Synthesis and application research of cyanostilbene derivative

Abstract

The invention discloses synthesis and application research of a cyanostilbene derivative, and relates to the technical field of organic fluorescent dyes. The invention relates to synthesis and application research of a cyanostilbene derivative. The synthesis and application research comprises the following steps: a synthesis route of a target product 2e, a focusing induction effect, an organic light-emitting diode, a solvent effect and an acid / alkali stimulated fluorescence response. According to the invention, 2e has a two-state luminescence property, and an AN solution of 2e has sensitive and reversible fluorescence response to acid / alkali stimulation, so that 2e is suitable for an acid / alkali fluorescence sensor. In solvents with different polarities, 2e emits fluorescence with different colors, the relative polarity of the solvents can be judged through naked eyes, the 2e is made into small LED lamp beads emitting green light, the 2e can be widely applied to toys, building decoration and warning signs of'safety channels' and'emergency exits', in addition, the 2e has the AIEE effect, the fluorescence intensity is the strongest when the water content is 85%, and the 2e can be used as a warning sign of the safety channels and the emergency exits. And the fluorescence performance of the material under specific conditions is improved.

Description

Technical Field

[0001] The invention relates to the technical field of organic fluorescent dyes, in particular to the synthesis and application research of cyanostilbene derivatives. Background Art

[0002] At present, most mainstream commercial products of light-emitting diodes (LEDs) use rare earth fluorescent materials. Rare earths are non-renewable, and their mining and refining processes also face potential economic and environmental pressures. Organic fluorescent materials have simple synthesis processes, easy purification, and low cost. In addition, organic light sources are glare-free and can provide very uniform lighting. Therefore, it is of great significance to synthesize organic luminescent materials for LEDs. However, most organic fluorescent materials have aggregation-induced quenching (ACQ) effects, which limits their application range. Therefore, the development of materials that can emit light in both solution and solid states (i.e., dual-state luminescence) can expand their applications. Stimuli-responsive luminescent materials are materials whose color and fluorescence emission peak position / intensity can be converted by external environment (such as heat, pressure, pH, light, water, ions, etc.). They are widely used in fluorescent sensors, memory chips, anti-counterfeiting paper, logic operations, optical coding, optical switches, data storage, security inks and bio-imaging. Fluorescent chemical sensors have been widely studied in recent years due to their high sensitivity, high selectivity, fast response, cheap instruments and easy operation. However, many fluorescent chemical sensors show fluorescence quenching response, which is not conducive to practical applications because many factors can lead to fluorescence attenuation. Therefore, the development of sensors with high selectivity, high sensitivity and "on" response is still a challenge.

[0003] Most a-cyanostilbene derivatives have aggregation-induced emission / aggregation-induced emission enhancement (AIE / AIEE) activity and are ideal for the development of functional materials. In this work, a new type of cyanostilbene derivative was designed and synthesized by introducing a-cyanostilbene units into the molecular structure; the product was characterized by 'HNMR and FT-IR; the optical properties, aggregation-induced effect, solvent effect and its application in LED and acid / base fluorescence sensing of the product were studied. However, the existing technology lacks characterization methods such as HNMR and FT-IR, and cannot accurately determine the structure and properties of the product, which affects the in-depth research and application of the product. It is impossible to accurately evaluate the fluorescence properties, fluorescence response characteristics and solvent polarity correlation of the product, which limits the application research and development of the product, and the product cannot be applied to the fields of fluorescence sensors, LED small lamp beads, etc., which limits the practical application and market promotion of the product. The lack of understanding of the AIEE effect may lead to the failure to exert the best fluorescence performance of the product when the water content is 85%, affecting the performance and efficiency of the product. In view of the above problems, the inventor proposes a synthesis and application study of cyanostilbene derivatives to solve the above problems. Summary of the invention

[0004] In order to solve the problem that the property and structure of the product cannot be accurately understood without appropriate technical means, thereby limiting the research and development and application scope of the product; the purpose of the present invention is to provide a synthesis and application research of cyanobenzene derivatives.

[0005] In order to solve the above technical problems, the present invention adopts the following technical scheme: a synthesis and application study of a cyanophenylethylene derivative comprises the following steps:

[0006] S1, the synthetic route of the target product 2e;

[0007] S2, focusing induction effect;

[0008] S3, organic light emitting diode;

[0009] S4, solvent effect;

[0010] S5, fluorescence response to acid / base stimulation.

[0011] The synthetic route of the target product 2e in S1: Synthesis of 2e: Weigh 0.18g (1mmol) le and add it to a 100mL round-bottom flask, add 10mL anhydrous ethanol, heat to dissolve, then add 0.39g (2mmol) 4-biphenylacetonitrile and 10mL anhydrous ethanol, after the raw materials are completely dissolved, add a few drops of saturated K2CO3 solution as a catalyst, reflux reaction, after the reaction is judged to be completed by thin layer chromatography, the reaction solution is cooled, filtered, and dried to obtain a crude product. The crude product is subjected to column chromatography (eluent is petroleum ether: EA = 3:1) to obtain an orange-yellow solid powder'HNMR (400MHz, CDC13, δin ppm): 8.30 (d, J=10.6Hz, 1H), 8.21 (s.1H), 7.79 (dd, j=17.7, 10.0Hz, 5H) 7.71-7.62 (m, 8H), 7.59 (s, 1H), 7.47 (dd, j=11.7, 7.5Hz, 4H), 7.42-7.37 (m, 2H), 7.14 (d, j=8.7Hz, 1H), 2.91 (s, 6H) FT-IR (KBr, v / cm-): 3208 (S), 2927-2794 (W), 2207 (VS), 1490-1595 (S).

[0012] The concentration of the 2e test solution in S1 is 1.0x10-5M, the excitation wavelength is the maximum ultraviolet absorption wavelength, and the excitation and emission slits are 10nm and 5nm, respectively; the volume ratios of water content (fw, vol%) of the water / THF solution for testing the AIE effect are 20%, 40%, 60%, 80%, 85%, 90%, and 95%, respectively; the solvent used to test the acid / base stimulus response of 2e is AN, and the acid / base is TFA and TEA, respectively; 20mg of 2e is fully mixed with 5g of silicone sealant (the weight ratio of silicone A to silicone B is 1:1), the mixture is degassed with vacuum, and then encapsulated on the surface of a commercial InGaN blue light emitting chip, and cured at 150℃ for 1h to obtain an LED, and the forward voltage of the LED performance test is 2.735V, the forward current is 25mA, the ambient temperature is 25℃, and the ambient humidity is 65.0%.

[0013] Focusing induced effect in S2: With the increase of fw in the solution, the UV-vis absorption spectrum showed a slight red shift (from 377nm to 395nm), and the maximum emission wavelength of compound 2e was around 540nm. With the increase of fw in the solution, the fluorescence intensity showed a trend of first increasing and then decreasing, reaching a maximum value when fw = 85%, indicating that compound 2e has aggregation-induced emission enhancement (AIEE) performance. This paper believes that the reason for the generation of AIEE is: 2e exists in a single molecule state in THF solution, and the rotation of the aromatic rotor around the C_C single bond consumes the excited state energy, and the fluorescence emission intensity decreases; in the aggregated state, the weak interaction between -CN and the hydrogen atoms of the adjacent molecules (CH...N) limits the rotation of the aromatic rotor around the CC single bond in the molecule (RIR), solidifies the molecular conformation, thereby reducing thermal radiation and enhancing fluorescence emission.

[0014] The reason for the generation of AIEE in S2 is that 2e exists in a single molecule state in THF solution, and the rotation of the aromatic rotor around the C_C single bond consumes the excited state energy, and the fluorescence emission intensity decreases; in the aggregated state, the weak interaction between -CN and the hydrogen atoms of the adjacent molecules (CH..N) restricts the rotation of the aromatic rotor around the CC single bond in the molecule (RIR), solidifies the molecular conformation, thereby reducing thermal radiation and enhancing fluorescence emission. This article believes that the reason for the generation of AIEE is: 2e exists in a single molecule state in THF solution, and the rotation of the aromatic rotor around the C_C single bond consumes the excited state energy, and the fluorescence emission intensity decreases; in the aggregated state, the weak interaction between -CN and the hydrogen atoms of the adjacent molecules (CH...N) restricts the rotation of the aromatic rotor around the CC single bond in the molecule (RIR), solidifies the molecular conformation, thereby reducing thermal radiation and enhancing fluorescence emission.

[0015] Organic light-emitting diode in S3: The chromaticity characteristics and optical properties of the LED were measured. The chromaticity coordinates (x, y) of the LED in the CIE193 chromaticity space at a current of 25 mA were (0.2271, 0.3443), which was located in the green light region. The corresponding color temperature (CCT, 12063K), color rendering index (CRIR, 55.4), and luminous efficacy (LE, 50.081 mW) were significantly higher than those of diphenylfumaronitrile-based dyes (29-40 lm / W). The results showed that compound 2e has the potential to be used in LEDs.

[0016] Solvent effect in S4: Solvents of different polarities may have a significant effect on the fluorescence emission of fluorescent materials. The fluorescence emission spectra of 2e in solvents of different polarities were tested. The fluorescence emission spectra and fluorescence photographs of compound 2e in solvents of different polarities showed that with the increase of solvent polarity, the fluorescence emission wavelength underwent a significant red shift (from 503 to 559 nm). Therefore, a fluorescence photometer can be used to detect the relative strength of solvent polarity. Under ultraviolet light, it is obvious to the naked eye that 2e exhibits different fluorescent colors in solvents of different polarities, which provides a way to visually identify the relative strength of solvent polarity.

[0017] Fluorescence response to acid / base stimulation in S5: The AN solution of 2e has a sensitive on-fluorescence response to acid stimulation. We can identify the acidity / alkalinity of the solution with the naked eye or a fluorescence spectrophotometer. Therefore, 2e can be used as a dual-recognition acid / base indicator.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. In the present invention, dialdehyde le is synthesized by Weissmeier reaction, and then a novel cyanostilbene derivative 2e is synthesized by Knoevenagel condensation reaction. 2e is characterized by HNMR and FT-IR;

[0020] 2. In the present invention, 2e has a dual-state luminescence property, and its AN solution has a sensitive and reversible fluorescence response to acid / base stimulation, and is suitable for acid / base fluorescence sensors. In solvents of different polarities, 2e emits fluorescence of different colors, and the relative size of the solvent polarity can be judged by the naked eye;

[0021] 3. In the present invention, 2e is made into small LED lamp beads that emit green light, which can be widely used in toys, building decorations, and as warning signs of "safe passage" and "emergency exit". In addition, 2e has an AIEE effect, and the fluorescence intensity is strongest when the water content is 85%, which improves its fluorescence performance under specific conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 Schematic diagram of the synthetic route of the target product 2e of the present invention;

[0024] Figure 2 Schematic diagram of the absorption and emission spectra of compound 2e of the present invention in different water / THF mixed solvents;

[0025] Figure 3 This is a schematic diagram of the color coordinates of LED lamp beads such as 2e of the present invention;

[0026] Figure 4 The fluorescence emission spectra and fluorescence schematic diagrams of the compound 2e of the present invention in different polar solvents;

[0027] Figure 5 The fluorescence photograph and fluorescence spectrum diagram of the AN solution of 2e of the present invention in response to acid / base stimulation;

[0028] Figure 6 Schematic diagram of the reversible change of emission wavelength and intensity of AN solution subjected to 2e of acid / base alternating treatment according to the present invention. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] like Figure 1-6 As shown, the present invention provides a synthesis and application study of cyanophenylethylene derivatives, comprising the following steps:

[0031] S1, the synthetic route of the target product 2e;

[0032] S2, focusing induction effect;

[0033] S3, organic light emitting diode;

[0034] S4, solvent effect;

[0035] S5, fluorescence response to acid / base stimulation.

[0036] The synthetic route of the target product 2e in S1: Synthesis of 2e: Weigh 0.18g (1mmol) le and add it to a 100mL round-bottom flask, add 10mL anhydrous ethanol, heat to dissolve, then add 0.39g (2mmol) 4-biphenylacetonitrile and 10mL anhydrous ethanol, after the raw materials are completely dissolved, add a few drops of saturated K2CO3 solution as a catalyst, reflux reaction, after the reaction is judged to be completed by thin layer chromatography, the reaction solution is cooled, filtered, and dried to obtain a crude product. The crude product is subjected to column chromatography (eluent is petroleum ether: EA = 3:1) to obtain an orange-yellow solid powder'HNMR (400MHz, CDC13, δin ppm): 8.30 (d, J=10.6Hz, 1H), 8.21 (s.1H), 7.79 (dd, j=17.7, 10.0Hz, 5H) 7.71-7.62 (m, 8H), 7.59 (s, 1H), 7.47 (dd, j=11.7, 7.5Hz, 4H), 7.42-7.37 (m, 2H), 7.14 (d, j=8.7Hz, 1H), 2.91 (s, 6H) FT-IR (KBr, v / cm-): 3208 (S), 2927-2794 (W), 2207 (VS), 1490-1595 (S).

[0037] By adopting the above technical solutions, 2e has dual-state luminescence properties, acid / base fluorescence sensor characteristics, solvent polarity indication function, application potential of small LED lamp beads and AIEE effect, which provides broad application prospects in the fields of fluorescence sensors, lighting and environmental monitoring.

[0038] The concentration of the 2e test solution in S1 is 1.0x10-5M, the excitation wavelength is the maximum ultraviolet absorption wavelength, and the excitation and emission slits are 10nm and 5nm, respectively; the volume ratios of water content (fw, vol%) of the water / THF solution for testing the AIE effect are 20%, 40%, 60%, 80%, 85%, 90%, and 95%, respectively; the solvent used to test the acid / base stimulus response of 2e is AN, and the acid / base is TFA and TEA, respectively; 20mg of 2e is fully mixed with 5g of silicone sealant (the weight ratio of silicone A to silicone B is 1:1), the mixture is degassed with vacuum, and then encapsulated on the surface of a commercial InGaN blue light emitting chip, and cured at 150℃ for 1h to obtain an LED, and the forward voltage of the LED performance test is 2.735V, the forward current is 25mA, the ambient temperature is 25℃, and the ambient humidity is 65.0%.

[0039] By adopting the above technical scheme, the provided experimental conditions and test results are helpful to evaluate the performance and application potential of 2e in fluorescence sensors, AIE effect, acid-base response and LED preparation.

[0040] Focusing induction effect in S2: Figure 2 As shown in (a), with the increase of fw in the solution, the UV-vis absorption spectrum showed a slight red shift (from 377nm to 395nm), and the maximum emission wavelength of compound 2e was around 540nm. With the increase of fw in the solution, the fluorescence intensity showed a trend of first increasing and then decreasing, reaching a maximum value when fw = 85%, which indicates that compound 2e has aggregation-induced emission enhancement (AIEE) performance. This paper believes that the reason for the generation of AIEE is that 2e exists in a single molecule state in THF solution, and the rotation of the aromatic rotor around the C_C single bond consumes the excited state energy, and the fluorescence emission intensity decreases; in the aggregated state, the weak interaction between -CN and the hydrogen atoms of the adjacent molecules (CH...N) limits the rotation of the aromatic rotor around the CC single bond in the molecule (RIR), solidifies the molecular conformation, thereby reducing thermal radiation and enhancing fluorescence emission.

[0041] By adopting the above technical scheme, compound 2e exhibits AIEE performance in S2. With the increase of water content in the solution, the fluorescence intensity first increases and then decreases. When it reaches the maximum value, it shows aggregation-induced emission enhancement effect. This is because the conformation of the molecule is solidified in the aggregated state, which restricts the rotation of the aromatic rotor and increases the fluorescence emission intensity. Figure 2 The middle insets show the fluorescence intensity changes and fluorescence photographs, respectively.

[0042] The reason for the generation of AIEE in S2 is that 2e exists in a single molecule state in THF solution, and the rotation of the aromatic rotor around the C_C single bond consumes the excited state energy, and the fluorescence emission intensity decreases; in the aggregated state, the weak interaction between -CN and the hydrogen atoms of the adjacent molecules (CH..N) restricts the rotation of the aromatic rotor around the CC single bond in the molecule (RIR), solidifies the molecular conformation, thereby reducing thermal radiation and enhancing fluorescence emission. This article believes that the reason for the generation of AIEE is: 2e exists in a single molecule state in THF solution, and the rotation of the aromatic rotor around the C_C single bond consumes the excited state energy, and the fluorescence emission intensity decreases; in the aggregated state, the weak interaction between -CN and the hydrogen atoms of the adjacent molecules (CH...N) restricts the rotation of the aromatic rotor around the CC single bond in the molecule (RIR), solidifies the molecular conformation, thereby reducing thermal radiation and enhancing fluorescence emission.

[0043] By adopting the above technical scheme, when 2e exists in a single molecule state in THF solution, the rotation of the aromatic rotor consumes the excited state energy, resulting in a decrease in the fluorescence emission intensity; in the aggregated state, by restricting the rotation of the aromatic rotor, solidifying the molecular conformation and reducing thermal radiation, the fluorescence emission intensity is enhanced, showing AIEE performance.

[0044] Organic Light Emitting Diodes in S3: The colorimetric characteristics and optical properties of LEDs were measured, such as Figure 2As shown, the chromaticity coordinates (x, y) of the CIE193 chromaticity space of the LED at a current of 25 mA are (0.2271, 0.3443), which is located in the green light region. The corresponding color temperature (CCT, 12063K), color rendering index (CRIR, 55.4), and luminous efficiency (LE, 50.081mW) are significantly higher than those of diphenylfumaronitrile dyes (29-40lm / W). The results show that compound 2e has the potential to be used in LEDs.

[0045] By adopting the above technical scheme, compound 2e exhibits superior chromaticity characteristics and optical properties in S3, and is suitable for use in LEDs, with potential application advantages, including good chromaticity characteristics, high color temperature, high color rendering index and outstanding light efficiency, and Figure 3 The middle illustration shows the LED lamp bead when it is powered off (left) and powered on (right).

[0046] Solvent effect in S4: Solvents of different polarities may have a significant effect on the fluorescence emission of fluorescent materials. The fluorescence emission spectra of 2e in solvents of different polarities were tested. The fluorescence emission spectra and fluorescence photos of compound 2e in solvents of different polarities are shown in Figure 4. Figure 4 As shown, with the increase of solvent polarity, the fluorescence emission wavelength undergoes a significant red shift (from 503 to 559 nm), so the relative strength of solvent polarity can be detected by a fluorescence photometer. Under ultraviolet light, it is obvious to the naked eye that 2e exhibits different fluorescence colors in solvents of different polarities, which provides a way to visually identify the relative strength of solvent polarity.

[0047] By adopting the above technical scheme, compound 2e exhibits superior chromaticity characteristics and optical properties in S3, including chromaticity coordinates in the green light region, high color temperature, color rendering index and luminous efficiency. In particular, its high luminous efficiency gives it potential advantages in LED applications.

[0048] Fluorescence response to acid / base stimulation in S5: The AN solution of 2e has a sensitive on-fluorescence response to acid stimulation. We can identify the acidity / alkalinity of the solution with the naked eye or a fluorescence spectrophotometer. Therefore, 2e can be used as a dual-recognition acid / base indicator.

[0049] By adopting the above technical scheme, compound 2e has a sensitive acid-stimulated fluorescence response and can be used as a dual-recognition acid-base indicator. It has the advantage of rapid and intuitive detection of the acidity and alkalinity of the solution and has potential application prospects.

[0050] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A study on the synthesis and application of cyanostilbene derivatives, characterized in that: The following steps are involved: S1, the synthetic route of the target product 2e; S2, focusing induction effect; S3, organic light emitting diode; S4, solvent effect; S5, fluorescence response to acid / base stimulation.

2. The synthesis and application research of a cyanophenylethylene derivative as claimed in claim 1, characterized in that: Synthesis route of target product 2e in S1: Synthesis of 2e: Weigh 0.18g (1mmol) le into a 100mL round-bottom flask, add 10mL anhydrous ethanol, heat to dissolve, then add 0.39g (2mmol) 4-biphenylacetonitrile and 10mL anhydrous ethanol, after the raw materials are completely dissolved, add a few drops of saturated K2CO3 solution as a catalyst, reflux reaction, after the reaction is judged to be completed by thin layer chromatography, the reaction solution is cooled, filtered, dried to obtain a crude product, and the crude product is subjected to column chromatography (eluent is petroleum ether: EA = 3:1) to obtain an orange-yellow solid powder'HNMR (400MHz, CDC13, δinppm): 8.30 (d, J=10.6Hz, 1H), 8.21 (s.1H), 7.79 (dd, j=17.7, 10.0Hz, 5H) 7.71-7.62 (m, 8H), 7.59 (s, 1H), 7.47 (dd, j=11.7, 7.5Hz, 4H ), 7.42-7.37 (m, 2H), 7.14 (d, j=8.7Hz, 1H), 2.91 (s, 6H) FT-IR (KBr, v / cm-): 3208 (S), 2927-2794 (W), 2207 (VS), 1490-1595 (S).

3. The synthesis and application research of a cyanophenylethylene derivative as claimed in claim 1, characterized in that: The concentration of the 2e test solution in S1 is 1.0x10-5M, the excitation wavelength is the maximum ultraviolet absorption wavelength, and the excitation and emission slits are 10nm and 5nm, respectively; the volume ratios of water content (fw, vol%) of the water / THF solution for testing the AIE effect are 20%, 40%, 60%, 80%, 85%, 90%, and 95%, respectively; the solvent used to test the acid / base stimulus response of 2e is AN, and the acid / base is TFA and TEA, respectively; 20mg of 2e is fully mixed with 5g of silicone sealant (the weight ratio of silicone A to silicone B is 1:1), the mixture is degassed with vacuum, and then encapsulated on the surface of a commercial InGaN blue light emitting chip, and cured at 150℃ for 1h to obtain an LED, and the forward voltage of the LED performance test is 2.735V, the forward current is 25mA, the ambient temperature is 25℃, and the ambient humidity is 65.0%.

4. The synthesis and application research of a cyanophenylethylene derivative as claimed in claim 1, characterized in that: Focusing induced effect in S2: With the increase of fw in the solution, the UV-vis absorption spectrum showed a slight red shift (from 377nm to 395nm), and the maximum emission wavelength of compound 2e was around 540nm. With the increase of fw in the solution, the fluorescence intensity showed a trend of first increasing and then decreasing, reaching a maximum value when fw = 85%, indicating that compound 2e has aggregation-induced emission enhancement (AIEE) performance. This paper believes that the reason for the generation of AIEE is: 2e exists in a single molecule state in THF solution, and the rotation of the aromatic rotor around the C_C single bond consumes the excited state energy, and the fluorescence emission intensity decreases; in the aggregated state, the weak interaction between -CN and the hydrogen atoms of the adjacent molecules (CH...N) limits the rotation of the aromatic rotor around the CC single bond in the molecule (RIR), solidifies the molecular conformation, thereby reducing thermal radiation and enhancing fluorescence emission.

5. The synthesis and application research of a cyanophenylethylene derivative as claimed in claim 4, characterized in that: The reason for the generation of AIEE in S2 is that 2e exists in a single molecule state in THF solution, and the rotation of the aromatic rotor around the C_C single bond consumes the excited state energy, and the fluorescence emission intensity decreases; in the aggregated state, the weak interaction between -CN and the hydrogen atoms of the adjacent molecules (CH..N) restricts the rotation of the aromatic rotor around the CC single bond in the molecule (RIR), solidifies the molecular conformation, thereby reducing thermal radiation and enhancing fluorescence emission. This article believes that the reason for the generation of AIEE is: 2e exists in a single molecule state in THF solution, and the rotation of the aromatic rotor around the C_C single bond consumes the excited state energy, and the fluorescence emission intensity decreases; in the aggregated state, the weak interaction between -CN and the hydrogen atoms of the adjacent molecules (CH...N) restricts the rotation of the aromatic rotor around the CC single bond in the molecule (RIR), solidifies the molecular conformation, thereby reducing thermal radiation and enhancing fluorescence emission.

6. The synthesis and application research of a cyanophenylethylene derivative as claimed in claim 1, characterized in that: Organic light-emitting diode in S3: The chromaticity characteristics and optical properties of the LED were measured. The chromaticity coordinates (x, y) of the LED in the CIE193 chromaticity space at a current of 25 mA were (0.2271, 0.3443), which was located in the green light region. The corresponding color temperature (CCT, 12063K), color rendering index (CRIR, 55.4), and luminous efficacy (LE, 50.081 mW) were significantly higher than those of diphenylfumaronitrile-based dyes (29-40 lm / W). The results showed that compound 2e has the potential to be used in LEDs.

7. The synthesis and application research of a cyanostilbene derivative as claimed in claim 1, characterized in that: Solvent effect in S4: Solvents of different polarities may have a significant effect on the fluorescence emission of fluorescent materials. The fluorescence emission spectra of 2e in solvents of different polarities were tested. The fluorescence emission spectra and fluorescence photographs of compound 2e in solvents of different polarities showed that with the increase of solvent polarity, the fluorescence emission wavelength underwent a significant red shift (from 503 to 559 nm). Therefore, a fluorescence photometer can be used to detect the relative strength of solvent polarity. Under ultraviolet light, it is obvious to the naked eye that 2e exhibits different fluorescent colors in solvents of different polarities, which provides a way to visually identify the relative strength of solvent polarity.

8. The synthesis and application research of a cyanostilbene derivative as claimed in claim 1, characterized in that: Fluorescence response to acid / base stimulation in S5: The AN solution of 2e has a sensitive on-fluorescence response to acid stimulation. We can identify the acidity / alkalinity of the solution with the naked eye or a fluorescence spectrophotometer. Therefore, 2e can be used as a dual-recognition acid / base indicator.

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