Tetraphenyl ethene functionalized dicyano ethylene, method of making and use thereof and inkless writing material

Abstract

The present application relates to the technical field of mechanoluminescent color-changing materials, in particular to a tetraphenyl ethylene functionalized dicyanoethylene, a preparation method and application thereof, and an inkless writing material. The tetraphenyl ethylene functionalized dicyanoethylene is selected from the compounds shown in the following structural formula: the synthesis route is short, the product yield is high, and when the tetraphenyl ethylene functionalized dicyanoethylene is used as an inkless writing material, the solid-state luminous efficiency after stress is high, the fluorescence contrast before and after stress is obvious, so that it is easier to identify when used as a mechanoluminescent color-changing material.

Description

Technical Field

[0001] This invention relates to the field of mechanosensitive fluorescent color-changing materials technology, and more specifically, to dicyanoethylene based on tetraphenylethylene functionalization, its preparation method and application, and inkless writing materials. Background Technology

[0002] Mechanochromatic fluorescent materials (MFCs) are a class of smart materials whose fluorescence emission changes significantly under external forces (such as grinding, shearing, stretching, or extrusion). To date, although numerous different types of MFCs have been designed and synthesized, some important but unresolved fundamental problems still hinder their further development and application. For example, most current MFCs involve a bicolor conversion process with a small shift difference between the colors, resulting in small differences in mechanochromatic fluorescence and low solid-state luminescence efficiency, thus affecting their usability. Alternatively, some molecules may have excellent properties, but their synthesis processes are complex, significantly limiting their application in practical production.

[0003] For various reasons, the development of MFC materials lags far behind other stimulus-responsive color-changing materials (such as photochromic and electrochromic materials). Summarizing the past and present development of MFC materials, it's clear that in the near future, MFC materials with simple structures, easy synthesis, and high contrast will become the mainstream of research and development. Research on MFC materials will inevitably drive their rapid development in cutting-edge fields such as anti-counterfeiting trademarks, security inks, storage devices, and optoelectronic devices. Therefore, developing MFC materials with novel structures, high contrast, and simple structures is particularly important.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide tetraphenylethylene-functionalized dicyanoethylene, its preparation method, its applications, and inkless writing materials. The tetraphenylethylene-functionalized dicyanoethylene provided in this invention has a short synthetic route, high product yield, and when used as an inkless writing material, it exhibits high solid-state luminescence efficiency under stress and a clear fluorescence contrast before and after stress, making it easier to identify as a mechanochromic fluorescent material.

[0006] This invention is implemented as follows:

[0007] In a first aspect, the present invention provides a tetraphenylethylene-functionalized dicyanoethylene, which is selected from compounds shown in the following structural formula:

[0008]

[0009] Secondly, the present invention provides a method for preparing dicyanoethylene based on tetraphenylethylene functionalized according to the foregoing embodiments, wherein the synthesis is carried out according to the following synthetic route:

[0010]

[0011] In an optional embodiment, the method includes: acylation reaction of compound 1 with isophthaloyl chloride to form compound 2, wherein compound 2 is added to malononitrile and then dehydrated.

[0012] In an optional embodiment, the mixture includes: mixing the compound 1, isophthaloyl chloride and dichloromethane, cooling the mixture to 0-4°C, and then reacting it with AlCl3 under reflux conditions.

[0013] In an optional embodiment, the molar ratio of compound 1 to isophthaloyl chloride is 1:0.4-0.5, and the molar ratio of compound 1 to AlCl3 is 1:1-1.3.

[0014] In an optional embodiment, the mixture includes: mixing the compound 2 with the malononitrile and cooling the mixture to 0-4°C, then mixing it with TiCl4, reacting the mixture at 0-4°C for 0.5-0.75 hours, and then mixing it with pyridine and refluxing the mixture for 4-8 hours.

[0015] In an optional embodiment, the molar ratio of compound 2 to malononitrile is 1:2-6;

[0016] The molar ratio of compound 2 to TiCl4 is 1:8-16; the molar ratio of compound 2 to pyridine is 1:8-16.

[0017] Thirdly, the present invention provides an application of the tetraphenylethylene-functionalized dicyanoethylene described in the foregoing embodiments in the preparation of inkless writing materials.

[0018] Fourthly, the present invention provides an inkless writing material, the raw material of which includes dicyanoethylene based on tetraphenylethylene functionalized as described in the foregoing embodiments.

[0019] Fifthly, the present invention provides a method for recycling inkless writing materials, comprising: placing the used inkless writing materials described in the foregoing embodiments into an organic solvent for recrystallization;

[0020] Preferably, the organic solvent is a mixed solvent formed by mixing any one of aliphatic hydrocarbon solvents and alcohol solvents with a haloalkane solvent;

[0021] Preferably, the volume ratio of the aliphatic hydrocarbon solvent or the alcohol solvent to the haloalkane solvent is 3:1-6:1.

[0022] The present invention has the following beneficial effects: The tetraphenylethylene-based functionalized cyanoethylene provided in the embodiments of the present invention is easy to synthesize. The desired compound can be synthesized from tetraphenylethylene in only two steps, and the synthesis process conditions are easy to achieve, with high yield, facilitating industrial production. The tetraphenylethylene-based functionalized cyanoethylene exhibits significant changes in fluorescence intensity before and after stress, and high solid-state luminescence efficiency after stress, making it easier to identify as a mechanochromic material, expanding the application of tetraphenylethylene-based functionalized cyanoethylene, and increasing the selection of mechanochromic materials. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 The fluorescence spectra of tetraphenylethylene-based dicyanoethylene prepared in Example 1 of this invention before and after stress are shown.

[0025] Figure 2 The fluorescence images of tetraphenylethylene-based dicyanoethylene prepared in Example 1 of this invention before and after stress are shown.

[0026] Figure 3 The result diagram provided for detection example 3 of the present invention;

[0027] Figure 4 The fluorescence spectra of compound 2 prepared in Example 1 of this invention before and after being subjected to force are shown.

[0028] Figure 5 The fluorescence images of compound 2 prepared in Example 1 of this invention before and after being subjected to force are shown.

[0029] Figure 6 Fluorescence spectra of compound 3 before and after stress, provided as a comparative example of this invention;

[0030] Figure 7 The fluorescence images of compound 3 before and after being subjected to force are provided as a comparative example of the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0032] Currently developed MFC materials based on intramolecular conformational changes generally possess highly distorted molecular conformations. On one hand, these distorted molecular conformations provide the basis for conformational changes under force; on the other hand, distorted molecular conformations can effectively prevent the formation of strong intermolecular couplings (such as H-aggregation) in crystals, which leads to low fluorescence quantum efficiency. The most well-known of these are tetraphenylethylene derivatives. Tetraphenylethylene (TPE) is a molecule composed of four phenyl groups directly linked to a double bond. Due to the strong steric repulsion of the four phenyl groups, tetraphenylethylene and its derivatives generally possess distorted molecular conformations. Furthermore, the synthesis of tetraphenylethylene derivatives is relatively simple, and they have strong molecular modification capabilities. Tetraphenylethylene derivatives are currently the most studied mechanochromic materials based on molecular conformational changes. However, even when using tetraphenylethylene derivatives to form mechanochromic materials, problems remain, such as low synthesis yield, unclear fluorescence contrast before and after stress, and low solid-state luminescence efficiency after stress. Therefore, this invention provides a novel dicyanoethylene based on tetraphenylethylene functionalization, selected from compounds with the following structural formula:

[0033]

[0034] Secondly, the present invention provides a method for preparing dicyanoethylene based on tetraphenylethylene functionalized according to the foregoing embodiments, wherein the synthesis is carried out according to the following synthetic route: The specific process is as follows:

[0035] Compound 1 is acylated with isophthaloyl chloride to form compound 2. Specifically, compound 1, isophthaloyl chloride, and dichloromethane are mixed and cooled to 0-4°C, then mixed with AlCl3 and reacted under reflux. The molar ratio of compound 1 to isophthaloyl chloride is 1:0.4-0.5, and the molar ratio of compound 1 to AlCl3 is 1:1-1.3.

[0036] Compound 2 is dehydrated after addition reaction with malononitrile; specifically, compound 2 is mixed with malononitrile and cooled to 0-4°C, then mixed with TiCl4, and reacted at 0-4°C for 0.5-0.75 hours, followed by mixing with pyridine and refluxed for 4-8 hours. The molar ratio of compound 2 to malononitrile is 1:2-6.

[0037] The molar ratio of compound 2 to TiCl4 is 1:8-16; the molar ratio of compound 2 to pyridine is 1:8-16.

[0038] Each reaction step is followed by post-processing, which is a well-known post-processing method in the art and will not be described in detail in the embodiments of the present invention.

[0039] The aforementioned tetraphenylethylene-functionalized dicyanoethylene can be used to prepare inkless writing materials or as a mechanosensitive fluorescent color-changing material.

[0040] Specifically, an inkless writing material includes dicyanoethylene based on tetraphenylethylene functionalization as its raw material.

[0041] It may also include other supplementary materials for inkless writing materials.

[0042] Fifthly, the present invention provides a method for recycling inkless writing materials or mechanochromic fluorescent materials, comprising: placing the used inkless writing material described in the foregoing embodiments into an organic solvent for recrystallization; wherein, the organic solvent is any one of aliphatic hydrocarbon solvents (e.g., including but not limited to petroleum ether, n-hexane, n-heptane, etc.) and alcohol solvents (e.g., methanol, ethanol, etc., C1-C5 monohydric alcohols) mixed with a haloalkane solvent (dichloromethane, chloroform, etc., chlorinated C1-C3 alkanes) to form a mixed solvent; preferably, the volume ratio of the aliphatic hydrocarbon solvent or the alcohol solvent to the haloalkane solvent is 3:1-6:1.

[0043] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0044] Example 1

[0045] This embodiment provides a tetraphenylethylene-functionalized dicyanoethylene (hereinafter referred to as DCE-TPE), whose structural formula is as follows:

[0046] This embodiment also provides a method for preparing the above-mentioned DCE-TPE, including:

[0047] The synthesis should be carried out according to the following synthetic route:

[0048] The specific steps are as follows:

[0049] Synthesis of Compound 2: Compound 1 (21.00 g, 63.17 mmol) and isophthaloyl chloride (6.00 g, 29.55 mmol) were dissolved in 350 mL of CH2Cl2. The system temperature was lowered to 0 °C using an ice bath. Anhydrous AlCl3 (8.60 g, 64.50 mmol) was added to the mixture in portions. After stirring for 30 minutes, the ice bath was removed, and the system was refluxed for 4 hours. After the reaction was completed, the system was cooled to room temperature, and the reaction solution was poured into water (1000 mL). The mixture was separated, and the upper aqueous phase was extracted with CH2Cl2. The organic phases were combined, dried over anhydrous Na2SO4, and filtered. The solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by silica gel column chromatography using petroleum ether / CH2Cl2 (v / v = 3 / 1) as the eluent to obtain a pale yellow solid (19.50 g, 83%). 1 HNMR (600MHz, CDCl3) δ8.11 (s, 1H), 7.93 (d, J = 7.2Hz, 2H), 7.60-7.56 (m, 5H), 7.18-7.14 (m, 22H), 7.07 (s, 12H); HRMS (Q Exactive Orbitrap MS, APCI) m / z: [M+H] + Calcd forC 60 H 43 O2795.3263; Found 795.3260.Anal.Calcd(%)for C 60 H 42 O2: C 90.65, H 5.33; Found: C 90.78, H 5.22.

[0050] Synthesis of the target molecule DCE-TPE (2,2'-(1,3-phenylene di((4-(1,2,2-tristyryl)phenyl)methylmethylene)dimalononitrile): Compound 2 (6.60 g, 7.58 mmol) and malononitrile (2.90 g, 43.90 mmol) were dissolved in 300 mL of dry CH2Cl2. The system temperature was lowered to 0 °C using an ice bath. 80 mL of solution containing TiCl4 (20.50 g, 108.08 mmol) was then added. CH2Cl2 solution was slowly added dropwise to the reaction system. After the addition was complete, the mixture was stirred in an ice bath for 0.5 hours. Then, pyridine (9.50 g, 120.10 mmol) was added dropwise to the reaction system. Finally, the mixture was refluxed for 6 hours. After the reaction was complete, the system was cooled to room temperature, and the reaction solution was poured into water (1500 mL). The layers were separated, and the upper aqueous phase was extracted with CH2Cl2. The organic phases were combined, dried over anhydrous Na2SO4, filtered, and the solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by silica gel column chromatography using petroleum ether / CH2Cl2 (v / v = 1 / 1) as the eluent to obtain a yellow solid (6.88 g, 93%). 1 HNMR(600MHz, CDCl3)δ7.62(t,J=7.8Hz,J=7.2Hz,1H),7.56(d,J=7.8Hz,2H),7.36(s,1 H),7.24(d,J=7.8Hz,4H),7.18-7.15(m,22H),7.05(s,12H); HRMS(QExactiveOrbitrap MS,APCI)m / z:[M+H] + Calcd for C66H42N4 891.3488; Found891.3485.Anal.Calcd(%) for C 66 H 42 N4: C 88.96, H 4.75, N 6.29; Found: C 88.82, H 4.88, N 6.39.

[0051] Comparative Example

[0052] This comparative example provides a compound 3, whose structural formula is as follows:

[0053]

[0054] Detection Example 1

[0055] Fluorescence spectra of DCE-TPE, compound 2, and the comparative compound 3 were detected and their fluorescence images were obtained under a UV lamp (365 nm). All three compounds were ground in an agate grinding machine under the same conditions for 5 minutes, and their fluorescence spectra after grinding were then measured and their fluorescence images were obtained under a UV lamp (365 nm). The results are shown in [link to results]. Figures 1-2 and Figures 4-7 .

[0056] according to Figure 1 and Figure 2 It is known that the initial crystalline powder of the target molecule DCE-TPE can only emit extremely weak yellow-green fluorescence, with its maximum emission peak located at 528 nm, and a solid-state luminescence efficiency of only 0.11%. After grinding the initial powder of DCE-TPE, its fluorescence intensity increased significantly, and the fluorescence color changed to orange. The maximum emission peak red-shifted to 589 nm, and the solid-state luminescence efficiency was 55.56%, which is 505 times that of the initial crystalline powder.

[0057] according to Figures 4-7 It can be seen that the initial crystalline powders of compound 2 and the comparative compound 3 exhibit fluorescence colors of blue-green and yellow-green, respectively, with maximum emission wavelengths of 487 and 527 nm, and solid-state luminescence efficiencies of 30.31% and 37.62%, respectively. After grinding the initial powders of compound 2 and the comparative compound 3, their fluorescence colors remained unchanged, still blue-green and yellow-green, respectively. The maximum emission peaks showed slight red and blue shifts, respectively, to 491 and 523 nm, and the solid-state luminescence efficiencies also changed only slightly, to 28.68% and 38.58%, respectively. Therefore, it can be concluded that the comparative compounds 2 and 3 do not possess mechanotropic fluorescence properties.

[0058] It is evident that even if the parent nuclei are all tetraphenylethylene, and some even have symmetrical structures or contain cyano groups, different connection methods result in different compounds, and their effects as mechanochromic fluorescent materials also differ. The dicyanoethylene based on tetraphenylethylene functionalized in this invention provides significant fluorescence differences before and after stress, especially the solid-state luminescence efficiency of 55.56% after stress, making it easier to identify as an inkless writing material.

[0059] Detection Example 2

[0060] Place 0.1-2.0 grams of the above-mentioned ground, inkless writing material into 10-100 ml of mixed solvent (V). DCM V 石油醚 The mixture was recrystallized at 40°C in a ratio of 1:5, and then subjected to fluorescence detection.

[0061] It was found that the fluorescence intensity of the ground material returned to its original state after recrystallization. When it was coated on filter paper and written on again, the fluorescence intensity increased again, indicating that the dicyanoethylene based on tetraphenylethylene functionalization provided in this embodiment of the invention has recyclability and reusability.

[0062] Detection Example 3

[0063] The tetraphenylethylene-functionalized dicyanoethylene prepared in Example 1 was coated onto filter paper. The word "turn on" was written with a metal spatula using normal writing pressure. Under a 365nm UV lamp, the bright orange lettering, distinct from the dark yellow-green background, was visible (see [link to example]). Figure 3 This indicates that the tetraphenylethylene-functionalized dicyanoethylene provided in the embodiments of the present invention has fluorescence sensitivity to mechanical force.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dicyanoethylene based on tetraphenylethylene functionalization, characterized in that, It is selected from compounds with the following structural formulas: 。 2. A method for preparing dicyanoethylene based on tetraphenylethylene functionalization as described in claim 1, characterized in that, Perform the synthesis according to the following synthesis path: 。 3. The preparation method according to claim 2, characterized in that, include: Compound 1 is acylated with isophthaloyl chloride to form compound 2, and compound 2 is then condensed with malononitrile.

4. The preparation method according to claim 3, characterized in that, include: The compound 1, isophthaloyl chloride, and dichloromethane were mixed and cooled to 0-4°C, and then mixed with AlCl3 and reacted under reflux.

5. The preparation method according to claim 4, characterized in that, The molar ratio of compound 1 to isophthaloyl chloride is 1:0.40-0.50, and the molar ratio of compound 1 to AlCl3 is 1:1-1.

3.

6. The preparation method according to claim 3, characterized in that, include: The compound 2 was mixed with the malononitrile and cooled to 0-4°C, then mixed with TiCl4, and reacted at 0-4°C for 0.5-0.75 hours. Then, it was mixed with pyridine and refluxed for 4-8 hours.

7. The preparation method according to claim 6, characterized in that, The molar ratio of compound 2 to malononitrile is 1:2-6; The molar ratio of compound 2 to TiCl4 is 1:8-16; the molar ratio of compound 2 to pyridine is 1:8-16.

8. The application of tetraphenylethylene-functionalized dicyanoethylene as described in claim 1 in the preparation of inkless writing materials or mechanosensitive fluorescent color-changing materials.

9. A writing material without ink, characterized in that, Its raw materials include dicyanoethylene based on tetraphenylethylene functionalization as described in claim 1.

10. A method for recycling inkless writing materials, characterized in that, include: The used inkless writing material of claim 9 is recrystallized in an organic solvent.

11. The method for recycling inkless writing materials according to claim 10, characterized in that, The organic solvent is a mixed solvent formed by mixing any one of aliphatic hydrocarbon solvents and alcohol solvents with a haloalkane solvent.

12. The method for recycling inkless writing materials according to claim 11, characterized in that, The volume ratio of the aliphatic hydrocarbon solvent or the alcohol solvent to the haloalkane solvent is 3:1 to 6:1.

Images