A pyridoquinazolinone doped organic phosphorescent material, and a preparation method and application thereof

Abstract

This invention discloses a pyridoquinazolinone-doped organic phosphorescent material, its preparation method, and its applications. The material comprises a room-temperature phosphorescent host matrix and a pyridoquinazolinone derivative guest molecule doped therein. The guest molecule has a mass of 0.2-1.3 wt% of the host matrix. The guest molecule can have a symmetric or asymmetric structure, and its LUMO energy level is below -1.01 eV, calculated using DFT theory. The room-temperature phosphorescent host matrix is ​​selected from small-molecule organic crystal matrices. The rigid crystal matrix and stable guest molecule structure of the phosphorescent material prepared by this invention give the material good photostability in air.

Description

Technical Field

[0001] This invention belongs to the field of organic optoelectronic materials technology, specifically relating to a pyridoquinazolinone-doped organic phosphorescent material, its preparation method, and its application. Background Technology

[0002] Organic long-persistent luminescence (OLPL) materials, due to their ability to continue emitting light even after the excitation source is removed, have shown significant application value in optoelectronic devices, information security, and biomedicine. The key to achieving efficient and long-lived organic luminescence lies in stabilizing triplet excitons and promoting their radiative transitions.

[0003] Currently, the host-guest doping strategy has proven to be an effective approach for constructing high-efficiency OLPL materials. This strategy utilizes a rigid host matrix to stabilize triplet excitons and achieves afterglow enhancement and color modulation through energy-level matched guest molecules accepting energy. The design of the guest molecules is crucial, requiring simultaneous satisfaction of suitable energy levels, effective intersystem crossing (ISC), and stable excited states.

[0004] Nitrogen-containing heterocyclic compounds are often used as building blocks for OLPL materials due to their abundant electronic properties and modifiability. For example, electron-rich heterocycles such as carbazole and phenothiazine are commonly used as donors, while electron-deficient heterocycles such as pyridine and triazine are commonly used as acceptors. However, in the current technology, guest molecules that possess strong electron acceptor capabilities, rigid planar structures, and ease of derivatization for finely tuned photoelectric properties are still relatively scarce. Pyridoquinazolinones are a class of rigid electron-deficient heterocyclic systems formed by the fusion of pyridine rings and quinazolinones. Their characteristics include: strong electron deficiency; rigid planar structure; and well-defined and modifiable structure. Currently, a method for synthesizing pyrido[1,2-c]quinazolinone compounds has been disclosed in the prior art (CN201811630556.3), but there are no publicly reported methods for using them as dopant guests to construct efficient, ultra-long-lived organic long-afterglow materials by utilizing their unique electron deficiency and rigid planar properties. Summary of the Invention

[0005] One objective of this invention is to provide a pyridoquinazolinone-doped organic phosphorescent material, comprising a room-temperature phosphorescent host matrix and a pyridoquinazolinone derivative guest molecule doped therein, wherein the mass of the guest molecule is 0.2-1.3 wt% of the mass of the host matrix.

[0006] As a preferred embodiment, the LUMO energy level of the guest molecule is below -1.01 eV. The LUMO energy level is obtained by DFT theory calculation. All calculations are performed using the Gaussian 16 package. The structure is optimized using the B3LYP / 6-31G(d) method to obtain the LUMO orbital energy levels of the molecule.

[0007] As a preferred embodiment, the room-temperature phosphorescence host matrix is ​​selected from small molecule organic crystal matrices.

[0008] As a preferred embodiment, the room temperature phosphorescence host matrix is ​​isophthalic acid crystals.

[0009] As a preferred embodiment, the guest molecule is pyrido[1,2-c]quinazolinone.

[0010] As a preferred embodiment, the material exhibits a phosphorescence lifetime decay component of ≥1000 ms at 510 nm.

[0011] The second objective of this invention is to provide a method for preparing pyrido[1,2-c]quinazolinone-doped organic phosphorescent materials, comprising the following steps: dissolving isophthalic acid and pyrido[1,2-c]quinazolinone together in a mixed solvent of ethanol and water, heating until completely dissolved, cooling to crystallize, and filtering to collect the crystals; wherein the pyrido[1,2-c]quinazolinone added is 0.2-1.3 wt% of the mass of isophthalic acid.

[0012] A third objective of this invention is to provide an application of pyridoquinazolinone-doped organic phosphorescent materials as described in any of the above claims in the preparation of information encryption elements or anti-counterfeiting labels.

[0013] To achieve the above objectives, the organic long-afterglow material prepared using the raw materials and method of this invention comprises a room-temperature phosphorescent host matrix and a pyrido[1,2-c]quinazolinone derivative guest molecule doped therein. The room-temperature phosphorescent host matrix is ​​selected from small-molecule organic crystal matrices: isophthalic acid crystals. The guest molecule is pyrido[1,2-c]quinazolinone. The guest molecule has a symmetrical or asymmetrical structure, and its LUMO energy level is calculated to be below -1.01 eV by DFT theory, which is conducive to its use as a terminal acceptor for energy transfer.

[0014] The present invention has the following beneficial effects: Firstly, this material is constructed by host-guest doping of a pyridoquinazolinone derivative with a rigid planar structure and strong electron acceptor properties with a rigid host matrix capable of generating room-temperature phosphorescence. Based on the unique electron-deficient nature and rigid planar structure of pyridoquinazolinone, the doped system formed with the host matrix can establish an efficient excited-state energy relay path, achieving efficient energy transfer from the host triplet state to the guest local state. The material obtained in this invention exhibits an ultra-long afterglow lifetime in the yellow-green emission band, with its main phosphorescence lifetime decay component exceeding 1000 milliseconds and a room-temperature phosphorescence quantum yield as high as 6.28%, while also possessing excellent stability, achieving a good balance between long lifetime and a certain luminous efficiency. The rigid crystal matrix and stable guest molecular structure of the phosphorescent material prepared in this invention give the material good photostability in air.

[0015] Secondly, this invention optimizes the preparation process by employing a classic solution co-crystallization method. This method is simple, reproducible, operates under mild conditions, and yields high output, facilitating mass production and patterning of the material. The material utilizes a pyridoquinazolinone derivative as a highly efficient electron acceptor guest, combined with a room-temperature phosphorescent host matrix such as isophthalic acid. By optimizing the host-guest energy level matching and crystallization process, and by strictly adhering to process steps and parameters, the pyridoquinazolinone guest and the isophthalic acid host are precisely screened. The energy level difference between the host triplet state (Tn*) and the guest excited state is controlled, thereby achieving efficient and thorough energy transfer. This constructs a highly efficient energy transfer channel, achieving ultralong afterglow luminescence with a phosphorescence lifetime exceeding 1000 milliseconds, a clear emission color, and good stability. This is of great significance for enriching the OLPL material system and realizing high performance and multifunctionality.

[0016] Thirdly, the organic long-afterglow material of the present invention can be used to make: information encryption patterns or labels (displaying afterglow information that changes over time after ultraviolet light excitation), advanced anti-counterfeiting marks, in vitro biological imaging probes (utilizing long-afterglow background fluorescence interference), low-power afterglow display devices, sensor devices, and optical storage media, etc. Attached Figure Description

[0017] Figure 1 These are photographs of the phosphorescent material of the present invention under ultraviolet irradiation and after the light source is removed (1s~15s). Figure 2 The emission wavelength diagram of the phosphorescent material of the present invention is shown (horizontal axis: wavelength / nanometer, vertical axis: count). Figure 3 This is a fitting graph of the phosphorescence decay curve of the phosphorescent material of the present invention (horizontal axis: time / milliseconds, vertical axis: count). Figure 4 The graph shows the room-temperature phosphorescence quantum yield test results of the material obtained in this invention (horizontal axis: wavelength / nanometer, vertical axis: count). Figure 5 A schematic diagram illustrating the application of the encryption ink made from the phosphorescent material of this invention; Detailed Implementation

[0018] To make the technical means, creative features, objectives, and beneficial effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0019] In addition, to better illustrate the present invention, numerous specific details are given in the following detailed embodiments. Those skilled in the art should understand that the present invention can be implemented even without certain specific details. In other embodiments, methods, means, equipment and steps well known to those skilled in the art are not described in detail in order to highlight the main points of the present invention.

[0020] This invention provides a pyridoquinazolinone-doped organic phosphorescent material, comprising a room-temperature phosphorescent host matrix and a pyridoquinazolinone derivative guest molecule doped therein, wherein the mass of the guest molecule is 0.2-1.3 wt% of the mass of the host matrix. Preferably, the doping concentration of the guest molecule in the host matrix is ​​preferably 1 wt%.

[0021] (1) Synthesis of pyridoquinazolinone guests: They can be prepared using synthetic methods known in the art, such as using the corresponding 2-pyridylbenzamide as a starting material and constructing a CN bond through an oxidative cyclization reaction to form a quinazolinone structure. The resulting product can be purified by recrystallization or other methods.

[0022] (2) Preparation of host-guest doped materials: Co-crystallization method: The purified isophthalic acid host and the synthesized pyrido[1,2-c]quinazolinone guest are dissolved together in a mixture of ethanol and water in a preset ratio (e.g., the guest accounts for 1 wt%). The mixture is heated to about 85°C to completely dissolve the substance, and then slowly cooled to room temperature to crystallize. The crystals are collected by filtration to obtain the doped material.

[0023] Example 1

[0024] Synthesis of pyrido[1,2-c]quinazolinone and its doping in isophthalic acid: This step is prepared according to the method described in the embodiment of Chinese Patent CN 109608454 A: Synthesis of pyrido[1,2-c]quinazolinone (6H-pyrido[1,2-c]quinazolin-6-one): 2-pyridylbenzamide, PIFA (bis(trifluoroacetoxy)iodobenzene), and MeCN (acetonitrile) were placed in a round-bottom flask and stirred at room temperature for 30 minutes until the reaction was complete. The reaction mixture was then added to NaHCO3 and extracted with DCM (dichloromethane). The combined organic layers were dried over anhydrous MgSO4. The product was recrystallized from diethyl ether and obtained by vacuum filtration as a yellow solid, with a yield of approximately 90% (purity above 95%). (The preparation method for this step is based on the published patent, application number CN201811630556.3, A new method for synthesizing 6H-pyrido[1,2-c]quinazolin-6-one compounds, publication number: CN 109608454 A, publication date: 2019.4.12).

[0025] Preparation of doped material: Isophthalic acid was dissolved in an aqueous ethanol solution (ethanol to water volume ratio 3:1), heated to 85°C until completely dissolved, then slowly cooled and recrystallized. The purified isophthalic acid was obtained by filtration. 1 g of recrystallized isophthalic acid and 0.01 g of pyrido[1,2-c]quinazolinone were placed in a 250 ml Erlenmeyer flask, and 40 ml of a mixed solvent of ethanol and water (ethanol:water volume ratio 3:1) was added. The mixture was heated to 85°C until completely dissolved, cooled to room temperature (25°C), crystallized, and then filtered to obtain the doped crystal.

[0026] Performance characterization: The solid exhibits blue fluorescence under 254 nm ultraviolet light irradiation. After the ultraviolet light source is removed, a yellow-green afterglow lasting approximately 12-15 seconds is visible to the naked eye. Figure 1 Tests showed that the phosphorescence emission wavelength of the doped material was 510 nm. Figure 2 This indicates that the afterglow emission originates from the characteristic emission of the guest molecules. The phosphorescence decay curve, after fitting, is 1001 ms ( Figure 3 The room-temperature phosphorescence quantum yield of the material was determined to be 6.28% using the integrating sphere method. Figure 4 ).

[0027] The core advantage of this invention lies in achieving an ultralong afterglow lifetime. Through a specific host-guest combination (pyrido[1,2-c]quinazolinone / isophthalic acid) and an optimized doping and crystallization process, the resulting material achieves a phosphorescence lifetime decay component of 1001 ms at 510 nm, significantly longer than the average phosphorescence lifetime of 798.4 ms reported for similar organic-doped afterglow materials. This provides ample observable time for advanced anti-counterfeiting and information encryption. While achieving an ultralong lifetime, the material also maintains a room-temperature phosphorescence quantum yield of 6.28%, achieving a good balance between long lifetime and a certain level of luminous efficiency.

[0028] Reference Figure 5As shown, 20 mg of 1 wt% pyrido[1,2-c]quinazolinone isophthalic acid crystals obtained in Example 1 were dissolved in 10 ml of ethanol-water solution (ethanol:water volume ratio of 3:1). After stirring and dissolving, it was used as "encryption ink". After drying, it showed no specific display under natural light, but showed a blue fluorescent pattern under 254 nm ultraviolet light. After turning off the ultraviolet light, the pattern turned into a yellow-green afterglow, which could be captured by a camera for several seconds to more than ten seconds. It can be used for high-level anti-counterfeiting or dynamic information display.

[0029] Example 2

[0030] The preparation method and other conditions were the same as in Example 1, except that the amount of pyrido[1,2-c]quinazolinone molecule incorporated was 0.002 g (doping concentration 0.2 wt%). After filtration, the doped crystal was obtained. The doped crystal fluoresced blue under a 254 nm UV lamp and still had afterglow after the UV lamp was removed. The afterglow lifetime was comparable to that of Example 1. The quantum yield was 4.25%, and the luminous efficiency was still at a relatively good level.

[0031] Example 3

[0032] The preparation method and other conditions were the same as in Example 1, except that the amount of pyrido[1,2-c]quinazolinone molecule incorporated was 0.013 g (1.3 wt%). After filtration, the doped crystal was obtained. The doped crystal fluoresced blue under a 254 nm UV lamp and still had afterglow after the UV lamp was removed. The afterglow lifetime was comparable to that of Example 1. The quantum yield was 3.6%, and the luminous efficiency was still at a relatively good level.

[0033] Comparative Example 1 The solid molecule of pyrido[1,2-c]quinazolinone alone exhibits blue fluorescence when irradiated with a 254 nm UV lamp, and no afterglow phenomenon is observed after the UV lamp is removed.

[0034] Comparative Example 2 The preparation method and other conditions were the same as in Example 1, except that the amount of pyrido[1,2-c]quinazolinone molecule incorporated was 0.001 g (0.1 wt%). After filtration, the doped crystal was obtained. The doped crystal exhibited blue fluorescence when irradiated with a 254 nm ultraviolet lamp. After the ultraviolet lamp was removed, there was still afterglow. The afterglow lifetime was comparable to that of Example 1, the quantum yield was reduced to 1.82%, and the luminous efficiency was low.

[0035] Comparative Example 3 The preparation method and other conditions were the same as in Example 1, except that the amount of pyrido[1,2-c]quinazolinone molecule incorporated was 0.02 g (2wt%). After filtration, the doped crystal was obtained. The doped crystal exhibited blue fluorescence when irradiated with a 254 nm ultraviolet lamp. After the ultraviolet lamp was removed, there was still afterglow. The afterglow lifetime was comparable to that of Example 1, but the quantum yield dropped sharply to 0.94%, and the luminous efficiency was low.

[0036] According to Examples 1-3 and Comparative Examples 2 and 3, afterglow could be observed with the naked eye at room temperature for different doping ratios of guest molecules ranging from 0.1% to 2% wt%. Quantum yield tests were performed on the above materials. When the doping ratio was 0.1% wt%, the quantum yield was 1.82%. Increasing the doping ratio improved the quantum yield, specifically: 4.25% at 0.2% wt% and 6.28% at 1% wt%. However, when the doping ratio of the guest molecule was increased to 1.3% wt%, the luminescence quantum yield decreased to 3.6%. Further increasing the doping ratio to 2% wt% resulted in a sharp drop in quantum yield to 0.94%.

[0037] The results show that a doping concentration of 1 wt% is the optimal concentration, resulting in the highest quantum yield and best luminescence efficiency. As the doping concentration gradually increases from 0.1 wt% to 1 wt%, the number of luminescent centers increases, the energy transfer from host to guest becomes more efficient, and triplet excitons are effectively utilized, thus the quantum yield continues to climb to a maximum of 6.28%. However, when the guest concentration exceeds 1 wt%, the intermolecular distance decreases, leading to intermolecular nonradiative losses. Simultaneously, high-concentration guests are more likely to come into contact with residual oxygen and other quenchers in the environment, further accelerating the deactivation of triplet excitons. This causes the quantum yield to decrease to 3.6% at a doping concentration of 1.3 wt%, and then plummet to 0.94% at a doping concentration of 2 wt%.

[0038] Comparative Example 4 0.01 g of pyrido[1,2-c]quinazolinone molecules were incorporated into 1 g of acridinone molecules and dissolved in 40 ml of a mixed solvent of ethanol and water (ethanol:water volume ratio of 3:1). The solution was heated to 85 °C to completely dissolve the solution, cooled to room temperature, crystallized, and then filtered. The resulting doped crystals exhibited blue fluorescence when irradiated with a 254 nm UV lamp. No afterglow was observed after the UV lamp was removed.

[0039] Comparative Example 5 0.01 g of pyrido[1,2-c]quinazolinone molecules were incorporated into 1 g of quinazolin molecules and dissolved in 40 ml of a mixed solvent of ethanol and water (ethanol:water volume ratio of 3:1). The solution was heated to 85 °C to completely dissolve the solution, cooled to room temperature, crystallized, and then filtered. The resulting doped crystals exhibited blue fluorescence when irradiated with a 254 nm UV lamp. No afterglow was observed after the UV lamp was removed.

[0040] Comparative Example 6 0.01 g of pyrido[1,2-c]quinazolinone was incorporated into 1 g of phthalic acid molecules and dissolved in 40 ml of a mixed solvent of ethanol and water (ethanol:water volume ratio of 3:1). The mixture was heated to 85 °C, and it was found that the host and guest components did not completely dissolve. After cooling to room temperature, the doped crystal exhibited blue fluorescence when irradiated with a 254 nm UV lamp. After the UV lamp was removed, the afterglow phenomenon was not obvious.

[0041] Comparative Example 7 0.01 g of pyrido[1,2-c]quinazolinone molecule was incorporated into 1 g of phthalimide molecule and dissolved in 40 ml of a mixed solvent of ethanol and water (ethanol:water volume ratio of 3:1). The solution was heated to 85 °C to completely dissolve the solution, cooled to room temperature, crystallized, and then filtered. The resulting doped crystal exhibited blue fluorescence when irradiated with a 254 nm UV lamp. No afterglow phenomenon was observed after the UV lamp was removed.

[0042] Comparative Example 8 0.01 g of pyrido[1,2-c]quinazolinone molecule was incorporated into 1 g of 2H-1,4-benzoxazine-3(4H)-one, dissolved in 40 ml of a mixed solvent of ethanol and water (ethanol:water volume ratio of 3:1), heated to 85 ℃ to completely dissolve, cooled to room temperature for crystallization, and then filtered. The resulting doped crystal exhibited blue fluorescence under 254 nm ultraviolet light irradiation, and no afterglow phenomenon was observed after the ultraviolet light was removed.

[0043] Comparative Example 9 0.01 g of pyrido[1,2-c]quinazolinone molecule was incorporated into 1 g of pentachloropyridine molecule and dissolved in 40 ml of a mixed solvent of ethanol and water (ethanol:water volume ratio of 3:1). The solution was heated to 85 °C to completely dissolve the solution, cooled to room temperature, crystallized, and then filtered. The resulting doped crystal exhibited blue fluorescence when irradiated with a 254 nm UV lamp. No afterglow was observed after the UV lamp was removed.

[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A pyridoquinazolinone-doped organic phosphorescent material, characterized in that: It includes a room-temperature phosphorescent host matrix and a pyridoquinazolinone derivative guest molecule doped therein, wherein the mass of the guest molecule is 0.2-1.3 wt% of the mass of the host matrix.

2. The pyridoquinazolinone-doped organic phosphorescent material according to claim 1, characterized in that: The LUMO energy level of the guest molecule is below -1.01 eV, and the LUMO energy level is obtained by DFT theory calculation.

3. The pyridoquinazolinone-doped organic phosphorescent material according to claim 1, characterized in that: The room-temperature phosphorescent host matrix is ​​selected from small molecule organic crystal matrix.

4. The pyridoquinazolinone-doped organic phosphorescent material according to claim 3, characterized in that: The room temperature phosphorescence host matrix is ​​isophthalic acid crystals.

5. The pyridoquinazolinone-doped organic phosphorescent material according to claim 1, characterized in that: The guest molecule is pyrido[1,2-c]quinazolinone.

6. The pyridoquinazolinone-doped organic phosphorescent material according to claim 1, characterized in that: The material exhibits a phosphorescence lifetime decay component of ≥1000 ms at 510 nm.

7. A method for preparing a pyridoquinazolinone-doped organic phosphorescent material, characterized in that: The process includes the following steps: dissolving isophthalic acid and pyrido[1,2-c]quinazolinone together in a mixed solvent of ethanol and water, heating until completely dissolved, cooling to crystallize, and filtering to collect the crystals; wherein the mass of pyrido[1,2-c]quinazolinone is 0.2-1.3 wt% of the mass of isophthalic acid.

8. The application of a pyridoquinazolinone-doped organic phosphorescent material as described in any one of claims 1-6 in the preparation of information encryption elements or anti-counterfeiting labels.

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