Preparation method of flexible room-temperature phosphorescent material

Abstract

The invention discloses a preparation method of a flexible room-temperature phosphorescent material, which comprises the following steps: adding ortho / para-morpholinylbenzaldehyde and malononitrile into a mortar, taking sodium hydroxide as a catalyst, taking acetone as a solvent, carrying out grinding reaction at room temperature to obtain a crude product, and then carrying out column chromatography separation and purification to obtain 3-amino-5-methyl-2 '-morpholinyl-2, 3, 4-triazole-5-one. And 3-amino-5-methyl-4 '-morpholinyl-2, 4-dicyanobiphenyl and 3-amino-5-methyl-4'-morpholinyl-2, 4-dicyanobiphenyl are selected from the group consisting of The compound and polyvinyl chloride (PVC) are doped according to the weight ratio of 1: 100, and the PVC doped film with long-life room-temperature phosphorescence emission performance is obtained through dissolution and film preparation processes, so that flexible three-dimensional modeling with long-afterglow room-temperature phosphorescence performance is realized, and the application of room-temperature phosphorescence in PVC elongation detection is realized.

Description

Technical Field

[0001] The invention belongs to the field of organic functional materials, and specifically relates to the preparation of two room temperature phosphorescent compounds and polyvinyl chloride doped films thereof, three-dimensional modeling with room temperature phosphorescence and application thereof in polyvinyl chloride elongation detection. Background Art

[0002] As an alternative to traditional heavy metal-containing inorganic phosphorescent materials, organic room temperature phosphorescent (ORTP) materials have the advantages of low cost, environmental friendliness, low toxicity, and easy structural regulation. However, due to the weak spin-orbit coupling (SOC) between singlet and triplet excitons, it is difficult to form a large number of triplet excitons through intersystem transitions (ISC). At the same time, the slow phosphorescence radiation rate easily leads to the quenching of triplet excitons by molecular vibration and oxygen. Therefore, most organic room temperature phosphorescent (ORTP) materials cannot emit visible RTP. Currently, heavy atoms (Cl, Br, I) or heteroatoms with lone pairs of electrons (N, O, S, P) are introduced to enhance SOC. Crystal engineering, H stacking, and host-guest doping systems provide a strict environment for phosphorescent molecules, restricting the vibration and rotation of the molecules while isolating non-radiative transition pathways such as inactivation by air or water. Therefore, ORTP materials have made significant progress in extending the lifetime of RTP. Despite this, the application of ORTP materials is mainly limited to information encryption and data anti-counterfeiting.

[0003] The key way to expand the application range of ORTP materials is to inhibit molecular motion and oxygen diffusion, but this often brings new problems. For example, polyvinyl alcohol (PVA) as a host material has long and tangled molecular chains, which can form dense intramolecular and intermolecular hydrogen bonds, provide a crystal-like rigid environment, reduce the non-radiative transition inactivation of phosphorescent chromophores, inhibit oxygen diffusion, and thus promote the generation of RTP. However, due to good water solubility, the host-guest doping system containing polyvinyl alcohol (PVA) often suffers from phosphorescence quenching and rapid decay in water environment, and polyvinyl alcohol has poor stretchability. Another commonly used polymer host material is polymethyl methacrylate (PMMA), which shows even worse stretchability. Most ORTP luminescent sources tend to show bright and long-lasting RTP in PVA and PMMA matrices, while showing invisible afterglow in other stretchable polymer matrices such as polyvinyl chloride (PVC). As we know, many organisms in nature exhibit various defensive behaviors when hunting or responding to environmental threats, such as mimosa, chameleons, morning glory, water lilies, and seaweed. In order to simulate the above phenomenon, some fluorescent materials with mechanical stimulus response have attracted the attention of researchers and made significant progress, showing potential application value in the fields of pressure sensors, actuators, information encryption, rewritable paper, etc., while ORTP materials with mechanical stimulus response are still in their infancy. Summary of the invention

[0004] The purpose of the present invention is to enhance the phosphorescence radiation rate and its intermolecular interaction with PVC through molecular design, thereby inhibiting non-radiative transitions and enhancing the phosphorescence radiation competitiveness, providing a flexible room temperature phosphorescent material, realizing flexible three-dimensional modeling with room temperature phosphorescent properties, and expanding the application of room temperature phosphorescence in PVC elongation detection.

[0005] The idea of ​​the present invention is as follows: ortho / para-morpholinylbenzaldehyde and malononitrile are added into a reaction bottle, sodium hydroxide is used as a catalyst, acetone is used as a solvent, a crude product is obtained by grinding reaction at room temperature, 3-amino-5-methyl-2'-morpholinyl-2,4-dicyanobiphenyl (PM-BTDA) and 3-amino-5-methyl-4'-morpholinyl-2,4-dicyanobiphenyl (OM-BTDA) are obtained by column chromatography separation and purification, and the two compounds are used as objects and are doped with PVC at a weight ratio of 1:100 respectively, and the PVC doped film with long-life room temperature phosphorescence emission performance is obtained by tetrahydrofuran dissolution, casting and drying, so as to realize flexible three-dimensional modeling with long afterglow room temperature phosphorescence performance and application of room temperature phosphorescence in PVC elongation detection.

[0006] The purpose of the present invention is achieved through the following technical solutions.

[0007] A method for synthesizing a flexible room temperature phosphorescent material comprises the following preparation process:

[0008] Add o- / p-morpholinylbenzaldehyde and malononitrile into a reaction flask, use sodium hydroxide as a catalyst, and use acetone as a solvent. Grind and react at room temperature to obtain a crude product, which is separated and purified by column chromatography to obtain PM-BTDA and OM-BTDA.

[0009] Further, the preparation formulas of PM-BTDA and OM-BTDA are as follows:

[0010]

[0011] In the above preparation method, the molar ratio of o- / p-morpholinylbenzaldehyde to malononitrile and sodium hydroxide is 1:2.5:2.5.

[0012] In the above preparation method, the organic solvent is acetone, and the molar ratio of o- / p-morpholinylbenzaldehyde to acetone is 1:1.5.

[0013] The principle of the present invention is: 5-methyldicyanoaniline is selected as the electron-withdrawing group and morpholine is used as the electron-donating group, and a distorted donor (D)-π-acceptor (A) molecular configuration is constructed through the connection of benzene, and it is expected that the ISC rate can be adjusted by changing the substitution position of morpholine. The distorted D-π-A molecular configuration can reduce the lowest excited singlet state (S 1 ) and triplet state (T1 ) between ST ), thereby increasing the ISC rate, generating more triplet excitons, more effectively offsetting the phosphorescence quenching caused by insufficient environmental rigidity and oxygen diffusion, and reducing the selectivity of the phosphorescent chromophore to the polymer matrix. 2 The oxygen atoms can enhance the interaction between the room temperature phosphorescent compound and polyvinyl chloride through intermolecular hydrogen bonds, reducing the non-radiative energy loss of triplet excitons. Through strong phosphorescent radiation and intermolecular interactions, polyvinyl chloride has long-life room temperature phosphorescence, and realizes flexible room temperature phosphorescent display and room temperature phosphorescent detection of polyvinyl chloride elongation.

[0014] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0015] (1) The present invention realizes flexible room temperature phosphorescent display. The flexible RTP film is suitable for preparing large-area, durable, transparent three-dimensional entities through various stretching, folding, curling and other methods. It is expected to provide more inspiration and possibilities for the application of organic room temperature phosphorescent materials in more cutting-edge fields such as wearable electronic devices.

[0016] (2) The polyvinyl chloride doped film prepared by the present invention has good flexibility. With mechanical stretching, the elongation of the polyvinyl chloride doped film can reach up to 147.49%, and the room temperature phosphorescence lifetime continues to decrease with the increase of elongation during the stretching process. This is expected to enable room temperature phosphorescence to be used for the detection of mechanical force and elongation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 , Figure 2 and Figure 3 The hydrogen spectrum, carbon spectrum and mass spectrum of the target product PM-BTDA obtained in Example 1;

[0018] Figure 4 , Figure 5 and Figure 6 The hydrogen spectrum, carbon spectrum and mass spectrum of the target product OM-BTDA obtained in Example 1 are shown in FIG.

[0019] Figure 7(a) Stress-strain curves of blank PVC film and 1% OM-BTDA@PVC doped film at different stretching rates (10, 20 and 50 mm / min) (film thickness is 0.412 mm). (b) Fluorescence and afterglow photos of 1% OM-BTDA@PVC doped film at different elongations with 365 nm UV light on and off (elongation from 0% to 80%, original length from 3 cm to 5.4 cm). (c) Room temperature phosphorescence spectra of 1% OM-BTDA@PVC doped film at different elongations. (d) Time-resolved delayed decay curves of 1% OM-BTDA@PVC doped film at different elongations. (e) Trends of room temperature phosphorescence intensity and lifetime of 1% OM-BTDA@PVC doped film at different elongations.

[0020] Figure 8 It is the three-dimensional modeling of 1% OM-BTDA@PVC doped film; DETAILED DESCRIPTION

[0021] The present invention is further described below through specific implementation examples, but the protection scope and implementation methods of the present invention are not limited thereto.

[0022] Example 1

[0023] Add o- / p-morpholinylbenzaldehyde (1.6 g, 8.4 mmol), malononitrile (1.4 g, 20.9 mmol), acetone (0.9 mL), sodium hydroxide (0.84 g, 20.9 mmol) in a mortar and grind at room temperature for 5 minutes. The crude product is directly filtered and washed with water three times, using ethyl acetate / petroleum ether (v / v = 1:5) as eluent, and the product is purified by column chromatography to obtain orange solid PM-BTDA and OM-BTDA. The yields are respectively: 67% and 70%.

[0024] Take 0.1 g of PM-BTDA or OM-BTDA and add it to 10 g of PVC. Add 20 mL of tetrahydrofuran and stir until completely dissolved. Spread evenly on a 20 cm diameter polytetrafluoroethylene culture dish and heat for 60 min. o C drying oven for 12 h to obtain 1% PM-BTDA / OM-BTDA@PVC film.

[0025] We used 1% OM-BTDA@PVC film to fold into three-dimensional airplanes and windmills. By turning on / off the 365 nm UV light, the three-dimensional airplane and windmill models showed a green afterglow that lasted for 3 s. The 1% OM-BTDA@PVC film (thickness 0.412 mm) was used for uniaxial tensile experiments (the film used for the test was prepared in a standard dumbbell shape, and the thickness was measured three times at different positions using a thousandth thickness gauge, and the average value was taken). The stress-strain curve shows that: 1% OM-BTDA@PVC film has a green afterglow of 10 min. -1 The tensile strength (19.39 MPa) and elongation at break (147.49%) were excellent at a tensile speed of 1.5 % and the room temperature phosphorescence lifetime decreased from 170.16 ms to 89.17 ms. This provides a method for the preparation of flexible room temperature phosphorescent materials and the room temperature phosphorescence detection method of polyvinyl chloride elongation.

[0026] The hydrogen spectrum, carbon spectrum and mass spectrum of the obtained target product PM-BTDA are as follows Figure 1 , Figure 2 and Figure 3 The structural characterization data are shown below:

[0027] 1 H NMR (500 MHz, DMSO-d6) δ / ppm = 7.45 (d, J = 8.7 Hz, 2H), 7.05 (d,J = 8.6 Hz, 2H), 6.71 (s, 1H), 6.61 (s, 2H), 3.75 (t, 4H), 3.21 (t, 4H), 2.42(s, 3H); 13 C NMR (126 MHz, DMSO-d6) δ / ppm = 154.13, 152.08, 149.98, 148.28,129.81, 127.79, 119.12, 117.11, 116.22, 114.77, 95.05, 92.49, 66.47, 48.00,21.42; HRMS (MALDI-TOF): m / z 319.1556 [[M +H] + , calculated value 319.1559].

[0028] The hydrogen spectrum, carbon spectrum and mass spectrum of the obtained target product OM-BTDA are as follows Figure 4 , Figure 5 and Figure 6 The structural characterization data are shown below:

[0029] 1H-NMR (500 MHz, DMSO-d6) δ / ppm= 7.42 (t, J = 7.9 Hz, 1H), 7.25 –7.10 (m, 3H), 6.75 (s, 1H), 6.60 (s, 2H), 3.49 (d, J = 28.4 Hz, 4H), 2.73 (d,J = 23.3 Hz, 4H), 2.44 (s, 3H); 13 C NMR (126 MHz, DMSO-d6) δ / ppm = 153.33,150.58, 149.47, 148.59, 132.37, 130.87, 130.82, 123.47, 119.77, 119.74,116.65, 116.15, 95.74, 94.97, 66.62, 51.54, 21.40; HRMS (MALDI-TOF): m / z319.1563 [[M +H] + , calculated value 319.1559].

[0030] The structure of the target compound is inferred from the above characterization data as follows:

[0031]

Claims

1. A method for preparing a flexible room temperature phosphorescent material, characterized in that: The specific steps are as follows: Adding ortho / paramorpholinylbenzaldehyde and malononitrile into a reaction bottle, using sodium hydroxide as a catalyst and acetone as a solvent, grinding and reacting at room temperature to obtain a crude product, separating and purifying by column chromatography to obtain 3-amino-5-methyl-2'-morpholinyl-2,4-dicyanobiphenyl (PM-BTDA) and 3-amino-5-methyl-4'-morpholinyl-2,4-dicyanobiphenyl (OM-BTDA), and then using the two compounds as objects to be doped with polyvinyl chloride (PVC) at a weight ratio of 1:100, dissolving in tetrahydrofuran, casting, and drying to obtain a PVC doped film with long-life room temperature phosphorescence emission performance, thereby realizing a flexible three-dimensional model with long afterglow room temperature phosphorescence performance and the application of room temperature phosphorescence in PVC elongation detection; The PM-BTDA and OM-BTDA structures are as follows: 。 2. The preparation method according to claim 1, characterized in that: The molar ratio of the p- / o-morpholinylbenzaldehyde to malononitrile is 1:2.

5.

3. The preparation method according to claim 1, characterized in that: The molar ratio of the p- / o-morpholinyl benzaldehyde to the sodium hydroxide catalyst is 1:2.

5.

4. The preparation method according to claim 1, characterized in that: The molar ratio of the p- / o-morpholinylbenzaldehyde to acetone is 1:1.

5.

5. The preparation method according to claim 1, characterized in that: The weight ratio of the PM-BTDA / OM-BTDA to polyvinyl chloride is 1:

100.

6. The preparation method according to claim 1, characterized in that: Dissolve 0.01 g of PM-BTDA / OM-BTDA with 1.0 g of PVC in THF to a volume of 2 mL.

7. The preparation method according to claim 1, characterized in that: The casting device is a petri dish with a diameter of 20 cm.

8. The preparation method according to claim 1, characterized in that: The drying temperature and time were 60 s℃ and 10 h, respectively.

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