Intrinsic dipole moment-driven asymmetrically emitting chichibabin diradical compounds and preparation and use thereof
By designing an asymmetric Chichibabin diradical compound driven by an intrinsic dipole moment, the challenges of diradical stability and preparation were solved, and intrinsic luminescence in the near-infrared II region was achieved, thus expanding the application of organic optoelectronic materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUNAN UNIV
- Filing Date
- 2024-11-07
- Publication Date
- 2026-06-02
AI Technical Summary
In existing technologies, asymmetric diradicals have poor stability, few types, and complicated preparation processes. The effects of dipole moment-induced charge separation on photophysical properties have not been fully studied, and the emission wavelength of near-infrared fluorescence imaging technology is difficult to achieve in the NIR-II region.
An asymmetric Chichibabin diradical compound driven by an intrinsic dipole moment was designed and prepared. The intrinsic luminescence properties in the near-infrared II region were achieved by controlling the dipole moment through the side chain. A multi-step synthetic method was adopted, including Miyaura borylation, Suzuki coupling, Friedel-Crafts reaction and oxidation reaction.
The stability of the two free radicals was improved, intrinsic luminescence in the near-infrared II region was realized, and the correlation between dipole moment, free radical contribution value and luminescence properties was revealed. Increasing the dipole moment can suppress the decrease in luminescence efficiency, which is suitable for applications in organic optoelectronic materials.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of functional molecular materials, and particularly to a class of organic functional materials with asymmetric diradical molecules. Background Technology
[0002] Functionalized organic π-conjugated systems enable control over electronic structure and motion within organic molecular regions, as well as regulation of molecular aggregation states. They also possess unique photoelectric response properties and ease of fabrication. Over the past two decades, organic π-conjugated molecular materials have seen rapid development in fields such as light-emitting diodes (LEDs), field-effect transistors (FETs), solar cells, chemical sensing, bioimaging, capacitors, and conductive coatings. With the continuous development of various high technologies, the functional requirements and demands on materials are increasing, making the exploration and research of new materials increasingly urgent.
[0003] Organic diradicals are a class of organic π-molecules with two unpaired electrons, possessing an open-shell ground-state electronic structure. Understanding the nature of chemical bonds and the physicochemical phenomena of π-conjugated systems is crucial for understanding open-shell polycyclic aromatic hydrocarbons. For diradical organic conjugated systems, quinone structures are commonly used as building blocks for the radicals; p-QDM and o-QDM, Thiele's hydrocarbons, and Chichibabin's hydrocarbons are widely employed. Figure 1 The transition between high and low spin states has opened the door to organic magnetic compounds, making them promising for applications in spintronic devices such as responsive materials, spin filters, and information storage. Among their many unique physicochemical properties, organic free radical materials with luminescent properties have attracted widespread attention in recent years. The most typical luminescent material is the triarylmethyl monoradical and its derivatives, which have received extensive research and attention due to their stability and modifiability. Although significant progress has been made in free radical luminescent materials, their research is still in its very early stages and faces a series of challenges: 1) Asymmetric diradicals have poor stability (locally distributed electrons or charges easily lead to poor chemical stability); 2) There are few types of asymmetric diradicals, attributed to the difficulty in designing and constructing them, and the cumbersome preparation process; 3) Dipole moment-induced charge separation can balance the contribution of free radicals in the electronic structure (a rule revealed by a few DA-type free radical systems), but the influence of this balance on photophysical properties, such as luminescence behavior, has been rarely reported in the literature.
[0004]
[0005] In recent years, near-infrared II (NIR-II, 1000-1700 nm) fluorescence imaging technology has become a popular imaging technique in basic research and clinical applications, showing great potential in the biomedical field. Due to reduced scattering, minimal absorption, and negligible autofluorescence, it provides high signal-to-noise ratio and high spatial and temporal resolution for deep tissue imaging. Fluorescence imaging technology is an effective tool for preclinical or clinical applications, including disease diagnosis and visualization of drug targeting. Unlike various non-invasive imaging techniques, fluorescence imaging does not involve the use of harmful radiation, and it can provide wide-field images with high signal-to-noise ratio and excellent spatiotemporal resolution for medical diagnosis and pathological analysis. Despite significant progress in fluorescence imaging technology, its research is still in its very early stages, and a series of challenges remain to be solved. The emission wavelength of most fluorophores is around 1000 nm, making imaging in the NIR-II region difficult. Summary of the Invention
[0006] To address the problems of existing technologies, this invention provides a class of intrinsically dipole moment-driven asymmetric luminescent Chichibabin diradical compounds, aiming to obtain new compounds with intrinsic luminescent properties in the near-infrared II region.
[0007] The second objective of this invention is to provide the preparation of the intrinsically dipole moment-driven asymmetric luminescent Chichibabin diradical compound and its application in organic luminescent materials.
[0008] A third objective of this invention is to provide an organic optoelectronic material comprising the aforementioned intrinsically dipole-moment-driven asymmetric luminescent Chichibabin diradical compound.
[0009] An intrinsically dipole moment-driven asymmetric luminescent chichibabin diradical compound with the structure of Formula 1:
[0010]
[0011] In Formula 1, R1, R2, R3, and R4 are individually H, -Cl, -Br, -I, -CN, -CF3, Cl-C, etc. 24 Alkyl, C3-C 24 cycloalkyl, C1-C 24 Alkoxy, C1-C 24 Alkyl-substituted aryl, halogenated C1-C 24 Alkyl, halogenated C3-C 24 Cycloalkyl or halogenated C1-C 24 Alkoxy;
[0012] The Z can be O, S, B-Mes, N-CH3, O=Se=O, P-Ph, or O=P-Ph;
[0013] The Ar mentioned is aryl or substituted aryl.
[0014] This invention provides a dual radical compound with an asymmetric structure of Formula 1, which can achieve intrinsic luminescence in the near-infrared II region based on intrinsic dipole moment drive. Moreover, it also has excellent stability and luminescence efficiency.
[0015] The luminescent material based on intrinsic dipole moment driven by Formula 1 of this invention has the following advantages: 1) The asymmetric diradical molecules driven by dipole moment have high stability; 2) The asymmetric diradical conjugated molecules possess intrinsic luminescence properties in the near-infrared II region (monomer luminescence in nonpolar solvents reflects intrinsic luminescence); 3) The intrinsic dipole moment can not only regulate the contribution of diradicals (when the dipole moment increases to a certain extent, the diradical index decreases, indicating that there is a competitive relationship between charge separation and diradicals), but also affect the luminescence properties in the near-infrared II region, further revealing the important correlation between dipole moment, radical contribution value, and luminescence properties; 4) Increasing the diradical dipole moment can suppress the common phenomenon of molecular materials luminescence in the near-infrared II region, that is, the redshift of the emission wavelength leads to an exponential decrease in luminescence efficiency (limited by the bandgap rule).
[0016] The asymmetric diradical molecule described in this invention can modulate the absorption and emission wavelengths and luminescence efficiency of the material by changing the strength of the dipole moment through the side chain, thus demonstrating its excellent application prospects in the field of organic optoelectronic materials.
[0017] In this invention, R1 is H, -Cl, -Br, -I, -CN, or -CF3, and is more preferably -CF3.
[0018] R2 is H, C1-C 24 Alkyl, C3-C 24 cycloalkyl, C1-C 24 Alkoxy, C1-C 24 Alkyl-substituted aryl, halogenated C1-C 24 Alkyl, halogenated C3-C 24 Cycloalkyl or halogenated C1-C 24 Alkoxy group, more preferably H.
[0019] The R3 is H, -Cl, -Br, -I, -CN, -CF3, -NO2, -ArCl, -C 24 Alkyl-substituted aryl, halogenated C1-C 24 Alkyl, halogenated C3-C 24 Cycloalkyl, more preferably H.
[0020] The R4 is H, -Cl, -Br, -I, -CN, -CF3, -NO2, or -Ar, and is more preferably -CF3.
[0021] Z is O.
[0022] In the Ar group, the aryl group includes a benzene ring, a five-membered aromatic heterocycle, a six-membered aromatic heterocycle, or a fused ring; the substituted aryl group is a group having at least one substituent selected from alkyl, alkoxy, trifluoromethyl, acyl, ester, nitro, and halogen groups on the aromatic ring.
[0023] Preferably, Ar is Further preferred
[0024] The present invention can be exemplified by asymmetric diradical molecules having structures of formula 1-A, formula 1-B, and formula 1-C:
[0025]
[0026] The present invention also provides a method for preparing the intrinsically dipole moment-driven asymmetric luminescent Chichibabin diradical compound, wherein the raw material, base and oxidant of Formula 2 are subjected to dehydrogenation to obtain the compound.
[0027]
[0028] In this invention, the dehydrogenation process can be conventional, for example:
[0029] In this invention, the alkali includes alkali metal alkali alkalis, such as potassium tert-butoxide.
[0030] The oxidant can be a quinone compound, and more specifically, tetrachlorobenzoquinone.
[0031] In the dehydrogenation process described in this invention, the dosage equivalent of the alkali is 1-5 Eqv, and considering cost, it can be further increased to 2-4 Eqv, while the dosage equivalent of the oxidant is 1-2 Eqv.
[0032] The dehydrogenation reaction is carried out under anaerobic conditions.
[0033] The solvent for the dehydrogenation reaction includes, for example, one of THF, Toluene, and DCM; more preferably, THF.
[0034] The reaction time for dehydrogenation is 6-12 hours.
[0035] In this invention, after dehydrogenation, an organic solvent can be used for extraction, and the collected organic phase can be concentrated and separated by chromatography to obtain the oxidation product.
[0036] In this invention, Formula 2 is obtained by oxidation using Formula 3;
[0037]
[0038] In this invention, the oxidation step can be conventional, for example:
[0039] Preferably, the oxidizing agent added during the oxidation reaction stage includes at least one of m-chloroperoxybenzoic acid, aluminum trichloride, ferric trichloride, scandium trifluoromethanesulfonate, and DDQ.
[0040] Preferably, the dosage equivalent of the oxidizing agent in the oxidation reaction stage is 1 to 5 Eqv, and considering cost, it can be further 2 to 4 Eqv.
[0041] Furthermore, the solvent for the oxidation reaction can be one of THF, Toluene, and DCM; DCM is more preferably preferred.
[0042] In this invention, after the oxidation reaction, an organic solvent can be used for extraction, and the collected organic phase can be concentrated and separated by chromatography to obtain the oxidation reaction product.
[0043] Formula 3 is prepared by mixing Formula 4 with ArH and a Friedel-Crafts catalyst via a Friedel-Crafts reaction.
[0044]
[0045] In this invention, the Friedel-Crafts reaction steps and conditions can be adjusted based on known principles, for example:
[0046] The Friedel-Crafts reaction catalyst can be a conventional Lewis acid or other catalyst, such as at least one of ferric chloride hexahydrate, boron trifluoride diethyl ether, gold trichloride, and zinc dichloride.
[0047] The dosage equivalent of the Friedel-Crafts reaction catalyst can be 0.1–0.3 Eqv.
[0048] The temperature for the Friedel-Crafts reaction is above 80°C, and can be further increased to 90–150°C.
[0049] The Friedel-Crafts reaction also allows for the addition of acid anhydrides, in amounts such as 5 to 10 eqv.
[0050] In this invention, Formula 4 is obtained by performing a Suzuki coupling reaction using Formulas 5 and 6.
[0051]
[0052] In this invention, the Suzuki coupling reaction steps and conditions can be adjusted based on known principles, for example:
[0053] The catalyst for the Suzuki coupling reaction is at least one of Pd(dppf)Cl2, Pd(PPh3)2Cl2, and Pd(PPh3)4. The amount used can be, for example, 0.01–0.05 eqv.
[0054] The Suzuki coupling reaction stage also allows the addition of an alkali, such as at least one of sodium carbonate and potassium carbonate, in an amount of, for example, 1 to 3 eqv.
[0055] Suzuki coupling is performed under anaerobic conditions.
[0056] The molar ratio of Equations 5 and 6 can be 1:1 to 2.
[0057] The preferred reaction temperature for Suzuki coupling is 90°C to 100°C.
[0058] The solvent for Suzuki coupling is at least one of DME, H2O, THF, Dioxane, and Toluene; more preferably DME and H2O, wherein the volume ratio of DME to H2O is 3:1.
[0059] In this invention, after Suzuki coupling, extraction can be performed using an organic solvent, and the collected organic phase can be concentrated and separated by chromatography to obtain Suzuki coupling.
[0060] Formula 5 is obtained by reacting Formula 7 with pinacol diboronic acid via the Miyaura borylation reaction.
[0061]
[0062] In this invention, the Miyaura borylation reaction steps and conditions can be adjusted based on known principles, for example:
[0063] The catalyst for the Miyaura borylation reaction is Pd(dppf)Cl2. Its dosage is, for example, 0.01–0.03 eqv.
[0064] The Miyaura borylation stage also allows the addition of carboxylates, such as potassium acetate, in amounts of, for example, 1 to 3 eqv.
[0065] The Miyaura borylation reaction is carried out under anaerobic conditions.
[0066] The preferred reaction temperature for the Miyaura borylation reaction is 90℃ to 100℃.
[0067] The solvent for the Miyaura borylation reaction is at least one of Dioxane, THF, Et3N, and DCM; Dioxane is more preferably preferred.
[0068] In this invention, after the Miyaura borylation reaction, an organic solvent can be used for extraction, and the collected organic phase can be concentrated and separated by chromatography to obtain the Miyaura borylation product.
[0069] The present invention also provides an application of the intrinsically dipole moment-driven asymmetric luminescent Chichibabin diradical compound described above, for the preparation of organic optoelectronic materials.
[0070] Preferably, it is used to prepare near-infrared II organic optoelectronic materials.
[0071] Preferably, the organic optoelectronic material is at least one of bioimaging materials, semiconductor electronic devices, energy storage materials, and spin materials.
[0072] The present invention also provides an organic optoelectronic material comprising or prepared therefrom an intrinsically dipole-moment-driven asymmetric luminescent Chichibabin diradical compound.
[0073] Beneficial effects
[0074] This invention discloses a method for controlling the dipole moment by utilizing side-chain groups to promote intramolecular charge transfer, which also promises to regulate the absorption and emission wavelengths and luminescence efficiency of materials, providing a class of asymmetric diradical molecules for design, synthesis, and application. The advantages of this invention are: 1) Dipole moment-driven asymmetric diradical molecules have high stability; 2) Asymmetric diradical conjugated molecules possess intrinsic luminescence properties in the near-infrared II region (monomer luminescence in nonpolar solvents reflects intrinsic luminescence); 3) The intrinsic dipole moment not only regulates the diradical contribution (as the dipole moment increases to a certain extent, the diradical exponent decreases, indicating a competitive relationship between charge separation and the diradical), but also affects the near-infrared II luminescence properties, further revealing the important correlation between dipole moment, diradical contribution value, and luminescence properties; 4) Increasing the diradical dipole moment can suppress the common phenomenon of molecular materials luminescence in the near-infrared II region, i.e., the redshift of the emission wavelength leads to an exponential decrease in luminescence efficiency (limited by the bandgap rule). Attached Figure Description
[0075] Figure 1 This is the mass spectrum of the DD-1 compound obtained in Example 1.
[0076] Figure 2 This is the mass spectrum of the DD-2 compound obtained in Example 1.
[0077] Figure 3 This is the mass spectrum of the DD-3 compound obtained in Example 1.
[0078] Figure 4 The low-temperature NMR (-80°C) of the DD-1 compound prepared in Example 1 is shown.
[0079] Figure 5 The low-temperature NMR (-80°C) of the DD-2 compound prepared in Example 1 is shown.
[0080] Figure 6 The low-temperature NMR (-80°C) of the DD-3 compound prepared in Example 1 is shown.
[0081] Figure 7 The temperature-dependent NMR of the DD-1 compound prepared in Example 1 is shown.
[0082] Figure 8 The temperature-dependent NMR of the DD-2 compound prepared in Example 1 is shown.
[0083] Figure 9 The temperature-dependent NMR of the DD-3 compound prepared in Example 1 is shown.
[0084] Figure 10 These are the temperature-dependent ESRs of the DD-1, DD-2, and DD-3 compounds prepared in Example 1.
[0085] Figure 11 The images show the UV-Vis absorption spectra, fluorescence spectra, and cyclic voltammetry curves of the solid solutions of compounds DD-1, DD-2, and DD-3 prepared in Example 1.
[0086] Figure 12 The UV-Vis solvent effect of the DD-1, DD-2, and DD-3 compounds prepared in Example 1 (DCM is dichloromethane, THF is tetrahydrofuran, Tol is toluene, PhCl is chlorobenzene, and Cy is cyclohexane).
[0087] Figure 13 This is the single-crystal structure of the SD compound obtained in Example 1.
[0088] Figure 14 This is the single-crystal structure of the DD-1 compound obtained in Example 1.
[0089] Figure 15 This is the single-crystal structure of the DD-2 compound obtained in Example 1.
[0090] Figure 16 This is the single-crystal structure of the DD-3 compound obtained in Example 1.
[0091] Figure 17 Application of the DD-1 to 3 compounds prepared in Example 1 - fluorescence imaging; Detailed Implementation
[0092] This invention provides a method for preparing optional asymmetric biradical molecules and their derivatives, comprising the following steps:
[0093] Step (1):
[0094] Compound a undergoes a Miyaura borylation reaction with pinacol diboronic acid to prepare compound b.
[0095] Step (2):
[0096] Compound b undergoes Suzuki coupling with compound c to prepare compound d.
[0097] Step (3):
[0098] Compound d undergoes a Friedel-Crafts reaction to produce compound e.
[0099] Step (4):
[0100] Compound e undergoes an oxidation reaction to produce compound f.
[0101] Step (5):
[0102] Compound f undergoes an oxidation reaction to produce compound g.
[0103]
[0104]
[0105] In step (1), R1, R4, R2, and R3 are hydrogen or trifluoromethyl, and Z is O; the catalyst is at least one of PdCl2-dppf and Pd(PPh3)2Cl2.
[0106] In step (2), the catalyst is at least one of PdCl2-dppf, Pd(PPh3)2Cl2, and Pd(PPh3)4.
[0107] In step (3), the reaction is carried out in the presence of ferric chloride hexahydrate and acetic anhydride;
[0108] The oxidizing agent in step (4) is at least one of m-chloroperoxybenzoic acid and H2O2.
[0109] In step (5), the oxidation reaction is carried out in the presence of a base and an oxidizing agent; the base and the oxidizing agent are potassium tert-butoxide and tetrachlorobenzoquinone, respectively.
[0110] Applications include biological imaging, semiconductor electronic devices, energy storage, and spin materials.
[0111] R2 and R3 are hydrogen, R1 and R4 are trifluoromethyl, Z is O, and the final product is an asymmetric diradical molecule.
[0112] In step (1), R1, R4, R2, and R3 are hydrogen or trifluoromethyl, Z is O or N-CH3, and the catalyst is at least one of Pd(dppf)Cl2 and Pd(PPh3)2Cl2.
[0113] R1 and R4 are trifluoromethyl, R2 and R3 are hydrogen, and Z is O;
[0114] The catalyst is Pd(dppf)Cl2;
[0115] The Miyaura borylation reaction is carried out under anaerobic conditions;
[0116] The preferred reaction temperature for the Miyaura borylation reaction is 90℃~100℃;
[0117] The solvent for the Miyaura borylation reaction is at least one of Dioxane, THF, Et3N, and DCM; more preferably Dioxane.
[0118] In this invention, after the Miyaura borylation reaction, an organic solvent can be used for extraction, and the collected organic phase can be concentrated and separated by chromatography to obtain the Miyaura borylation product.
[0119] In step (2), the catalyst is at least one of Pd(dppf)Cl2, Pd(PPh3)2Cl2, and Pd(PPh3)4.
[0120] The catalyst is Pd(PPh3)4;
[0121] Suzuki coupling is performed under anaerobic conditions;
[0122] The preferred reaction temperature for Suzuki coupling is 90℃~100℃;
[0123] The solvent for Suzuki coupling is at least one of DME, H2O, THF, Dioxane, and Toluene; more preferably DME and H2O, wherein the volume ratio of DME to H2O is 3:1.
[0124] In this invention, after Suzuki coupling, extraction can be performed using an organic solvent, and the collected organic phase can be concentrated and separated by chromatography to obtain Suzuki coupling.
[0125] In step (3), the reaction is carried out in the presence of ferric chloride hexahydrate and acetic anhydride;
[0126] The Friedel-Crafts reaction solvent is at least one of mesitylene, mesitylene triethylbenzene, trichlorobenzene, and mesitylene triisopropylbenzene; more preferably mesitylene.
[0127] The preferred reaction temperature for the Friedel-Crafts reaction is 100°C.
[0128] In this invention, after the Friedel-Crafts reaction, an organic solvent can be used for extraction, and the collected organic phase can be concentrated and separated by chromatography to obtain the Friedel-Crafts reaction product.
[0129] In step (4), the oxidation reaction is carried out in the presence of an oxidant; the oxidant is at least one of m-chloroperoxybenzoic acid and H2O2, and more preferably m-chloroperoxybenzoic acid;
[0130] The solvent for the oxidation reaction is at least one of THF, Toluene, and DCM; DCM is more preferably used.
[0131] In this invention, after the oxidation reaction, an organic solvent can be used for extraction, and the collected organic phase can be concentrated and separated by chromatography to obtain the oxidation reaction product.
[0132] In step (5), the alkali and oxidizing agent used are potassium tert-butoxide and tetrachlorobenzoquinone;
[0133] The oxidation reaction takes place under anaerobic conditions;
[0134] The solvent for the oxidation reaction is at least one of THF, Toluene, and DCM; more preferably THF.
[0135] With the synergistic effect of the preferred reaction solvent system and the dosage of the oxidant, the preferred reaction time is 6-12 hours; more preferably 12 hours.
[0136] In this invention, after the oxidation reaction, an organic solvent can be used for extraction, and the collected organic phase can be concentrated and separated by chromatography to obtain the oxidation product.
[0137] Example 1:
[0138] The synthesis route is as follows:
[0139]
[0140] The specific steps for DD-1 are as follows (the steps for DD-2 and DD-3 are the same as those for DD-1):
[0141] (1) Under argon protection, compound 1 (1.00 g, 2.90 mmol), B2Pin2 (1.5 g, 5.80 mmol), and CH3COOK (426 mg, 4.34 mmol) were dissolved in 80 mL of dioxane solvent. The mixture was purged for half an hour, and Pd(dfft)Cl2 (42 mg, 0.06 mmol) was added. The mixture was heated to 90 °C and refluxed overnight. After the reaction was complete, the mixture was brought to room temperature and extracted with water (50 mL) and dichloromethane (100 mL). The organic phase was collected and dried over anhydrous magnesium sulfate. After filtration, the solvent was removed under reduced pressure. The crude product was purified by silica gel column chromatography (eluting with a gradient of PE:EA = 30:1-10:1) to obtain solid compound 2.
[0142] (2) Under argon protection, compound 3 (1.00 g, 2.77 mmol), compound 2 (1.2 g, 4.15 mmol), and K2CO3 (766 mg, 5.54 mmol) were dissolved in 100 mL of a mixture of DME and water (DME / H2O = 3:1). After purging for half an hour, Pd(PPh3)4 (64 mg, 0.06 mmol) was added. The mixture was heated to 100 °C and refluxed overnight. After the reaction was complete, the mixture was allowed to return to room temperature, and water (30 mL) was added. The mixture was extracted with dichloromethane (3 × 10 mL). The organic phase was collected, dried over Na2SO4, filtered, and evaporated to dryness. The mixture was then purified by silica gel chromatography using PE:EA = 20:1 as the eluent to obtain an oily compound 4.
[0143] (3) Under argon protection, compound 4 (1 g, 1.8 mmol), acetic anhydride (1.5 g, 14.64 mmol), and FeCl3·6H2O (99 mg, 0.4 mmol) were dissolved in 30 mL of Mesitylene, heated to 110 °C, and refluxed overnight. After the reaction was complete, the mixture was allowed to return to room temperature and extracted with water (100 mL) and ethyl acetate (200 mL). The organic phase was collected and dried over anhydrous magnesium sulfate. After filtration to remove the solvent, the mixture was purified by silica gel chromatography (PE as eluent) to obtain liquid compound 5.
[0144] (4) Compound 5 (200 mg, 0.27 mmol) was dissolved in dichloromethane (50 mL), and m-chloroperoxybenzoic acid (138 mg, 0.80 mmol) was added. The reaction was carried out at room temperature for 2-3 hours. After the reaction was completed, the reaction solution was extracted with water (10 mL) and dichloromethane (20 mL). The organic phase was collected and dried over anhydrous magnesium sulfate. After removing the solvent by filtration, the solution was purified by silica gel chromatography (PE / DCM = 10:1) to obtain compound 6.
[0145] (5) Compound 6 (100 mg, 0.13 mmol) was dissolved in anhydrous THF (50 mL), potassium tert-butoxide (43 mg, 0.39 mmol) was added, and the reaction was carried out overnight at room temperature. Then tetrachlorobenzoquinone (48 mg, 0.19 mmol) was added. After the reaction was completed, the reaction solution was extracted with water (10 mL) and dichloromethane (20 mL), the organic phase was collected and dried over anhydrous magnesium sulfate, the solvent was removed by filtration, and the solution was purified by silica gel chromatography (PE / THF = 10:1) to obtain compound 7.
[0146] Verification of the properties of DD-1 to DD-3
[0147] In this invention, the structures of DD-1 to DD-3 were confirmed by means of variable-temperature nuclear magnetic resonance hydrogen spectroscopy, mass spectrometry, ultraviolet-visible-near-infrared absorption spectroscopy, and single-crystal diffraction, and their related properties were studied.
[0148] Figure 11 The UV-Vis-NIR absorption spectra, fluorescence spectra, and cyclic voltammetry curves of dichloromethane solutions of compounds DD-1 to DD-3, along with related photophysical properties, are shown in Table 1. Figure 11 In the text, the SD described is a DD-2 compound with Z being -SO2-, and its structure is as follows:
[0149]
[0150] Electronic absorption spectroscopy results showed that the maximum absorption wavelength of compound DD-1 was 855 nm, while the absorption bands of compounds DD-2 and DD-3 exhibited red shifts of approximately 48 nm and 115 nm, respectively, with maximum absorption wavelengths of 903 nm and 970 nm. Fluorescence spectroscopy results indicated that the emission wavelengths of compounds DD-1–3 were 1023 nm, 1074 nm, and 1180 nm, with a Stokes shift of 179 nm. -1 186nm -1 210nm -1 The fluorescence quantum yields (PLQY) of compounds DD-1 to DD-3 were calculated to be 0.84%, 0.22%, and 0.17%, respectively, indicating that the substituents of asymmetric diradical compounds, which utilize side chain groups to regulate the dipole moment, play an important role in their radiative decay process.
[0151] Table 1. Photophysical properties of DD-1 to DD-3 in dichloromethane
[0152]
[0153] Figure 13-16The single-crystal structures of SD, DD-1 to 3 are shown. The four compounds were dissolved in DCM, toluene, THF, and toluene solutions, respectively, and then subjected to gas-phase diffusion with n-hexane to obtain high-quality crystals. In the asymmetric compounds, as the dipole moment increases, the molecules gradually change from planar to twisted to a dihedral angle of 15°. In DD-2, the twist angle of the two benzene rings of zijibaben is 14.9°, while the other three are parallel. Aromaticity calculations revealed that all benzene rings in the zijibaben skeleton are aromatic, indicating that these four molecules may possess biradical properties. Calculations showed that these molecules have relatively large biradical indices (70-79%). Interestingly, the biradical indices gradually decrease with increasing dipole moment, indicating that the intrinsic dipole moment can regulate the contribution of biradicals, suggesting a competitive relationship between charge separation and biradicals.
[0154] Figure 16 The image shows the application of compounds DD-1 to 3 in fluorescence imaging. Image a is the fluorescence image of DD-1 to 3 under 808 nm light illumination; image c is the near-infrared II fluorescence image of DD-1 to 3 in mouse subcutaneous tissue under 808 nm excitation (10 μg / mL); and image d shows the corresponding fluorescence intensity. Since the emission wavelength of the compound reaches the near-infrared II region, and it is well known that near-infrared II emission exhibits lower scattering in biological tissues, it can achieve deeper tissue penetration, which is particularly important for imaging deep tissues or organs. Therefore, compound DD-1 to 3 was subjected to fluorescence imaging tests in mice. Image d shows that, compared to the blank control group, compound DD-1 to 3 has a stronger fluorescence intensity, indicating that DD-1 to 3 can be applied to fluorescence imaging. Simultaneously, it also verifies the common phenomenon that increasing the diradical dipole moment can suppress the emission of molecular materials in the near-infrared II region, i.e., the redshift of the emission wavelength leads to an exponential decrease in luminescence efficiency (limited by the bandgap rule).
[0155] In summary, the asymmetric diradical molecule described in this invention can modulate the absorption and emission wavelengths and luminescence efficiency of the material by changing the strength of the dipole moment through the side chain, thus demonstrating its excellent application prospects in the field of organic optoelectronic materials.
Claims
1. An asymmetrically emitting Chichibabin diradical compound driven by an intrinsic dipole moment, characterized in that, It has the structure of Formula 1: ； Formula 1 In Formula 1, R1 is H, -Cl, -Br, -I, -CN, or -CF3; R2 is H; R3 is H; The R4 is H, -Cl, -Br, -I, -CN, -CF3, or -NO2; Z is O; The Ar is an aryl or substituted aryl group, wherein the aryl group is a benzene ring, and the substituted aryl group is a halogen-substituted group on the benzene ring; or the substituted aryl group is mesitylene.
2. The intrinsic dipole moment-driven asymmetrically emitting Chichibabin diradical compound according to claim 1, wherein R1 is -CF3; R2 is H; R3 is H; R4 is -CF3; The Ar is .
3. A process for the preparation of the intrinsic dipole moment-driven asymmetrically emitting Chichibabin diradical compound according to any one of claims 1 to 2, characterized in that The raw materials, alkali, and oxidant of Formula 2 are subjected to dehydrogenation to obtain the product; ； Equation 2.
4. The process for the preparation of intrinsic dipole moment-driven asymmetrically emitting Chichibabin's diradical compounds according to claim 3, characterized in that, The alkali is an alkali metal alkali ... The oxidant is a quinone compound; In the dehydrogenation process, the dosage of the alkali is 1~5 Eqv and the dosage of the oxidant is 1~2 Eqv.
5. The process for the preparation of intrinsic dipole moment-driven asymmetrically emitting Chichibabin's diradical compounds according to claim 4, characterized in that, The dehydrogenation reaction is carried out under anaerobic conditions; The solvent for the dehydrogenation reaction is one of THF, toluene, or DCM. The reaction time for dehydrogenation is 6-12 hours.
6. The method of preparing intrinsic dipole moment-driven asymmetrically emitting Chichibabin diradical compounds according to any one of claims 3 to 5, characterized in that, Formula 2 is obtained by oxidation using Formula 3; Formula 3.
7. The process for the preparation of intrinsic dipole moment-driven asymmetrically emitting Chichibabin's biradical compounds according to claim 6, characterized in that, The oxidizing agent added during the oxidation reaction stage is at least one of m-chloroperoxybenzoic acid and DDQ; The dosage equivalent of the oxidizing agent in the oxidation reaction stage is 1~5 Eqv; The solvent for the oxidation reaction is one of THF, toluene, or DCM.
8. The method for preparing the intrinsically dipole-moment-driven asymmetric luminescent Chichibabin diradical compound as described in claim 6, characterized in that, Formula 3 is prepared by mixing Formula 4 with ArH and a Friedel-Crafts catalyst via a Friedel-Crafts reaction. Formula 4.
9. The method of preparing intrinsic dipole moment-driven asymmetrically emitting Chichibabin diradical compounds according to claim 8, characterized in that, The Friedel-Crafts catalyst is at least one of ferric chloride hexahydrate, boron trifluoride diethyl ether, gold trichloride, and zinc dichloride. The dosage equivalent of the Friedel-Crafts reaction catalyst is 0.1~0.3 Eqv; The Friedel-Crafts reaction takes place at temperatures above 80°C.
10. The method for preparing the intrinsically dipole-moment-driven asymmetric luminescent Chichibabin diradical compound as described in claim 8, characterized in that, Equation 4 is obtained by performing a Suzuki coupling reaction using Equations 5 and 6. ； Formula 5 ； Formula 6.
11. The method of preparing intrinsic dipole moment-driven asymmetrically emitting Chichibabin diradical compounds according to claim 10, characterized in that, The catalyst for the Suzuki coupling reaction is at least one of Pd(dppf)Cl2, Pd(PPh3)2Cl2, and Pd(PPh3)4; The reaction temperature for Suzuki coupling is 90℃~100℃.
12. The method of preparing intrinsic dipole moment-driven asymmetrically emitting Chichibabin diradical compounds according to claim 10, wherein Formula 5 is obtained by reacting Formula 7 with pinacol diboronic acid via the Miyaura borylation reaction; Formula 7.
13. The method of preparing intrinsic dipole moment-driven asymmetrically emitting Chichibabin diradical compounds according to claim 12, wherein The catalyst for the Miyaura borylation reaction is Pd(dppf)Cl2; The Miyaura borylation reaction is carried out under anaerobic conditions; The reaction temperature for the Miyaura borylation reaction is 90℃~100℃; The solvent for the Miyaura borylation reaction is one of dioxane, THF, Et3N, or DCM.
14. Use of the internally dipole moment-driven asymmetrically luminescent Chichibabin diradical compound according to any one of claims 1 to 2, characterized in that It can be used to prepare organic optoelectronic materials; The organic optoelectronic material is a bioimaging material.
15. An organic optoelectronic material, characterized in that, The compound comprising or prepared therefrom the intrinsically dipole moment-driven asymmetric luminescent Chichibabin diradical compound as described in any one of claims 1 to 2.