Organic conjugated small molecule and preparation method thereof

Abstract

The invention provides an organic conjugated small molecule and a preparation method thereof, the organic conjugated small molecule contains a diquinone-2-(5-methylenethiazole-2 (5H)-subunit) malononitrile terminal, has a narrow-band gap characteristic, can realize near-infrared absorption with a spectrum exceeding 1.5 [mu] m and strong near-infrared light absorption and emission capability, and can be used for preparing the organic conjugated small molecule. And the material can be used in the biomedical fields of efficient photothermal therapy, photodynamic therapy, bioluminescence imaging and the like. Meanwhile, the molecules can realize higher film crystallinity and charge mobility, and can be applied to the fields of organic electronics such as organic solar cells, organic photodetectors, organic transistors, organic electroluminescence and organic electrochemical transistors. Meanwhile, the synthetic method provided by the invention can break through the problem that the organic conjugated molecule at the tail end of the diquinone-2-(5-methylenethiazole-2 (5H)-subunit) malononitrile cannot be prepared by the existing synthetic method, and the synthetic product has higher yield.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic optoelectronic functional materials, and particularly relates to an organic conjugated small molecule containing a bisquinoid 2-(5-methylene thiazol-2(5H)-ylidene) malononitrile terminal and a preparation method thereof. Background Art

[0002] Organic conjugated small molecule materials are widely used in many fields such as organic optoelectronic functional devices, biological fluorescence imaging, and photothermal therapy. Quinoid 2-(5-methylene thiazol-2(5H)-ylidene) malononitrile is a terminal structural group with strong electron-withdrawing ability and can be used to prepare narrow-bandgap organic conjugated molecules. At present, there have been many reports on organic conjugated molecules containing a single quinoid 2-(5-methylene thiazol-2(5H)-ylidene) malononitrile terminal (Angew. Chem. Int. Ed. 2011, 50, 11628–11632; Angew. Chem. Int. Ed. 2015, 54, 10512–10515; Adv. Funct. Mater. 2019, 29, 1805058; J. Mater. Chem. B, 2019, 7, 3950—3957; Aggregate. 2023, 4, e288). They have high light absorption coefficients, strong near-infrared light emission, good photothermal effects, and charge transport capabilities, and have good application prospects in fields such as organic solar cells, organic photodetectors, photothermal therapy, and biological fluorescence imaging. However, there are no reports on the successful preparation of organic conjugated molecules containing a bisquinoid 2-(5-methylene thiazol-2(5H)-ylidene) malononitrile terminal.

[0003] Currently, there are two types of synthetic methods for organic optoelectronic molecules with a quinoid 2-(5-methylene thiazol-2(5H)-ylidene) malononitrile terminus (Chem. Eur. J. 2011, 17, 826–838; J. Mater. Chem. B, 2019, 7, 3950—3957): one is the condensation reaction at a relatively high temperature (80–110 °C) in an acid anhydride; the other is the condensation reaction at a relatively high temperature (90–120 °C) in an acetic anhydride solvent using an acetate as a catalyst. Since the activation energy of the reaction between an aldehyde group and a 2-(5-methylene thiazol-2(5H)-ylidene) malononitrile derivative is relatively large, side reactions are extremely likely to occur during heating. As a result, these two methods are usually only applicable to the synthesis of molecules with a D-A (A is an electron-accepting structural unit, D is an electron-donating structural unit, and 2-(5-methylene thiazol-2(5H)-ylidene) malononitrile terminus serves as A here) structure. When synthesizing organic optoelectronic molecules with two 2-(5-methylene thiazol-2(5H)-ylidene) malononitrile termini, the yield is extremely low or impossible to achieve. In addition, compared with D-A structured organic conjugated molecules containing a single quinoid 2-(5-methylene thiazol-2(5H)-ylidene) malononitrile terminus, A-D-A, A-D-A’-D-A, A-A’-D-A’-A (A’ is also an electron-accepting structural unit) structured organic conjugated molecules containing two quinoid 2-(5-methylene thiazol-2(5H)-ylidene) malononitrile termini are expected to achieve a narrower bandgap, stronger absorption coefficient, stronger fluorescence emission, and higher optoelectronic performance, which is of great significance for fields such as organic optoelectronic functional devices, biofluorescence imaging, and photothermal therapy.

[0004] Therefore, it is of great significance to design organic conjugated small molecules containing bis-quinoid 2-(5-methylene thiazol-2(5H)-ylidene) malononitrile termini and develop an efficient and general synthetic method for such molecules. Summary of the Invention

[0005] Aiming at the problems in the background technology, the purpose of the present invention is to provide an organic conjugated small molecule containing bis-quinoid 2-(5-methylene thiazol-2(5H)-ylidene) malononitrile termini and a preparation method thereof. The preparation method innovatively uses a Lewis acid as a catalyst in a solvent containing an acid anhydride, thereby achieving the efficient preparation of such organic conjugated small molecules.

[0006] To achieve the above purpose, the technical solution of the present invention is as follows:

[0007] An organic conjugated small molecule, whose structural general formula is shown in Formula I:

[0008]

[0009] In formula I, A is a conjugated structure containing any of the five basic structural units of thiophene, selenophene, pyrrole, furan, benzene, pyridine, as well as group-substituted derivatives, bridged-ring derivatives, and fused-ring derivatives of these five basic structural units.

[0010] Further, in formula I, Ar 1 and Ar 2 are the same or different and are any one of those shown in formula II:

[0011]

[0012] Further, in formula II, X 1 , X 2 , X 3 , X 4 , X 5 are independently selected from any one of hydrogen, fluorine, chlorine, bromine, iodine, cyano group, trifluoromethyl group, C1-C30 straight-chain or branched-chain alkyl group, C1-C30 alkoxy group, and C1-C30 alkylthio group, and Y 1 , Y 2 are independently selected from any one of oxygen, sulfur, and selenium atoms.

[0013] A preparation method of an organic conjugated small molecule, the specific process is: mixing an aldehyde-group-containing substrate, a 2-(thiazol-2(3H)-ylidene) malononitrile derivative, an acid anhydride and a solvent, adding a Lewis acid as a catalyst, and reacting under an inert atmosphere; after the reaction is completed, precipitation treatment is carried out, and the precipitate is treated by silica gel column chromatography to obtain an organic conjugated small molecule containing a bisquinoid 2-(5-methylenethiazol-2(5H)-ylidene) malononitrile terminal;

[0014] Among them, the structural formula of the aldehyde-group-containing substrate is as shown in formula III, and the structural formula of the 2-(thiazol-2(3H)-ylidene) malononitrile derivative is any one of those shown in formula IV; Ar is the same as Ar 1 or Ar 2 described in formula (I).

[0015]

[0016] Further, the Lewis acid used as the catalyst is specifically a boron-containing Lewis acid, a halogenated metal Lewis acid or a metal salt of trifluoromethanesulfonic acid.

[0017] Further, the boron-containing Lewis acid is boron trifluoride and its complexes, boron trichloride and its complexes, tris(pentafluorophenyl) borane; the halogenated metal Lewis acid is TeCl 4 , SbCl 3 , SnCl 4 , InCl 3 , NbCl5 , GaCl 3 , FeCl 3 , TiCl 4 , ZnCl 2 ; The metal salt of trifluoromethanesulfonic acid as a Lewis acid is Sc(OTf) 3 , Y(OTf) 3 , Ce(OTf) 3 , Er(OTf) 3 , La(OTf) 3 , Gd(OTf) 3 , Yb(OTf) 3 , In(OTf) 3 , Fe(OTf) 3 .

[0018] Furthermore, the acid anhydride is at least one of those shown in Formula V, preferably propionic anhydride;

[0019]

[0020] Furthermore, the solvent is the acid anhydride itself, or at least one of organic solvents of haloalkanes, esters, ethers, and aromatics, preferably the acid anhydride itself.

[0021] Furthermore, the organic solvent of haloalkanes is dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane or tetrachloroethane; the organic solvent of esters is ethyl acetate; the organic solvent of ethers is diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran or 1,4-dioxane; the organic solvent of aromatics is toluene, xylene, chlorobenzene or dichlorobenzene.

[0022] Furthermore, the molar feed ratio of the Lewis acid catalyst, the substrate containing an aldehyde group, and the 2-(thiazol-2(3H)-ylidene)malononitrile derivative is 0.01 to 10:1:1 to 20, preferably 1:1:3; the molar feed ratio of the substrate containing an aldehyde group and the acid anhydride is 1:1 to 10000, preferably 1:600; if the solvent is not the acid anhydride itself, the volume ratio of the acid anhydride to the solvent is 100:1 to 1:100, preferably 3:1; the reaction temperature is -20°C to 60°C, preferably 25°C; the reaction time is 5 minutes to 120 hours, preferably 12 hours.

[0023] The mechanism of the present invention is:

[0024] In terms of the synthesis method, when preparing organic conjugated small molecules with a bisquinoid 2-(5-methylenethiazol-2(5H)-ylidene)malononitrile end, the reported methods will result in only by-products being obtained and the effective preparation being unable to be achieved because after one of the two aldehyde groups in the substrate reacts, the charge density of the substrate significantly decreases, the energy barrier for the condensation reaction of the second aldehyde group greatly increases, while the energy barrier for side reactions decreases. The synthesis method proposed in the present invention has been optimized in terms of mechanism: the aldehyde group contained in the substrate reacts with propionic anhydride under the catalysis of a Lewis acid to form a bis-ester derivative of the substrate. At the same time, the 2-(thiazol-2(3H)-ylidene)malononitrile derivative also undergoes a coordination effect with the Lewis acid. These two factors greatly reduce the activation energy during the condensation reaction, thereby reducing the reaction temperature, significantly suppressing side reactions due to insufficient temperature, and achieving the effective preparation of organic conjugated small molecules containing two quinoid 2-(5-methylenethiazol-2(5H)-ylidene)malononitrile ends under room temperature or low temperature conditions.

[0025] In terms of material design, the quinoid 2-(5-methylenethiazol-2(5H)-ylidene)malononitrile end is a type of extremely strong electron-accepting unit, which can form an extremely strong intramolecular charge transfer effect with an electron-donating unit, achieving a narrow molecular bandgap and near-infrared absorption. Compared with the reported DA-type organic conjugated molecules containing a single quinoid 2-(5-methylenethiazol-2(5H)-ylidene)malononitrile end, the organic conjugated molecules containing two quinoid 2-(5-methylenethiazol-2(5H)-ylidene)malononitrile ends have structures such as A-D-A, A-D-A’-D-A, A-A’-D-A’-A, with a lower bandgap, a higher transition dipole moment, and can achieve a wider near-infrared absorption spectrum, higher light absorption intensity, and fluorescence emission efficiency. In addition, this type of molecule can achieve higher symmetry, higher film order, and higher charge mobility. Therefore, the molecular structure proposed in the present invention can achieve better optoelectronic device performance, as well as better functions such as biological imaging and photothermal therapy.

[0026] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0027] 1. The organic conjugated molecules provided by the present invention containing two quinoid 2-(5-methylenethiazol-2(5H)-ylidene)malononitrile ends have the characteristics of a narrow bandgap, can achieve near-infrared absorption with a spectrum exceeding 1.5 μm, as well as strong near-infrared light absorption and emission capabilities, and can be used in biological medical fields such as efficient photothermal therapy, photodynamic therapy, and biological fluorescence imaging. At the same time, this type of molecule can achieve relatively high film crystallinity and charge mobility, enabling applications in organic electronics fields such as organic solar cells, organic photodetectors, organic transistors, organic electroluminescence, and organic electrochemical transistors.

[0028] 2. The synthesis method proposed by the present invention can overcome the problem that the existing synthesis methods cannot prepare the organic conjugated molecules at the ends of bisquinoid 2-(5-methylenethiazol-2(5H)-ylidene)malononitrile, realize the preparation of organic conjugated small molecules with excellent performance in the fields of organic optoelectronics and biomedicine, and the synthesized products have a high yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the synthesis route of the organic conjugated small molecule TM1 in Example 1 of the present invention.

[0030] Figure 2 It is a schematic diagram of the synthesis route of the organic conjugated small molecule TM2 in Example 2 of the present invention.

[0031] Figure 3 It is the thin film absorption spectra of TM1 and TM2 in Example 1 and Example 2 of the present invention.

[0032] Figure 4 It is a schematic diagram of the synthesis route of the organic conjugated small molecule TM3 in Example 3 of the present invention.

[0033] Figure 5 It is the solution and thin film absorption spectra of TM3 in Example 3 of the present invention.

[0034] Figure 6 It is the specific detectivity curve graph of the organic photodetector based on TM3 in Example 3 of the present invention.

[0035] Figure 7 It is a schematic diagram of the synthesis route of the organic conjugated small molecule TM4 in Example 4 of the present invention.

[0036] Figure 8 It is a schematic diagram of the synthesis route of the organic conjugated small molecule TM5 in Example 5 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the embodiments and the drawings.

[0038] Example 1

[0039] A preparation method of an ADA-structured organic conjugated small molecule, and its synthesis process schematic diagram is as Figure 1 shown, and the specific steps are as follows:

[0040] Step 1: Mix compound 2-bromo-1-(thiophen-2-yl)ethan-1-one (410 mg, 2 mmol), NH 4SCN (167 mg, 1.1 mmol) and absolute ethanol (10 mL) were added to a dry nitrogen-filled two-necked flask; the mixture was heated to 95 °C and reacted for 2 h; subsequently, malononitrile (159 mg, 2.4 mmol) was added, and the mixture was heated to 50 °C and reacted for 0.5 h, then triethylamine (NEt 3 )(0.33 mL, 2.4 mmol) was added; subsequently, the reaction mixture was stirred overnight at room temperature and poured into ice water; hydrochloric acid was added to acidify the mixture and stirred at room temperature for 1 h; the precipitate 2-(4-(thiophen-2-yl)thiazol-2(3H)-ylidene)malononitrile (TTM) was filtered out and washed with acetonitrile;

[0041] The yield of TTM was 401 mg (yield 87%);

[0042] The mass spectrometry information and 1H nuclear magnetic resonance spectrum information of molecule TTM are as follows:

[0043] MS (ESI) m / z: 231.87. 1 1H NMR (400 MHz, DMSO-d6) δ 7.62 (dd, J = 5.0, 1.2 Hz,

[0044] 1H), 7.59 (dd, J = 3.7, 1.2 Hz, 1H), 7.18 (s, 1H), 7.14 (dd, J = 5.1, 3.7 Hz, 1H).

[0045] Step 2: At room temperature, compound COTA (263.8 mg, 0.3 mmol), TTM (208 mg, 0.9 mmol), catalyst indium(III) chloride anhydrous (265 mg, 1.2 mmol), and acetic anhydride (1 mL) were added to a dry nitrogen-filled two-necked flask and stirred for reaction for 12 h; subsequently, the reaction mixture was poured into ice water and stirred for 0.5 h to precipitate the insoluble matter; the insoluble matter was filtered out, dissolved in dichloromethane, dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation in an organic phase to obtain a solid. Finally, separation by silica gel column chromatography gave the desired organic conjugated small molecule TM1 with an ADA structure, and its yield was 219.4 mg (yield 56%);

[0046] The mass spectrometry information and 1H nuclear magnetic resonance spectrum information of molecule TM1 are as follows:

[0047] MS (MALDI-TOF) m / z: 1304.51. 11H NMR (600 MHz, Chloroform-d) δ 8.08 (s, 2H), 7.87 (s, 2H), 7.77 (d, J = 4.8 Hz, 2H), 7.50 (t, J = 2.3 Hz, 2H), 7.28 (d, J = 5.4 Hz, 4H), 4.17 (d, J = 5.2 Hz, 4H), 2.10–2.00 (m, 4H), 1.90 (p, J = 5.8 Hz, 2H), 1.64 (ddq, J = 21.2, 14.1, 7.2, 6.8 Hz, 5H), 1.40 (s, 8H), 1.03 (qd, J = 7.5, 7.0, 1.7 Hz, 13H), 0.96 (q, J = 6.9, 5.3 Hz, 15H), 0.75 (s, 1H), 0.79–0.70 (m, 7H), 0.67 (td, J = 7.4, 1.4 Hz, 6H), 0.07 (s, 3H).

[0048] Comparative experiment 1 of conventional method: At room temperature, compound COTA (263.8 mg, 0.3 mmol), TTM (208 mg, 0.9 mmol), and acetic anhydride (2 mL) were added to a dry nitrogen-filled two-necked flask, and the reaction was stirred at 90 °C for 12 hours. Subsequently, the reaction mixture was poured into ice water and stirred for 0.5 hour. The insoluble matter was filtered out, dissolved in dichloromethane, and thin-layer chromatography analysis showed that COTA was almost exhausted but no TM1 was formed.

[0049] Comparative experiment 2 of conventional method: At room temperature, compound COTA (263.8 mg, 0.3 mmol), TTM (208 mg, 0.9 mmol), ammonium acetate (5 mg), and acetic anhydride (2 mL) were added to a dry nitrogen-filled two-necked flask, and the reaction was stirred at 120 °C for 12 hours. Subsequently, the reaction mixture was poured into ice water and stirred for 0.5 hour. The insoluble matter was filtered out, dissolved in dichloromethane, and thin-layer chromatography analysis showed that COTA was almost exhausted and no TM1 was formed.

[0050] The comparative experiments show that the synthesis method proposed by the present invention can efficiently prepare an organic conjugated molecule with an ADA structure having a bis-quinoid 2-(5-methylenethiazol-2(5H)-ylidene)propanedinitrile terminus, while the two reported methods cannot.

[0051] The ultraviolet-visible-near-infrared absorption spectrum of the organic optoelectronic small molecule TM1 prepared in Preparation Example 1 was measured in the thin film state. The specific process was as follows: An appropriate amount of the organic optoelectronic small molecule TM1 was dissolved in chloroform to prepare solutions with concentrations of 20 mg / mL respectively, and a part of the 20 mg / mL solution was spin-coated onto a quartz wafer to form a thin film, and the absorption spectrum was measured. The measured absorption spectrum is as Figure 3As shown. It can be seen from the figure that the thin film absorption cut-off wavelength of TM1 exceeds 1.3 μm, indicating that this type of molecule has an ultra-narrow bandgap.

[0052] Example 2

[0053] A preparation method of an ultra-narrow bandgap ADA-structured organic optoelectronic molecule TM2 with a quinoid 2-(5-methylenethiazol-2(5H)-ylidene)malononitrile terminal. The schematic diagram of its synthesis process is as Figure 2 shown, and the specific steps are as follows:

[0054] Step 1: Add compound 2-bromo-1-(thiazol-2-yl)ethan-1-one (412 mg, 2 mmol), NH 4 SCN (167 mg, 2.2 mmol) and anhydrous ethanol (8 mL) into a dry nitrogen-filled two-necked flask; heat the mixture to 95 °C and react for 2 hours; then, add malononitrile (159 mg, 2.4 mmol), heat the mixture to 50 °C and react for 0.5 hour, then add triethylamine (0.33 mL, 2.4 mmol), stir the reactant overnight at room temperature, and pour it into ice water; add acetic acid to acidify the mixture, stir for 1 hour at room temperature, filter out the precipitate 2-([2,4'-bithiazol]-2'(3'H)-ylidene)malononitrile (Tz TM), and wash it with acetonitrile. The yield is 316 mg (yield 68%).

[0055] The mass spectrometry information and nuclear magnetic resonance hydrogen spectrum information of molecule TzTM are as follows:

[0056] MS(ESI) m / z: 231.71. 1 H NMR (400 MHz, DMSO-d6) δ 7.94 (d, J = 3.2 Hz, 1H), 7.

[0057] 81 (d, J = 3.2 Hz, 1H), 7.57 (s, 1H).

[0058] Step 2: At room temperature, add compound COTA (263.8 mg, 0.3 mmol), TzTM (209 mg, 0.9 mmol), catalyst anhydrous antimony trichloride (274 mg, 1.2 mmol), and propionic anhydride (1 mL) into a dry nitrogen-filled two-necked flask, stir and react for 12 hours; then, pour the reactant into ice water and stir for 0.5 hour; filter out the insoluble matter, dissolve it in dichloromethane, dry it with anhydrous sodium sulfate, then remove the solvent by rotary evaporation in the organic phase to obtain a solid, and finally separate it by silica gel column chromatography to obtain TM2 with a yield of 231.5 mg (yield 59%).

[0059] The mass spectrometry information and nuclear magnetic resonance hydrogen spectrum information of molecule TM2 are as follows:

[0060] MS (MALDI-TOF) m / z: 1307.52. 1 H NMR (600 MHz, Chloroform-d) δ 9.58 (s, 2H), 8.12 (d, J = 3.1 Hz, 2H), 7.73 (d, J = 3.1 Hz, 2H), 7.54 (t, J = 2.7 Hz, 2H), 7.37 (s, 2H), 4.20 (d, J = 5.3 Hz, 4H), 2.12–2.02 (m, 4H), 1.91 (p, J = 6.1 Hz, 2H), 1.65 (dq, J = 21.5, 7.6 Hz, 6H), 1.44–1.39 (m, 8H), 1.03 (td, J = 7.5, 1.9 Hz, 14H), 0.96 (s, 10H), 0.96 (d, J = 13.7 Hz, 4H), 0.73 (q, J = 9.4, 6.5 Hz, 10H), 0.66 (t, J = 7.3 Hz, 6H).

[0061] Comparative experiment 1 of conventional methods: At room temperature, compound COTA (263.8 mg, 0.3 mmol), TzTM (209 mg, 0.9 mmol), and acetic anhydride (2 mL) were added to a dry nitrogen-filled two-necked flask and stirred at 90 °C for 12 hours. Subsequently, the reaction mixture was poured into ice water and stirred for 0.5 hour. The insoluble matter was filtered out, dissolved in dichloromethane, and thin-layer chromatography analysis showed that COTA was almost exhausted but no TM2 was formed.

[0062] Comparative experiment 2 of conventional methods: At room temperature, compound COTA (263.8 mg, 0.3 mmol), TzTM (209 mg, 0.9 mmol), ammonium acetate (5 mg), and acetic acid (2 mL) were added to a dry nitrogen-filled two-necked flask and stirred at 120 °C for 12 hours. Subsequently, the reaction mixture was poured into ice water and stirred for 0.5 hour. The insoluble matter was filtered out, dissolved in dichloromethane, and thin-layer chromatography analysis showed that COTA was almost exhausted and no TM2 was formed.

[0063] The comparative experiments show that the synthesis method proposed in the present invention can efficiently prepare TM2, while the two reported methods cannot.

[0064] The ultraviolet-visible-near-infrared absorption spectrum of the organic optoelectronic small molecule TM2 prepared in Example 2 was measured in the thin film state. The specific process was as follows: An appropriate amount of the organic optoelectronic small molecule TM2 was dissolved in chloroform to prepare solutions with a concentration of 20 mg / mL respectively. Then, a part of the 20 mg / mL solution was spin-coated onto a quartz wafer to form a thin film, and the absorption spectrum was measured. The measured absorption spectrum is as Figure 3As shown. It can be seen from the figure that the thin film absorption cut-off wavelength of TM2 exceeds 1.5 μm, indicating that this type of molecule has an ultra-narrow bandgap.

[0065] Example 3

[0066] A preparation method of an organic optoelectronic molecule TM1 with a quinoid 2-(5-methylenethiazol-2(5H)-ylidene)malononitrile terminal and an ADA’DA structure. The schematic diagram of the synthesis process is as Figure 4 shown, and it includes the following steps:

[0067] At room temperature, compound TQDA (359.3 mg, 0.3 mmol), TTM (208 mg, 0.9 mmol), catalyst anhydrous indium chloride (265 mg, 1.2 mmol), and propionic anhydride (1 mL) were added to a dry nitrogen-filled two-necked flask, and stirred for reaction for 12 hours; subsequently, the reactants were poured into ice water and stirred for 0.5 hour; the insoluble matter was filtered out, dissolved in dichloromethane, dried with anhydrous sodium sulfate, and the solvent was removed by rotary evaporation in an organic phase to obtain a solid. Finally, TM3 with a yield of 311.9 mg (yield 64%) was obtained by silica gel column chromatography.

[0068] The mass spectrometry information and nuclear magnetic resonance hydrogen spectrum information of molecule TM3 are as follows:

[0069] MS (MALDI-TOF) m / z: 1622.81. 1 H NMR (600 MHz, Chloroform-d) δ 9.40–9.36 (m, 2H), 8.22 (d, J = 3.1 Hz, 2H), 7.89 (td, J = 7.4, 6.7, 3.7 Hz, 2H), 7.80 (dd, J = 7.6, 3.2 Hz, 6H), 7.57 (dt, J = 14.7, 7.2 Hz, 6H), 7.45 (dd, J = 13.2, 6.5 Hz, 2H), 7.30 (t, J = 4.4 Hz, 2H), 2.17 (t, J = 12.6 Hz, 4H), 2.05 (t, J = 16.3 Hz, 4H), 1.02 (dd, J = 14.4, 7.3 Hz, 22H), 0.97 (s, 12H), 0.82–0.77 (m, 2H), 0.77–0.72 (m, 8H), 0.68–0.55 (m, 16H).

[0070] Comparative experiment of conventional method 1: At room temperature, compound TQDA (359.3 mg, 0.3 mmol), TTM (208 mg, 0.9 mmol), and acetic anhydride (2 mL) were added to a dry nitrogen-filled two-necked flask, and the reaction was stirred at 90 °C for 12 hours. Subsequently, the reaction mixture was poured into ice water and stirred for 0.5 hour. The insoluble matter was filtered out, dissolved in dichloromethane, and thin-layer chromatography analysis showed that TQDA was almost exhausted, but no TM3 was formed.

[0071] Comparative experiment of conventional method 2: At room temperature, compound TQDA (359.3 mg, 0.3 mmol), TTM (208 mg, 0.9 mmol), ammonium acetate (5 mg), and acetic acid (2 mL) were added to a dry nitrogen-filled two-necked flask, and the reaction was stirred at 120 °C for 12 hours. Subsequently, the reaction mixture was poured into ice water and stirred for 0.5 hour. The insoluble matter was filtered out, dissolved in dichloromethane, and thin-layer chromatography analysis showed that TQDA was almost exhausted, but no TM3 was formed.

[0072] The comparative experiments show that the synthesis method proposed in the present invention can efficiently prepare an organic optoelectronic molecule with an ADA’DA structure having a quinoid 2-(5-methylenethiazol-2(5H)-ylidene) malononitrile terminus, while the two reported methods cannot.

[0073] Measure the ultraviolet-visible-near-infrared absorption spectra of the organic optoelectronic small molecule TM3 prepared in Example 3 in chloroform solution and in thin film state. The specific process is as follows: An appropriate amount of the organic optoelectronic small molecule TM3 was dissolved in chloroform to prepare solutions with concentrations of 10 -5 mol / L and 20 mg / mL respectively, and a part of the 20 mg / mL solution was spin-coated onto a quartz wafer to form a thin film. 10 -5 mol / L chloroform solution and the thin film were respectively subjected to absorption spectrum tests, and the measured absorption spectra are as Figure 5 shown. It can be seen from the figure that the absorption cut-off wavelengths of the solution and thin film of TM3 exceed 1.1 μm and 1.3 μm respectively, indicating that this molecule can be used as a short-wave infrared optoelectronic material.

[0074] An organic optoelectronic detector was fabricated based on the organic optoelectronic small molecule TM3, and the optoelectronic performance of the device was tested. The device structure is ITO / ZnO / TM3:PTB7-Th / MoOx / Ag, and the preparation process is as follows:

[0075] Step 1. The transparent conductive glass with ITO was ultrasonically cleaned with deionized water, acetone, and isopropanol for 15 minutes each in turn, and then the substrate surface was treated with ozone.

[0076] Step 2. A ZnO modification layer with a thickness of 30 nm was coated on the surface of ITO.

[0077] Step 3. The organic photoelectric molecule TM3 and PTB7-Th were mixed (mass ratio of 1:1.2), dissolved in chlorobenzene to obtain 15 mg / mL, 20 mg / mL, and 25 mg / mL solutions; the solution was evenly spin-coated on the ZnO modified layer at a speed of 600-4000 rpm in a glove box to obtain an active material layer with a thickness of 100-300 nm, and annealed on a hot stage at 80-120°C for 10-30 minutes;

[0078] Step 4. Finally, in 2×10 -6 MoOx was evaporated onto the active material layer under a vacuum degree of 100 torr to form a 10 nm modified layer; and -6 Ag was evaporated onto the MoOx modified layer under a vacuum degree of 100 nm to form an electrode with a thickness of 100 nm, thereby obtaining an organic photodetection device.

[0079] The light detection performance results of organic photodetectors are shown in Figure 6 As shown in the figure, 15-A-0.5V represents the spin coating solution concentration of 15mg / mL, thermal annealing, and the test voltage of -0.5V. Other symbols are analogous. It can be seen that the specific detection rate of the organic photodetector based on TM3 in the 0.4-1.3μm spectral detection range can reach 10 11 Jones and above.

[0080] Example 4

[0081] A method for preparing an organic photoelectric molecule TM4 having a quinone-type 2-(5-methylenethiazole-2(5H)-ylidene)malononitrile terminal AA'DA'A structure, the schematic diagram of the synthesis process is as follows Figure 7 As shown, the following steps are included:

[0082] Compound DBTA (218.1 mg, 0.3 mmol), TTM (208 mg, 0.9 mmol), catalyst anhydrous indium chloride (265 mg, 1.2 mmol) and propionic anhydride (1 mL) were added to a two-necked flask filled with dry nitrogen at room temperature and stirred for 12 hours; then, the reactants were poured into ice water and stirred for 0.5 hours; the insoluble matter was filtered out, dissolved in dichloromethane, and then dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation to obtain a solid, which was finally separated by silica gel column chromatography to obtain TM4 with a yield of 117.7 mg (yield 34%).

[0083] The mass spectrum information of molecule TM4 is as follows:

[0084] MALDI–TOF MS: m / z 1152.8.

[0085] Comparative experiment of conventional method 1: At room temperature, add compound DBTA (218.1 mg, 0.3 mmol), TTM (208 mg, 0.9 mmol), and acetic anhydride (2 mL) into a dry two-necked flask filled with nitrogen. Stir and react at 110 °C for 12 hours. Subsequently, pour the reactant into ice water and stir for 0.5 hours. Filter out the insoluble matter, dissolve it in dichloromethane, and thin-layer chromatography analysis shows that DBTA hardly reacts and no TM4 is generated.

[0086] Comparative experiment of conventional method 2: At room temperature, add compound DBTA (218.1 mg, 0.3 mmol), TTM (208 mg, 0.9 mmol), ammonium acetate (5 mg), and acetic acid (2 mL) into a dry two-necked flask filled with nitrogen. Stir and react at 120 °C for 12 hours. Subsequently, pour the reactant into ice water and stir for 0.5 hours. Filter out the insoluble matter, dissolve it in dichloromethane, and thin-layer chromatography analysis shows that DBTA hardly reacts and no TM4 is generated.

[0087] The comparative experiments show that the synthesis method proposed in the present invention can prepare an organic optoelectronic molecule with a quinoid 2-(5-methylenethiazol-2(5H)-ylidene)malononitrile-terminated AA’DA’A structure, while the two reported methods cannot.

[0088] Example 5

[0089] A preparation method of an organic optoelectronic molecule TM5 with a fused-ring central structure and a quinoid 2-(5-methylenethiazol-2(5H)-ylidene)malononitrile-terminated AD A’DA structure. The schematic diagram of the synthesis process is as Figure 8 shown and includes the following steps:

[0090] Step 1: Add compound 2-bromo-1-(4,5-dichlorothiophen-2-yl)ethan-1-one (548 mg, 2 mmol), NH 4 SCN (167 mg, 2.2 mmol), and absolute ethanol (10 mL) into a dry two-necked flask filled with nitrogen. Heat the mixture to 95 °C and react for 2 hours; subsequently, add malononitrile (159 mg, 2.4 mmol), heat the mixture to 50 °C and react for 0.5 hours, then add triethylamine (0.33 mL, 2.4 mmol), stir the reactant overnight at room temperature, pour it into ice water, add acetic acid to acidify the mixture, and stir at room temperature for 1 hour. Filter out the precipitate 2-(4-(4,5-dichlorothiophen-2-yl)thiazol-2(3H)-ylidene)malononitrile (2CTM), and wash it with acetonitrile; the yield is 510 mg (yield 85%).

[0091] The mass spectrometry information and nuclear magnetic resonance hydrogen spectrum information of molecule 2CTM are as follows:

[0092] MS(ESI) m / z: 299.96. 1 H NMR (400 MHz, DMSO-d6) δ 7.55 (s, 1H), 7.31 (s, 1H).

[0093] Step 2: At room temperature, add compound BTPA (341.9 mg, 0.3 mmol), 2CTM (270.2 mg, 0.9 mmol), the catalyst anhydrous antimony trichloride (274 mg, 1.2 mmol), and propionic anhydride (1 mL) into a dry nitrogen-filled two-necked flask, and stir the reaction for 12 hours. Subsequently, pour the reactant into ice water and stir for 0.5 hours. Filter out the insoluble matter, dissolve it in dichloromethane, dry it with anhydrous sodium sulfate, then remove the solvent by rotary evaporation under reduced pressure to obtain a solid. Finally, separate it by silica gel column chromatography to obtain 434.1 mg of TM5 (yield 85%).

[0094] The mass spectrometry information and 1H nuclear magnetic resonance spectrum information of molecule TM5 are as follows:

[0095] MS (MALDI-TOF) m / z: 1702.98. 1 H NMR (400 MHz, Chloroform-d) δ 8.32 (s, 2H), 7.68 (s, 2H), 4.74 (dt, J = 9.0, 4.6 Hz, 4H), 3.09 (t, J = 7.8 Hz, 4H), 2.11–2.01 (m, 2H), 1.92 (q, J = 7.5 Hz, 4H), 1.52 (s, 2H), 1.52–1.42 (m, 2H), 1.45–1.35 (m, 4H), 1.27 (d, J = 6.3 Hz, 32H), 1.19–1.10 (m, 4H), 1.09 (s, 4H), 1.07 (d, J = 7.3 Hz, 2H), 0.92 (dt, J = 36.3, 7.0 Hz, 16H), 0.72 (t, J = 7.1 Hz, 2H), 0.68–0.63 (m, 6H), 0.67–0.57 (m, 8H).

[0096] Conventional method comparative experiment 1: At room temperature, add compound BTPA (341.9 mg, 0.3 mmol), 2CTM (270.2 mg, 0.9 mmol), and acetic anhydride (2 mL) into a dry nitrogen-filled two-necked flask, and stir the reaction at 110 °C for 12 hours. Subsequently, pour the reactant into ice water and stir for 0.5 hours. Filter out the insoluble matter, dissolve it in dichloromethane, and thin-layer chromatography analysis shows that COTA is almost exhausted but no TM1 is formed.

[0097] Comparative experiment of conventional methods 2: At room temperature, compound BTPA (341.9 mg, 0.3 mmol), 2CTM (270.2 mg, 0.9 mmol), ammonium acetate (5 mg), and acetic acid (2 mL) were added to a dry nitrogen-filled two-necked flask and stirred at 120 °C for 12 hours. Subsequently, the reaction mixture was poured into ice water and stirred for 0.5 hour. The insoluble matter was filtered out, dissolved in dichloromethane, and thin-layer chromatography analysis showed that COTA was almost exhausted but no TM1 was formed.

[0098] The comparative experiments show that the synthesis method proposed by the present invention can prepare TM5, while the two reported methods cannot.

[0099] As described above, the above are only specific embodiments of the present invention. Any feature disclosed in this specification, unless specifically described, can be replaced by other equivalent or similar-purpose alternative features; all the disclosed features, or all the steps in any method or process, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. An organic conjugated small molecule, characterized in that: The general structural formula is shown in Formula I: In formula I, A is any conjugated structure containing five basic structural units of thiophene, selenophene, pyrrole, furan, benzene and pyridine, as well as group-substituted derivatives, bridged ring derivatives and condensed ring derivatives of the five basic structural units.

2. The organic conjugated small molecule according to claim 1, characterized in that: In Formula I, Ar1 and Ar2 are the same or different and are any of those shown in Formula II:

3. The organic conjugated small molecule according to claim 1, characterized in that: In formula II, X1, X2, X3, X4, and X5 are independently selected from any one of hydrogen, fluorine, chlorine, bromine, iodine, cyano, trifluoromethyl, C1-C30 straight or branched alkyl, C1-C30 alkoxy, and C1-C30 alkylthio; Y1 and Y2 are independently selected from any one of oxygen, sulfur, and selenium atoms.

4. A method for preparing an organic conjugated small molecule, characterized in that: The specific process of the preparation method is: mixing an aldehyde-containing substrate, a 2-(thiazole-2(3H)-ylidene)malononitrile derivative, an acid anhydride and a solvent, adding a Lewis acid as a catalyst, and reacting under an inert atmosphere; after the reaction is completed, a precipitation treatment is performed, and the precipitate is treated by a gel column chromatography method to obtain an organic conjugated small molecule containing a diquinone-type 2-(5-methylenethiazole-2(5H)-ylidene)malononitrile terminal; Wherein, the structural formula of the aldehyde-containing substrate is shown in Formula III, the structural formula of the 2-(thiazole-2(3H)-ylidene)malononitrile derivative is shown in any one of Formula IV; Ar is the same as Ar1 or Ar2 described in Formula (I), 5. The preparation method according to claim 4, characterized in that: The Lewis acid used as the catalyst is specifically a boron-containing Lewis acid, a halogenated metal Lewis acid or a trifluoromethanesulfonic acid metal salt Lewis acid.

6. The preparation method according to claim 5, characterized in that: The boron-containing Lewis acids are boron trifluoride and its complexes, boron trichloride and its complexes, and tri(pentafluorophenyl)borane; the halogenated metal Lewis acids are TeCl4, SbCl3, SnCl4, InCl3, NbCl5, GaCl3, FeCl3, TiCl4, and ZnCl2; the trifluoromethanesulfonic acid metal salt Lewis acids are Sc(OTf)3, Y(OTf)3, Ce(OTf)3, Er(OTf)3, La(OTf)3, Gd(OTf)3, Yb(OTf)3, In(OTf)3, and Fe(OTf)3. 3； .

7. The preparation method according to claim 4, characterized in that: The acid anhydride is at least one of those shown in Formula V; 8. The preparation method according to claim 4, characterized in that: The solvent is the acid anhydride itself, or at least one of a halogenated alkane organic solvent, an ester organic solvent, an ether organic solvent, and an aromatic organic solvent.

9. The preparation method according to claim 8, characterized in that: The halogenated alkane organic solvent is dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane or tetrachloroethane; the ester organic solvent is ethyl acetate; the ether organic solvent is diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran or 1,4-dioxane; the aromatic organic solvent is toluene, xylene, chlorobenzene or dichlorobenzene.

10. The preparation method according to claim 4, characterized in that: The molar feed ratio of the Lewis acid catalyst, the substrate containing the aldehyde group and the 2-(thiazole-2(3H)-ylidene)malononitrile derivative is 0.01-10:1:1-20; the molar feed ratio of the substrate containing the aldehyde group and the acid anhydride is 1:1-10000; if the solvent is not the acid anhydride itself, the volume ratio of the acid anhydride to the solvent is 100:1-1:100; the reaction temperature is -20°C to 60°C; and the reaction time is 5 minutes to 120 hours.

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