Chromophores and their preparation methods, organic electro-optic materials and their applications

Abstract

This application relates to the field of electro-optic materials, providing a chromophore and its preparation method, as well as organic electro-optic materials and their applications. The chromophore includes a conjugated bridge and an acceptor and a donor connected to both ends of the conjugated bridge by chemical bonds, wherein the acceptor is 2-dicyanomethylene-3-cyano-4-methyl-5,5-bis(4-fluorophenyl)-2,5-dihydrofuran. The chromophore provided in this application has a high β value, as well as good chemical and thermal stability.

Description

Technical Field

[0001] This application belongs to the field of electro-optic materials technology, and particularly relates to a chromophore and its preparation method, as well as an organic electro-optic material and its application. Background Technology

[0002] Electro-optic materials are optical functional materials exhibiting electro-optic effects. Currently, the most commonly used electro-optic material in the industry is lithium niobate crystal. While its development is relatively mature, its low electro-optic coefficient (approximately 30 pm / V) and high dielectric constant limit the modulation efficiency and bandwidth of electro-optic terminal devices, which is one of the main constraints on the development of optical communication technology. Furthermore, lithium niobate is difficult to process, requiring specialized etching processes, and it is difficult to directly grow high-quality crystals on silicon wafers, resulting in high manufacturing costs for electro-optic terminal devices. Organic electro-optic materials possess advantages such as high second-order nonlinear coefficients, low dielectric constants, solution-processability, ease of integration and fabrication with silicon-based photonics integration platforms, and low processing costs. Compared to lithium niobate crystals, organic electro-optic materials have advantages in electro-optic coefficients, dielectric constants, ease of processing, process compatibility, and cost. Therefore, researching and developing promising organic electro-optic material systems is one of the urgent tasks in the current development of optical communication technology, providing new high-bandwidth, low-power information processing and transmission technologies to serve future data centers, telecommunications networks, and other applications.

[0003] Organic electro-optic materials are generally composed of polymers by doping or chemically bonding chromophore dipole molecules with high hyperpolarizability (β value). The chromophore is typically a conjugated system with an electron donor and an electron acceptor at each end, connected by a conjugated bridge structure. To enable the mixed polymer to possess electro-optic modulation capabilities, it needs to be polarized: the polymer is heated to near its glass transition temperature (Tg) and a strong DC electric field is applied, causing the chromophores in the polymer to have a certain macroscopic orientation. Then, while maintaining the electric field, the temperature is lowered to room temperature, preserving the orientation of the chromophores. After polarization treatment, the organic electro-optic material exhibits an electro-optic effect macroscopically; under the influence of an externally applied electric field, the refractive index of the organic electro-optic material changes.

[0004] Currently, high-β chromophore dipole molecules in the industry are usually based on TCF receptors substituted with trifluoromethyl (-CF3) that have a strong electron absorption capacity, namely CF3-TCF receptors. Figure 1The images show two typical push-pull tetraene chromophores (AJLZ53 and AJY-SBu) based on the strong acceptor CF3-TCF. These two chromophores represent the best-performing push-pull tetraene chromophores currently available. The preparation of this type of chromophore is typically based on a stepwise synthesis method. The synthesis process begins with modification and protection of the donor end, followed by reaction with the modified conjugated bridge, the addition of double bonds, and the extension of the main chain's conjugation length. Finally, it condenses with the strong acceptor (CF3-TCF). CF3-TCF-based push-pull tetraene chromophores exhibit high β values, which is beneficial for achieving electro-optic polymers with high electro-optic coefficients. However, CF3-TCF-based push-pull tetraene chromophores also present some challenges. Due to the presence of multiple active sites, the products are susceptible to attack by impurities, thus limiting the chemical and thermal stability of the resulting products (CF3-TCF-based chromophores and the electro-optic polymers composed of them). For example, under alkaline conditions, dipole molecules are easily decomposed and deteriorated, losing their electro-optic properties; the thermal decomposition temperature of this type of chromophore is not high, which makes the electro-optic polymer have thermal stability problems.

[0005] Therefore, how to efficiently synthesize chromophore dipole molecules with large β values, design electro-optic material systems with high stability, and obtain polarized polymer films with high electro-optic coefficients through electric field polarization are problems that the industry urgently needs to solve. Summary of the Invention

[0006] The purpose of this application is to provide a chromophore and its preparation method, as well as an organic electro-optic material containing the chromophore and its application, aiming to solve the problem that existing chromophores are difficult to have both high β value and good chemical and thermal stability.

[0007] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0008] The first aspect of this application provides a chromophore including a conjugated bridge and an acceptor and a donor connected by chemical bonds to the two ends of the conjugated bridge, wherein the acceptor is 2-dicyanomethylene-3-cyano-4-methyl-5,5-bis(4-fluorophenyl)-2,5-dihydrofuran (FP-TCF).

[0009] The chromophore provided in this application uses FP-TCF as the acceptor. FP-TCF has a strong electron acceptance ability, which is beneficial to improving the β value of the chromophore. At the same time, FP-TCF has weak reactivity with reagents such as bases and a high thermal decomposition temperature, thus improving the chemical and thermal stability of the chromophore.

[0010] In one possible implementation, the donor is a Michaelis base derivative donor or a benzo[cd]indole donor;

[0011] The structure of the Michaelis base derivative donor is shown in Formula 1A, wherein R1, R2, R3, and R4 are each independently selected from alkyl groups having 1 to 8 carbon atoms.

[0012]

[0013] The structure of the benzo[cd]indole donor is shown in Formula 2A, wherein R5 is selected from alkyl groups having 1 to 8 carbon atoms.

[0014]

[0015] The Michaelis base derivative donor shown in Formula 1A and the benzo[cd]indole donor shown in Formula 2A possess strong electron-donating capabilities and, in synergy with FP-TCF, can effectively increase the β value of the chromophore. Compared to the benzo[cd]indole donor shown in Formula 2A, the Michaelis base derivative donor shown in Formula 1A has a more significant effect on increasing the β value of the chromophore.

[0016] As one possible implementation, the conjugated bridge is a first conjugated group containing a 4,5-diphenyl-oxazol-2-ylsulfanyl substituent or a second conjugated group containing a halogen atom. The 4,5-diphenyl-oxazol-2-ylsulfanyl substituent can form a larger conjugated system, but with less π-π stacking, while the halogen atom can donate free electrons. Both conjugated groups have good electron transport capabilities, which is beneficial for transferring electrons donated by the donor to the FP-TCF acceptor. Among them, the 4,5-diphenyl-oxazol-2-thioalkyl group has significant steric hindrance. When it connects to the conjugated groups linking the acceptor and donor (the portion of the conjugated bridge excluding the 4,5-diphenyl-oxazol-2-thioalkyl group), it effectively reduces chromophore aggregation and π-π stacking of chromophore molecules. Simultaneously, the 4,5-diphenyl-oxazol-2-thioalkyl group influences weak intermolecular hydrogen bond interactions (such as CH…N or CH…Cl), increasing the polarization order parameter and giving the chromophore better orientation. Specifically, when the halogen atom is replaced by the 4,5-diphenyl-oxazol-2-thioalkyl group, the alternation of bond lengths (BLA) on the main chain changes significantly. For example, based on single-crystal data, the BLA of the structure shown in Formula 5 is... After thiol substitution, the structure BLA is shown in Formula 6. This indicates that the chromophore containing the first conjugated group with a 4,5-diphenyl-oxazol-2-thioalkyl substituent as a conjugated bridge has a stronger anthocyanin-like resonance structure, resulting in electro-optic materials with better nonlinear optical properties and a larger electro-optic coefficient.

[0017] As one possible implementation, the structure of the first conjugated group is shown in Formula 3A:

[0018]

[0019] R6 is selected from alkyl groups having 1 to 8 hydrogen atoms;

[0020] The structure of the second conjugated group is shown in Formula 4A below:

[0021]

[0022] R6 is selected from hydrogen atoms or alkyl groups having 1 to 8 carbon atoms, and X is a halogen atom.

[0023] The conjugated groups having the above structural formulas 3A and 4A contain multiple consecutive double bonds, with the double bonds on both sides connecting the acceptor and donor of the chromophore, respectively, and transferring electrons through the consecutive conjugated groups.

[0024] As one possible implementation, the chromophore is selected from at least one of the structures shown in Equations 5-8:

[0025]

[0026]

[0027] In the formula, R1, R2, R3 and R4 are each independently selected from alkyl groups having 1 to 8 carbon atoms, R6 is selected from hydrogen atoms or alkyl groups having 1 to 8 carbon atoms, and X is a halogen atom.

[0028] The chromophores shown in Formulas 5 to 8 possess extremely high β values. When combined with polymer doping or chemical bonding to form organic electro-optic materials, these high β values ​​enhance the polarization effect, resulting in improved photoelectric effects. Furthermore, the chromophores exhibiting these structures also demonstrate excellent chemical and thermal stability.

[0029] In one possible implementation, R1, R2, R3, and R4 are identical and selected from ethyl, n-propyl, n-butyl, n-pentyl, or n-hexyl; R6 is selected from H atoms, ethyl, isopropyl, or tert-butyl. The identical R1, R2, R3, and R4 provide a certain degree of symmetry in the donor structure, which is beneficial for chromophore synthesis and simplifies the synthesis process. R1, R2, R3, and R4 are selected from ethyl, n-propyl, n-butyl, n-pentyl, or n-hexyl. Because the chromophore skeleton contains many aromatic groups and has a rigid skeleton, the alkyl chain can improve the solubility of the chromophore, thus giving it solution processability. However, excessively long molecular chains will increase the molecular weight of the chromophore; that is, at the same mass percentage, the chromophore number concentration (the number of chromophores per unit volume) will decrease, and the electro-optic properties will worsen. Conversely, when the number concentration is constant, a higher doping mass will affect the polarization difficulty and film formation quality. Furthermore, choosing these groups for R1, R2, R3, and R4, compared to longer-chain alkyl groups, can reduce steric hindrance to some extent. R6 is selected from H atoms, ethyl, isopropyl, or tert-butyl. Similarly, selecting an alkyl group for R6 is beneficial for improving the solubility of the chromophore, especially when R6 is selected from tert-butyl, as the chromophore has suitable solubility and molecular weight, thus better balancing solubility and photoelectric properties.

[0030] As one possible implementation, the chromophore is selected from one of the following structures:

[0031]

[0032]

[0033] The chromophore shown in the above structure has an extremely high β value. Specifically, the chromophore has a number concentration of 1.3 × 10⁻⁶. 20 cm -3 At a wavelength of 1.3 μm, the β value reaches 8437 × 10⁻⁶. -30 ESU. When these organic electro-optic materials are formed by polymer doping or chemical bonding, the ultra-high β value is beneficial to improving the polarization effect of the organic electro-optic materials, resulting in better photoelectric effects. Furthermore, the chromophores shown in the above structures exhibit weak alkali reactivity, and their thermal decomposition temperature is above 200℃, reaching up to 281℃, demonstrating excellent chemical and thermal stability.

[0034] A second aspect of this application provides a method for preparing a chromophore, comprising the following steps:

[0035] Prepare compounds with structures as shown in Formula 1B and Formula 4B, wherein in Formula 1B, R1, R2, R3 and R4 are each independently selected from alkyl groups having 1 to 8 carbon atoms, and in Formula 4B, R6 is selected from hydrogen atoms or alkyl groups having 1 to 8 carbon atoms, and X is a halogen atom.

[0036]

[0037] Using the compound shown in Formula 9 as a starting material, trimethylcyanosilane was used as a nucleophile to prepare the intermediate 2,2-bis(4-fluorophenyl)-2-((trimethylsilyl)oxy)acetonitrile via an addition reaction. The intermediate was then reacted with methyllithium to give (1,1-bis(4-fluorophenyl)-1-((trimethylsilyl)oxy)prop-2-imideyl)aminolithium, which was hydrolyzed under acidic conditions to give the compound shown in Formula 10. Using the compound shown in Formula 10 as a starting material, malononitrile was added, and an addition-elimination reaction was carried out under sodium ethoxide catalysis to give an imine intermediate. Further reaction with malononitrile yielded the compound shown in Formula 11.

[0038]

[0039] Using the compound with the structure shown in Formula 11 and the compound with the structure shown in Formula 4B as raw materials, a condensation reaction was carried out to obtain the compound with the structure shown in Formula 12.

[0040]

[0041] Using compounds with structures as shown in Formula 12 and Formula 1B as starting materials, a condensation reaction is carried out to obtain a compound with a structure as shown in Formula 5; or using compounds with structures as shown in Formula 12 and Formula 2B as starting materials, a condensation reaction is carried out to obtain a compound with a structure as shown in Formula 7.

[0042]

[0043] The method for preparing chromophores provided in this application allows for the synthesis of the 2-dicyanomethylene-3-cyano-4-methyl-5,5-bis(4-fluorophenyl)-2,5-dihydrofuran (FP-TCF) acceptor via two consecutive multi-step one-pot reactions, achieving an overall yield of 50%, significantly higher than that of the existing CF3-TCF acceptor. Furthermore, by condensing the acceptor with a conjugate bridge, followed by condensation with the donor, the chromophore is prepared with fewer reaction steps and higher yield. In summary, the method for preparing chromophores provided in this application offers advantages such as simple process, high yield, and low cost.

[0044] As one possible implementation, when the obtained compound is the compound shown in Formula 5, the method further includes: using the compound with the structure shown in Formula 5 and the compound with the structure shown in Formula 13 as starting materials, performing a nucleophilic substitution reaction to obtain the compound with the structure shown in Formula 6.

[0045]

[0046] In this implementation, the structure shown in Formula 6 is obtained by replacing the halogen atom in the structure shown in Formula 5 with a 4,5-diphenyl-oxazol-2-thioalkyl substituent. The 4,5-diphenyl-oxazol-2-thioalkyl group has significant steric hindrance. When it connects to the conjugated group linking the acceptor and donor (the portion of the conjugated bridge other than the 4,5-diphenyl-oxazol-2-thioalkyl group), it effectively reduces chromophore aggregation and π-π stacking of chromophore molecules. Simultaneously, the 4,5-diphenyl-oxazol-2-thioalkyl group affects weak intermolecular hydrogen bond interactions (such as CH…N or CH…Cl), increasing the polarization order parameter and giving the chromophore better orientation. Specifically, when the halogen atom is replaced by the 4,5-diphenyl-oxazol-2-thioalkyl group, the alternation of bond lengths (BLA) on the main chain changes significantly. For example, according to single-crystal data, the BLA of the structure shown in Formula 5 is… After thiol substitution, the structure BLA is shown in Formula 6. This indicates that the chromophore containing the first conjugated group with a 4,5-diphenyl-oxazol-2-thioalkyl substituent as a conjugated bridge has a stronger anthocyanin-like resonance structure, resulting in a polymer material with better nonlinear optical properties and a larger electro-optic coefficient.

[0047] As one possible implementation, when the obtained compound is the compound shown in Formula 6, the method further includes: using the compound with the structure shown in Formula 7 and the compound with the structure shown in Formula 13 as starting materials, performing a nucleophilic substitution reaction to obtain the compound with the structure shown in Formula 8.

[0048]

[0049] In this implementation, the structure shown in Formula 8 is prepared by replacing the halogen atom in the structure shown in Formula 7 with a 4,5-diphenyl-oxazol-2-thioalkyl substituent. This reduces π-π stacking, and with fine-tuned bond length alternation, the nonlinear optical properties of the organic electro-optic material based on the chromophore of 2-dicyanomethylene-3-cyano-4-methyl-5,5-bis(4-fluorophenyl)-2,5-dihydrofuran (FP-TCF) are improved, resulting in a larger electro-optic coefficient.

[0050] As one possible implementation, the compound with the structure shown in Formula 1B is prepared by reacting the compound shown in Formula 14 with methyllithium to obtain the compound with the structure shown in Formula 1B, as shown in the following reaction:

[0051]

[0052] This method allows for the one-step preparation of Michaelis base derivatives represented by structural formula 1B, with a yield of up to 95%.

[0053] As one possible implementation, the compound with the structure shown in Formula 4B is prepared by reacting the compound shown in Formula 15 with phosphorus oxychloride or phosphorus oxybromide to obtain the compound with the structure shown in Formula 4B, as shown in the following reaction:

[0054]

[0055] In formulas 4B and POX3, X is a chlorine atom or a bromine atom.

[0056] A third aspect of this application provides an organic electro-optic material comprising a polymer and a chromophore, wherein the chromophore is doped in the polymer or chemically bonded to the polymer, wherein the chromophore is the chromophore described in the first aspect of this application or a chromophore obtained by the method described in the second aspect of this application.

[0057] The organic electro-optic material provided in this application has a chromophore provided in the first aspect of this application or a chromophore obtained in the second aspect of this application. Since the above-mentioned chromophore has a high β value, excellent chemical stability and thermal stability, it can improve the nonlinear optical properties of the organic electro-optic material and produce a larger electro-optic coefficient.

[0058] The fourth aspect of this application provides an electro-optical terminal device, wherein at least one component of the electro-optical terminal device contains the organic electro-optical material provided in the first aspect of this application.

[0059] The electro-optic terminal device provided in this application contains components formed of organic electro-optic materials, which enable the components to better perform electro-optical functions, thereby improving the performance of the electro-optic terminal device.

[0060] As one possible implementation, the electro-optic terminal device includes an electro-optic modulator, an electric field sensor, or a wireless signal receiver. The resulting electro-optic modulator has advantages such as low driving voltage, high bandwidth, and small size. Attached Figure Description

[0061] Figure 1 Chemical structure diagrams of two typical push-pulltetraene chromophores (AJLZ53 and AJY-SBu) based on the strong acceptor CF3-TCF provided by existing technology;

[0062] Figure 2 This is a schematic diagram of the structure of the electro-optic modulator provided in the embodiments of this application;

[0063] Figure 3 This is a process flow diagram of the preparation of chromophores provided in the embodiments of this application;

[0064] Figure 4 The two-dimensional chromophore provided in Embodiment 1 of this application is1 H- 1 H ROESY overall spectrum;

[0065] Figure 5 This application Figure 4 A magnified view of a portion of the image;

[0066] Figure 6 This is a state diagram of the organic electro-optic material formed by chromophores and polymers before and after polarization treatment, provided in the embodiments of this application.

[0067] Figure 7 These are the ultraviolet-visible-near-infrared spectra of the chromophore (M1-FP-ON, corresponding to Figure (a)) provided in Example 1 of this application and the push-pull tetraene chromophore (AJY-SBu, corresponding to Figure (b)) based on CF3-TCF.

[0068] Figure 8 This is a thermogravimetric analysis (TGA) diagram based on FP-TCF chromophores provided in the embodiments of this application. Detailed Implementation

[0069] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0070] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0071] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0072] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0073] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The singular forms "a", "the", and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0074] As used herein, "comprising", "including", "containing", "having" or other variants are intended to cover non-closed inclusion, and no distinction is made between these terms. The term "including" means that other steps and components can be added without affecting the final result. The term "including" also includes the terms "consisting of" and "consisting essentially of". The compositions and methods / processes of the present application contain, consist of, and consist essentially of the essential elements and limitations described herein, as well as any additional or optional ingredients, components, steps or limitations described herein.

[0075] The terms "first" and "second" are only used for descriptive purposes to distinguish objects such as substances from each other, and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX can also be referred to as the second XX, and similarly, the second XX can also be referred to as the first XX. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0076] The term "chromophore", also known as a coloring group, is represented in English as "chromophore";

[0077] The term "polymethines" is represented in English as "polymethines";

[0078] The term "heptamethine" is represented in English as "heptamethine";

[0079] The term "dipolar polyene" is represented in English as "dipolar polyene";

[0080] The term "β value", which is an abbreviation of "hyperpolarizability" and can also be expressed as "β value", represents hyperpolarizability;

[0081] The term "Tg", which is an abbreviation of "glass transition temperature", represents the glass transition temperature;

[0082] The term "push-pull tetraene" is represented in English as "push-pull tetraene";

[0083] The term "TGA" is an abbreviation for "thermogravimetric analysis," which refers to thermogravimetric analysis.

[0084] The term "ROESY" is an abbreviation for "rotating frame overhauser enhancement spectroscopy," which refers to the NOE spectrum in a rotating coordinate system.

[0085] The term "DMSO" is an abbreviation for "dimethyl sulfoxide," which stands for dimethyl sulfoxide.

[0086] The term "P(S-co-MMA)" is an abbreviation for "poly(styrene-co-methyl methacrylate)," which represents methyl methacrylate-styrene copolymer.

[0087] The term "MZ" is an abbreviation for "Mach-Zehnder".

[0088] The term "FP" stands for bis(4-fluorophenyl);

[0089] The term "TCF" is an abbreviation for "(2-dicyanomethylidene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran)," which stands for 2-dicyanomethylidene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran.

[0090] Organic electro-optic materials possess advantages such as high second-order nonlinear coefficients, low dielectric constants, solution-processability, ease of integration with silicon-based photonics platforms, and low fabrication costs. They are among the key optoelectronic functional materials for designing and developing next-generation high-bandwidth, low-drive-voltage high-speed electro-optic modulation and optical switching devices. By doping or chemically bonding chromophores with high β values ​​into polymers, organic electro-optic materials, also known as electro-optic polymers, can be formed. After polarization treatment, organic electro-optic materials exhibit electro-optic effects and can be used to realize electro-optic terminal devices based on organic electro-optic materials, applicable to future data centers, telecommunications networks, and other systems.

[0091] In one possible implementation, the electro-optic terminal device can be an electro-optic modulator, an electric field sensor, or a wireless signal receiver. An organic electro-optic material composed of chromophores doped or chemically bonded to a polymer is used to fabricate at least one component of the electro-optic terminal device. For example, the organic electro-optic material composed of chromophores doped or chemically bonded to a polymer is used to fabricate the phase shifter of the electro-optic modulator; the organic electro-optic material composed of chromophores doped or chemically bonded to a polymer is used to fabricate the electro-optic conversion region of the electric field sensor; and the organic electro-optic material composed of chromophores doped or chemically bonded to a polymer is used to fabricate the electro-optic conversion region of the wireless signal receiver.

[0092] In one implementation, an electro-optic modulator is used as an example for illustration. (Reference) Figure 2 The electro-optic modulator has a Mach-Zehnder interferometer structure. An electro-optic polymer based on chromophores is applied to the Mach-Zehnder interferometer to form at least one arm, used to modulate the optical signal, thus forming the modulation region of the electro-optic modulator. The effective refractive index of the waveguide in this region can be affected by the electric field applied to the electrodes, changing the phase of the optical signal in that arm. This alters the intensity or phase of the optical signal at the output end, achieving the conversion from electrical to optical signals. Besides the Mach-Zehnder interferometer structure, electro-optic modulators based on electro-optic polymers can also be implemented using optical structures such as microring resonators, Fabry-Perot (FP) resonators, and photonic crystals.

[0093] The following provides a detailed description of organic electro-optic materials. Organic electro-optic materials include polymers. As the main component of organic electro-optic materials, polymers, after being doped with or chemically bonded to chromophores, exhibit electro-optic effects upon polarization. These polymers can be used to obtain high-bandwidth, high-efficiency, and low-cost electro-optic terminal devices based on organic electro-optic materials. This application does not specify the polymer used in the organic electro-optic materials; polymers known in the field of organic electro-optic materials can be used. For example, the polymer is P(S-co-MMA).

[0094] Organic electro-optic materials also include chromophores. Chromophores and polymers together constitute the components of organic electro-optic materials. They can be blended through physical doping or combined through chemical bonding to form organic compound systems. Chromophores are generally conjugated systems with an electron donor and an electron acceptor at each end, connected by a conjugated bridge structure. That is, a chromophore includes a conjugated bridge and the acceptor and donor connected at both ends of the bridge by chemical bonds. The β value, thermal stability, and chemical stability of chromophores are important indicators characterizing their performance. Currently, representative high-performance chromophores in the industry include the push-pulltetraene chromophores AJLZ53 and AJY-SBu, based on the strong acceptor CF3-TCF. These two types of chromophores have high β values, which can endow organic electro-optic materials with good electro-optic properties. However, their preparation processes are complex, and their stability, such as chemical and thermal stability, is relatively poor. In view of this, embodiments of this application provide a chromophore molecule with a high β value, good chemical and thermal stability, and high synthesis yield, which is applied to the synthesis of organic electro-optic materials with high electro-optic coefficients, high stability, and low cost, thereby realizing high bandwidth, high efficiency, and low cost electro-optic terminal devices based on organic electro-optic materials.

[0095] Specifically, the chromophore is heptamethrin, and it uses 2-dicyanomethylene-3-cyano-4-methyl-5,5-bis(4-fluorophenyl)-2,5-dihydrofuran (hereinafter referred to as FP-TCF) as its receptor, i.e., the FP-TCF receptor. The structure of FP-TCF is shown below:

[0096]

[0097] FP-TCF has strong electron-accepting ability, which is beneficial to improving the β value of chromophores. At the same time, FP-TCF has weak reactivity with reagents such as bases and high thermal decomposition temperature, thus improving the chemical and thermal stability of chromophores.

[0098] As one possible implementation, the chromophore donor provided in this application is a Michaelis base derivative donor or a benzo[cd]indole donor. Specifically, the structure of the Michaelis base derivative donor is shown in Formula 1A below, wherein R1, R2, R3, and R4 are each independently selected from alkyl groups having 1 to 8 carbon atoms.

[0099]

[0100] The structure of the benzo[cd]indole donor is shown in Formula 2A, where R5 is selected from alkyl groups having 1 to 8 carbon atoms.

[0101]

[0102] The Michler's base derivatives donors shown in Formula 1A and the benzo[cd]indoline donors shown in Formula 2A possess strong electron-donating capabilities and, synergistically with FP-TCF, can effectively increase the β value of the chromophore. Compared to the benzo[cd]indoline donor shown in Formula 2A, the Michler's base derivatives donors shown in Formula 1A have a more significant effect on increasing the β value of the chromophore. It should be understood that the structures of the Michler's base derivatives donors shown in Formula 1A and the benzo[cd]indoline donors shown in Formula 2A show their binding sites with conjugated bridges. The original structures of the Michler's base derivatives donors shown in Formula 1A and the benzo[cd]indoline donors shown in Formula 2A are shown in Formula 1B and Formula 2B, respectively:

[0103]

[0104] In the above structural formulas 1A and 1B, R1, R2, R3, and R4 are each selected from alkyl groups having 1 to 8 carbon atoms; similarly, in formulas 2A and 2B, R5 is selected from alkyl groups having 1 to 8 carbon atoms. This is because chromophores contain a large number of aromatic groups, which form a rigid framework. By introducing alkyl groups, the solubility of the chromophore is improved, thereby giving the chromophore solution processability. However, excessively long molecular chains will increase the molecular weight of the chromophore, that is, at the same mass percentage, the number concentration of the chromophore (the number of chromophores per unit volume) will decrease, and the electro-optical performance will worsen; while when the number concentration is constant, the doping mass becomes higher, and the polarization difficulty and film formation quality will be affected. Therefore, in the embodiments of this application, R1, R2, R3, and R4 in formulas 1A and 1B, and R5 in formulas 2A and 2B are all selected from alkyl groups having 1 to 8 carbon atoms.

[0105] In one possible implementation, R1, R2, R3, and R4 are the same in the structures shown in Formula 1A and Formula 1B, which makes the Michaelis base derivative donor structure shown in Formula 1B have a certain degree of symmetry, which is beneficial to simplifying the synthesis process of chromophores.

[0106] In one possible implementation, R1, R2, R3, and R4 are selected from ethyl, n-propyl, n-butyl, n-pentyl, or n-hexyl. These alkyl chains can improve the solubility of the chromophore, thereby giving the chromophore solution processability, and can balance the electro-optic properties, polarization difficulty, and film quality of the chromophore. Furthermore, compared to longer-chain alkyl groups, selecting these groups for R1, R2, R3, and R4 can also reduce steric hindrance to some extent. For example, the Michaelis base derivative shown in Formula 1B can be selected from the following structures:

[0107]

[0108] In one possible implementation, in the structure shown in Formula 2A or Formula 2B, R5 is selected from ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, or 2-ethylhexyl, ensuring good solubility of the chromophore and balancing the electro-optic properties, polarization difficulty, and film quality of the chromophore. For example, the benzo[cd]indole shown in Formula 2B can be selected from the following structures:

[0109]

[0110] In the embodiments of this application, the chromophore's acceptor and donor are bonded via a conjugated bridge. In one possible implementation, the conjugated bridge is a first conjugated group containing a 4,5-diphenyl-oxazol-2-ylsulfanyl group. The 4,5-diphenyl-oxazol-2-ylsulfanyl group increases the volume of the first conjugated group but reduces π-π stacking, which is beneficial for transferring electrons provided by the donor to the FP-TCF acceptor.

[0111] In some embodiments, the structure of the first conjugated group is shown in Formula 3A:

[0112]

[0113] R6 is selected from alkyl groups having 1 to 8 hydrogen atoms or carbon atoms.

[0114] The aforementioned conjugated structure contains a 4,5-diphenyl-oxazol-2-thioalkyl substituent. The 4,5-diphenyl-oxazol-2-thioalkyl group has significant steric hindrance. When it connects to the conjugated groups linking the acceptor and donor (the portion of the conjugated bridge excluding the 4,5-diphenyl-oxazol-2-thioalkyl group), it effectively reduces chromophore aggregation and π-π stacking of chromophore molecules. Simultaneously, the 4,5-diphenyl-oxazol-2-thioalkyl group influences weak intermolecular hydrogen bond interactions (such as CH...N or CH...Cl), increasing the polarization order parameter and giving the chromophore better orientation. Specifically, when the halogen atom is replaced by the 4,5-diphenyl-oxazol-2-thioalkyl group, the alternation of bond lengths (BLA) on the main chain changes significantly. For example, based on single-crystal data, the BLA of the structure shown in Formula 5 is... After thiol substitution, the structure BLA is shown in Formula 6. This indicates that the chromophore containing the first conjugated group with a 4,5-diphenyl-oxazol-2-thioalkyl substituent as a conjugated bridge has a stronger anthocyanin-like resonance structure, resulting in electro-optic materials with better nonlinear optical properties and a larger electro-optic coefficient.

[0115] It should be understood that the structure of the first conjugated group shown in Formula 3A above reveals two binding sites for its binding to the acceptor and donor.

[0116] In one possible implementation, R6 is selected as an alkyl group, which is beneficial for improving the solubility of the chromophore. For example, when R6 is selected as tert-butyl, the chromophore has suitable solubility and molecular weight, thereby better balancing solubility and photoelectric properties.

[0117] In another possible implementation, the conjugated bridge is a second conjugated group containing a halogen atom, which can provide free electrons, facilitating the transfer of electrons provided by the donor to the FP-TCF acceptor.

[0118] In some embodiments, the structure of the second conjugated group is shown in Formula 4A:

[0119]

[0120] R6 is selected from hydrogen atoms or alkyl groups having 1 to 8 carbon atoms, and X is a halogen atom.

[0121] The above conjugated structure contains halogen atoms, which have a certain electron-withdrawing ability, thus affecting the push-pull structure of the main chain. Furthermore, halogen atoms are active groups and can undergo further reactions. Chromophores can be modified by replacing halogen atoms with different thiol groups. For example, replacing X in 4A with a 4,5-diphenyl-oxazol-2-thioalkyl substituent, i.e., modifying Formula 5 with 4,5-diphenyl-oxazol-2-thioalkyl, yields Formula 6, which improves both solubility and electro-optic properties. It should be understood that the structure of the first conjugated group shown in Formula 4A above shows its two binding sites for the acceptor and donor. The original structure of the first conjugated group shown in Formula 4A above is shown in Formula 4B:

[0122]

[0123] R6 is selected from hydrogen atoms or alkyl groups having 1 to 8 carbon atoms, and X is a halogen atom.

[0124] In one possible implementation, the halogen atom can be either a chlorine atom or a bromine atom. For example, X is a chlorine atom, which is advantageous for preparation and processing. This is because dialdehydes are obtained via the Vilsmeier-Haack reaction, typically using phosphorus oxychloride. Phosphorus oxychloride is a liquid, while phosphorus oxybromide is a solid; the liquid has the advantage of being easy to handle due to the stepwise addition during the experiment. Furthermore, compared to bromine, chlorine atoms have a lower molecular weight and a lower doping percentage for halogen-containing chromophores; therefore, chlorine is the preferred atom for X in this application.

[0125] In one possible implementation, R6 is selected from a hydrogen atom or a tert-butyl group; when R6 is selected from a tert-butyl group, the solubility of the chromophore can be effectively improved. For example, the compound corresponding to the second conjugated group of formula 4B can be selected from the following structures:

[0126]

[0127] The conjugated group with the above structural formula 4B contains multiple consecutive double bonds, with the double bonds on both sides connecting the acceptor and donor of the chromophore, respectively, and transferring electrons through the consecutive conjugated groups. Furthermore, the introduction of 4,5-diphenyl-oxazol-2-thioalkyl substituents or halogen atoms further enhances the electron transfer capability.

[0128] In one possible implementation, the chromophore is selected from at least one of the structures shown in Formulas 5-8:

[0129]

[0130]

[0131] In the formula, R1, R2, R3 and R4 are each independently selected from alkyl groups having 1 to 8 carbon atoms, R6 is selected from hydrogen atoms or alkyl groups having 1 to 8 carbon atoms, and X is a halogen atom.

[0132] The chromophores shown in Formulas 5 to 8 possess extremely high β values. When combined with polymer doping or chemical bonding to form organic electro-optic materials, these high β values ​​enhance the polarization effect, resulting in improved photoelectric effects. Furthermore, the chromophores exhibiting these structures also demonstrate excellent chemical and thermal stability.

[0133] As one possible implementation, in the above structural formulas 5 and 6, R1, R2, R3, and R4 are the same and selected from ethyl, n-propyl, n-butyl, n-pentyl, or n-hexyl. The identical R1, R2, R3, and R4 give the donor structure a certain degree of symmetry, which is beneficial for the synthesis of chromophores and simplifies the synthesis process. For example, R1, R2, R3, and R4 are selected from ethyl, n-propyl, n-butyl, n-pentyl, or n-hexyl, giving the chromophore suitable solubility and molecular weight. Since the chromophore skeleton contains many aromatic groups and has a rigid skeleton, the alkyl chain can improve the solubility of the chromophore, thus giving it solution processability. However, excessively long molecular chains will increase the molecular weight of the chromophore; that is, at the same mass percentage, the number concentration of chromophores (the number of chromophores per unit volume) will decrease, and the electro-optical performance will worsen. Conversely, when the number concentration is constant, a higher doping mass will affect the polarization difficulty and film formation quality. In addition, choosing these groups for R1, R2, R3, and R4, compared to longer-chain alkyl groups, can also reduce steric hindrance to some extent.

[0134] In the above structural formulas 7 and 8, R5 is selected from larger alkyl chains such as 2-ethylhexyl to improve the solubility of the chromophore.

[0135] In formulas 5 to 8 above, R6 is selected from tert-butyl to improve the solubility of the chromophore. In formulas 5 and 7 above, X is selected from a chlorine atom, which is beneficial for preparation and processing. This is because dialdehydes are obtained through the Vilsmeier-Haack reaction, which generally uses phosphorus oxychloride. Phosphorus oxychloride is a liquid, while phosphorus oxybromide is a solid. Due to the stepwise addition during the experiment, the liquid has the advantage of being easy to handle. In addition, compared with bromine, chlorine has a lower molecular weight, resulting in a lower doping mass percentage for halogen-containing chromophores. Therefore, in this application, chlorine is the preferred atom for X.

[0136] As one possible implementation, the chromophore is selected from one of the following structures:

[0137]

[0138]

[0139] The chromophore shown in the above structure has an extremely high β value. Specifically, the chromophore has a number concentration of 1.3 × 10⁻⁶. 20 cm -3 At a wavelength of 1.3 μm, the β value reaches 8437 × 10⁻⁶. -30 ESU. When these organic electro-optic materials are formed by polymer doping or chemical bonding, the ultra-high β value is beneficial to improving the polarization effect of the organic electro-optic materials, resulting in better photoelectric effects. Furthermore, the chromophores shown in the above structures exhibit weak alkali reactivity, and their thermal decomposition temperature is above 200℃, reaching up to 281℃, demonstrating excellent chemical and thermal stability.

[0140] Push-pull tetraene chromophores based on CF3-TCF not only suffer from poor stability but also present a difficult synthesis process. Both the donor and the conjugate bridge require prior modification before the reaction can proceed, resulting in a lengthy process often requiring more than ten steps to obtain the final product, consuming significant time. Some steps require palladium noble metal catalysts, increasing synthesis costs. Furthermore, the purification of intermediate and final products is difficult, leading to low yields and failing to meet the basic requirements for continuous basic research, large-scale material processing optimization, and device fabrication. Therefore, this application provides a relatively simple method for preparing the aforementioned chromophores. The method for preparing chromophores provided in this application can employ a continuous synthesis approach with fewer reaction steps, a shorter cycle time, higher yields, lower operating condition requirements, and good reaction reproducibility, facilitating large-scale applications. Moreover, the synthesis of chromophores does not require noble metal catalysts, thus reducing production costs. Therefore, this application provides a method for preparing chromophores based on the aforementioned FP-TCF to achieve a simplified synthesis process.

[0141] Specifically, in combination Figure 3 The method for preparing chromophores provided in this application includes the following steps:

[0142] S10. Prepare compounds with structures as shown in Formula 1B and Formula 4B, wherein in Formula 1B, R1, R2, R3 and R4 are each independently selected from alkyl groups having 1 to 8 carbon atoms, and in Formula 4B, R6 is selected from hydrogen atoms or alkyl groups having 1 to 8 carbon atoms, and X is a halogen atom.

[0143]

[0144] In this step, the compound with the structure shown in Formula 1B serves as the donor for preparing the chromophore. After binding to the conjugate bridge, it forms the structure shown in Formula 1A above. The compound with the structure shown in Formula 4B serves as the conjugate bridge for preparing the chromophore. After binding to the donor and acceptor, it forms the structure shown in Formula 4A above. In the embodiments of this application, the order of preparation of the compounds shown in Formula 1B and Formula 4B is not limited.

[0145] In this embodiment, the selection of R1, R2, R3 and R4 in the compound shown in Formula 1B, and the example compound of the compound shown in Formula 1B; the selection of R6 and X in the compound shown in Formula 4B, and the example compound of the compound shown in Formula 4B, as described above, will not be repeated here for the sake of brevity.

[0146] In one possible embodiment, the compound with the structure shown in Formula 1B is prepared by reacting the compound shown in Formula 14 with methyllithium to obtain the compound with the structure shown in Formula 1B, as shown in the following reaction:

[0147]

[0148] This method allows for the one-step preparation of Michaelis base derivatives represented by structural formula 1B, with a yield of up to 95%.

[0149] In one possible embodiment, the compound with the structure shown in Formula 4B is prepared by reacting the compound shown in Formula 15 with phosphorus oxychloride or phosphorus oxybromide to obtain the compound with the structure shown in Formula 4B, as shown in the following reaction:

[0150]

[0151] In formulas 4B and POX3, X is a chlorine atom or a bromine atom.

[0152] S20. Using the compound with the structure shown in Formula 9 as a starting material, trimethylcyanosilane is used as a nucleophile to prepare the intermediate 2,2-bis(4-fluorophenyl)-2-((trimethylsilyl)oxy)acetonitrile by addition reaction. Methyllithium is added to give (1,1-bis(4-fluorophenyl)-1-((trimethylsilyl)oxy)prop-2-imideyl)aminolithium, which is then hydrolyzed under acidic conditions to give the compound with the structure shown in Formula 10. Using the compound with the structure shown in Formula 10 as a starting material, malononitrile is added, and an addition-elimination reaction is carried out under the catalysis of sodium ethoxide to give an imine intermediate. Further addition of malononitrile yields the compound with the structure shown in Formula 11.

[0153]

[0154] This step involves the synthesis of the FP-TCF receptor (Formula 11) via two consecutive multi-step one-pot reactions. In some embodiments, the reaction steps of the compound represented by Formula 11 are as follows:

[0155]

[0156] For example, using a compound with the structure shown in Formula 9 as a starting material, lithium chloride and tetrahydrofuran were added under ice bath conditions, followed by the dropwise addition of trimethylsilane cyanide. The reaction was carried out at 50°C for about 3 hours to form the intermediate 2,2-bis(4-fluorophenyl)-2-((trimethylsilyl)oxy)acetonitrile. The ice bath was then restored, methyl lithium was added, and the reaction was allowed to return to room temperature for 3 hours to obtain (1,1-bis(4-fluorophenyl)-1-((trimethylsilyl)oxy)prop-2-imideyl)aminolithium. Subsequently, 50% hydrochloric acid solution was added dropwise, and the reaction was refluxed overnight to hydrolyze (1,1-bis(4-fluorophenyl)-1-((trimethylsilyl)oxy)prop-2-imideyl)aminolithium. The resulting product was purified by column chromatography to obtain the compound with the structure shown in Formula 10. Using the compound shown in Formula 10 as a starting material, an equivalent of malononitrile was added to undergo an addition-elimination reaction with the carbonyl group. Catalyzed by sodium ethoxide, an imine intermediate was obtained. This intermediate then reacted with an equivalent of malononitrile to remove an ammonia molecule, followed by column chromatography purification to yield the compound with the structure shown in Formula 11. Exemplarily, the reflux reaction time for adding malononitrile and sodium ethoxide was one day. This method synthesized the FP-TCF receptor via two consecutive one-pot processes, achieving an overall yield of approximately 50%, significantly higher than that of the CF3-TCF receptor.

[0157] S30. Using the compound with the structure shown in Formula 11 and the compound with the structure shown in Formula 4B as raw materials, a condensation reaction is carried out to obtain the compound with the structure shown in Formula 12.

[0158]

[0159] In this step, the compound shown in Formula 11 and the compound with the structure shown in Formula 4B undergo a condensation reaction to obtain the compound shown in Formula 12, as shown below. The yield of this step is approximately 87%.

[0160]

[0161] S40. Using the compound with the structure shown in Formula 12 and the compound with the structure shown in Formula 1B as starting materials, a condensation reaction is carried out to obtain the compound with the structure shown in Formula 5; or using the compound with the structure shown in Formula 12 and the compound with the structure shown in Formula 2B as starting materials, a condensation reaction is carried out to obtain the compound with the structure shown in Formula 7.

[0162]

[0163] This step involves two methods to prepare the structures shown in Formula 5 and Formula 7, respectively, with a yield of approximately 78%.

[0164] In one possible implementation, a condensation reaction is carried out using a compound with the structure shown in Formula 12 and a compound with the structure shown in Formula 1B as starting materials to obtain a compound with the structure shown in Formula 5. The reaction formula for this step is shown below.

[0165]

[0166] In another possible implementation, a condensation reaction is carried out using a compound with the structure shown in Formula 12 and a compound with the structure shown in Formula 2B as starting materials to obtain a compound with the structure shown in Formula 7. The reaction formula for this step is shown below:

[0167]

[0168] In one possible implementation, the compound with the structure shown in Formula 5 or Formula 7 is subjected to nucleophilic substitution to prepare a chromophore containing a 4,5-diphenyl-oxazol-2-thioalkyl substituent, with a yield of approximately 68%.

[0169] In one embodiment, when the obtained compound is the compound shown in Formula 5, the method further includes: using the compound with the structure shown in Formula 5 and the compound with the structure shown in Formula 13 as starting materials, performing a nucleophilic substitution reaction to obtain the compound with the structure shown in Formula 6.

[0170]

[0171] The nucleophilic substitution reaction between the compound shown in Formula 5 and the compound shown in Formula 13 to give the compound shown in Formula 6 is shown below:

[0172]

[0173] In this implementation, the structure shown in Formula 6 is obtained by replacing the halogen atom in the structure shown in Formula 5 with a 4,5-diphenyl-oxazol-2-thioalkyl substituent. The 4,5-diphenyl-oxazol-2-thioalkyl group has significant steric hindrance. When it connects to the conjugated group linking the acceptor and donor (the portion of the conjugated bridge other than the 4,5-diphenyl-oxazol-2-thioalkyl group), it effectively reduces chromophore aggregation and π-π stacking of chromophore molecules. Simultaneously, the 4,5-diphenyl-oxazol-2-thioalkyl group affects weak intermolecular hydrogen bond interactions (such as CH…N or CH…Cl), increasing the polarization order parameter and giving the chromophore better orientation. Specifically, when the halogen atom is replaced by the 4,5-diphenyl-oxazol-2-thioalkyl group, the alternation of bond lengths (BLA) on the main chain changes significantly. For example, according to single-crystal data, the BLA of the structure shown in Formula 5 is… After thiol substitution, the structure BLA is shown in Formula 6. This indicates that the chromophore containing the first conjugated group with a 4,5-diphenyl-oxazol-2-thioalkyl substituent as a conjugated bridge has a stronger anthocyanin-like resonance structure, resulting in a polymer material with better nonlinear optical properties and a larger electro-optic coefficient.

[0174] In another embodiment, when the compound obtained is the compound shown in Formula 6, the method further includes: using the compound with the structure shown in Formula 7 and the compound with the structure shown in Formula 13 as raw materials, performing a nucleophilic substitution reaction to obtain the compound with the structure shown in Formula 6.

[0175] The compound shown in Formula 8,

[0176]

[0177] The nucleophilic substitution reaction between the compound with the structure shown in Formula 7 and the compound with the structure shown in Formula 13 to give the compound with the structure shown in Formula 8 is shown below:

[0178]

[0179] The chromophore preparation method provided in this application allows for the synthesis of the 2-dicyanomethylene-3-cyano-4-methyl-5,5-bis(4-fluorophenyl)-2,5-dihydrofuran (FP-TCF) acceptor via two consecutive multi-step one-pot reactions, achieving an overall yield of 50%, significantly higher than that of the existing CF3-TCF acceptor. Furthermore, by condensing the acceptor with a conjugate bridge and then with the donor to prepare the chromophore, the number of reaction steps is reduced, and the yield is high. In summary, the chromophore preparation method provided in this application offers advantages such as simple process, high yield, and low cost.

[0180] The chromophores prepared using the embodiments of this application have ultra-high β values ​​(exceeding two industry-leading but difficult-to-synthesize push-pull tetraene chromophores based on CF3-TCF acceptors), good chemical and thermal stability, and can be used to synthesize organic electro-optic materials with high electro-optic coefficients, high stability, and low cost, thereby realizing high-bandwidth, high-efficiency, and low-cost electro-optic terminal devices based on organic electro-optic materials.

[0181] The following description is based on specific embodiments.

[0182] Example 1

[0183] A chromophore, based on the heptamethrin chromophore molecular structure of the bis(4-fluorophenyl)(FP)-substituted TCF (2-dicyanomethylene-3-cyano-4-methyl-5,5-bis(4-fluorophenyl)-2,5-dihydrofuran) receptor (i.e., FP-TCF receptor), is shown below:

[0184]

[0185] The preparation method of this chromophore is as follows: first, the donor, conjugate bridge, and acceptor are synthesized separately, then assembled; next, the acceptor and conjugate bridge are condensed, followed by condensation with the donor; finally, the chromophore is modified by adding a side chain. The reaction flow of each step in the preparation process is as follows:

[0186]

[0187] Existing chromophores based on push-pull tetraenes require 11 reaction steps, with an overall yield of less than 10%, and generate flammable materials during synthesis. In contrast, the chromophore synthesis process described above involves only 7 steps, achieving an overall yield of 25%, and avoids the use of flammable materials such as tert-butyllithium. Furthermore, the synthesis of the FP-TCF acceptor can be achieved through two consecutive multi-step one-pot reactions, with an overall yield of 50%, significantly higher than that of the existing CF3-TCF acceptor. Therefore, the chromophore preparation process provided in this application offers advantages of high yield and low cost.

[0188] The chromophore obtained in Example 1 was subjected to spectral analysis, and its two-dimensional... 1 H- 1 The overall spectrum and its magnified local images of the H ROESY (rotating frameoverhauser enhancement spectroscopy) spectrum (NOE spectrum in a rotating coordinate system) are shown below. Figure 4 and Figure 5 As shown, the chromophore dissolves in CDCl3 during measurement.

[0189] The chromophore provided in Example 1 was combined with a polymer through doping or chemical bonding to form an organic electro-optic material. This organic electro-optic material was then polarized to impart a photoelectric effect. For example... Figure 6 As shown in the figure, (a) represents the state of the organic electro-optic material before polarization, and (b) represents the state of the organic electro-optic material after polarization. As can be seen from the figure, before polarization, the orientation of the chromophore molecules is random; after polarization, the chromophore molecules exhibit a certain orientation on a macroscopic scale, enabling the organic electro-optic material to have an electro-optic effect as a whole.

[0190] The chromophore provided in Example 1 was subjected to performance testing, including the following index detection:

[0191] (1) The performance of the chromophore provided in Example 1 (hereinafter referred to as M1-FP-ON) and two push-pull tetraene chromophores based on CF3-TCF (hereinafter referred to as AJLZ53 and AJY-SBu, respectively) was determined. The specific test method is as follows: The chromophore and polymer were mixed at a certain mass ratio, dissolved and mixed with an organic solvent, and a film was spin-coated onto ITO conductive glass. After vacuum drying, gold was plated as the positive electrode and ITO as the negative electrode to prepare the device. An electric field of 100V / μm was applied, and the temperature was programmed to rise until the polymer reached T. g Near the surface, the current increases sharply. When the current increase slows down, the temperature drops while maintaining the voltage, and polarization ends. The refractive index of the film under different electric fields was measured using a prism coupler, and parameters such as the electro-optic coefficient were calculated based on the refractive index. The electro-optic coefficients and β values ​​of the chromophore provided in Example 1 (hereinafter referred to as M1-FP-ON) and two push-pull tetraene chromophores based on CF3-TCF (hereinafter referred to as AJLZ53 and AJY-SBu, respectively) are shown in Table 1 below. It should be understood that, for comparison, the chromophore was mixed with the polymer poly(styrene-co-methyl methacrylate) (P(S-co-MMA)) and polarized under the same conditions. In Table 1, N is the number concentration, λ... max n is the wavelength of maximum absorption of the thin film. TE and n TM For thin film birefringence, r 33 Electro-optic coefficients at 1.3 μm and 1.54 μm, Φ is the order parameter, and β... μ (-ω; ω, 0) represents the hyperpolarizability. Specifically, Example 1 of this application provides detection results for the M1-FP-ON at three different concentrations, while AJLZ53 provides detection results at two different concentrations.

[0192] Table 1

[0193]

[0194] As shown in Table 1, the electro-optic material formed by the chromophores provided in Example 1 of this application, at a concentration of 1.3 × 10⁻⁶, exhibits good performance. 20 cm -3 The electro-optic coefficient of the electro-optic polymer at a wavelength of 1.3 μm reaches 126.8 pm / V, and the β value reaches 8437 × 10⁻⁶. -30 esu. At the same mixing concentration, the chromophore of Example 1 exhibits the highest β value, exceeding the best-performing push-pull tetraene chromophores currently available using the strong electron acceptor CF3-TCF (AJLZ53 and AJY-SBu).

[0195] (2) Chemical stability analysis: M1-FP-ON and tetraene molecule AJY-SBu were placed in DMSO (dimethyl sulfoxide) solvent and UV-vis-NIR (ultraviolet-visible-near-infrared) spectra were measured. Figure 7 The figure shows a comparison of the chemical stability of the chromophore (M1-FP-ON, corresponding to Figure (a)) in Example 1 and the push-pull tetraene chromophore (AJY-SBu, corresponding to Figure (b)) under alkaline conditions. As can be seen from the figure, after 5 minutes, the maximum absorption peak of AJY-SBu decreased by 26%, while the absorption at shorter wavelengths increased, indicating that AJY-SBu had decomposed. In contrast, the absorption of M1-FP-ON remained almost unchanged, demonstrating that it exhibits higher chemical stability under alkaline conditions compared to AJY-SBu.

[0196] (3) Thermal stability analysis: Figure 8 The results of thermogravimetric analysis (TGA) for various FP-TCF-based chromophores are shown. As can be seen from the figure, the decomposition temperature of this type of chromophore is higher than 200℃, with the decomposition temperature of chromophore M1-FP-ON in Example 1 being 233℃. It is evident that the thermal decomposition temperature of the chromophores provided in Example 1 is generally 40-60℃ higher than that of the push-pull tetraene chromophores based on CF3-TCF.

[0197] Example 2

[0198] A chromophore, denoted as M1-FP, is based on the heptamethrin chromophore molecular structure of the bis(4-fluorophenyl)(FP)-substituted TCF receptor (i.e., FP-TCF receptor), and its molecular structure is shown below:

[0199]

[0200] Compared to Example 1, which contains a conjugated bridge structure with a 4,5-diphenyl-oxazol-2-thioalkyl substituent, Example 2 omits the last step, thus reducing the number of synthesis steps and increasing the synthesis yield.

[0201] Example 3

[0202] A chromophore, based on the heptamethrin chromophore molecular structure of the bis(4-fluorophenyl)(FP)-substituted TCF receptor (i.e., FP-TCF receptor), is denoted as M1-FP-C6, and its molecular structure is shown below:

[0203]

[0204] Compared to Example 2, the donor provided in Example 3 contains multiple hexyl groups, which can be dissolved in more organic solvents, improve the solubility of chromophores, and facilitate processing and characterization.

[0205] Example 4

[0206] A chromophore, based on the heptamethrin chromophore molecular structure of the bis(4-fluorophenyl)(FP)-substituted TCF receptor (i.e., FP-TCF receptor), is denoted as F3-FP-ON, and its molecular structure is shown below:

[0207]

[0208] Example 4 uses benzo[cd]indoline as the electron donor for the chromophore. Compared to Example 1, which uses a Michaelis base derivative as the donor, the chromophore provided in Example 4 can increase the thermal decomposition temperature of the chromophore. Figure 8 As shown, the decomposition temperature of chromophore M1-FP-ON is 233℃, while the decomposition temperature of chromophore F3-FP-ON in this embodiment 4 reaches 281℃.

[0209] Example 5

[0210] A chromophore, denoted as F3-FP, is based on the heptamethrin chromophore molecular structure of the bis(4-fluorophenyl)(FP)-substituted TCF receptor (i.e., FP-TCF receptor), and its molecular structure is shown below:

[0211]

[0212] Compared to Example 4, Example 5 uses a conjugated bridge structure containing chlorine atoms. Compared to the conjugated bridge structure with 4,5-diphenyl-oxazol-2-thioalkyl substituents, it can reduce one synthesis step and improve the synthesis yield.

[0213] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A chromophore comprising a conjugated bridge, and an acceptor and a donor connected by chemical bonds at both ends of the conjugated bridge, respectively, characterized in that, The acceptor is 2-dicyanomethylene-3-cyano-4-methyl-5,5-bis(4-fluorophenyl)-2,5-dihydrofuran; the chromophore is selected from at least one of the structures shown in Formulas 5-8 below: In the formula, R1, R2, R3 and R4 are each independently selected from alkyl groups having 1 to 8 carbon atoms, R5 is selected from alkyl groups having 1 to 8 carbon atoms, R6 is selected from hydrogen atoms or alkyl groups having 1 to 8 carbon atoms, and X is a halogen atom.

2. The chromophore of claim 1, wherein, R1, R2, R3, and R4 are identical and selected from ethyl, n-propyl, n-butyl, n-pentyl, or n-hexyl; R6 is selected from H atoms, ethyl, isopropyl, or tert-butyl.

3. The chromophore as described in any one of claims 1 to 2, characterized in that, The chromophore is selected from one of the following structures: 。 4. A method for preparing a chromophore as described in any one of claims 1 to 3, characterized in that, Includes the following steps: Prepare compounds with structures as shown in Formula 1B and Formula 4B, wherein in Formula 1B, R1, R2, R3 and R4 are each independently selected from alkyl groups having 1 to 8 carbon atoms, and in Formula 4B, R6 is selected from hydrogen atoms or alkyl groups having 1 to 8 carbon atoms, and X is a halogen atom. Using the compound shown in Formula 9 as a starting material, trimethylcyanosilane was used as a nucleophile to prepare the intermediate 2,2-bis(4-fluorophenyl)-2-((trimethylsilyl)oxy)acetonitrile via an addition reaction. The intermediate was then reacted with methyllithium to give (1,1-bis(4-fluorophenyl)-1-((trimethylsilyl)oxy)prop-2-imideyl)aminolithium, which was hydrolyzed under acidic conditions to give the compound shown in Formula 10. Using the compound shown in Formula 10 as a starting material, malononitrile was added, and an addition-elimination reaction was carried out under sodium ethoxide catalysis to give an imine intermediate. Further reaction with malononitrile yielded the compound shown in Formula 11. Using the compound with the structure shown in Formula 11 and the compound with the structure shown in Formula 4B as raw materials, a condensation reaction was carried out to obtain the compound with the structure shown in Formula 12. Using compounds with structures as shown in Formula 12 and Formula 1B as starting materials, a condensation reaction is carried out to obtain a compound with a structure as shown in Formula 5; or using compounds with structures as shown in Formula 12 and Formula 2B as starting materials, a condensation reaction is carried out to obtain a compound with a structure as shown in Formula 7. 。 5. The method for preparing chromophores as described in claim 4, characterized in that, When the compound obtained is the compound shown in Formula 5, the method further includes: using the compound with the structure shown in Formula 5 and the compound with the structure shown in Formula 13 as raw materials, performing a nucleophilic substitution reaction to obtain the compound with the structure shown in Formula 6. 。 6. The method for preparing chromophores as described in claim 4, characterized in that, When the obtained compound is the compound shown in Formula 6, the method further includes: using the compound with the structure shown in Formula 7 and the compound with the structure shown in Formula 13 as raw materials, performing a nucleophilic substitution reaction to obtain the compound with the structure shown in Formula 8. 。 7. The method for preparing chromophores according to any one of claims 4 to 6, characterized in that, The compound with the structure shown in Formula 1B is prepared by reacting the compound shown in Formula 14 with methyllithium to obtain the compound with the structure shown in Formula 1B, as shown in the following reaction: 。 8. The method for preparing chromophores according to any one of claims 4 to 6, characterized in that, The compound with the structure shown in Formula 4B is prepared by reacting the compound shown in Formula 15 with phosphorus oxychloride or phosphorus oxybromide to obtain the compound with the structure shown in Formula 4B, as shown in the following reaction: In formulas 4B and POX3, X is a chlorine atom or a bromine atom.

9. An organic electro-optic material, characterized in that, The invention comprises a polymer and a chromophore, wherein the chromophore is doped in the polymer or is chemically bonded to the polymer, wherein the chromophore is the chromophore according to any one of claims 1 to 3 or the chromophore obtained by the method according to any one of claims 4 to 8.

10. An electro-optical terminal device, characterized in that, At least one component of the electro-optical terminal device contains the organic electro-optical material as described in claim 9.

11. The electro-optical terminal device as described in claim 10, characterized in that, The electro-optic terminal equipment includes an electro-optic modulator, an electric field sensor, or a wireless signal receiver.

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