Eutectic material, hydrate physical mixture as well as preparation and application of eutectic material and hydrate physical mixture

Abstract

The invention relates to a eutectic material, a hydrate physical mixture as well as preparation and application thereof. The eutectic material comprises an electron donor and an electron acceptor, wherein the electron donor is a bidentate benzimidazole compound with V-type conformation, and the electron acceptor is an aromatic compound containing a strong electron withdrawing group. The material can be widely applied to the fields of multiple anti-counterfeit labels, visual temperature sensing, polar solvent recognizers, nitrobenzene toxic compound detection and the like, and has important practical application value.

Description

Technical Field

[0001] This invention belongs to the field of fluorescent functional materials, and specifically relates to a eutectic material, a hydrated physical mixture, and its preparation and application. Background Technology

[0002] Stimulus-responsive fluorescent cocrystals have significant application value in environmental sensing, bioimaging, and information encryption. Their core performance depends on their sensitive luminescence response to external stimuli such as temperature, solvent, humidity, and light. Traditional fluorescent cocrystals are typically assembled from relatively rigid organic molecules, as the rigid structure facilitates interaction between different molecules, resulting in dense molecular packing. However, the rigid framework and dense molecular packing limit the free volume of the crystal, often leading to fluorescence quenching and severely restricting their ability to accommodate other guest molecules (such as solvents or other small molecules), thus affecting their guest-induced stimulus-responsiveness. To improve guest capacity, researchers have attempted to use macrocyclic hosts (such as columnar aromatics and cyclodextrins) for cocrystal assembly. While this has improved guest capacity to some extent, it still generally faces problems such as complex synthesis, poor stability, and weak luminescence performance. Therefore, achieving efficient guest adsorption and controllable release while maintaining good luminescence properties has become a major challenge in this field. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide a eutectic material, a hydrated physical mixture, and its preparation and application, overcoming the technical defects of existing eutectic materials that are difficult to balance structural stability and dynamic response function. This invention, through reasonable molecular design and assembly strategies, breaks through the limitations of existing eutectic materials in terms of response performance and reversibility, and develops a new fluorescent material with excellent stability and stimulus response characteristics, providing a basic support for its practical application in sensing, anti-counterfeiting and detection fields.

[0004] The present invention provides a eutectic material comprising an electron donor and an electron acceptor; wherein the electron donor is a bidentate benzimidazole compound having a V-shaped conformation, and the electron acceptor is an aromatic compound containing a strong electron-withdrawing group.

[0005] Preferably, the bidentate benzimidazole compounds having a V-shaped conformation include one or more of 2,6-bis(2-benzimidazolyl)pyridine 26PY, 3,5-bis(2-benzimidazolyl)pyridine 35PY, and 1,3-bis(2-benzimidazolyl)benzene 13PH.

[0006] Preferably, the aromatic compound containing a strong electron-withdrawing group is one or more of tetracyanobenzene, dinitrobenzene, tetrafluorobenzoquinone, and cyanopyrazine derivatives.

[0007] Preferably, the molar ratio of the electron donor to the electron acceptor is 1:(1-2).

[0008] More preferably, the aromatic compound containing a strong electron-withdrawing group includes one or more of 1,2,4,5-tetracyanobenzene (TCNB), 1,5-dinitrobenzene (DNB), 1,3-dinitrobenzene (13DNB), 1,4-dinitrobenzene (14DNB), 1-bromo-2,4-dinitrobenzene (1Br24DNB), and 3,5-dinitrobenzoyl chloride (35DNBzCl).

[0009] Preferably, the eutectic material is assembled by dehydration of a hydrated physical mixture containing electron donors and electron acceptors, or by assembly of electron donors and electron acceptors under strongly polar solvent conditions, or by assembly of electron donors, electron acceptors, and solvent molecules through CH···N hydrogen bonds and π-π stacking interactions.

[0010] Furthermore, eutectic materials are assembled through dehydration of a hydrated physical mixture containing electron donors and electron acceptors to form electron donors and electron acceptors that are reversibly assembled through a hydration-dehydration cycle.

[0011] Furthermore, the electron donor, electron acceptor, and solvent molecules are stably assembled through CH···N hydrogen bonds and π-π stacking interactions to form a layered structure.

[0012] The hydrated physical mixture undergoes a conformational change under thermal or polar solvent stimulation, achieving co-assembly, which in turn leads to a redshift (up to 180 nm) or complete quenching of fluorescence emission.

[0013] Preferably, the eutectic material is one or more of the following: 26PY / TCNB-H eutectic, 26PYTC-DMF eutectic, 26PYTC-DMSO eutectic, 26PY / DNB-H eutectic, 26PYDN-DMF eutectic, 26PYDN-DMSO eutectic, 35PY / TCNB-H eutectic, 35PYTC-DMF eutectic, 35PYTC-DMSO eutectic, 13PH / TCNB-H eutectic, 13PHTC-DMF eutectic, 13PHTC-DMSO eutectic, and 13PHTC-THF eutectic.

[0014] The 26PYTC-DMF eutectic belongs to the monoclinic crystal system with space group P121 / m1. Its asymmetric unit comprises one 26PY molecule, two TCNB molecules, and one DMF molecule. The cell parameters are: a = 6.7534(12) Å, b = 36.699(8) Å, c = 7.3850(15) Å, α = 90.00 ° , β=92.679(17) °γ=90.00 ° The unit cell volume V = 1828.3(6) Å 3 ; or X-ray powder diffraction of the 26PYTC-DMF eutectic, including the following 2θ angle values: 4.85±0.2 ° 9.71±0.2 ° 14.24±0.2 ° 15.07±0.2 ° 16.38±0.2 ° 24.56±0.2 ° 26.48±0.2 ° 27.54±0.2 ° 27.87±0.2 ° 28.40±0.2 ° ;

[0015] The 26PYTC-DMSO eutectic belongs to the triclinic crystal system with space group P-1. Its asymmetric unit comprises one 26PY molecule, 1.5 TCNB molecules, and one DMSO molecule. The cell parameters are: a=10.5927(14) Å, b=11.1478(18) Å, c=15.672(2) Å, α=73.433(13) Å. ° , β=79.096(11) ° , γ=67.492(14) ° The unit cell volume V = 1632.0(4) Å 3 ; or X-ray powder diffraction of the 26PYTC-DMSO eutectic, including the following 2θ angle values: 5.89±0.2 ° 9.07±0.2 ° 11.24±0.2 ° 11.73±0.2 ° 13.23±0.2 ° 15.55±0.2 ° 16.34±0.2 ° 20.68±0.2 ° 22.17±0.2 ° 26.27±0.2 ° 27.24±0.2 ° ;

[0016] The 26PYDN-DMF eutectic belongs to the triclinic crystal system with space group P-1. Its asymmetric unit comprises one 26PY molecule, one DNB molecule, and one DMF molecule. The cell parameters are: a=11.5446(10)Å, b=11.8382(8)Å, c=12.5805(10)Å, α=90.640(6). ° , β=117.278(9) ° , γ=110.826(7) ° The unit cell volume V = 1396.57(19) Å 3 Or X-ray powder diffraction of the 26PYDN-DMF eutectic, including the following 2θ angle values: 8.17±0.2 ° 8.85±0.2 ° 9.41±0.2 ° 17.28±0.2 ° 17.80±0.2 ° 20.50±0.2 ° 22.85±0.2 ° 24.11±0.2 ° 26.78±0.2 ° 28.16±0.2 ° ;

[0017] The 26PYDN-DMSO eutectic belongs to the triclinic crystal system with space group P-1. Its asymmetric unit comprises one 26PY molecule, one DNB molecule, and one DMSO molecule. The cell parameters are: a=11.3441(5) Å, b=11.6747(6) Å, c=12.3066(6) Å, α=64.7120(10) Å. ° , β=72.7600(10) ° , γ=69.814(2) ° The unit cell volume V = 1361.69(11) Å 3 ; or X-ray powder diffraction of the 26PYDN-DMSO eutectic, including the following 2θ angle values: 8.64±0.2 ° 9.46±0.2 ° 10.61±0.2 ° 12.67±0.2 ° 15.79±0.2 ° 16.89±0.2 ° 17.34±0.2 ° 20.05±0.2 ° 20.93±0.2 ° 25.49±0.2° 27.02±0.2 ° 28.39±0.2 ° ;

[0018] The X-ray powder diffraction of the 26PY / TCNB-H eutectic yielded the following 2θ angle value: 13.83 ± 0.2. ° 18.30±0.2 ° 22.38±0.2 ° 26.94±0.2 ° 29.18±0.2 ° 29.63±0.2 ° ;

[0019] The X-ray powder diffraction of the 26PY / DNB-H eutectic yielded the following 2θ angle value: 7.64 ± 0.2. ° 9.77±0.2 ° 10.66±0.2 ° 11.85±0.2 ° 12.43±0.2 ° 17.59±0.2 ° 19.08±0.2 ° 20.78±0.2 ° 22.59±0.2 ° 23.11±0.2 ° 25.15±0.2°, 27.57±0.2° ° 29.24±0.2 ° ;

[0020] The X-ray powder diffraction of the 35PY / TCNB-H eutectic yielded the following 2θ angle value: 5.59 ± 0.2. ° 11.35±0.2 ° 13.80±0.2 ° 18.38±0.2 ° 22.42±0.2 ° 29.26±0.2 ° 29.64±0.2 ° ;

[0021] The X-ray powder diffraction of the 13PH / TCNB-H eutectic yielded the following 2θ angle value: 10.03 ± 0.2. ° 12.01±0.2 ° 13.83±0.2 ° 14.34±0.2 ° 18.35±0.2 °20.08±0.2 ° 22.33±0.2 ° 25.46±0.2 ° 25.69±0.2 ° 26.74±0.2 ° 27.50±0.2 ° 29.17±0.2 ° 29.62±0.2 ° .

[0022] The preparation methods of the eutectic material of the present invention include solvent-assisted grinding (such as method 1 and method 2) and solvent slow evaporation method (such as method 3).

[0023] This invention provides a method for preparing a eutectic material, comprising:

[0024] Method 1: Grind the electron donor and electron acceptor together in a solvent to obtain a hydrated physical mixture, and then perform heat treatment or solvent replacement to obtain a eutectic material;

[0025] Method 2: Grind the electron donor and electron acceptor together in a polar solvent to obtain a eutectic material;

[0026] Method 3: Mix the electron donor, electron acceptor and polar solvent, stir, and let stand at room temperature to evaporate the solvent to obtain a eutectic material.

[0027] In methods 1 to 3, the molar ratio of electron donor to electron acceptor is 1:(1 to 2).

[0028] In Method 1, the solvent used for co-grinding is one or more of toluene, ethanol, acetonitrile, acetone, ethyl acetate, dichloromethane, and chloroform; the solvent used for solvent replacement is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropionamide, dimethyl sulfoxide, and tetrahydrofuran; and the heat treatment temperature is 383K to 423K.

[0029] In Method 2, the polar solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropionamide, dimethyl sulfoxide, and tetrahydrofuran.

[0030] In method 3, the polar solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropionamide, dimethyl sulfoxide, and water; the stirring is carried out at 25~80℃ for 0.5-1 hour.

[0031] The present invention provides a hydrated physical mixture comprising the electron donor and electron acceptor.

[0032] The present invention provides a method for preparing a hydrated physical mixture, comprising: grinding the electron donor and electron acceptor together in a solvent.

[0033] The solvent is one or more of toluene, ethanol, acetonitrile, acetone, ethyl acetate, dichloromethane, and chloroform.

[0034] This invention achieves a reversible transition from the hydrated state to the eutectic state through two "dynamic deshielding" strategies:

[0035] One method is thermally driven dehydration, which involves disrupting the hydration network at high temperatures (383K~423K), exposing active sites, and driving the donor and acceptor to self-assemble into a stable charge-transfer eutectic through CH···N hydrogen bonds and face-to-face π-π stacking.

[0036] The second method is competitive solvation, which uses highly polar solvents (such as DMF and DMSO) to replace water molecules at room temperature, inducing rapid formation of eutectic.

[0037] The key innovation of the eutectic material lies in its dual dynamic synergistic characteristics of "structure-function": the V-shaped conformational arm acts as a conformational switch, with an angle change of more than 4°, which can reversibly regulate the opening and closing of the cavity and the adsorption / release of the guest; at the same time, this process exposes sites such as amine groups, which stabilize the assembly through hydrogen bonding and π-π interaction with the acceptor unit, and directly modulate the charge transfer intensity to achieve a significant fluorescence redshift or quenching effect.

[0038] This invention provides an application of any of the eutectic materials and the hydrated physical mixtures in the fields of anti-counterfeiting labels, temperature sensors, solvent identification, and detection of nitrobenzene-based toxic compounds.

[0039] Furthermore, information anti-counterfeiting: the hydrated physical mixture is made into ink and printed on paper or frosted glass substrate to form a pattern. By heating the pattern locally, color and fluorescence changes can be triggered to achieve multiple anti-counterfeiting measures.

[0040] Visualized temperature sensing: A hydration physical mixture is coated onto the surface of paper, dried, and then used to prepare a sensing test paper. The paper exhibits visible color and fluorescence changes as the temperature rises, making it suitable for visual monitoring of temperature thresholds.

[0041] Detection of nitrobenzene poisons: The above test strips are used to detect nitrobenzene toxic compounds such as 13DNB and 14DNB. High sensitivity and visual detection can be achieved through fluorescence quenching or color change.

[0042] Polar solvent identification: Using test paper containing a hydrated physical mixture, a significant color or fluorescence response can be observed after adding a small amount of polar solvent (such as DMF or DMSO), which can be used for solvent identification and leak detection.

[0043] One type of eutectic material described in this invention is reversibly assembled from a hydrated physical mixture with a V-shaped conformation through a dehydration process. This hydrated physical mixture achieves reversible assembly through a hydration-dehydration cycle, undergoes structural recombination under thermal stimulation or the action of polar solvents, exhibiting significant fluorescence redshift or fluorescence quenching phenomena, and possessing excellent cycle stability and high response sensitivity. The hydrated physical mixture of this invention can be widely applied in fields such as multi-layer anti-counterfeiting labels, visual temperature sensors, polar solvent identifiers, and the detection of nitrobenzene-based toxic compounds, possessing significant practical application value.

[0044] Beneficial effects

[0045] This invention utilizes bidentate benzimidazole compounds with a V-shaped conformation as electron donors and aromatic compounds containing strong electron-withdrawing groups as electron acceptors to obtain eutectic materials.

[0046] This invention constructs a novel eutectic material system based on reversible assembly of hydration-dehydration cycles using a hydrated physical mixture with a V-shaped conformation, achieving an organic unity of structural stability and dynamic stimulus response performance. This material undergoes reversible structural recombination under thermal or polar solvent stimulation. The opening and closing of cavities and the adsorption and release of guests are controlled by changes in the angle of the V-shaped conformation arms, inducing a significant fluorescence redshift (up to 180 nm) or complete quenching effect, and exhibiting excellent cyclic stability (no performance degradation after 10 cycles). Its unique "structure-function" dual dynamic synergistic mechanism not only achieves multiple sensitive responses to temperature, polar solvents, and nitrobenzene toxins, but also expands its practical applications in anti-counterfeiting encryption, temperature sensing, solvent identification, and toxic substance detection. Furthermore, the solvent grinding and evaporation preparation process employed has advantages such as simple operation, mild conditions, and environmental friendliness, providing an important technical foundation and application prospect for the development of next-generation intelligent fluorescent materials. Attached Figure Description

[0047] Figure 1 The molecular structural formulas of the electron donor and electron acceptor used in the embodiments of the present invention are shown.

[0048] Figure 2 (a~b) are the solid-state UV-Vis absorption spectra of the 26PY / TCNB series compounds in Examples 1-3;

[0049] Figure 3 The images (a~b) show the solid-state UV-Vis absorption spectra of the 26PY / DNB series compounds in Examples 4-6.

[0050] Figure 4 The images (a~b) show the solid-state UV-Vis absorption spectra of 35PY / TCNB in ​​Example 7, 13PH / TCNB in ​​Example 10, and a series of compounds.

[0051] Figure 5 (a~c) show the fluorescence spectral changes of 26PY in Comparative Example 1 and 26PY / TCNB compounds in Examples 1-3 under thermal and solvent stimulation.

[0052] Figure 6 The images (a~b) show the fluorescence spectral changes of the 26PY / DNB compounds in Examples 4-6 under thermal and solvent stimulation.

[0053] Figure 7 (a~c) show the fluorescence spectral changes of 35PY in Comparative Example 2 and 35PY / TCNB compounds in Examples 7-9 under thermal and solvent stimulation.

[0054] Figure 8 (a~c) show the fluorescence spectral changes of the 13PH compound in Comparative Example 3 and the 13PH / TCNB compound in Examples 10-13 under thermal and solvent stimulation.

[0055] Figure 9 (a~b) are the fluorescence lifetime decay curves of 26PY in Comparative Example 1 and the 26PY / TCNB series compounds in Examples 1 and 3;

[0056] Figure 10 The fluorescence lifetime decay curves of the 26PY / DNB series compounds in Example 4 are shown.

[0057] Figure 11 Fluorescence quantum yield diagrams of 26PY in Comparative Example 1, 26PY / TCNB in ​​Examples 1-3, and the 26PY / DNB series compounds in Example 4;

[0058] Figure 12 The electron paramagnetic resonance spectra of 26PY / TCNB-H in Example 1 and 26PYTC-DMF in Example 2 are shown below.

[0059] Figure 13 The diagrams (a~d) in the middle are analytical diagrams of the single crystal structure of the 26PYTC-DMF eutectic in Example 14;

[0060] Figure 14 The diagrams (a~d) in the middle are analytical diagrams of the single crystal structure of the 26PYTC-DMSO eutectic in Example 15;

[0061] Figure 15 The diagrams (a~d) in the middle are analytical diagrams of the single crystal structure of the 26PYDN-DMF eutectic in Example 16;

[0062] Figure 16 The diagrams (a~d) in the middle are analytical diagrams of the single crystal structure of the 26PYDN-DMSO eutectic in Example 17;

[0063] Figure 17 The middle (a~b) are the powder X-ray diffraction patterns of 26PY in Comparative Example 1 and the 26PY / TCNB series compounds in Examples 1-3;

[0064] Figure 18 The middle (a~b) are the powder X-ray diffraction patterns of the 26PY / DNB series compounds in Examples 4 to 6;

[0065] Figure 19 The images (a~b) show the powder X-ray diffraction patterns of the 35PY / TCNB series compounds in Example 7 and the 13PH / TCNB series compounds in Example 10.

[0066] Figure 20 (a~b) are differential scanning calorimetry curves of the 26PY / TCNB series compounds in Examples 1-3 and the 26PY / DNB series compounds in Examples 4-6;

[0067] Figure 21 (a~b) are the thermogravimetric analysis curves of the 26PY / TCNB series compounds in Example 1 and the 26PY / DNB series compounds in Example 4;

[0068] Figure 22 (a~b) are schematic diagrams illustrating the application of 26PY / TCNB-based thermosensitive fluorescent test strips in temperature detection;

[0069] Figure 23 The images (a~b) show the composite anti-counterfeiting patterns of 26PY / TCNB and 26PY / DNB and the results of their 10-cycle stability test.

[0070] Figure 24 The diagrams (a~b) show the detection of various dinitro compounds (including 13DNB, 14DNB, 1Br24DNB and 35DNBzCl) by the 26PY test paper.

[0071] Figure 25 Figures (a-b) show schematic diagrams illustrating the application of 26PY / TCNB and 26PY / DNB test strips in the detection of DMF and DMSO solvents. Detailed Implementation

[0072] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0073] The embodiments of the present invention employ solvent evaporation and solvent-assisted grinding methods to prepare eutectic materials.

[0074] The molecular structural formulas of electron donors and electron acceptors are as follows: Figure 1 As shown.

[0075] Example 1

[0076] Step S1: Accurately weigh 26PY (100.0 mg, 0.32 mmol) and TCNB (114.4 mg, 0.64 mmol), place them in an agate mortar at a molar ratio of 1:2, slowly add 5 mL of toluene (TL), and grind at room temperature until homogeneous to obtain a white powder 26PY / TCNB. This sample exhibits blue fluorescence under 365 nm ultraviolet light.

[0077] Step S2: Place the powder obtained in step S1 in a 393K oven for 10 minutes for heat treatment. The sample turns into a yellow powder, which is denoted as 26PY / TCNB-H. Its fluorescence emission changes from blue to yellow.

[0078] Step S3: Add 5 mL of TL to the yellow powder obtained in step S2, grind evenly, and the 26PY / TCNB-H-TL sample will turn back into a white powder, and the fluorescence emission will change from yellow back to blue.

[0079] Example 2

[0080] Accurately weigh 26PY (100.0 mg, 0.32 mmol) and TCNB (114.4 mg, 0.64 mmol) and place them in an agate mortar at a molar ratio of 1:2. Slowly add 0.5 mL of N,N-dimethylformamide (DMF) and grind until homogeneous at room temperature to obtain a yellow powder, 26PYTC-DMF. This sample emits yellow fluorescence under 365 nm ultraviolet light.

[0081] Example 3

[0082] Accurately weigh 26PY (100.0 mg, 0.32 mmol) and TCNB (85.5 mg, 0.48 mmol) and place them in an agate mortar at a molar ratio of 1:1.5. Slowly add 0.5 mL of dimethyl sulfoxide (DMSO) and grind until homogeneous at room temperature to obtain a yellow powder, 26PYTC-DMSO. This sample emits yellow fluorescence under 365 nm ultraviolet light.

[0083] Example 4

[0084] Step S1: Accurately weigh 26PY (100.0 mg, 0.32 mmol) and DNB (62.0 mg, 0.32 mmol) in a 1:1 molar ratio into an agate mortar. Slowly add 5 mL of dichloromethane (DCM) and grind at room temperature until homogeneous to obtain a creamy white powder, 26PY / DNB. This sample exhibits blue fluorescence under 365 nm ultraviolet light.

[0085] Step S2: Place the powder obtained in step S1 in a 393K oven for 5 minutes for heat treatment. The sample turns into a yellowish-brown powder, which is denoted as 26PY / DNB-H, and the fluorescence changes from blue to quenched.

[0086] Step S3: Add 5 mL of DCM to the powder obtained in step S2, grind evenly, and the 26PY / DNB-H-DCM sample will revert to a creamy white powder and re-emit blue fluorescence.

[0087] Example 5

[0088] Accurately weigh 26PY (100.0 mg, 0.32 mmol) and DNB (62.0 mg, 0.32 mmol) and place them in an agate mortar at a 1:1 molar ratio. Slowly add 0.5 mL of DMF and grind at room temperature until homogeneous to obtain a yellowish-brown powder, 26PYDN-DMF. This sample showed no fluorescence emission under 365 nm ultraviolet light.

[0089] Example 6

[0090] Accurately weigh 26PY (100.0 mg, 0.32 mmol) and DNB (62.0 mg, 0.32 mmol) into an agate mortar at a 1:1 molar ratio. Slowly add 0.5 mL of DMSO and grind at room temperature until homogeneous to obtain a yellowish-brown powder, 26PYDN-DMSO. This sample showed no fluorescence emission under 365 nm ultraviolet light.

[0091] Example 7

[0092] Step S1: Accurately weigh 35PY (100.0 mg, 0.32 mmol) and TCNB (114.4 mg, 0.64 mmol), place them in an agate mortar at a molar ratio of 1:2, slowly add 5 mL of TL, and grind at room temperature until homogeneous to obtain a white powder 35PY / TCNB. This sample emits blue fluorescence under 365 nm ultraviolet light.

[0093] Step S2: Place the above powder in a 403K oven and heat for 10 minutes. The sample turns into an orange powder, denoted as 35PY / TCNB-H, and the fluorescence emission changes from blue to yellow.

[0094] Step S3: Add 5 mL of TL to the powder obtained in step S2, grind evenly, and the 35PY / TCNB-H-TL sample will revert to a white powder and re-emit blue fluorescence.

[0095] Example 8

[0096] Accurately weigh 35PY (100.0 mg, 0.32 mmol) and TCNB (114.4 mg, 0.64 mmol) and place them in an agate mortar at a molar ratio of 1:2. Slowly add 0.5 mL of DMF and grind at room temperature until homogeneous to obtain a yellow powder, 35PYTC-DMF. This sample emits yellow fluorescence under 365 nm ultraviolet light.

[0097] Example 9

[0098] Accurately weigh 35PY (100.0 mg, 0.32 mmol) and TCNB (114.4 mg, 0.64 mmol) and place them in an agate mortar at a molar ratio of 1:2. Slowly add 0.5 mL of DMSO and grind at room temperature until homogeneous to obtain a yellow powder, 35PYTC-DMSO. This sample emits yellow fluorescence under 365 nm ultraviolet light.

[0099] Example 10

[0100] Step S1: Accurately weigh 13PH (100.0 mg, 0.32 mmol) and TCNB (114.8 mg, 0.64 mmol), place them in an agate mortar at a molar ratio of 1:2, slowly add 5 mL of DCM, and grind at room temperature until homogeneous to obtain a light brown 13PH / TCNB powder. This sample exhibits blue fluorescence under 365 nm ultraviolet light.

[0101] Step S2: Place the above powder in a 423K oven and heat for 15 minutes. The sample turns into a brown powder, which is denoted as 13PH / TCNB-H, and the fluorescence emission changes from blue to orange.

[0102] Step S3: Add 5 mL of DCM to the powder obtained in step S2, grind evenly, and the 13PH / TCNB-H-DCM sample will revert to a light brown powder and re-emit blue fluorescence.

[0103] Example 11

[0104] Accurately weigh 13PH (100.0 mg, 0.32 mmol) and TCNB (114.8 mg, 0.64 mmol) and place them in an agate mortar at a molar ratio of 1:2. Slowly add 0.5 mL of DMF and grind at room temperature until homogeneous to obtain a yellow powder, 13PHTC-DMF. This sample emits orange fluorescence under 365 nm ultraviolet light.

[0105] Example 12

[0106] Accurately weigh 13PH (100.0 mg, 0.32 mmol) and TCNB (114.8 mg, 0.64 mmol) and place them in an agate mortar at a molar ratio of 1:2. Slowly add 0.5 mL of DMSO and grind at room temperature until homogeneous to obtain a yellow powder, 13PHTC-DMSO. The sample emits orange fluorescence under 365 nm ultraviolet light.

[0107] Example 13

[0108] Accurately weigh 13PH (100.0 mg, 0.32 mmol) and TCNB (114.8 mg, 0.64 mmol) and place them in an agate mortar at a molar ratio of 1:2. Slowly add 1 mL of THF and grind at room temperature until homogeneous to obtain a yellow powder, 13PHTC-THF. This sample emits orange fluorescence under 365 nm ultraviolet light.

[0109] Example 14

[0110] 26PY (20.0 mg, 0.064 mmol) and TCNB (22.9 mg, 0.128 mmol) were dissolved in a DMF / H₂O mixed solvent (2 mL: 1 mL) at a molar ratio of 1:2. The solution was heated at 40 °C. ° The mixture was stirred at C for 1 hour, and then the solvent was slowly evaporated at room temperature. After 30 days, yellow blocky crystals of 26PYTC-DMF precipitated. The crystals emitted yellow fluorescence under 365 nm ultraviolet light.

[0111] Example 15

[0112] 26PY (20.0 mg, 0.064 mmol) and TCNB (17.2 mg, 0.096 mmol) were dissolved in a DMSO / H2O mixed solvent (2 mL: 1 mL) at a molar ratio of 2:3. The solution was heated at 40 °C. ° Stirred at C for 1 hour, then slowly evaporate the solvent at room temperature. After 60 days, yellow flaky crystals 26PYTC-DMSO were obtained, which emitted yellow fluorescence under 365nm ultraviolet light.

[0113] Example 16

[0114] 26PY (20.0 mg, 0.064 mmol) and DNB (12.4 mg, 0.064 mmol) were dissolved in a 1:1 molar ratio in a DMF:H₂O mixed solvent (2 mL: 1 mL). The solution was heated at 40 °C. °Stirred at C for 1 hour, then slowly evaporate the solvent at room temperature. After 30 days, yellow blocky crystals 26PYDN-DMF were produced. The crystals showed no fluorescence emission under 365nm ultraviolet light.

[0115] Example 17

[0116] 26PY (20.0 mg, 0.064 mmol) and DNB (12.4 mg, 0.064 mmol) were dissolved in a 1:1 molar ratio in a DMSO:H2O mixed solvent (2 mL: 1 mL). The solution was heated at 40 °C. ° The mixture was stirred at C for 1 hour, and then the solvent was slowly evaporated at room temperature. After 60 days, yellow needle-like crystals 26PYDN-DMSO were obtained. The crystals showed no fluorescence emission under 365nm ultraviolet light.

[0117] Comparative Example 1

[0118] Step S1: Weigh 26PY (100.0 mg, 0.32 mmol) into an agate mortar, slowly add 5 mL of TL, and grind until homogeneous at room temperature to obtain a white powder of 26PY. The sample emits blue fluorescence under 365 nm ultraviolet light.

[0119] Step S2: The powder was placed in a 393K oven and heated for 10 minutes. The sample was still a white powder, denoted as 26PY-H, and its fluorescence was still blue, with no obvious change.

[0120] Comparative Example 2

[0121] Step S1: Weigh 35PY (100.0 mg, 0.32 mmol) into an agate mortar, slowly add 5 mL of TL, and grind until homogeneous at room temperature to obtain a white powder of 35PY. The sample emits blue fluorescence under 365 nm ultraviolet light.

[0122] Step S2: Place the powder in a 403K oven and heat for 10 minutes. The sample is still a white powder and is designated as 35PY-H. Its fluorescence is still blue and no obvious change is observed.

[0123] Comparative Example 3

[0124] Step S1: Weigh 13PH (100.0 mg, 0.32 mmol) into an agate mortar, slowly add 5 mL of DCM, and grind until homogeneous at room temperature to obtain a light brown powder, 13PH. This sample emits a weak blue fluorescence under 365 nm ultraviolet light.

[0125] Step S2: Place the powder in a 423K oven and heat for 15 minutes. The sample is still a white powder, labeled 13PH-H. Its fluorescence is still a weak blue emission, with no obvious changes observed.

[0126] Experimental Example 1

[0127] Ultraviolet-Visible Absorption Spectroscopy: A Perkin-Elmer Lambda 750 ultraviolet-visible spectrophotometer equipped with a BaSO4 reference and white light mode was used to test solid samples in the wavelength range of 200–800 nm. Figure 2 As shown in Figure a, the maximum absorption peak of 26PY / TCNB-H obtained by heat treatment in Example 1 is located at 523 nm in the solid state, which is significantly red-shifted compared with the 26PY / TCNB sample, and forms a broad absorption band in the range of 250 to 523 nm, indicating the formation of intermolecular charge transfer (CT) interaction.

[0128] Figure 3 As shown in Figure a, a similar phenomenon was observed in the 26PY / DNB system of Example 4, with its maximum absorption peak red-shifted from 426 nm to 470 nm, a redshift of 44 nm. Comparison with the eutectic samples prepared by the solvent method revealed that the maximum absorption of 26PYTC-DMF in Example 2 and 26PYTC-DMSO in Example 3 were located at 518 nm and 522 nm, respectively. Figure 2 b), which is highly consistent with the absorption behavior of the thermochromic sample 26PY / TCNB-H; while the maximum absorption of 26PYDN-DMF in Example 5 and 26PYDN-DMSO in Example 6 is located at 493nm and 485nm, respectively. Figure 3 (b) Compared to 26PY / DNB-H, it is redshifted by about 20 nm, indicating that its CT interaction is significantly enhanced.

[0129] from Figure 4 As can be seen, the 35PY / TCNB in ​​Example 7 changed from white to orange-yellow after heat treatment, and its maximum absorption shifted from 400 nm to 560 nm. Similarly, the maximum absorption peak of the 13PH / TCNB in ​​Example 10 was located at 400 nm, while the heat-treated sample 13PH / TCNB-H not only showed a significant red shift in its absorption peak, but also exhibited a new broad absorption band in the 600–800 nm range, indicating significant charge recombination. Figure 4 (b) This further confirms that heat treatment induces a strong CT effect and changes in molecular configuration, resulting in a significant absorption redshift and macroscopic color change.

[0130] Experimental Example 2

[0131] Emission spectroscopy test: The fluorescence spectrum of the sample was measured using a Hitachi F-4700 spectrophotometer. Figure 5The results show that the fluorescence properties of 26PY in Comparative Example 1 and its heated sample 26PY-H did not change significantly. In contrast, the fluorescence emission peak of the 26PY / TCNB powder in Example 1, after heat treatment, shifted from 405 nm to 545 nm; however, after the addition of toluene again, the fluorescence emission peak shifted back to 405 nm, indicating that its luminescence behavior is reversible. Figure 5 b). From Figure 5 As can be seen, both 26PYTC-DMF in Example 2 and 26PYTC-DMSO in Example 3 exhibit fluorescence emission peaks around 544 nm, indicating that the introduction of DMF or DMSO solvent can promote the formation of a eutectic structure with specific luminescence behavior in this type of composite. Figure 6 As shown in Figure a, the 26PY / DNB sample in Example 4 initially emitted blue fluorescence. After heat treatment, fluorescence quenching occurred. Re-addition of dichloromethane restored the sample to its off-white appearance, and the fluorescence returned to blue emission at 405 nm. Similarly, no fluorescence emission was observed in the 26PYDN-DMF of Example 5 and the 26PYDN-DMSO of Example 6. Figure 6 b).

[0132] Furthermore, Figure 7 a and Figure 8 a shows that the fluorescence properties of 35PY and 13PH in Comparative Examples 2 and 3 remained essentially unchanged before and after heat treatment. However, the 35PY / TCNB in ​​Example 7 and the 13PH / TCNB in ​​Example 10 both showed a significant red shift in fluorescence after heating ( Figure 7 b and Figure 8 b), indicating that its structure has undergone significant changes. Furthermore, the 35PYTC-DMF of Example 8 and the 35PYTC-DMSO of Example 9 ( Figure 7 c) They emit yellow fluorescence at 533 nm and 539 nm, respectively. The 13PHTC-DMF, 13PHTC-DMSO, and 13PHTC-THF in Examples 11-13 have fluorescence emission peaks at 557 nm, 567 nm, and 552 nm, respectively. Figure 8 c). The above results consistently indicate that both thermal stimulation and polar solvent treatment can induce structural reorganization in this type of eutectic material, thereby significantly altering its luminescence properties.

[0133] Experimental Example 3

[0134] Photoluminescence lifetime: The fluorescence lifetime of the samples was measured using an Edinburgh FLS1000 and a Horiba Fluoro Max+ fluorescence spectrophotometer. For example... Figure 9As shown, the transient fluorescence lifetimes of 26PY / TCNB and 26PY / TCNB-H in Example 1 were 1.88 ns and 80.81 ns, respectively. In contrast, the transient fluorescence lifetime of 26PY in Comparative Example 1 was 1.83 ns, similar to that of 26PY / TCNB, indicating that the 26PY / TCNB system may only be a physical mixture rather than a chemical complex. The lifetime of sample 26PY / TCNB-H was significantly prolonged after heat treatment, indicating a significant change in its luminescence mechanism. The transient fluorescence lifetime of 26PYTC-DMSO in Example 3 was 75.29 ns, similar to that of 26PY / TCNB-H, further supporting the possibility that heat treatment or solvent treatment can induce the formation of a eutectic structure with long-lifetime luminescence properties. Furthermore, from... Figure 10 As can be seen, the transient fluorescence lifetimes of 26PY / DNB and 26PY / DNB-H in Example 4 are 1.70 ns and 2.59 ns, respectively.

[0135] Experiment Example 4

[0136] Photoluminescence quantum yield measurement: Absolute photoluminescence quantum yield (PLQY) was measured using the Quantaurus-QY absolute quantum yield measurement system (model: C11347-11) from Hamamatsu Photonics Trading (China) Co., Ltd. For example... Figure 11 As shown, the fluorescence quantum yield of 26PY in Comparative Example 1 was 8.4%, and that of 26PY / TCNB in ​​Example 1 was 5.6%. These values ​​are close, indicating similar luminescence behavior. In contrast, 26PY / TCNB-H, 26PYTC-DMF, and 26PYTC-DMSO in Examples 1-3 exhibited fluorescence quantum yields of 16.7%, 15.7%, and 17.8%, respectively, with similar values, suggesting high structural similarity among these samples. On the other hand, the quantum yield of 26PY / DNB in ​​Example 4 was comparable to that of 26PY, while the fluorescence quantum yield of its heat-treated sample, 26PY / DNB-H, decreased significantly to 0.2%, indicating a significant fluorescence quenching phenomenon.

[0137] Experimental Example 5

[0138] Electron paramagnetic resonance spectroscopy: Electron spin resonance (ESR) spectra were measured at room temperature using a Bruker A300 spectrometer. Figure 12As shown, the ESR signal intensity of 26PYTC-DMF in Example 2 is higher than that of 26PY / TCNB-H in Example 1. This is mainly due to the dual optimization effect of the solvent environment on the charge transfer state: the highly polar solvent DMF forms a synergistic hydrogen bond network with the amino groups of 26PY and the cyano groups of TCNB through its carbonyl group, which significantly enhances the CT efficiency between the donor and acceptor and promotes the generation of high-concentration free radical cations. At the same time, the dynamic solvation layer effectively stabilizes the free radical state and inhibits electron-hole recombination. In contrast, although 26PY / TCNB-H achieves structural optimization such as increased Δ angle and shortened DA spacing through the dehydration process, it lacks the solvent shielding effect in the completely solid environment, making the free radicals more susceptible to lattice vibrations and exacerbating the nonradiative recombination process, ultimately resulting in a significantly reduced ESR signal.

[0139] Experimental Example 6

[0140] Single-crystal X-ray diffraction analysis: Single-crystal X-ray diffraction data were acquired on a Bruker Apex II CCD diffractometer, operating at 50 kV and 30 mA, using Mo Kα radiation (λ = 0.71073 Å) or Cu Kα radiation (λ = 1.54178 Å) as the light source. The crystal structure was resolved using the SHELXS program based on the direct method, and subsequently refined using Diamond software. Figure 13 As shown, the 26PYTC-DMF eutectic in Example 14 belongs to the monoclinic crystal system with space group P121 / m1. Its asymmetric unit comprises one 26PY molecule, two TCNB molecules, and one DMF molecule. The cell parameters are: a = 6.7534(12) Å, b = 36.699(8) Å, c = 7.3850(15) Å, α = 90.00 ° , β=92.679(17) ° γ=90.00 ° The unit cell volume V = 1828.3(6) Å 3 The 26PYTC-DMF eutectic connects 26PY and DMF molecules via NH···O hydrogen bonds (2.153 Å) and DMF and TCNB molecules via CH···N interactions (2.545 Å and 2.614 Å). In this eutectic, the donor molecules exhibit a V-shaped conformation with a dihedral angle of 114.83°. ° And through π-π stacking (3.796Å and 3.857Å), a regular layered structure is formed between 26PY and TCNB.

[0141] In contrast, the 26PYTC-DMSO eutectic of Example 15 belongs to the triclinic crystal system with space group P-1. Its asymmetric unit comprises one 26PY molecule, 1.5 TCNB molecules, and one DMSO molecule; the unit cell parameters are: a=10.5927(14) Å, b=11.1478(18) Å, c=15.672(2) Å, α=73.433(13) Å. ° , β=79.096(11) ° , γ=67.492(14) ° The unit cell volume V = 1632.0(4) Å 3 The 26PYTC-DMSO eutectic connects 26PY and DMSO via NH···O hydrogen bonds (2.094 Å and 2.147 Å), and DMSO and TCNB via CH···N interactions (2.552 Å and 2.510 Å). Approximately two-thirds of the TCNB-26PY pairs exhibit face-to-face π-π stacking (distances of 3.395 Å and 3.619 Å, respectively), while the remaining molecular pairs are arranged approximately perpendicularly at an angle of 53.39°. Figure 14 ).

[0142] Figure 15 The 26PYDN-DMF eutectic of Example 16 shown belongs to the triclinic crystal system with space group P-1. Its asymmetric unit comprises one 26PY molecule, one DNB molecule, and one DMF molecule. The cell parameters are: a = 11.5446(10) Å, b = 11.8382(8) Å, c = 12.5805(10) Å, α = 90.640(6). ° , β=117.278(9) ° , γ=110.826(7) ° The unit cell volume V = 1396.57(19) Å 3 In the 26PYDN-DMF eutectic, the shorter NH···O hydrogen bonds (2.177 Å and 2.080 Å) reduce the V-angle to 110.61°. ° It connects adjacent 26PY molecules through CH···N interaction (2.479 Å), and together with interlayer π-π stacking (3.433 Å and 3.581 Å), it stabilizes the V-shaped layered structure.

[0143] At the same time, such as Figure 16As shown, the 26PYDN-DMSO eutectic of Example 17 belongs to the triclinic crystal system with space group P-1. Its asymmetric unit includes one 26PY molecule, one DNB molecule, and one DMSO molecule. The cell parameters are: a=11.3441(5) Å, b=11.6747(6) Å, c=12.3066(6) Å, α=64.7120(10) Å. ° , β=72.7600(10) ° , γ=69.814(2) ° The unit cell volume V = 1361.69(11) Å 3 The 26PYDN-DMSO eutectic fixes 26PY and DMSO through NH···O hydrogen bonds (2.012 Å and 2.065 Å). The DMSO molecules further connect the two DNB units through CH···O interactions and are linked to the neighboring 26PY via CH···N interactions, ultimately forming a stable layered superstructure through interlayer π-π stacking (3.366 Å and 3.430 Å).

[0144] Experimental Example 7

[0145] Powder X-ray diffraction analysis: Powder X-ray diffraction (PXRD) analysis was performed using a Bruker D8 ADVANCE diffractometer. The test used Cu-Kα radiation (λ = 1.5418 Å), with tube voltage and tube current set to 40 kV and 40 mA, respectively, and a scanning range (2θ) of 3°–50°. Figure 17 As shown in Figure a, the X-ray diffraction pattern of 26PY / TCNB in ​​Example 1 shows a simple superposition of the diffraction peaks of 26PY and TCNB, with no new diffraction peaks appearing, indicating that it is a physical mixture. In contrast, the diffraction pattern of 26PY / TCNB-H shows a significant change, displaying a completely new diffraction peak shape, indicating that heat treatment induced the formation of a new crystalline phase. Specifically, compared to 26PY in Comparative Example 1, 26PY / TCNB-H at 6.6 ° ±0.2, 9.9 ° ±0.2 and 10.6 ° The diffraction peak intensity decreases at ±0.2, while it decreases at 9.6. ° ±0.2 and 26.9 ° Enhanced diffraction was observed at ±0.2, further confirming the occurrence of a thermally induced phase transition. Similarly, from... Figure 18 As can be seen, the 26PY / DNB-H of Example 4, compared to the original 26PY / DNB, exhibits a performance improvement of 6.6%. ° ±0.2 and 18.1 ° The characteristic diffraction peak at ±0.2 disappears, and at 7.6 ° ±0.2 and 12.4 °The appearance of a new diffraction peak at ±0.2 indicates that a new phase has also formed in this system. Similarly, Figure 19 The results showed that the 35PY / TCNB-H sample from Example 7 and the 13PH / TCNB-H sample from Example 10 also exhibited new diffraction peaks compared to their initial samples, further confirming that heat treatment induced eutectic structure recombination. Furthermore, Figure 17 b and Figure 18 b shows that the experimental diffraction patterns of the eutectic samples (26PYTC-DMF, 26PYTC-DMSO, 26PYDN-DMF and 26PYDN-DMSO) prepared by solvent method are completely consistent with the simulation results of their single crystal structures, verifying that these powder samples all have high phase purity.

[0146] 26PY / TCNB-H contains the following 2θ angle value: 13.83±0.2 ° 18.30±0.2 ° 22.38±0.2 ° 26.94±0.2 ° 29.18±0.2 ° 29.63±0.2 ° The 26PYTC-DMF contains the following 2θ angle value: 4.85 ± 0.2. ° 9.71±0.2 ° 14.24±0.2 ° 15.07±0.2 ° 16.38±0.2 ° 24.56±0.2 ° 26.48±0.2 ° 27.54±0.2 ° 27.87±0.2 ° 28.40±0.2 ° 26PYTC-DMSO contains the following 2θ angle value: 5.89 ± 0.2 ° 9.07±0.2 ° 11.24±0.2 ° 11.73±0.2 ° 13.23±0.2 ° 15.55±0.2 ° 16.34±0.2 ° 20.68±0.2 ° 22.17±0.2 ° 26.27±0.2 ° 27.24±0.2 ° 26PY / DNB-H contains the following 2θ angle value: 7.64 ± 0.2 °9.77±0.2 ° 10.66±0.2 ° 11.85±0.2 ° 12.43±0.2 ° 17.59±0.2 ° 19.08±0.2 ° 20.78±0.2 ° 22.59±0.2 ° 23.11±0.2 ° 25.15±0.2 ° 27.57±0.2 ° 29.24±0.2 ° The 26PYDN-DMF contains the following 2θ angle value: 8.17 ± 0.2. ° 8.85±0.2 ° 9.41±0.2 ° 17.28±0.2 ° 17.80±0.2 ° 20.50±0.2 ° 22.85±0.2 ° 24.11±0.2 ° 26.78±0.2 ° 28.16±0.2 ° 26PYDN-DMSO contains the following 2θ angle value: 8.64 ± 0.2 ° 9.46±0.2 ° 10.61±0.2 ° 12.67±0.2 ° 15.79±0.2 ° 16.89±0.2 ° 17.34±0.2 ° 20.05±0.2 ° 20.93±0.2 ° 25.49±0.2 ° 27.02±0.2 ° 28.39±0.2 ° .

[0147] 35PY / TCNB-H includes the following 2θ angle value: 5.59±0.2 ° 11.35±0.2 ° 13.80±0.2 ° 18.38±0.2 ° 22.42±0.2 ° 29.26±0.2 °29.64±0.2 ° .

[0148] 13PH / TCNB-H contains the following 2θ angle value: 10.03±0.2 ° 12.01±0.2 ° 13.83±0.2 ° 14.34±0.2 ° 18.35±0.2 ° 20.08±0.2 ° 22.33±0.2 ° 25.46±0.2 ° 25.69±0.2 ° 26.74±0.2 ° 27.50±0.2 ° 29.17±0.2 ° 29.62±0.2 ° .

[0149] Experimental Example 8

[0150] Thermal Analysis: Thermal analysis tests included differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC tests were performed using a Mettler Toledo instrument at a rate of 10°C / min under a nitrogen atmosphere. TGA tests were performed using a PerkinElmer TGA4000 instrument at a rate of 10°C / min under nitrogen purging. Figure 20 As shown in Figure a, differential scanning calorimetry (DSC) analysis revealed that the 26PY / TCNB of Example 1 exhibited a broad endothermic peak in the temperature range of 85–135 °C, attributed to the evaporation of water molecules in the material. In contrast, 26PY / TCNB-H did not show a significant endothermic peak in this temperature range, indicating that water molecules were removed after heat treatment, resulting in an anhydrous compound. Similarly, the 26PY / DNB-H of Example 4, compared to 26PY / DNB, also did not show an endothermic peak for water, indicating that it also underwent dehydration during the heating process. Figure 21 The TGA results of a further quantitatively showed that the water content in 26PY / TCNB was 8.15%; Figure 21 b shows that the water content in 26PY / DNB is 4.94%, which corroborates the DSC results and jointly confirms the effectiveness of heat treatment in removing moisture. Furthermore, the DSC spectra of Examples 5 and 6 (26PYTC-DMF, 26PYTC-DMSO) and Examples 8 and 9 (26PYDN-DMF, 26PYDN-DMSO) all show obvious solvent endothermic peaks. Figure 20 (b) indicates that solvent molecules are present in these samples, and their thermal behavior is affected by the solvation structure.

[0151] Experimental Example 9

[0152] Visualized temperature sensing: such as Figure 22 As shown, the 26PY / TCNB material obtained in Example 1 was coated onto the surface of paper and dried to obtain a temperature-sensing test paper. During the temperature rise from 298K to 393K, the test paper's color gradually changed from white to yellow, and its fluorescence emission continuously shifted from blue light at 405nm to yellow light at 545nm, thus achieving intuitive and visual monitoring and early warning of temperature changes.

[0153] Experimental Example 10

[0154] Information anti-counterfeiting: such as Figure 23 As shown, flower patterns were drawn on a black substrate using 26PY / TCNB (left) obtained in Example 1 and 26PY / DNB ink (right) obtained in Example 4, respectively. Initially, the patterns were white. Under 365nm UV light, both the left and right flowers exhibited blue fluorescence. After heating at 393K for 5 minutes, the left flower turned yellow (the fluorescence simultaneously changed to yellow), while the right flower pattern "disappeared" due to the fluorescence quenching effect of 26PY / DNB-H. After recoating with a TL:H2O (20:1) mixed solvent, both the pattern color and fluorescence completely recovered to their initial state. This system maintained excellent stability after 10 cycles, demonstrating superior fatigue resistance.

[0155] Experimental Example 11

[0156] Detection of Nitrobenzene Toxic Substances: Based on the fluorescence quenching effect of the 26PY / DNB system, this study further extends the application of 26PY to the detection of toxic and harmful nitrobenzene compounds. Four nitrobenzene compounds with significant water pollution risks—13DNB, 14DNB, 1Br24DNB, and 35DNBzCl—were selected as detection targets. Figure 24 As shown, 26PY exhibits significant fluorescence quenching after forming a eutectic with the aforementioned nitro compounds. Based on this characteristic, a test strip for detecting nitrobenzene-type poisons was developed. Specifically, 26PY is first coated onto the surface of the test strip, followed by the addition of a DMSO solution containing the aforementioned nitro compounds. Significant fluorescence quenching is observed in the dripped area, thus enabling rapid and visual detection of this type of harmful substance.

[0157] Experimental Example 12

[0158] Polar solvent identification: such as Figure 25As shown, when the 26PY / TCNB test paper obtained in Example 1 and the 26PY / DNB test paper obtained in Example 4 were applied to solvent detection, both test papers rapidly turned yellow after the addition of DMF or DMSO. Specifically, the fluorescence of the 26PY / TCNB test paper changed from blue to yellow, while the 26PY / DNB test paper exhibited fluorescence quenching. This result confirms that this type of material has high sensitivity and high specificity in response to strongly polar solvents.

Claims

1. A eutectic material, characterized in that, The eutectic material includes an electron donor and an electron acceptor; wherein the electron donor is a bidentate benzimidazole compound with a V-shaped conformation, and the electron acceptor is an aromatic compound containing a strong electron-withdrawing group.

2. The eutectic material according to claim 1, characterized in that, The bidentate benzimidazole compounds with a V-shaped conformation include one or more of 2,6-bis(2-benzimidazolyl)pyridine 26PY, 3,5-bis(2-benzimidazolyl)pyridine 35PY, and 1,3-bis(2-benzimidazolyl)benzene 13PH. The aromatic compound containing a strong electron-withdrawing group is one or more of the following: tetracyanobenzene, dinitrobenzene, tetrafluorobenzoquinone, and cyanopyrazine derivatives. The molar ratio of the electron donor to the electron acceptor is 1:(1-2).

3. The eutectic material according to claim 2, characterized in that, The aromatic compounds containing strong electron-withdrawing groups include one or more of 1,2,4,5-tetracyanobenzene (TCNB), 1,5-dinitrobenzene (DNB), 1,3-dinitrobenzene (13DNB), 1,4-dinitrobenzene (14DNB), 1-bromo-2,4-dinitrobenzene (1Br24DNB), and 3,5-dinitrobenzoyl chloride (35DNBzCl).

4. The eutectic material according to claim 1, characterized in that, The eutectic material is formed by dehydration of a hydrated physical mixture containing electron donors and electron acceptors, or by assembly of electron donors and electron acceptors under strongly polar solvent conditions, or by assembly of electron donors, electron acceptors, and solvent molecules through CH···N hydrogen bonds and π-π stacking interactions.

5. The eutectic material according to claim 1, characterized in that, The eutectic material is one or more of the following: 26PY / TCNB-H eutectic, 26PYTC-DMF eutectic, 26PYTC-DMSO eutectic, 26PY / DNB-H eutectic, 26PYDN-DMF eutectic, 26PYDN-DMSO eutectic, 35PY / TCNB-H eutectic, 35PYTC-DMF eutectic, 35PYTC-DMSO eutectic, 13PH / TCNB-H eutectic, 13PHTC-DMF eutectic, 13PHTC-DMSO eutectic, and 13PHTC-THF eutectic. The 26PYTC-DMF eutectic belongs to the monoclinic crystal system with space group P121 / m1. Its asymmetric unit comprises one 26PY molecule, two TCNB molecules, and one DMF molecule. The cell parameters are: a = 6.7534(12) Å, b = 36.699(8) Å, c = 7.3850(15) Å, α = 90.00 ° , β=92.679(17) ° , γ=90.00 ° The unit cell volume V = 1828.3(6) Å 3 ; or X-ray powder diffraction of the 26PYTC-DMF eutectic, including the following 2θ angle values: 4.85±0.2 ° 9.71±0.2 ° 14.24±0.2 ° 15.07±0.2 ° 16.38±0.2 ° 24.56±0.2 ° 26.48±0.2 ° 27.54±0.2 ° 27.87±0.2 ° 28.40±0.2 ° ; The 26PYTC-DMSO eutectic belongs to the triclinic crystal system with space group P-1. Its asymmetric unit comprises one 26PY molecule, 1.5 TCNB molecules, and one DMSO molecule. The cell parameters are: a=10.5927(14) Å, b=11.1478(18) Å, c=15.672(2) Å, α=73.433(13) Å. ° , β=79.096(11) ° , γ=67.492(14) ° The unit cell volume V = 1632.0(4) Å 3 ; or X-ray powder diffraction of the 26PYTC-DMSO eutectic, including the following 2θ angle values: 5.89±0.2 ° 9.07±0.2 ° 11.24±0.2 ° 11.73±0.2 ° 13.23±0.2 ° 15.55±0.2 ° 16.34±0.2 ° 20.68±0.2 ° 22.17±0.2 ° 26.27±0.2 ° 27.24±0.2 ° ; The 26PYDN-DMF eutectic belongs to the triclinic crystal system with space group P-1. Its asymmetric unit comprises one 26PY molecule, one DNB molecule, and one DMF molecule. The cell parameters are: a=11.5446(10)Å, b=11.8382(8)Å, c=12.5805(10)Å, α=90.640(6). ° , β=117.278(9) ° , γ=110.826(7) ° The unit cell volume V = 1396.57(19) Å 3 Or X-ray powder diffraction of the 26PYDN-DMF eutectic, including the following 2θ angle values: 8.17±0.2 ° 8.85±0.2 ° 9.41±0.2 ° 17.28±0.2 ° 17.80±0.2 ° 20.50±0.2 ° 22.85±0.2 ° 24.11±0.2 ° 26.78±0.2 ° 28.16±0.2 ° ; The 26PYDN-DMSO eutectic belongs to the triclinic crystal system with space group P-1. Its asymmetric unit comprises one 26PY molecule, one DNB molecule, and one DMSO molecule. The cell parameters are: a=11.3441(5)Å, b=11.6747(6)Å, c=12.3066(6)Å, α=64.7120(10)Å. ° , β=72.7600(10) ° , γ=69.814(2) ° The unit cell volume V = 1361.69(11) Å 3 ; or X-ray powder diffraction of the 26PYDN-DMSO eutectic, including the following 2θ angle values: 8.64±0.2 ° 9.46±0.2 ° 10.61±0.2 ° 12.67±0.2 ° 15.79±0.2 ° 16.89±0.2 ° 17.34±0.2 ° 20.05±0.2 ° 20.93±0.2 ° 25.49±0.2 ° 27.02±0.2 ° 28.39±0.2 ° ; The X-ray powder diffraction of the 26PY / TCNB-H eutectic yielded the following 2θ angle value: 13.83 ± 0.

2. ° 18.30±0.2 ° 22.38±0.2 ° 26.94±0.2 ° 29.18±0.2 ° 29.63±0.2 ° ; The X-ray powder diffraction of the 26PY / DNB-H eutectic yielded the following 2θ angle value: 7.64 ± 0.

2. ° 9.77±0.2 ° 10.66±0.2 ° 11.85±0.2 ° 12.43±0.2 ° 17.59±0.2 ° 19.08±0.2 ° 20.78±0.2 ° 22.59±0.2 ° 23.11±0.2 ° 25.15±0.2°, 27.57±0.2° ° 29.24±0.2 ° ; The X-ray powder diffraction of the 35PY / TCNB-H eutectic yielded the following 2θ angle value: 5.59 ± 0.

2. ° 11.35±0.2 ° 13.80±0.2 ° 18.38±0.2 ° 22.42±0.2 ° 29.26±0.2 ° 29.64±0.2 ° ; The X-ray powder diffraction of the 13PH / TCNB-H eutectic yielded the following 2θ angle value: 10.03 ± 0.

2. ° 12.01±0.2 ° 13.83±0.2 ° 14.34±0.2 ° 18.35±0.2 ° 20.08±0.2 ° 22.33±0.2 ° 25.46±0.2 ° 25.69±0.2 ° 26.74±0.2 ° 27.50±0.2 ° 29.17±0.2 ° 29.62±0.2 ° .

6. A method for preparing the eutectic material according to any one of claims 1-5, comprising: Method 1: Grind the electron donor and electron acceptor together in a solvent to obtain a hydrated physical mixture, and then perform heat treatment or solvent displacement to obtain a eutectic material; Method 2: Grind the electron donor and electron acceptor together in a polar solvent to obtain a eutectic material; Method 3: Mix the electron donor, electron acceptor and polar solvent, stir, and let stand at room temperature to evaporate the solvent to obtain a eutectic material.

7. The preparation method according to claim 6, characterized in that, In Method 1, the solvent used for co-grinding is one or more of toluene, ethanol, acetonitrile, acetone, ethyl acetate, dichloromethane, and chloroform; the solvent used for solvent replacement is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropionamide, dimethyl sulfoxide, and tetrahydrofuran; and the heat treatment temperature is 383K to 423K. In Method 2, the polar solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropionamide, dimethyl sulfoxide, and tetrahydrofuran. In method 3, the polar solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropionamide, dimethyl sulfoxide, and water; the stirring is carried out at 25~80℃ for 0.5-1 hour.

8. A hydrated physical mixture, characterized in that, The hydrated physical mixture includes the electron donor and electron acceptor as described in claim 1.

9. A method for preparing a hydrated physical mixture, comprising: The electron donor and electron acceptor described in claim 1 are obtained by co-grinding in a solvent.

10. The application of any one of the eutectic materials of claims 1-5 and the hydrated physical mixture of claim 8 in the fields of anti-counterfeiting labels, temperature sensors, solvent identification, and detection of nitrobenzene-based toxic compounds.

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