A flexible crystal of a 4-benzyloxyphenyl-substituted barbituric acid derivative, its preparation method and application

Abstract

This invention provides a 4-benzyloxyphenyl-substituted barbituric acid derivative and its preparation method, a flexible crystal of the 4-benzyloxyphenyl-substituted barbituric acid derivative and its preparation method and application, belonging to the field of organic optoelectronic materials technology. Under mechanical stimulation, the flexible crystal of the 4-benzyloxyphenyl-substituted barbituric acid derivative bends into a semi-ring without any breakage. After the mechanical force is removed, the crystal does not break or fracture and quickly returns to its original straight shape. This reversible bending-relaxation process can be repeated multiple times, highlighting its good elasticity and indicating that the flexible crystal of the 4-benzyloxyphenyl-substituted barbituric acid derivative possesses excellent mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of organic optoelectronic materials technology, and in particular to a flexible crystal of a 4-benzyloxybenzene-substituted barbituric acid derivative, its preparation method, and its application. Background Technology

[0002] Organic crystals possess inherently brittle / hard properties, limiting their potential applications in flexible fields. Fortunately, Ghosh and Reddy reported the first elastic crystal in 2012. They prepared needle-like elastic crystals by dissolving caffeine (CAF) and 4-chloro-3-nitrobenzoic acid (CNB) in methanol using a slow evaporation method. When the crystal was held at both ends with tweezers and pressure was applied to its middle section using a needle (three-point test), the crystal could bend into a semi-circle and immediately return to its original straight position after the pressure was removed, exhibiting remarkable elastic bending behavior. This process could be repeated many times until the crystal broke beyond a threshold limit. Single-crystal data showed that CAF molecules, through O... H…N and C H…O hydrogen bonds form dimers with CNB molecules, and adjacent dimers are connected by weak C…O bonds. Hydrogen bonds (H…O) further connect the crystals, forming a one-dimensional network structure. These network structures further develop into two-dimensional and even three-dimensional network structures through π…π interactions. These interactions effectively buffer external mechanical forces, preventing crystal breakage under stress.

[0003] Although elastic crystals were obtained through the eutectic method, the design strategy for elastic crystals remains elusive. Simultaneously controlling flexibility and crystallinity in organic crystals is a significant challenge. Researching a flexible crystal of a 4-benzyloxybenzene-substituted barbituric acid derivative, its preparation method, and its applications is of great importance. Summary of the Invention

[0004] The purpose of this invention is to provide a flexible crystal of 4-benzyloxybenzene-substituted barbituric acid derivative, its preparation method and application, so as to solve the problem that organic crystals in the prior art cannot simultaneously adjust flexibility and crystallinity.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a 4-benzyloxyphenyl-substituted barbituric acid derivative having a structure as shown in formula (I):

[0007] (I).

[0008] The present invention provides a method for preparing the above-mentioned 4-benzyloxybenzaldehyde-substituted barbituric acid derivative, comprising the following steps: mixing 1,3-dimethylbarbituric acid and 4-benzyloxybenzaldehyde in ethanol and refluxing to obtain the 4-benzyloxybenzaldehyde-substituted barbituric acid derivative.

[0009] Preferably, the molar ratio of 1,3-dimethylbarbituric acid to 4-benzyloxybenzaldehyde is 1:1.

[0010] Preferably, the molar volume ratio of 4-benzyloxybenzaldehyde to ethanol is 5~8 mmol: 40~60 mL.

[0011] Preferably, the reflux reaction time is 4 to 8 hours.

[0012] The present invention also provides a flexible crystal of a 4-benzyloxyphenyl-substituted barbituric acid derivative, wherein the flexible crystal of the 4-benzyloxyphenyl-substituted barbituric acid derivative is prepared from a 4-benzyloxyphenyl-substituted barbituric acid derivative with the structure shown in formula (I).

[0013] The present invention also provides a method for preparing the above-mentioned flexible crystal of 4-benzyloxyphenyl-substituted barbituric acid derivative, comprising the following steps: dissolving the 4-benzyloxyphenyl-substituted barbituric acid derivative in a mixed solvent and allowing it to stand to obtain the flexible crystal of 4-benzyloxyphenyl-substituted barbituric acid derivative.

[0014] Preferably, the mixed solvent is composed of dichloromethane and ethanol, wherein the volume ratio of dichloromethane to ethanol is 1:2~6; and the mass-volume ratio of the 4-benzyloxybenzene-substituted barbituric acid derivative to the mixed solvent is 20~40 mg:10 mL.

[0015] Preferably, the settling temperature is room temperature and the time is 8-12 days.

[0016] The present invention also provides the application of the above-described 4-benzyloxybenzene-substituted barbituric acid derivative flexible crystal in the preparation of organic optical fiber or waveguide materials.

[0017] The beneficial effects of this invention are:

[0018] The flexible crystals of 4-benzyloxyphenyl-substituted barbituric acid derivatives prepared in this invention bend into a semi-ring shape under mechanical stimulation without any breakage. After the mechanical force is removed, the crystals do not break or fracture and quickly return to their original straight shape. This reversible bending-relaxation process can be repeated multiple times, highlighting its good elasticity and indicating that the flexible crystals of 4-benzyloxyphenyl-substituted barbituric acid derivatives possess excellent mechanical properties. Attached Figure Description

[0019] Figure 1The hydrogen spectrum of BBDPT obtained in Example 1;

[0020] Figure 2 The carbon spectrum of BBDPT obtained in Example 1;

[0021] Figure 3 The UV-Vis absorption and fluorescence emission spectra of BBDPT from Example 1 and the flexible crystals of 4-benzyloxybenzene-substituted barbituric acid derivatives prepared in Example 2 are shown.

[0022] Figure 4 The image shows the elastic bending test result of the flexible crystal of the 4-benzyloxybenzene-substituted barbituric acid derivative prepared in Example 2.

[0023] Figure 5 The molecular packing and crystal morphology of the flexible crystal of the 4-benzyloxybenzene-substituted barbituric acid derivative prepared in Example 2 are shown, where a is the (100) plane, b is the (001) plane, d is the (010) plane, c is the crystal morphology, and C, H, N, and O correspond to blue, gray, purple, and red atoms, respectively. CH π and CH O corresponds to the green and orange dashed lines respectively;

[0024] Figure 6 The images show the Hirshfeld surface map, two-dimensional fingerprint, and proportion of each interaction in the crystal relative to all interactions of the flexible crystal of the 4-benzyloxybenzene-substituted barbituric acid derivative prepared in Example 2. Here, a is the Hirshfeld surface map, b is the two-dimensional fingerprint, and c is the proportion of each interaction in the crystal relative to all interactions. Detailed Implementation

[0025] This invention provides a 4-benzyloxyphenyl-substituted barbituric acid derivative having a structure as shown in formula (I):

[0026] (I).

[0027] The present invention provides a method for preparing the above-mentioned 4-benzyloxybenzaldehyde-substituted barbituric acid derivative, comprising the following steps: mixing 1,3-dimethylbarbituric acid and 4-benzyloxybenzaldehyde in ethanol and refluxing to obtain the 4-benzyloxybenzaldehyde-substituted barbituric acid derivative.

[0028] In this invention, the synthetic route for the 4-benzyloxyphenyl-substituted barbituric acid derivative is shown below:

[0029]

[0030] In this invention, the molar ratio of 1,3-dimethylbarbituric acid and 4-benzyloxybenzaldehyde is 1:1.

[0031] In this invention, the molar volume ratio of 4-benzyloxybenzaldehyde to ethanol is 5~8 mmol: 40~60 mL, preferably 6~7 mmol: 45~55 mL, and more preferably 6.4 mmol: 50 mL.

[0032] In this invention, the reflux reaction time is 4-8 hours, preferably 5-7 hours, and more preferably 6 hours.

[0033] In this invention, the product of the reflux reaction is filtered, precipitated, and recrystallized in ethanol to obtain a 4-benzyloxybenzene-substituted barbituric acid derivative.

[0034] The present invention also provides a flexible crystal of a 4-benzyloxyphenyl-substituted barbituric acid derivative, wherein the flexible crystal of the 4-benzyloxyphenyl-substituted barbituric acid derivative is prepared from a 4-benzyloxyphenyl-substituted barbituric acid derivative with the structure shown in formula (I).

[0035] The present invention also provides a method for preparing the above-mentioned flexible crystal of 4-benzyloxyphenyl-substituted barbituric acid derivative, comprising the following steps: dissolving the 4-benzyloxyphenyl-substituted barbituric acid derivative in a mixed solvent and allowing it to stand to obtain the flexible crystal of 4-benzyloxyphenyl-substituted barbituric acid derivative.

[0036] In this invention, the mixed solvent is composed of dichloromethane and ethanol, wherein the volume ratio of dichloromethane to ethanol is 1:2 to 6, preferably 1:3 to 5, and more preferably 1:4; the mass-volume ratio of the 4-benzyloxybenzene-substituted barbituric acid derivative to the mixed solvent is 20 to 40 mg:10 mL, preferably 30 mg:10 mL.

[0037] In this invention, the settling temperature is room temperature, preferably 20~30℃, more preferably 25℃, and the settling time is 8~12 days, preferably 9~11 days, more preferably 10 days.

[0038] The present invention also provides an application of the above-described 4-benzyloxybenzene-substituted barbituric acid derivative flexible crystal in the preparation of organic optical fiber or waveguide materials.

[0039] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0040] Example 1

[0041] 1,3-Dimethylbarbituric acid (1.00 g, 6.4 mmol) and 4-benzyloxybenzaldehyde (1.36 g, 6.4 mmol) were mixed in anhydrous ethanol (50 mL) and refluxed at room temperature for 6 h. The reaction product was filtered to precipitate and recrystallized in ethanol to give 1.84 g of 4-benzyloxybenzene-substituted barbituric acid derivative (denoted as BBDPT) as shown in formula (Ⅰ), which was a yellow solid with a yield of 82%. 1 H NMR (600 MHz, DMSO-) d 6 ) δ 8.34-8.32 (m, 3H), 7.48 (d, J = 7.2 Hz, 2H), 7.42 (t, J = 7.5 Hz, 2H), 7.36 (t, J = 7.3 Hz, 1H), 7.15 (d, J = 8.9 Hz, 2H), 5.25 (s, 2H), 3.23 (s, 3H), 3.21 (s, 3H). 13 C NMR (151 MHz, CDCl3) δ 163.46,163.12, 161.00, 158.83, 151.42, 137.97, 135.88, 128.77, 128.39, 127.53,125.73, 114.80, 114.40, 70.32, 29.09, 28.41.

[0042] Example 2

[0043] 30 mg BBDPT was dissolved in 10 mL of a mixed solvent of dichloromethane and anhydrous ethanol (volume ratio of dichloromethane to anhydrous ethanol was 1:4), and allowed to stand at 25 °C for 10 days to obtain flexible crystals of 4-benzyloxybenzene-substituted barbituric acid derivative, which were yellow needle-like crystals.

[0044] Example 3

[0045] The difference from Example 2 is that the amount of BBDPT added is 40mg, while all other conditions are the same.

[0046] Example 4

[0047] The difference from Example 2 is that the amount of BBDPT added is 20mg, while all other conditions are the same.

[0048] The UV-Vis absorption and fluorescence emission spectra (λ) of the flexible crystals of the 4-benzyloxyphenyl-substituted barbituric acid derivatives of Example 1 and Example 2 were tested. ex = 404 nm), the 4-benzyloxyphenyl-substituted barbituric acid derivative of Example 1 was dissolved in acetonitrile to form an acetonitrile solution of the 4-benzyloxyphenyl-substituted barbituric acid derivative with a concentration of 1.0 × 10⁻⁴ nm. -5 M, the test results are as follows Figure 3 As shown, Figure 3 In the diagram, *Acetonitrile* represents an acetonitrile solution of a 4-benzyloxybenzene-substituted barbituric acid derivative, and *Microcrystal* represents a flexible crystal of the 4-benzyloxybenzene-substituted barbituric acid derivative from Example 2 (the flexible crystal of the 4-benzyloxybenzene-substituted barbituric acid derivative from Example 2 was lightly ground before UV-Vis absorption and fluorescence emission spectra were measured). From... Figure 3 It can be seen that in acetonitrile solution, compound BBDPT at 265 nm (π-π) (transition) and 404 nm (π-π) Two main absorption peaks were observed at the transition ( ). Compared to the absorption of the compound in solution, the absorption peak of the 4-benzyloxyphenyl-substituted barbituric acid derivative flexible crystals red-shifted to 421 nm, indicating the presence of ... J Aggregation. Similarly, compared to the emission peak of the acetonitrile solution, the emission peak of the flexible crystals of the 4-benzyloxybenzene-substituted barbituric acid derivative redshifted by 28 nm from 479 nm to 507 nm.

[0049] The flexible crystals of the 4-benzyloxybenzene-substituted barbituric acid derivative prepared in Example 2 were subjected to bending performance testing using a three-point bending test. The results are as follows: Figure 4 As shown, under mechanical force, the crystal bends into a semi-circle without any breakage. After the mechanical force is removed, the crystal quickly returns to its original straight shape without breaking or fracturing. This reversible bending-relaxation process can be repeated many times, highlighting its good elasticity and indicating that the crystal has excellent mechanical properties.

[0050] from Figure 5 As can be seen from a, the flexible crystal molecules of the 4-benzyloxybenzene-substituted barbituric acid derivative prepared in Example 2 of this invention exhibit CH…π (3.526 Å) and CH…O (2.606 Å, 2.685 Å) interactions on the (100) plane; from Figure 5 As can be seen from b, there exists a CH…π (3.574 Å) force on the (001) plane; from Figure 5As can be seen from d, there are three forces (CH…O, 2.883 Å) on the (010) plane. Under mechanical stimulation, the above interactions can effectively relieve pressure, thereby preventing crystal breakage.

[0051] from Figure 6 As shown in Figure c, HH, OH, CC, and CH interactions account for 50.8%, 20.5%, 11.0%, and 10.9% of all interactions in the crystal, respectively, totaling approximately 93.2% of all interactions. Although HH interactions account for 50.8% of the total interactions, their contribution to the crystal's stability is minimal. These results further demonstrate that van der Waals interactions (CH…π) and hydrogen bonds (CH…O) constitute a significant proportion of the crystal, forming a structural buffer zone and having a crucial impact on its elasticity.

[0052] As can be seen from the above embodiments, the present invention provides a 4-benzyloxyphenyl-substituted barbituric acid derivative and its preparation method, a 4-benzyloxyphenyl-substituted barbituric acid derivative flexible crystal and its preparation method and application. The 4-benzyloxyphenyl-substituted barbituric acid derivative flexible crystal bends into a semi-ring under mechanical force without any breakage. After the mechanical force is removed, the crystal does not break or fracture and quickly returns to its original straight shape. This reversible bending-relaxation process can be repeated multiple times, highlighting its good elasticity and indicating that the 4-benzyloxyphenyl-substituted barbituric acid derivative flexible crystal has excellent mechanical properties.

[0053] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A flexible crystal of a 4-benzyloxyphenyl-substituted barbituric acid derivative, characterized in that, The 4-benzyloxyphenyl-substituted barbituric acid derivative flexible crystals are prepared from 4-benzyloxyphenyl-substituted barbituric acid derivatives with the structure shown in Formula (I); The method for preparing the flexible crystal of the 4-benzyloxyphenyl-substituted barbituric acid derivative includes the following steps: dissolving the 4-benzyloxyphenyl-substituted barbituric acid derivative with the structure shown in formula (Ⅰ) in a mixed solvent and allowing it to stand to obtain the flexible crystal of the 4-benzyloxyphenyl-substituted barbituric acid derivative. The mixed solvent is composed of dichloromethane and ethanol, wherein the volume ratio of dichloromethane to ethanol is 1:2 to 6; the mass-volume ratio of the 4-benzyloxybenzene-substituted barbituric acid derivative to the mixed solvent is 20 to 40 mg: 10 mL.

2. The method for preparing the flexible crystal of the 4-benzyloxybenzene-substituted barbituric acid derivative according to claim 1, characterized in that, The process includes the following steps: dissolving the 4-benzyloxybenzene-substituted barbituric acid derivative of the structure shown in formula (Ⅰ) of claim 1 in a mixed solvent and allowing it to stand to obtain flexible crystals of the 4-benzyloxybenzene-substituted barbituric acid derivative. The mixed solvent is composed of dichloromethane and ethanol, wherein the volume ratio of dichloromethane to ethanol is 1:2 to 6; the mass-volume ratio of the 4-benzyloxybenzene-substituted barbituric acid derivative to the mixed solvent is 20 to 40 mg: 10 mL.

3. The method for preparing flexible crystals of 4-benzyloxyphenyl-substituted barbituric acid derivatives according to claim 2, characterized in that, The settling temperature is room temperature, and the time is 8 to 12 days.

4. The application of the 4-benzyloxybenzene-substituted barbituric acid derivative flexible crystal according to claim 1 in the preparation of organic optical fiber or waveguide materials.

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