CN111205858A

CN111205858A - Imine-doped dicarboxylic acid long afterglow material and preparation method and application thereof

Info

Publication number: CN111205858A
Application number: CN202010111134.6A
Authority: CN
Inventors: 梁福顺; 王向明; 冯花; 姚淑华
Original assignee: Liaoning University
Current assignee: Liaoning University
Priority date: 2020-02-24
Filing date: 2020-02-24
Publication date: 2020-05-29
Anticipated expiration: 2040-02-24
Also published as: CN111205858B

Abstract

The invention discloses an imine-doped dicarboxylic acid long afterglow material and a preparation method and application thereof. Dissolving an imine guest molecule in acetonitrile to obtain an acetonitrile solution of the imine guest molecule; adding dicarboxylic acid main molecules into the solution, adding deionized water, methanol, ethanol or glacial acetic acid, heating and stirring to obtain a clear solution; standing at room temperature to precipitate crystal grains or amorphous powder. Washing with water or ethanol to obtain the imine doped dicarboxylic acid long afterglow material. The invention utilizes an organic host-guest doping system, can realize the regulation and control of phosphorescence luminescent color through low guest doping concentration (0.5-10 percent), prolongs afterglow time or improves phosphorescence quantum yield. The material system has the advantages of cheap and easily obtained raw materials, simple preparation method and the like. The doping system provided by the invention not only expands the range of an organic room temperature phosphorescent material system, but also has potential application in the fields of anti-counterfeiting information, photochemical sensors and the like.

Description

Imine-doped dicarboxylic acid long afterglow material and preparation method and application thereof

Technical Field

The invention relates to the technical field of long afterglow materials, in particular to an imine-doped dicarboxylic acid long afterglow material and a preparation method thereof.

Background

Metal-free host-guest dopant molecular systems have been reported. In 2013, Hirata et al used deuterated compounds as Guest (Guest) molecules, and dispersed in steroids with high triplet levels at a ratio of 0.3%, and obtained efficient and durable room temperature phosphorescence (adv. funct. mater.2013,23(27), 3386-3397.). In 2016, Adachi et al introduced carbazole unit as host matrix and deuterated polyphenyl compound as guest unit in cholesterol androstene, and adopted doping of host and guest in different proportions to obtain ultra-long organic phosphorescent material under photo-induced and electro-induced conditions (Adv. Mater.2016,28(4), 655-660.). Adachi et al in 2017 reported that benzidine as a guest molecule dispersed in a host molecule phosphorus-oxygen compound can continuously emit light for more than 1 hour under weak radiation (Nature 2017,550(7676), 384-387.). The content of the host and the guest is changed, and the amorphous film is prepared by adopting a fusion casting method, can be excited by a white LED light source, and can emit light for a long time even under the condition of higher than 100 ℃. The long afterglow material has light emitting mechanism of charge recombination via long life charge separating state. In 2018, Adachi transferred the energy of an exciplex system consisting of benzidine and phosphorus-oxygen compounds to the emitter by doping the emitter (adv. mater.2018,30(38), e 1800365.). The luminous brightness and emission time are improved by effective radiation attenuation and electron capture. In 2019, Wang et al prepared an organic small-molecule doped crystal material in which diphenylaminofluorene was dispersed in a phosphorus-oxygen compound by an ultrasonic method, had a high-quality single crystal structure, and could realize a long afterglow luminescence high-performance material exceeding 6s under low-energy light excitation (adv.funct.mater.2019,29(30), 1902503.). Recently, Dong et al developed a series of pure organic doping materials, in which triphenylamine having a D-a structure and phenylacetonitrile as guest compounds are doped into triphenylamine having donor properties and p-cyanobenzene acetonitrile host having acceptor properties, respectively. The obtained doped materials have strong fluorescence and phosphorescence emission, and the materials are relatively stable to light, heat and moisture (J.Phys.chem.Lett.2019,10(20), 6019-. Tang et al also reported a simple host-guest room temperature phosphorescence system, which comprises a host molecule of pentachloropyridine, phthalic anhydride, and dicyanobenzene, and a guest molecule of 1, 8-naphthalic anhydride, respectively, which are melt-doped. The system realizes the room temperature phosphorescence with high efficiency and ultra-long service life, and the ultra-long room temperature phosphorescence of the system can be excited by mechanical force; the transition state of the host and the guest together forming "cluster excitons" in the excited state is proposed, and it is also shown that aggregation-induced emission or aggregation-induced enhancement phenomenon has a promoting effect on the luminance of force-induced emission, while force-induced room temperature phosphorescence, which has been reported so far as having the longest lifetime, is also achieved by a simple host-guest strategy (nat. Commun.2019,10(1), 5161.).

Compared with inorganic and metal organic complex phosphorescent luminescent materials, organic room temperature phosphorescent luminescent materials are relatively difficult to realize due to factors such as weak spin-orbit coupling of organic molecules, fast non-radiative decay and the like. At present, the number of the organic phosphorus luminescent molecular systems and the organic host-guest doped systems is relatively small, and further development is needed.

Disclosure of Invention

Aiming at the defects of insufficient quantity of the existing organic phosphorescent material system and further development of the system, the invention provides an organic host-guest doped room temperature phosphorescent system-imine doped dicarboxylic acid long afterglow material system which has the advantages of low cost, easy obtaining of materials, simple preparation method and long service life. The invention utilizes an organic host-guest doping system, can realize the regulation and control of the luminescent color through low guest doping concentration, prolongs the afterglow time or improves the phosphorescence quantum yield.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows: the imine-doped dicarboxylic acid long afterglow material is prepared by mixing dicarboxylic acid host molecules and imine guest molecules according to a certain mole percentage.

The imine guest molecule is:

the dicarboxylic acid main molecules are as follows:

preferably, the imine-doped dicarboxylic acid long afterglow material comprises, in mole percent, imine guest molecules: the dicarboxylic acid comprises (0.5-10)% of a main molecule of dicarboxylic acid and (99.5-90)%.

The preparation method of the imine-doped dicarboxylic acid long afterglow material comprises the following steps: dissolving an imine guest molecule in acetonitrile to obtain an acetonitrile solution of the imine guest molecule; adding dicarboxylic acid host molecules into acetonitrile solution of imine guest molecules, adding deionized water or methanol or ethanol or glacial acetic acid, and heating and stirring to obtain clear solution; standing the obtained clear solution at room temperature to precipitate crystal or amorphous powder, and washing with deionized water or ethanol to obtain the imine-doped dicarboxylic acid long afterglow material.

Preferably, in the preparation method, the heating is performed at a temperature of 70-150 ℃.

The imine-doped dicarboxylic acid long afterglow material provided by the invention can be used as an anti-counterfeiting material.

In the imine-doped dicarboxylic acid long afterglow material system, carboxylic acid is used as a main molecule and is a good luminescent material, and carboxyl groups contained in the material system are easy to form intermolecular and intramolecular hydrogen bonds, so that a rigid environment is provided, and the non-radiative transition of triplet excitons is inhibited. The oxygen atom on the aromatic carbonyl group has a certain degree of orbital coupling, and can promote intersystem crossing and generation of triplet excitons. The imine guest molecules (1, 8-naphthalimide, phthalimide and saccharin) have a rigid coplanar chemical structure and a large pi-bond conjugated system, and are favorable for exciting and transferring pi electrons so as to generate fluorescence. Aromatic carbonyl and nitrogen heteroatom in the molecule are favorable for promoting intersystem crossing, thereby improving the phosphorescence quantum yield and generating room temperature phosphorescence. The invention adopts an organic small molecule host-guest doping system, and further improves the duration of phosphorescence and the phosphorescence quantum yield by forming hydrogen bonds and proton transfer. In addition, both imines and carboxylic acids have good photochemical properties and thermal stability.

Compared with the prior art, the invention has the following beneficial effects:

1. the imine-doped dicarboxylic acid long afterglow material can generate purple fluorescence under the irradiation of a room temperature ultraviolet lamp, and can generate yellow phosphorescence by turning off an excitation light source. The persistence duration is obviously prolonged by doping guest molecules, and the longest persistence time can reach 6.9 s. The material realizes the changes of luminescent color, phosphorescence lifetime and phosphorescence quantum yield under room temperature. Not only expands the range of organic room temperature phosphorescent materials, but also has potential application in the fields of anti-counterfeiting information, photochemical sensors and the like.

2. According to the imine-doped dicarboxylic acid long afterglow phosphor material, guest amines are uniformly dispersed in host acids, heated and stirred, cooled to room temperature, and subjected to suction filtration and washing to obtain the organic room temperature phosphor material. The material of the invention does not need rare elements, has no heavy atoms, low cost, low material consumption and simple components, does not cause pollution to the environment, provides new theoretical data information for pure organic phosphorescent materials, and also expands the types and the number of organic room temperature phosphorescent material systems.

3. The imine-doped dicarboxylic acid long afterglow material is an organic small molecule compound. The luminescent property of the phosphorescent material can be changed by doping the guest molecules with low molar percentage in the host molecules. And the material is expected to have potential application in the fields of multiple encryption and the like.

Drawings

FIG. 1 shows the phosphorescence emission spectra (5 ms delay) of PA and NI/PA under 360nm excitation.

FIG. 2 is a time-resolved attenuation curve for PA and NI/PA at 360nm excitation.

FIG. 3 is a digital photograph of a doping system NI/PA in different solvents.

In the figure, a is glacial acetic acid; and b, deionized water.

FIG. 4 shows fluorescence emission spectra of solid states of different doped molecular systems.

FIG. 5 is a digital photograph of dopant molecules under daylight (ambient), 365nm ultraviolet (UV ON) and UV OFF conditions;

fig. 6 shows the application of the anti-counterfeiting method in multiple encryption.

Detailed Description

The present invention will be described in further detail with reference to examples.

Example 1

1, 8-naphthalimide-doped phthalic acid long afterglow material (NI/PA) (glacial acetic acid as solvent)

(A) Material

The imine guest molecule is 1, 8-Naphthalimide (NI), the dicarboxylic acid host molecule is Phthalic Acid (PA), and the structural formula is as follows:

the preparation method comprises the following steps:

0.002g (0.01mmol) of 1, 8-naphthalimide was weighed into a round-bottomed flask, and then 2mL of acetonitrile was added. Stirring and heating to 60 ℃ to obtain a clear 1, 8-naphthalimide acetonitrile solution.

To the 1, 8-naphthalimide acetonitrile solution, 0.331g (1.99mmol) of phthalic acid and 7mL of glacial acetic acid were added, and the temperature was raised to 85 ℃ and maintained for 45min to obtain a clear solution. Cooling to room temperature, standing, and precipitating granular 1, 8-naphthalimide doped phthalic acid long afterglow material (NI/PA) (the molar percentage of imine guest molecules: dicarboxylic acid host molecules: 0.5%: 99.5%).

Example 2

1, 8-naphthalimide-doped phthalic acid long afterglow material (NI/PA) (deionized water as solvent)

(A) Material

The same as in example 1.

The preparation method comprises the following steps:

To the 1, 8-naphthalimide acetonitrile solution, 0.331g (1.99mmol) of phthalic acid and 7mL of deionized water were added, and the temperature was raised to 85 ℃ and maintained for 45min to obtain a clear solution. Cooling to room temperature, standing, and precipitating granular 1, 8-naphthalimide doped phthalic acid long afterglow material (NI/PA) (the molar percentage of imine guest molecules: dicarboxylic acid host molecules: 0.5%: 99.5%).

(III) comparative example

0.1g of phthalic acid is weighed into a round bottom flask, then 2mL of acetonitrile and 7mL of deionized water are added, stirred and heated to 85 ℃, and the temperature is kept for 30min until the mixture is clear. Cooling to room temperature gave a bulk crystalline comparative material (PA).

(IV) detection

1. The 1, 8-naphthalimide doped phthalic acid long afterglow material (0.5% NI/PA) prepared in example 2 and the PA material prepared in the comparative example are respectively excited under an ultraviolet lamp of 360nm to obtain an emission spectrum, and the result is shown in FIG. 1.

As can be seen from the figure, PA has strong phosphorescence emission at 511nm, 0.5% NI/PA has strong phosphorescence emission at 439nm, 545nm and 594nm under room temperature, and the luminescence intensity of the host-guest doped material is obviously higher than that of the undoped guest molecule.

2. The 1, 8-naphthalimide-doped phthalic acid long afterglow material (0.5% NI/PA) prepared in example 2 and the PA material prepared in the comparative example are respectively excited under an ultraviolet lamp of 360nm to obtain a time-resolved attenuation curve, as shown in FIG. 2.

As can be seen from the graph, the PA decays very fast with a lifetime of only 0.42ms at room temperature; the 0.5% NI/PA extended the life of the PA, which was 412 ms. Therefore, the service life of the material after the host and the guest are doped can be obviously improved.

3. The 1, 8-naphthalimide-doped phthalic acid long afterglow material (glacial acetic acid solvent) prepared in example 1 and the 1, 8-naphthalimide-doped phthalic acid long afterglow material (deionized water solvent) prepared in example 2 are respectively put under a 365nm ultraviolet lamp for excitation, and the result is shown in figure 3. As can be seen from the figure, in the doped system NI/PA, when the solvent is replaced by glacial acetic acid (FIG. 3a) and deionized water (FIG. 3b), the long afterglow of the NI/PA material changes from crystal grains to bulk crystals, and the afterglow time is longer. The solvent is more ideal for deionized water effect.

Example 3

1, 8-naphthalimide doped isophthalic acid long afterglow material (NI/IPA)

(A) Material

The imine guest molecule is 1, 8-Naphthalimide (NI), the dicarboxylic acid host molecule is isophthalic acid (IPA), and the structural formula is as follows:

the preparation method comprises the following steps:

0.002g (0.01mmol) of 1, 8-naphthalimide was weighed into a round-bottomed flask, and then 2mL of acetonitrile was added. Stirring and heating to 60 ℃ to obtain a clear 1, 8-naphthalimide acetonitrile solution. Then, 0.331g (1.99mmol) of isophthalic acid and 11 mL of methanol were added, stirred well to clarify, and the temperature was raised to 85 ℃ and held for 45min to obtain a clear and transparent solution. Cooling to room temperature, standing, and precipitating granular 1, 8-naphthalimide doped isophthalic acid long afterglow material (NI/IPA) (the molar percentage of imine guest molecules: dicarboxylic acid host molecules: 0.5%: 99.5%).

Example 4

1, 8-naphthalimide-doped terephthalic acid long afterglow material (NI/TPA)

(A) Material

The imine guest molecule is 1, 8-Naphthalimide (NI), the dicarboxylic acid host molecule is terephthalic acid (TPA), and the structural formula is as follows:

the preparation method comprises the following steps:

0.004g (0.02mmol) of 1, 8-naphthalimide is weighed into a round-bottom flask, and then 2mL of acetonitrile is added. Stirring and heating to 60 ℃ to obtain a clear 1, 8-naphthalimide acetonitrile solution. Then, 0.329g (1.98mmol) of terephthalic acid and 18mL of ethanol are added, the mixture is fully stirred until the mixture is clear, and the mixture is heated to 120 ℃ for reflux and kept for 30 hours to obtain a clear and transparent solution. Cooling to room temperature, standing, and precipitating the sheet-shaped 1, 8-naphthalimide-doped terephthalic acid long afterglow material (NI/TPA) (the molar percentage of imine guest molecules: dicarboxylic acid host molecules is 1%: 99%).

Example 5

Phthalimide doped phthalic acid long afterglow material (PI/PA)

(A) Material

The imine guest molecule is Phthalimide (PI), the dicarboxylic acid host molecule is Phthalic Acid (PA), and the structural formula is as follows:

the preparation method comprises the following steps:

0.0015g (0.01mmol) of phthalimide was weighed into a round-bottom flask, and then 2mL of acetonitrile was added. Stirring and heating to 60 ℃ to obtain a clear phthalimide acetonitrile solution. 0.331g (1.99mmol) of phthalic acid and 6mL of ethanol are added, and the temperature is raised to 85 ℃ and kept for 45min to obtain a clear and transparent solution. Cooling to room temperature, standing to obtain blocky phthalimide doped phthalic acid long afterglow material (PI/PA) (in mol percentage, imine guest molecules: dicarboxylic acid host molecules: 0.5%: 99.5%).

Example 6

1. The long-afterglow materials prepared in example 2(NI/PA), example 3(NI/IPA) and example 4(NI/TPA) were excited with a 365nm UV lamp at room temperature, and the emission patterns were measured (FIG. 4).

As can be seen from the figure, the three materials NI/PA, NI/IPA and NI/TPA have maximum emission at 398nm, 461nm and 407nm, respectively.

2. The imine doped dicarboxylic long afterglow materials prepared in example 2(NI/PA), example 3(NI/IPA) and example 4(NI/TPA) were irradiated by sunlight and 365nm UV light, and then the UV light was turned off to detect the change of the long afterglow, and the results are shown in FIG. 5. It can be seen that under the irradiation of ultraviolet lamp, NI/PA has purple fluorescence, NI/IPA has blue fluorescence, and NI/TPA has light blue fluorescence. Yellow afterglow can be observed after the ultraviolet lamp is turned off.

3. The patterns of two small fish (NI/IPA for the upper right small fish and NI/TPA for the lower left small fish) and one aquatic grass (NI/PA) prepared from example 2(NI/PA), example 3(NI/IPA) and example 4(NI/TPA) doped material, respectively, were illuminated with room light and 365nm UV light, respectively, and then the UV light was turned off and the color change was observed (FIG. 6). It can be seen that the milled dopant material is patterned to be white in room light (as shown in FIG. 6 a); under the irradiation of a 365nm ultraviolet lamp, the waterweeds show purple fluorescence, the small fish at the upper right are blue fluorescence, and the small fish at the lower left are light blue fluorescence (figure 6 b); after turning off the uv lamp for 1s, yellow waterweeds and small fish (upper right) were observed. The lower left fish glows away (fig. 6 c); after turning off the ultraviolet lamp for 2s, the small fish in the lower left gradually disappear (fig. 6 d); after turning off the uv lamp for 3s, the small fish in the upper right gradually disappeared (fig. 6 e); after turning off the ultraviolet lamp for 4s, the aquatic weeds gradually disappear (fig. 6 f); therefore, the invention can be applied to multiple encryption anti-counterfeiting technology.

The above description is only exemplary of the present invention and should not be taken as limiting, and any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The imine-doped dicarboxylic acid long afterglow material is characterized by consisting of dicarboxylic acid host molecules and imine guest molecules;

the imine guest molecule is:

the dicarboxylic acid main molecules are as follows:

2. the imine-doped dicarboxylic acid long afterglow material of claim 1, wherein the molar percentage of the imine guest molecule: the dicarboxylic acid comprises (0.5-10)% of a main molecule of dicarboxylic acid and (99.5-90)%.

3. The preparation method of the imine doped dicarboxylic acid long afterglow material of claim 1, comprising the following steps: dissolving an imine guest molecule in acetonitrile to obtain an acetonitrile solution of the imine guest molecule; adding dicarboxylic acid host molecules into acetonitrile solution of imine guest molecules, adding deionized water or methanol or ethanol or glacial acetic acid, and heating and stirring to obtain clear solution; standing the obtained clear solution at room temperature to precipitate crystal or amorphous powder, and washing with deionized water or ethanol to obtain the imine-doped dicarboxylic acid long afterglow material.

4. The method according to claim 3, wherein the heating is carried out at a temperature of 70 to 150 ℃.

5. The use of the imine-doped dicarboxylic acid long afterglow material according to claim 1 or 2 in anti-counterfeiting materials.