIG. 15 is a CIE chromaticity diagram of color change room temperature phosphorescence of the carbon-based composite prepared in example 2;

FIG. 16 is a graph of the room temperature phosphorescence lifetime of the carbon-based composite prepared in example 2 at different peak positions;

FIG. 17 is a 3D fluorescence plot of carbon quantum dots prepared in example 4;

fig. 18 is a transmission electron micrograph of a carbon-based composite prepared according to example 4.

Detailed Description

The present invention will be described in further detail with reference to specific examples. The examples will help to understand the present invention given the detailed embodiments and the specific operation procedures, but the scope of the present invention is not limited to the examples described below.

Example 1

0.2522g of melamine and 0.4802g of cystine are weighed and added into 15mL of water, stirred for 10min, the mixed solution is transferred into a 25mL reaction kettle, sealed and put into an oven to react for 4h at 180 ℃. Naturally cooling to room temperature after reaction, centrifuging at a high speed of 10000r/min, refrigerating the obtained clear liquid in a refrigerator at 4 ℃ for 12h, centrifuging at a high speed of 10000r/min, dialyzing by a dialysis bag (3500D), and freeze-drying at-55 ℃, wherein the obtained powder is the yellow fluorescent light-emitting carbon quantum dot. And then 0.0450g of the carbon quantum dots are weighed and dispersed in 30mL of water, 0.3000g of melamine is added, the temperature is raised to 100 ℃, reflux is carried out for 2h, self-assembly is carried out, the temperature is naturally reduced after reaction, massive crystals are separated out, and the target carbon-based compound is obtained through washing, filtering and vacuum drying at 50 ℃, and the yield is 75.3%. After excitation with a 365nm ultraviolet lamp, a color-changing afterglow of orange to orange-yellow to green (tau. 101ms) is observed. The prepared carbon-based composite material is prepared into ink according to a conventional method, an anti-counterfeiting icon is printed by using a printer, the ink is filled in the icon printed by the printer to prepare the anti-counterfeiting icon, and the anti-counterfeiting color-changing afterglow observation can be carried out by using a 365nm ultraviolet lamp.

Fig. 1 and 2 are transmission electron microscope and size distribution pictures of the carbon quantum dots prepared in example 1, and it can be seen that the obtained carbon quantum dots have an average particle size of 2.5nm, are spherical, and have uniform size distribution. FIG. 3 is an XPS chart of carbon quantum dots in example 1, which shows that the content of each element is C52.9 wt%, O20.95 wt%, N17.87 wt%, S8.28 wt%, COOH, OH, NH are present on the surface₂S ═ O, C ═ N, and the like. FIG. 4 is a 3D fluorescence emission graph of the carbon quantum dots of example 1, with an optimal emission wavelength of 542 nm. Fig. 5 is a transmission electron microscope and element distribution picture of the carbon-based composite of example 1, showing that the carbon quantum dots are uniformly embedded in the melamine matrix. FIG. 6 is a photograph of a color-changing afterglow luminance in 7s after the 365nm UV lamp is turned off of the carbon-based composite of example 1, which is seen to undergo a phosphorescent transition at room temperature from orange to yellow to green. FIG. 7 is a graph of the room temperature phosphorescence emission of the carbon-based composite of example 1 and a Gaussian fit thereof, wherein two centers of phosphorescence emission are shown, corresponding to the phosphorescence emission of a carbon quantum dot at 567nm and the phosphorescence emission of melamine at 532nm, respectively. FIG. 8 is a graph of the phosphorescence emission at room temperature of the carbon-based composite of example 1 at 0.1,1,10,50,100,500ms time delay, respectively, and it is clearly observed that the phosphorescence emission at room temperature is blue-shifted from around 570nm to around 530nm over time, which is consistent with the CIE graph (FIG. 9) and the afterglow color change observed by the naked eye. Fig. 10 is a graph of the phosphorescence lifetimes at room temperature of a carbon quantum dot and a two-optical center of a melamine substrate, respectively, and shows that the decay lifetimes of the carbon quantum dot (τ 81ms) at the orange luminescence center and the melamine (τ 101ms) at the blue-green luminescence center are different, thereby forming a color-changing afterglow. The resulting security icon is shown in fig. 11, where the "pigeon" pattern turns from orange to yellow and finally to green with continuous illumination.

Example 2

0.2522g of melamine and 0.4802g of cystine are weighed and added into 15mL of water, stirred for 10min, the mixed solution is transferred into a 25mL reaction kettle, sealed and put into an oven to react for 4h at 180 ℃. Naturally cooling to room temperature after reaction, centrifuging at a high speed of 10000r/min, refrigerating the obtained clear liquid in a refrigerator at 4 ℃ for 12h, centrifuging at a high speed of 10000r/min, dialyzing by a dialysis bag (3500D), and freeze-drying at-55 ℃, wherein the obtained powder is the yellow fluorescent light-emitting carbon quantum dot. And then 0.0450g of the carbon quantum dots are weighed and dispersed in 30mL of water, 0.4500g of isophthalic acid is added, the temperature is raised to 120 ℃, reflux is carried out for 2h, self-assembly is carried out, the temperature is naturally reduced after reaction, needle-shaped crystals are separated out, water washing, filtering and vacuum drying at 50 ℃ are carried out, and the obtained target carbon-based compound is obtained, wherein the yield is 90.7%. After excitation with a 365nm uv lamp, a color-changing afterglow of orange to yellow to green was observed (τ 582 ms). And dissolving the prepared carbon-based composite material to prepare ink, printing an anti-counterfeiting icon by using a printer, and observing the anti-counterfeiting color-changing afterglow by using a 365nm ultraviolet lamp.

Fig. 12 is a transmission electron micrograph of the carbon-based composite of example 2 showing that the carbon quantum dots are uniformly embedded in the isophthalic acid matrix. Fig. 6 is a photograph of a color-changing afterglow of the carbon-based composite of example 2 in 7s after the 365nm ultraviolet lamp is turned off, and it can be seen that room temperature phosphorescence transition (τ 582ms) from orange to yellow to green occurs. FIG. 13 is a graph of the room temperature phosphorescent emission of the carbon-based composite of example 2 and a Gaussian fit showing two phosphorescent emission centers, corresponding to the phosphorescent emission of the carbon quantum dot at 574nm and the phosphorescent emission of isophthalic acid at 525 nm. FIG. 14 is a graph of the phosphorescence emission at room temperature of the carbon-based composite of example 2 at 0.1,1,10,50,100,500ms time delay, respectively, and it is clearly observed that the phosphorescence emission at room temperature is blue-shifted from around 570nm to around 530nm over time, which is consistent with the CIE graph (FIG. 15) and the afterglow color change observed by the naked eye. Fig. 16 is a graph showing the room temperature phosphorescence lifetimes of the carbon quantum dot and the isophthalic acid matrix bi-optic center, respectively, and shows that the decay lifetimes of the carbon quantum dot (τ 395ms) at the orange luminescence center and the isophthalic acid (τ 686ms) at the green luminescence center are different, and thus the color-changing afterglow is formed. The resulting security icon is shown in fig. 11, where the "pigeon" pattern turns from orange to yellow and finally to green with continuous illumination.

Example 3

0.2522g of melamine and 0.4802g of cystine are weighed and added into 15mL of water, stirred for 10min, the mixed solution is transferred into a 25mL reaction kettle, sealed and put into an oven to react for 4h at 180 ℃. Naturally cooling to room temperature after reaction, centrifuging at a high speed of 10000r/min, refrigerating the obtained clear liquid in a refrigerator at 4 ℃ for 12h, centrifuging at a high speed of 10000r/min, dialyzing by a dialysis bag (3500D), and freeze-drying at-55 ℃, wherein the obtained powder is the yellow fluorescent light-emitting carbon quantum dot. And then 0.0450g of the carbon quantum dots are weighed and dispersed in 30mL of water, 0.4500g of phthalic acid is added, the temperature is raised to 120 ℃, reflux is carried out for 2h, self-assembly is carried out, the temperature is naturally reduced after reaction, needle-shaped crystals are separated out, and the target carbon-based compound is obtained after washing, filtering and vacuum drying at 50 ℃, and the yield is 89.8%. After the excitation with 365nm ultraviolet lamp in fig. 6, the color-changing afterglow of orange to yellow-green (tau 212ms) can be observed. And dissolving the prepared carbon-based composite material to prepare ink, printing an anti-counterfeiting icon by using a printer, filling the ink into the icon printed by the printer to prepare the anti-counterfeiting icon, and observing the anti-counterfeiting color-changing afterglow by using a 365nm ultraviolet lamp.

Example 4

0.2522g of melamine and 0.6720g of selenocysteine are weighed and added into 15mL of water, stirred for 10min, the mixed solution is transferred into a 25mL reaction kettle, sealed and put into an oven to react for 4h at the temperature of 180 ℃. Naturally cooling to room temperature after reaction, centrifuging at a high speed of 12000r/min, refrigerating the obtained clear liquid in a refrigerator at the temperature of 4 ℃ for 12h, centrifuging at a high speed of 12000r/min, dialyzing by a dialysis bag (3500D), and freeze-drying at the temperature of-55 ℃ to obtain the powder, namely the yellow fluorescent light-emitting carbon quantum dots. And then 0.0450g of the carbon quantum dots are weighed and dispersed in 30mL of water, 0.4500g of isophthalic acid is added, the temperature is raised to 130 ℃, reflux is carried out for 2h, self-assembly is carried out, the temperature is naturally reduced after reaction, needle-shaped crystals are separated out, water washing, filtering and vacuum drying at 50 ℃ are carried out, and the obtained target carbon-based compound is obtained, wherein the yield is 88.1%. Upon removal of the excitation with a 365nm UV lamp, a color-changing afterglow of orange to yellow to green was observed (τ 511 ms). And dissolving the prepared carbon-based composite material to prepare ink, printing an anti-counterfeiting icon by using a printer, filling the ink in the icon printed by the printer, and observing the anti-counterfeiting color-changing afterglow by using a 365nm ultraviolet lamp.

FIG. 17 is a 3D fluorescence emission diagram of the carbon quantum dots of example 4, with the optimal emission wavelength being 551nm, located in the yellow fluorescence region. Fig. 18 is a transmission electron micrograph of the carbon-based composite of example 4 showing that the carbon quantum dots are uniformly embedded in the isophthalic acid matrix. FIG. 6 is a photograph of the color-changing afterglow in 7s after the 365nm UV lamp is turned off in the carbon-based composite of example 4, which is seen to undergo the phosphorescence transition at room temperature from orange to yellow to green. The resulting security icon is shown in fig. 11, where the "pigeon" pattern turns from orange to yellow and finally to green with continuous illumination.

The invention provides a preparation idea and a preparation method of a room temperature phosphorescent carbon-based composite material capable of changing color under a single excitation source. While there have been shown and described what are at present considered to be the preferred embodiments of the present invention, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention. All the components not specified in the present embodiment can be realized by the prior art.

Claims

1. the preparation method of the room temperature phosphorescent carbon-based composite material that changes color under a single excitation source, is characterized in that, comprises the steps:

(1) Stir melamine and sulfur- or selenium-containing amino acids in a solvent to obtain a solution;

(2) The solution obtained in step (1) is transferred to a reaction kettle, sealed, then cooled to room temperature after high temperature reaction in an oven, centrifuged at high speed, and the obtained clear liquid is refrigerated and then centrifuged at high speed, dialyzed and freeze-dried. The powder is yellow fluorescent emitting carbon quantum dots;

(3) dissolving the carbon quantum dots obtained in the step (2) in a solvent, adding an aromatic compound with crystallization-induced room temperature phosphorescence properties, performing self-assembly under heating and refluxing and natural cooling for co-crystallization, and then filtering, solvent washing, and vacuum drying, The obtained crystal is a room temperature phosphorescent carbon-based composite material.

2. preparation method according to claim 1 is characterized in that, described sulfur-containing or selenium-containing amino acid is cystine, cysteine, selenocystine and selenocysteine. any kind.

3 . The preparation method according to claim 1 , wherein the aromatic compound in step (3) is any one of isophthalic acid, phthalic acid, terephthalic acid and melamine. 4 .

4 . The preparation method according to claim 1 , wherein the solvent in step (1) and step (3) is water or ethanol. 5 .

5 . The preparation method according to claim 1 , wherein in step (2), the reaction is carried out in an oven at 160-200° C. for 4-6 h. 6 .

6 . The preparation method according to claim 1 , wherein in step (1), the molar ratio of the melamine to the sulfur- or selenium-containing amino acid is 1:1 to 1:5. 7 .

7 . The preparation method according to claim 1 , wherein, in step (3), the mass ratio of the carbon quantum dots to the aromatic compound is 1:5 to 1:20. 8 .

8 . The method for preparing a color-changing room temperature phosphorescent carbon-based composite material under a single excitation source according to claim 1 , wherein in step (3), the reflow temperature is 80-130° C., and the self-assembly time under reflow is 0.5-2 h.

9. The application of the room temperature phosphorescent carbon-based composite material prepared by the preparation method according to any one of claims 1 to 8 in the preparation of anti-counterfeiting icons.

10. The application according to claim 9, wherein the room temperature phosphorescent carbon-based composite material prepared by the preparation method according to any one of claims 1 to 8 is dissolved as an anti-counterfeiting ink, and filled and coated on a printer printed by a printer. You can get a color-changing afterglow anti-counterfeiting picture in the icon of .