A eutectic material based on organic macrocyclic aromatic hydrocarbons and its preparation method and application

Abstract

The present invention is applicable to the field of eutectic material technology and provides a eutectic material based on organic macrocyclic aromatic hydrocarbons, its preparation method, and application. The eutectic material is a metastable material EtLP6-F4TCNQα, which uses tilting tower aromatic hydrocarbons as a host and electron-deficient 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanodimethyl-p-benzoquinone as a guest. The tilting tower aromatic hydrocarbons and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanodimethyl-p-benzoquinone are mechanically ground. The present invention directly mixes two or more organic molecules and induces them to form a eutectic structure through a simple mechanical grinding operation. The eutectic material with a metastable structure is prepared with high efficiency, low cost, and easy large-scale production. The metastable structure shows higher sensitivity and faster response speed in gas-induced color change detection.

Description

Technical Field

[0001] The present invention belongs to the technical field of eutectic materials, and in particular relates to a eutectic material based on organic macrocyclic aromatic hydrocarbons, and a preparation method and application thereof. Background Art

[0002] Fatty aldehydes have a high degree of similarity in structure, which is mainly reflected in the arrangement of their functional groups and carbon chains. Fatty aldehyde compounds all contain a common functional group - aldehyde group (-CHO), and the aldehyde group is always located at the end of the carbon chain, starting from acetaldehyde, and with the increase of carbon chain length, it is followed by propionaldehyde (C3H6O), butyraldehyde (C4H8O), valeraldehyde (C5H 10 O) and hexanal (C6H 12 O), their carbon chains are all straight-chain structures, with carbon atoms connected by single bonds, forming a linear molecular skeleton. This structural similarity not only gives them many common chemical properties, such as their susceptibility to nucleophilic addition and oxidation reactions, but also makes them very similar in physical properties. For example, most of them are colorless liquids at room temperature and have similar pungent odors.

[0003] However, it is precisely this high degree of structural similarity that makes visual detection and differentiation of these fatty aldehydes quite difficult. First, these compounds are typically colorless liquids at room temperature, with little difference in appearance, making them difficult to distinguish visually by color or morphology. Second, low-molecular-weight fatty aldehydes (such as acetaldehyde and propionaldehyde) are highly volatile and have very similar, irritating odors, making their identification by smell unreliable. Furthermore, due to their similar chemical properties, many conventional chemical detection methods (such as colorimetric reactions with certain reagents) are often unable to effectively distinguish them, as these reactions generally rely on the presence of an aldehyde group, which is the same in all fatty aldehydes. Finally, when the concentrations of these compounds are low, conventional detection methods may not provide sufficient sensitivity, further increasing the difficulty of detection.

[0004] The organic eutectic strategy has significant advantages in the field of gasochromic detection and has become a research hotspot in materials science and sensor technology. Organic eutectics are crystalline materials formed by two or more organic molecules through non-covalent interactions (such as hydrogen bonding and π-π stacking). Their core advantage lies in the precise control of material properties through molecular design. In gasochromic detection, this strategy can design highly sensitive and highly selective detection materials for specific gas molecules. For example, by introducing specific functional groups, the interaction between the material and the target gas molecules can be enhanced, improving detection performance. In addition, organic eutectics have rapid response and reversibility. Gas molecules can quickly diffuse into the interior of the crystal and induce color changes. This change is usually reversible, making the material reusable. The obvious color change is easy to observe with the naked eye or simple optical equipment, making it suitable for real-time, on-site detection.

[0005] Although organic eutectic materials have shown many advantages in the field of gasochromism, they still have some significant limitations and disadvantages in practical applications. First, the preparation process of organic eutectic materials is usually complicated, requiring precise control of reaction conditions (such as solvent selection, temperature, concentration, etc.), and is often time-consuming and costly. For example, traditional solution methods or vapor diffusion methods require multiple crystallization and purification steps, which not only increases the difficulty of preparation but also limits its feasibility of large-scale production. Second, organic eutectic materials have poor structural stability and are easily affected by environmental factors (such as humidity and temperature), resulting in performance degradation or failure. In addition, although organic eutectic materials have high sensitivity and selectivity for certain gases, their response range is still relatively limited, making it difficult to meet the detection needs of multiple gases simultaneously. The reusability and long-term stability of organic eutectic materials are also problematic, and performance degradation or structural damage may occur after repeated use. Summary of the Invention

[0006] The purpose of the embodiments of the present invention is to provide a eutectic material based on organic macrocyclic aromatic hydrocarbons, aiming to solve the problems raised in the above background technology.

[0007] The embodiment of the present invention is achieved as follows: a eutectic material based on organic macrocyclic aromatic hydrocarbons, wherein the eutectic material is a metastable material EtLP6-F4TCNQα, which has tilted tower aromatic hydrocarbons as the main body and electron-deficient 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanodimethyl-p-benzoquinone as the guest.

[0008] Another object of an embodiment of the present invention is to provide a method for preparing a eutectic material based on organic macrocyclic aromatic hydrocarbons, comprising the following steps: mechanically grinding tantalum aromatic hydrocarbon (EtLP6) and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanodimethyl-p-benzoquinone (F4TCNQ).

[0009] Preferably, the molar ratio of the tilted aromatic hydrocarbon to 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanodimethyl-p-benzoquinone is 1:2.5-3.5.

[0010] Preferably, the molar ratio of the tilted aromatic hydrocarbon to 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanodimethyl-p-benzoquinone is 1:3.

[0011] Preferably, the mechanical grinding time is 25-35 min.

[0012] Another object of an embodiment of the present invention is to provide an application of a eutectic material based on organic macrocyclic aromatic hydrocarbons in the detection of fatty aldehydes.

[0013] Preferably, the organic macrocyclic aromatic hydrocarbon-based eutectic material is placed in a container containing a fatty aldehyde solution, and a gas-induced color change test is performed on fatty aldehydes of different chain lengths. The color deepens in short-chain acetaldehyde, propionaldehyde, and butyraldehyde, and becomes lighter in long-chain valeraldehyde and hexanal.

[0014] The embodiments of the present invention directly mix two or more organic molecules and induce them to form a eutectic structure through a simple mechanical grinding operation, without the need for complex solvent treatment or a long crystallization process. This method is efficient, low-cost, and easy to scale up. At the same time, it can prepare a eutectic material with a metastable structure. This metastable structure exhibits higher sensitivity and faster response speed in gas-induced color change detection. In addition, the mechanical grinding method can also achieve precise control of material properties by adjusting the grinding conditions (such as time and force), thereby broadening its application range. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of a solid-gas adsorption device provided in an embodiment of the present invention;

[0016] Figure 2 This is the H NMR spectrum of EtLP6 after adsorption of acetaldehyde provided by an embodiment of the present invention;

[0017] Figure 3 This is the H NMR spectrum of EtLP6 after adsorption of propionaldehyde provided by an embodiment of the present invention;

[0018] Figure 4 This is the H NMR spectrum of EtLP6 after adsorption of butyraldehyde provided by an embodiment of the present invention;

[0019] Figure 5 This is the H NMR spectrum of EtLP6 after adsorption of valeraldehyde provided by an embodiment of the present invention;

[0020] Figure 6 This is the H NMR spectrum of EtLP6 after adsorption of hexanal provided in an embodiment of the present invention;

[0021] Figure 7Thermogravimetric and differential thermal scanning curves of EtLP6 after exposure to fatty aldehyde vapor provided in an embodiment of the present invention (a is the thermogravimetric and differential thermal scanning curve of EtLP6 after adsorbing acetaldehyde, b is the thermogravimetric and differential thermal scanning curve of EtLP6 after adsorbing propionaldehyde);

[0022] Figure 8 Thermogravimetric and differential thermal scanning curves of EtLP6 after exposure to fatty aldehyde vapor provided in an embodiment of the present invention (a is the thermogravimetric and differential thermal scanning curve of EtLP6 after adsorption of butyraldehyde, b is the thermogravimetric and differential thermal scanning curve of EtLP6 after adsorption of valeraldehyde, and c is the thermogravimetric and differential thermal scanning curve of EtLP6 after adsorption of hexanal);

[0023] Figure 9 Top view, side view, and two-dimensional stacking diagram of EtLP6 and fatty aldehyde crystals provided in an embodiment of the present invention (a is a top view, side view, and two-dimensional stacking diagram of EtLP6 and acetaldehyde crystals; b is a top view, side view, and two-dimensional stacking diagram of EtLP6 and propionaldehyde crystals; c is a top view, side view, and two-dimensional stacking diagram of EtLP6 and butyraldehyde crystals; d is a top view, side view, and two-dimensional stacking diagram of EtLP6 and valeraldehyde crystals; e is a top view, side view, and two-dimensional stacking diagram of EtLP6 and hexanal crystals);

[0024] Figure 10 PXRD (a) and single crystal simulated XRD (b) of EtLP6 after adsorption of fatty aldehydes provided by an embodiment of the present invention;

[0025] Figure 11 Schematic diagram of the preparation of EtLP6-F4TCNQα provided in an embodiment of the present invention;

[0026] Figure 12 X-ray diffraction spectra of EtLP6, F4TCNQ and EtLP6-F4TCNQα provided in the embodiments of the present invention;

[0027] Figure 13 Fourier transform infrared spectra of EtLP6, F4TCNQ and EtLP6-F4TCNQα provided in the embodiments of the present invention;

[0028] Figure 14 UV-visible diffuse reflectance spectra of EtLP6, F4TCNQ, and EtLP6-F4TCNQα provided in the embodiments of the present invention;

[0029] Figure 15 The gas-induced color change behavior of EtLP6-F4TCNQα in fatty aldehydes provided in the embodiments of the present invention;

[0030] Figure 16UV-visible diffuse reflectance spectra of EtLP6-F4TCNQα after exposure to acetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde, and hexanal vapors provided in an embodiment of the present invention;

[0031] Figure 17 Interaction force analysis between EtLP6 and fatty aldehydes provided in an embodiment of the present invention (a is the interaction force analysis between EtLP6 and propionaldehyde; b is the interaction force analysis between EtLP6 and butyraldehyde; c is the interaction force analysis between EtLP6 and valeraldehyde; d is the interaction force analysis between EtLP6 and hexanal);

[0032] Figure 18 Schematic diagram of the eutectic of EtLP6 and F4TCNQ provided in an embodiment of the present invention (a is the single crystal structure of EtLP6 and F4TCNQ; b is the interaction force analysis of EtLP6 and F4TCNQ; c is the stacking mode of the EtLP6+F4TCNQ eutectic in the ab and bc planes, respectively);

[0033] Figure 19 The simulated XRD spectrum of the EtLP6+F4TCNQ cocrystal provided in an embodiment of the present invention (a) and the XRD spectrum of EtLP6-F4TCNQα after exposure to various fatty aldehyde vapors (b);

[0034] Figure 20 This is the H NMR spectrum of EtLP6-F4TCNQα after exposure to acetaldehyde provided in an embodiment of the present invention;

[0035] Figure 21 This is the H NMR spectrum of EtLP6-F4TCNQα after exposure to propionaldehyde provided in an embodiment of the present invention;

[0036] Figure 22 This is the H NMR spectrum of EtLP6-F4TCNQα after exposure to butyraldehyde provided in an embodiment of the present invention;

[0037] Figure 23 This is the H NMR spectrum of EtLP6-F4TCNQα after exposure to valeraldehyde provided in an embodiment of the present invention;

[0038] Figure 24 This is the H NMR spectrum of EtLP6-F4TCNQα after exposure to hexanal provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0040] The adsorption behavior of EtLP6 on fatty aldehydes was analyzed. Only when EtLP6 has adsorption behavior on fatty aldehydes can it be used in gaseous color change. In the embodiment of the present invention, the adsorption behavior of EtLP6 on fatty aldehydes was studied by solid-gas adsorption method. The solid-gas adsorption device is as follows: Figure 1 As shown, 3 mg of EtLP6 was spread evenly on the bottom of a 2 mL open vial and placed in a 20 mL closed vial containing 20 μL of aliphatic aldehyde solution. The specific adsorption amount was determined by H NMR spectroscopy and thermogravimetry.

[0041] The H NMR spectrum of EtLP6 after exposure to fatty aldehyde vapor is shown in Figure 2. Figures 2 to 6 As shown, it can be judged from the NMR integration that EtLP6 can adsorb 0.5 equivalents of acetaldehyde, 1 equivalent of propionaldehyde, butyraldehyde, valeraldehyde and hexanal respectively;

[0042] Thermogravimetric and differential thermal scanning curves are as follows Figures 7 and 8 As shown, it can be seen that before melting, EtLP6 has an endothermic behavior of releasing the solvent;

[0043] In addition, EtLP6 grew corresponding crystals in different fatty aldehyde solutions, such as Figure 9 As shown, in the crystals of EtLP6 and acetaldehyde, EtLP6 presents a bowl-shaped structure, one molecule of acetaldehyde exists in the cavity of EtLP6, and the crystal presents a two-dimensional stacking pattern on the ac plane; the crystals of EtLP6 and propionaldehyde are similar to those of acetaldehyde, and the fatty aldehyde molecules all exist in the cavity of EtLP6, but the difference is that the complexation ratio of EtLP6 to propionaldehyde is 1:2, and the stacking on the bc plane presents a two-dimensional pattern similar to that of acetaldehyde; while the complexation pattern of EtLP6 with butyraldehyde, valeraldehyde and hexanal is similar, and it can be seen from the top view and side view that the aldehyde is sandwiched between two EtLP6s, while it can be seen from the stacking diagram that the aldehyde molecule is fixed in the cavity assembled by EtLP6;

[0044] like Figure 10 As shown in Figure 3, the corresponding simulated XRD patterns were derived from the single crystal XRD patterns of EtLP6 and aliphatic aldehydes, which matched well with the XRD patterns measured by actual solid-gas adsorption.

[0045] The EtLP6 used in the embodiment of the present invention was prepared with reference to the content in the prior art "Jia-Rui Wu and Ying-Wei Yang, High-Performance n-Hexane Purification by Nonporous Adaptive Crystals of LeaningPillar[6]arene, CCS Chem. 2021, 3, 836–843", and the specific process is not repeated here;

[0046] The CAS number of F4TCNQ is 29261-33-4; it was purchased from Anaiji Chemical; product number: D0504030010.

[0047] The specific implementation of the present invention is described in detail below with reference to specific embodiments.

[0048] Example 1: A eutectic material based on organic macrocyclic aromatic hydrocarbons, the preparation process of which is as follows Figure 11 As shown in Figure 2, the specific process is as follows: 89.32 mg (0.1 mmol) of EtLP6 and 80.16 mg (0.3 mmol) of F4TCNQ were taken and ground in an agate mortar for 30 min to obtain metastable EtLP6-F4TCNQα.

[0049] Characterization and morphological analysis of EtLP6-F4TCNQα:

[0050] The X-ray diffraction spectra of EtLP6, F4TCNQ and EtLP6-F4TCNQα were tested and the results were as follows: Figure 12 As shown, it can be clearly seen that the spectrum of EtLP6-F4TCNQα contains the characteristic peaks of EtLP6 and F4TCNQ, indicating the successful preparation of the composite material;

[0051] Fourier transform infrared spectroscopy Figure 13 As shown in the figure, compared with F4TCNQ, the stretching vibration peak of C≡N in the spectrum of EtLP6-F4TCNQα shifts from 2227 cm -1 Blue shift to 2222 cm -1 The stretching vibration peaks of CF also shifted from 1344, 974, and 802 cm -1 Shifts to 1338, 970, and 794 cm -1 The bending vibration peak and symmetric stretching vibration peak of CF also blue-shifted, which is mainly due to the charge transfer interaction after the combination of F4TCNQ and EtLP6, which causes the CF bond to be extended and weakened;

[0052] UV-visible diffuse reflectance spectroscopy Figure 14 As shown, EtLP6 has no absorption in the visible region, the visible light absorption range of F4TCNQ is around 550 nm, and a charge transfer (CT) absorption band as high as 1400 nm appears in the spectrum of EtLP6-F4TCNQα, which again indicates the existence of charge transfer interaction between the host and the guest, proving the successful preparation of the metastable state.

[0053] Analysis of the gasochromic behavior of EtLP6-F4TCNQα in fatty aldehydes:

[0054] Use Figure 1 In the device shown, 3 mg of EtLP6-F4TCNQα was spread evenly on the bottom of a 2 mL vial without a cap, which was then placed in a 20 mL vial with a cap containing 20 µL of aliphatic aldehyde solution to perform gaseous colorimetric detection of aliphatic aldehydes of different chain lengths.

[0055] like Figure 15 As shown, the color of EtLP6-F4TCNQα deepens in the presence of short-chain fatty aldehydes acetaldehyde, propionaldehyde, and butyraldehyde, and becomes lighter in the presence of long-chain valeraldehyde and hexanal;

[0056] UV-vis spectrum such as Figure 16 As shown, the test results are consistent with the color change. Compared with EtLP6-F4TCNQα, after being exposed to short-chain fatty aldehydes, its absorption intensity of visible light is significantly enhanced, while after being exposed to long-chain fatty aldehydes, the original CT absorption band of the metastable state disappears, corresponding to the color change.

[0057] In order to explore the mechanism of this color change behavior, the co-crystal of EtLP6 and F4TCNQ was grown in dichloromethane and methylcyclohexane, and the interaction forces in the crystal were analyzed: first, the interaction force between EtLP6 and fatty aldehydes was analyzed, such as Figure 17 As shown in Figure 3, propanal is mainly fixed in the cavity of EtLP6 through CH···π interactions, while butyraldehyde, valeraldehyde and hexanal are complexed with EtLP6 not only through CH···π interactions but also through CH···O interactions; for the cocrystal of EtLP6 and F4TCNQ, as shown in Figure 3, Figure 18 As shown, from Figure 18 As can be seen in (a), the complexation ratio of EtLP6 and F4TCNQ is 1:2. Figure 18 (b) shows that one of the F4TCNQs is complexed with EtLP6 through CH···N interaction, while the other F4TCNQ is complexed with EtLP6 not only through CH···N interaction, but also the F atom on the F4TCNQ provides CH···F interaction between the two. Figure 18 (c) is the topology of EtLP6+F4TCNQ eutectic in the ab and bc planes, both showing a two-dimensional planar structure with host and guest interlaced; the XRD spectra of metastable EtLP6-F4TCNQα after exposure to various fatty aldehyde vapors are shown in Figure 2. Figure 19 As shown in the figure, it can be seen that the XRD spectrum of EtLP6-F4TCNQα after exposure to acetaldehyde, propionaldehyde and butyraldehyde is similar to the spectrum of the single crystal simulated EtLP6+F4TCNQ cocrystal; the nuclear magnetic H spectrum is shown in Figures 20 to 24As shown, the metastable state did not adsorb acetaldehyde, propionaldehyde and butyraldehyde, so the metastable state was promoted to a eutectic structure in the vapors of these three fatty aldehydes. Compared with fatty aldehydes, F4TCNQ has a stronger binding ability with EtLP6, so fatty aldehydes provide the driving force for EtLP6 and F4TCNQ to further bind tightly. However, after exposure to valeraldehyde and hexanal vapors, the XRD spectrum of the metastable state matched well with the XRD of EtLP6 and valeraldehyde and hexanal, and the color of the metastable state became lighter. The nuclear magnetic hydrogen spectrum also showed that the metastable state adsorbed one equivalent of valeraldehyde or hexanal, indicating that valeraldehyde and hexanal successfully destroyed the charge transfer interaction between EtLP6 and F4TCNQ by binding to EtLP6.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A eutectic material based on organic macrocyclic aromatic hydrocarbons, characterized in that: The eutectic material is a metastable material EtLP6-F4TCNQα, which uses the tilted aromatic hydrocarbon EtLP6 as a host and electron-deficient 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanodimethyl-p-benzoquinone as a guest, and has a powder X-ray diffraction pattern as shown in FIG12 .

2. A method for preparing a eutectic material based on organic macrocyclic aromatic hydrocarbons according to claim 1, characterized in that: The method comprises the following steps: mechanically grinding tilted tower aromatic hydrocarbon EtLP6 and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanodimethyl-p-benzoquinone.

3. The method for preparing a eutectic material based on organic macrocyclic aromatic hydrocarbons according to claim 2, characterized in that: The molar ratio of the tilted column aromatic hydrocarbon EtLP6 to 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanodimethyl-p-benzoquinone is 1:2.5-3.

5.

4. The method for preparing a eutectic material based on organic macrocyclic aromatic hydrocarbons according to claim 3, characterized in that: The molar ratio of the tilted column aromatic hydrocarbon EtLP6 to 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanodimethyl-p-benzoquinone is 1:

3.

5. The method for preparing a eutectic material based on organic macrocyclic aromatic hydrocarbons according to claim 2, characterized in that: The mechanical grinding time is 25-35 min.

6. Use of the organic macrocyclic aromatic hydrocarbon-based eutectic material according to claim 1 in the detection of fatty aldehydes, characterized in that: The fatty aldehyde is one of acetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde and hexanal.

7. The use according to claim 6, characterized in that The organic macrocyclic aromatic hydrocarbon-based eutectic material is placed in a container containing a fatty aldehyde solution, and a gas-induced color change test is performed on fatty aldehydes with different chain lengths. The color deepens in short-chain acetaldehyde, propionaldehyde, and butyraldehyde, and becomes lighter in long-chain valeraldehyde and hexanal.

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