Benzotriazine free radical compound, preparation method thereof and application of benzotriazine free radical compound in organic memristor and artificial synapse

Abstract

The invention belongs to the technical field of synthesis and application of organic semiconductor materials, and particularly relates to a benzotriazine free radical compound, a preparation method thereof and application of the benzotriazine free radical compound in organic memristors and artificial synapses. The prepared benzotriazine free radical compound has magnetism and good thermal stability, can bear thermal deterioration in a storage device, and can be used for preparing magnetic materials or preparing electronic devices such as organic memristors or artificial synapses. The prepared organic memristor has relatively low threshold voltage and good device stability; the prepared organic artificial synapse has synaptic plasticity and low threshold voltage, and accords with the low energy consumption characteristic of biological synapse.

Description

Technical Field

[0001] The invention belongs to the technical field of synthesis and application of organic semiconductor materials, and specifically relates to a benzotriazine free radical compound and a preparation method thereof, and application thereof in organic memristors and artificial synapses. Background Art

[0002] As computing ecosystems become more complex, the classic von Neumann bottleneck faced by traditional digital computers (characterized by the sequential processing of fetching, decoding, and executing instructions) has led to a decrease in machine efficiency. Although modern digital computers are now able to simulate the brain functions of animals as diverse as spiders, mice, and cats, the corresponding energy consumption increases exponentially with the intelligence level of the animal being modeled.

[0003] In contrast, the architecture of biological brains is fundamentally different from that of digital von Neumann architectures. The high efficiency of biological systems stems from the extensive connectivity between neurons, such as approximately 10 synapses per neuron in the mammalian cortex, which enables a high degree of parallel processing capabilities. The strength of a synapse between two neurons can be finely tuned by ion flow, and this adaptability is fundamental to learning and function in biological systems. Synapses, essentially the connection point between two neurons, bear a striking resemblance to an electronic device called a memristor (an electronic component that combines the properties of a memory and a resistor). Similar to biological synapses, the conductance of a memristor can be gradually changed by controlling the charge or current, providing a promising approach to mimic neural plasticity. Memristors have attracted much attention due to their simple design, flexible material selection, and potential for applications such as wearable electronics. This study focuses on a class of organic memristors that employ Bratt radicals conjugated to a BTBT core.

[0004] Organic free radical molecules contain one or more unpaired electrons and can be oxidized or reduced by an applied bias voltage. Benzotriazine radicals are highly delocalized, have good chemical and photostability, and reversible electrochemical behavior, which make them very suitable for organic electrical storage. The presence of heteroatoms in free radicals can enhance the contact between molecules, which is conducive to increasing the interaction between molecules and improving conductivity. These excellent properties make benzotriazine radicals promising for application in electronic devices. This is of great significance for future research on Bratt radicals in the fields of artificial synapses and neuromorphic computing, and may provide solutions for the development of next-generation memory and brain-inspired computing technologies. Summary of the invention

[0005] In view of the problems and shortcomings in the prior art, the purpose of the present invention is to provide a benzotriazine free radical compound and a preparation method thereof and application in organic memristors and artificial synapses.

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

[0007] The first aspect of the present invention provides a benzotriazine free radical compound, the structural formula of which is shown in Formula 1:

[0008]

[0009] Wherein, R is selected from any one of dimethylamino, nitro, cyano, fluoro or methoxy.

[0010] The second aspect of the present invention provides a method for preparing the benzotriazine free radical compound described in the first aspect, comprising the following steps:

[0011] S1: Compound A and compound B are added to tetrahydrofuran and mixed evenly, and then triethylamine is added, and the mixture is heated under reflux at 75°C to 85°C for 12h to 36h to separate the intermediate product;

[0012] S2: dissolving the intermediate product obtained in step S1 in dichloromethane, adding 1,8-diazabicyclo[5.4.0]undec-7-ene and palladium-carbon powder, stirring to react, filtering and collecting the filtrate after the reaction, separating and purifying the filtrate to obtain a benzotriazine free radical compound as shown in Formula 1;

[0013] The overall reaction process is expressed as:

[0014]

[0015] Wherein, R is selected from any one of dimethylamino, nitro, cyano, fluoro or methoxy.

[0016] Wherein, the structural formula of the compound A is specifically a-1, a-2, a-3, a-4 or a-5:

[0017]

[0018] The structural formula of the compound B is shown in formula b:

[0019]

[0020] In the step S1, the molar ratio of compound A to compound B is (2-3):1; the molar ratio of triethylamine to compound A is (1-3):1.

[0021] Preferably, after the reaction in step S1 is completed, the reaction solution is cooled to room temperature, filtered and the filtrate is collected; the filtrate is purified by silica gel column chromatography, eluted with ethyl acetate / petroleum ether in a volume ratio of 1:30, the eluate is collected, and the eluate is evaporated under reduced pressure to remove the solvent to obtain an intermediate product.

[0022] In the step S2, the molar ratio of 1,8-diazabicyclo[5.4.0]undec-7-ene to compound A is 1:(1-2), and the molar ratio of palladium carbon powder to compound A is 1:(5-12).

[0023] Preferably, after the reaction in step S2 is completed, the reaction solution is filtered with diatomaceous earth, the filtrate is purified by chromatography on a silica gel column, eluted with ethyl acetate / n-hexane in a volume ratio of (1:30) to (1:20), the eluate is collected, the solvent is removed by evaporation under reduced pressure, and further purified to obtain the target product compound.

[0024] Furthermore, the compound A is prepared by the following method:

[0025] Compound C and triphenylphosphine are added to acetonitrile, and then carbon tetrachloride is added, and the mixture is stirred at room temperature for reaction; after the reaction is completed, the mixture is filtered, and the filtrate is separated and purified to obtain compound A; wherein the structural formula of compound C is selected from any one of formula c-1, formula c-2, formula c-3, formula c-4, and formula c-5:

[0026]

[0027] The molar ratio of compound C to triphenylphosphine is 1:(1-2), and the molar ratio of carbon tetrachloride to compound C is (1-2):1.

[0028] The compound C is obtained by amidation reaction of compound D and compound E. The specific preparation method is: adding compound E and triethylamine to tetrahydrofuran, stirring for 10min to 15min in an ice-water bath, and then adding compound D to obtain a mixed solution; naturally warming to room temperature, stirring and reacting for 18h, filtering after the reaction, collecting the filtrate, and evaporating the solvent to obtain a solid product, and purifying the solid product to obtain compound C; wherein the structural formula of the compound D is selected from any one of formula d-1, formula d-2, formula d-3, formula d-4 or formula d-5, and the structural formula of compound E is shown in formula e:

[0029]

[0030] The third aspect of the present invention provides the use of the benzotriazine free radical compound described in the first aspect in the preparation of magnetic materials or electronic devices.

[0031] The electronic device is an organic memristor or an artificial synapse, and its structure includes a substrate layer, an organic active layer and a top electrode layer. The organic active layer is prepared from any one of the benzotriazine free radical compounds described in the first aspect.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The present invention successfully prepared a group of benzotriazine free radical compounds based on benzothienobenzothiophene, in which the main part is benzothienobenzothiophene, and different substituents are introduced at one site of the benzotriazine free radical to convert it into a BPP-R type free radical. The benzotriazine free radical compounds prepared by the present invention are all p-type materials; they can withstand thermal deterioration in storage devices and have a wide range of applications in practical applications; they are magnetic at room temperature, and their film magnetism decreases as the temperature decreases, and can be used in electronic devices.

[0034] 2. The organic memristor prepared by the present invention successfully realizes the design and regulation of the Blatter radical end group to form FLASH-type electrical storage behavior. The device is simple to prepare, has high film quality and shows good stability under high temperature conditions, which confirms the application research prospects of Blatter radicals in the field of organic memristive devices.

[0035] 3. The artificial synaptic device prepared by the present invention successfully achieved a preliminary simulation of the plasticity of artificial synapses, which will be conducive to the next step of exploring the mechanism of action of Blatter free radical derivatives in the field of artificial synapses and lay a good foundation for better applications in brain-like learning, computing and other aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The compound A of the structural formula a-1 is 1 H NMR spectra;

[0037] Figure 2 The compound C of the structural formula shown in formula c-1 1 H NMR spectra;

[0038] Figure 3 is a mass spectrum of a benzotriazine free radical compound having a structural formula as shown in Formula 1-1;

[0039] Figure 4 The mass spectrum of the benzotriazine free radical compound with the structural formula shown in Formula 1-2;

[0040] Figure 5 The mass spectrum of the benzotriazine free radical compound with the structural formula shown in Formula 1-3;

[0041] Figure 6 The mass spectrum of the benzotriazine free radical compound with the structural formula shown in Formula 1-4;

[0042] Figure 7 is a mass spectrum of a benzotriazine free radical compound having a structural formula as shown in Formula 1-5;

[0043] Figure 8The UV spectra of five benzotriazine free radical compounds prepared in Examples 7 to 11;

[0044] Fig. 9 The infrared spectra of five benzotriazine free radical compounds prepared in Examples 7 to 11;

[0045] Fig.10 Cyclic voltammograms of five benzotriazine free radical compounds prepared in Examples 7 to 11;

[0046] Fig.11 Thermogravimetric analysis diagrams of BPP-NO2, BPP-CN, BPP-F, and BPP-OCH3 benzotriazine free radical compounds;

[0047] Fig.12 The ESR graphs of five benzotriazine free radical compounds prepared in Examples 7 to 11;

[0048] Fig.13 A structural diagram of an organic memristor prepared in Example 13;

[0049] Fig.14 The polarized morphology images of the films of the five benzotriazine free radical compounds prepared in Examples 7 to 11;

[0050] Fig.15 The film XRD diffraction patterns and G1WAXS patterns of four benzotriazine free radical compound molecules, BPP-F, BPP-NO2, BPP-CN and BPP-OCH3;

[0051] Fig.16 This is a graph showing IV characteristics of the organic memristor memory prepared in Example 13;

[0052] Fig.17 Schematic diagram of signal transmission in artificial synapses;

[0053] Fig.18 This is a graph showing IV characteristics of the artificial synapse prepared in Example 15;

[0054] Fig.19 The paired pulse facilitation (PPF) characteristic curve, short-term synaptic plasticity (STP) characteristic curve and long-term synaptic plasticity (LTP) characteristic curve of the artificial synapse prepared in Example 15. DETAILED DESCRIPTION

[0055] The following examples are only for further explanation of the present invention. It should be noted that all technical and scientific terms used in the present invention have the same meaning as in the technical field to which the present invention belongs unless otherwise specified. The experimental methods in the following examples without specifying specific conditions are all based on conventional techniques in the technical field, or according to the conditions recommended by the manufacturer; the reagents or instruments used without specifying the manufacturer are all conventional products that can be purchased from the market, or can be prepared according to conventional techniques in the technical field.

[0056] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0057] Example 1

[0058] A method for preparing compound B with a structural formula as shown in formula b, the specific steps are as follows:

[0059] (1) 1 g (2.352 mmol) of compound F (substance name: [1]Benzothieno[3,2-b][1]benzothiophene, 2-decyl-7-nitro, CAS: 1398398-35-0) and 0.5 g (4.704 mmol) of catalyst palladium carbon were added to 30 mL of anhydrous ethanol, and then 1.71 mL of hydrazine hydrate was added to obtain a mixture; the mixture was heated to 85° C. and heated under reflux for 2 h;

[0060] (2) After the reaction is completed, the reaction solution is filtered while hot, and the filtrate is collected. The filtrate is evaporated under reduced pressure to remove the solvent to obtain compound B (CAS No. 1398398-41-8). The yield of compound B is 91.5%.

[0061] Wherein, the structural formula of the compound F is shown in formula f, and the structural formula of the compound B is shown in formula b:

[0062]

[0063] Example 2

[0064] A method for preparing compound A with a structural formula as shown in formula a-1, comprising the following specific steps:

[0065] 5.56 g (1 eq) of compound C and 7.13 g (1.25 eq) of triphenylphosphine were added to 60 mL of anhydrous acetonitrile, and then 2.62 mL (1.25 eq) of anhydrous carbon tetrachloride were added, and the mixture was stirred at room temperature overnight. After the reaction was completed, if any product precipitated, the bottle was washed with cold acetonitrile solution. The product was collected by suction filtration, and the filtrate was purified by silica gel column chromatography using ethyl acetate / petroleum ether in a volume ratio of 1:20 as an eluent. The eluent was collected, the solvent was evaporated, and the obtained product was combined with the suction filtration product to obtain compound A.

[0066] Wherein, the structural formula of compound C is shown in formula c-1, and the substance name is (Z)-4-(dimethylamino)-N-phenylbenzohydrazonoyl chloride; the structural formula of compound A is shown in formula a-1, and the substance name is 4-(dimethylamino)-N'-phenylbenzohydrazide,

[0067]

[0068] The reaction equation for preparing compound A of formula a-1 is:

[0069]

[0070] Wherein, the preparation method of compound C having the structural formula shown in formula c-1 is:

[0071] 5.02 mL of compound E was added to tetrahydrofuran, and then 14.16 mL (2 eq) of triethylamine was added to obtain a mixed solution, which was stirred for 10 minutes under an ice-water bath, and 5.33 mL (0.9 eq) of compound D was added dropwise to the mixed solution while maintaining an ice-water bath. After the addition was completed, the temperature was naturally raised to room temperature, and the reaction was stirred for 18 hours. After the reaction was completed, the filtrate was filtered and collected, and the filtrate was evaporated under reduced pressure to remove the solvent and then recrystallized to obtain compound C.

[0072] The structural formula of the compound E is shown in formula e, the substance name is phenylhydrazine, and the CAS number is 100-63-0; the structural formula of the compound D is shown in formula d-1, the substance name is 4-(dimethylamino)benzoyl chloride, and the CAS number is 4755-50-4:

[0073]

[0074] The reaction equation for preparing compound C with the structural formula shown in formula c-1 is:

[0075]

[0076] The prepared compound A was subjected to NMR analysis (NMR results are shown in Figure 1 (shown) L: 1 H NMR (400 MHz, Chloroform-d) 67.89 (s, 1H), 7.81 (d, J = 8.0 Hz, 2H), 7.31 (t, J = 8.0, 8.0 Hz, 2H), 7.17 (d, J = 8.0 Hz, 2H), 6.91 (t, J = 8.0, 4.0 Hz, 1H), 6.73 (d, 8.0 Hz, 1H), 3.02 (s, 6H). The above results confirmed that the obtained product was the target product.

[0077] The prepared compound C was subjected to NMR analysis (the NMR results are shown in Figure 2 shown): 1 H NMR (400 MHz, Chloroform-d) 67.76 (d, J=8.0 Hz, 2H), 7.26-7.21 (m, 3H), 6.95-6.90 (m, 3H), 6.73 (d, J=8.0 Hz, 2H), 3.05 (s, 6H). The above results confirmed that the obtained product was the target product.

[0078] Example 3

[0079] A compound A with a structural formula as shown in formula a-2, the substance name is (Z)-4-nitro-N-phenylbenzohydrazonoyv chloride, and the CAS number is 20147-55-1:

[0080]

[0081] The preparation method of the compound A of the structural formula shown in formula a-2 described in this embodiment is basically the same as the preparation method of the compound A of the structural formula shown in formula a-1 in Example 2, except that: the structural formula of the compound C in this embodiment is shown in formula c-2, the substance name is 4-nitro-N'-phenylbenzohydrazide, and the CAS number is 39718-99-5:

[0082]

[0083] The preparation method of compound C with the structural formula shown in formula c-2 is basically the same as the preparation method of compound C in Example 2, except that the structural formula of compound D in this example is shown in formula d-2, the substance name is 4-nitrobenzoyl chloride, and the CAS number is 122-04-3:

[0084]

[0085] Example 4

[0086] A compound A with a structural formula as shown in formula a-3, the substance name is (Z)-4-cyano-N-phenylbenzohydrazonoyl chloride, and the CAS number is 50656-04-7:

[0087]

[0088] The preparation method of the compound A of the structural formula a-3 described in this embodiment is basically the same as that of the compound A of the structural formula a-1 in Example 2, except that the structural formula of the compound C in this embodiment is shown in formula c-3, the substance name is 4-cyano-N'-phenylbenzohydrazide, and the CAS number is 88405-47-4:

[0089]

[0090] The preparation method of the compound C with the structural formula shown in formula c-3 is basically the same as the preparation method of the compound C in Example 2, except that the structural formula of the compound D in this example is shown in d-3, the substance name is 4-cyanobenzoyl chloride, and the CAS number is 6068-72-0:

[0091]

[0092] Example 5

[0093] A compound A with a structural formula as shown in formula a-4, the substance name is (Z)-4-fluoro-N-phenylbenzohydrazonoyl chloride, and the CAS number is 25939-02-0:

[0094]

[0095] The preparation method of compound A with the structural formula shown in formula a-4 in this embodiment is basically the same as the preparation method of compound A with the structural formula shown in formula a-1 in embodiment 2, except that: the structural formula of compound C in this embodiment is shown in formula c-4, the substance name is 4-fluoro-N'-phenylbenzohydrazide, and the CAS number is 1496-02-2:

[0096]

[0097] The preparation method of the compound C with the structural formula shown in formula c-4 is basically the same as that of the compound C in Example 2, except that the structural formula of the compound D in this example is shown in formula d-4, the substance name is 4-fluorobenzoyl chloride, and the CAS number is 403-43-0:

[0098]

[0099] Example 6

[0100] A compound A having a structural formula as shown in formula a-5, the substance name is (Z)-4-methoxy-N-phenylbenzohydrazonoylchloride, and the CAS number is 40277-63-2:

[0101]

[0102] The preparation method of compound A with the structural formula shown in formula a-5 in this embodiment is basically the same as the preparation method of compound A with the structural formula shown in formula a-1 in embodiment 2, except that the structural formula of compound C in this embodiment is shown in formula c-5, the substance name is 4-methoxy-N'-phenylbenzohydrazide, and the CAS number is 15089-03-9:

[0103]

[0104] The preparation method of compound C with the structural formula shown in formula c-5 is basically the same as the preparation method of compound C in Example 2, except that: the structural formula of compound D in this example is shown in formula d-5, the substance name is 4-methoxybenzoyl chloride, and the CAS number is 100-07-2:

[0105]

[0107] Example 7

[0108] A benzotriazine free radical compound, the structural formula of which is shown in Formula 1-1:

[0109]

[0110] The preparation method of the above-mentioned benzotriazine free radical compound comprises the following specific steps:

[0111] S1: Compound B (0.9 g, 2.352 mmol) and compound A (1.35 g, 2.5 eq) were added to 40 ml of anhydrous tetrahydrofuran to obtain a mixed solution, 1.6 ml of triethylamine was added to the mixed solution, and the mixture was refluxed at 80°C for 24 h. After the reaction was completed, the reaction solution was cooled to room temperature and filtered, the filtrate was collected, and the silica gel column was purified by using a mixed solvent of ethyl acetate / petroleum ether with a volume ratio of 1:30 as an eluent, and the eluate was collected. The eluate was evaporated under reduced pressure to remove the solvent to obtain an intermediate product.

[0112] Wherein, the compound B is prepared in Example 1, and the compound A is prepared in Example 2 and has a structural formula shown in formula a-1.

[0113] S2: The intermediate product (1 eq) was dissolved in anhydrous dichloromethane (50 ml), and 1,8-diazabicyclo[5.4.0]undec-7-ene (2 eq) and palladium carbon powder (0.1 eq, the specification of palladium carbon powder is 10 wt%) were added, and the reaction was stirred in air. After the reaction was completed, the filtrate was filtered with diatomaceous earth and the filtrate was collected. The filtrate was purified by chromatography on a silica gel column, and an ethyl acetate / n-hexane mixture with a volume ratio of 1:30 was used as an eluent for elution. The eluate was collected, the solvent was evaporated, and a small amount of dichloromethane and a large amount of anhydrous ethanol were added for recrystallization to obtain the target product compound.

[0114] The specific overall reaction equation is as follows:

[0115]

[0116] The benzotriazine free radical compounds prepared in this example were subjected to mass spectrometry analysis (mass spectrometry results are shown in Figure 3 HRMS (ESI+): [M]+C 39 H 41 N4S2·calculated 629.28, found 629.1794. The above results confirmed that the obtained product was the target product.

[0117] Example 8

[0118] A benzotriazine free radical compound, the structure of which is shown in Formula 1-2:

[0119]

[0120] The preparation method of the benzotriazine free radical compounds described in this embodiment is basically the same as that in Example 7, except that: in step S1, the compound A is the compound A prepared in Example 3 with the structural formula shown in formula a-2 (the amount of compound A remains unchanged).

[0121] The benzotriazine free radical compounds prepared in this example were subjected to mass spectrometry analysis (mass spectrometry results are shown in Figure 4 HRMS (ESI+): [MH]+C 37 H 35 N4O2S2 calculated to be 631.22, found to be 631.9139. The above results confirm that the obtained product is the target product.

[0122] Example 9

[0123] A benzotriazine free radical compound, the structure of which is shown in Formula 1-3:

[0124]

[0125] The preparation method of the benzotriazine free radical compounds described in this embodiment is basically the same as that in Example 7, except that: in step S1, the compound A is the compound A prepared in Example 4 with the structural formula shown in formula a-3 (the amount of compound A remains unchanged).

[0126] The benzotriazine free radical compounds prepared in this example were subjected to mass spectrometry analysis (mass spectrometry results are shown in Figure 5 HRMS (ESI+): [MH]+C 38 H 35 N4S2 calculated 611.23, found 611.1410. The above results confirmed that the obtained product was the target product.

[0127] Example 10

[0128] A benzotriazine free radical compound, the structure of which is shown in Formula 1-4:

[0129]

[0130] The preparation method of the benzotriazine free radical compounds described in this embodiment is basically the same as that in Example 7, except that: in step S1, the compound A is the compound A prepared in Example 5 with the structural formula shown in formula a-4 (the amount of compound A remains unchanged).

[0131] The benzotriazine free radical compounds prepared in this example were subjected to mass spectrometry analysis (mass spectrometry results are shown in Figure 6 HRMS (ESI+): [MH]+C 43 H 48 N3S2·calculated 604.23, found 604.0837. The above results confirmed that the obtained product was the target product.

[0132] Embodiment 11

[0133] A benzotriazine free radical compound, the structure of which is shown in Formula 1-5:

[0134]

[0135] The preparation method of the benzotriazine free radical compounds described in this embodiment is basically the same as that in Example 7, except that: in step S1, the compound A is the compound A prepared in Example 6 with the structural formula shown in formula a-5 (the amount of compound A remains unchanged).

[0136] The benzotriazine free radical compounds prepared in this example were subjected to mass spectrometry analysis (mass spectrometry results are shown in Figure 7 HRMS (ESI+): [MH]+C 38 H 38 N3OS2 was calculated to be 616.25, and found to be 616.0590. The above results confirmed that the obtained product was the target product.

[0137] Example 12 Product Characterization and Performance Testing

[0138] The benzotriazine free radical compounds prepared in Examples 7 to 11 were named BPP-NMe2, BPP-NO2, BPP-CN, BPP-F, and BPP-OCH3, respectively, and their performance characteristics were tested.

[0139] (I) Optical characterization

[0140] (1) UV-absorption spectroscopy characterization

[0141] The five benzotriazine free radical compounds prepared in Examples 7 to 11 were subjected to UV-absorption spectrum measurement, and the data were normalized. The results are as follows: Figure 8 shown.

[0142] from Figure 8 It can be seen that within the ultraviolet wavelength range (280-380nm), the five benzotriazine free radical compounds all have a strong absorption peak and a weak absorption peak, corresponding to the π→π* transition and n→π* transition in the aromatic ring, respectively. Due to the influence of the substituents, the maximum absorption wavelengths are different.

[0143] According to the initial absorption wavelengths of the five benzotriazine free radical compounds in the ultraviolet absorption spectra, it can be calculated that the optical band gaps Eg of the five compounds are 0.82, 0.97, 0.96, 0.93 and 0.92 eV respectively.

[0144] The above results show that the spectra obtained from the five compounds prepared in the present invention are consistent with the typical optical absorption characteristics of the Blatter free radical, including one strong absorption peak and three weak absorption peaks, which further proves the accuracy of the molecular structure of the obtained products.

[0145] (2) Infrared spectroscopy characterization

[0146] The five benzotriazine free radical compounds prepared by the present invention were characterized by infrared spectroscopy. Fig. 9 As shown in the figure, at wave numbers 3300-3500cm -1 No typical NH stretching vibration absorption was observed, proving that the molecule has been completely converted into BPP-R type free radicals.

[0147] (II) Electrochemical performance test

[0148] (1) Cyclic voltammetry test

[0149] Cyclic voltammetry test was performed on the five benzotriazine free radical compounds prepared by the present invention: anhydrous dichloromethane was used as solvent, 0.1MBu4NPF6 was used as supporting electrolyte, Ag / AgCl was used as reference electrode, glassy carbon was used as working electrode, platinum wire was used as auxiliary electrode, and the scanning rate was 100mV / s.

[0150] The cyclic voltammograms of the five compounds are shown in Fig.10 As shown, the measured ferrocene is 0.52 eV. The HOMO and LUMO energy levels are calculated by the following formula:

[0151]

[0152] E g =E HOMo -E LUMO .

[0153] Fig.10 The red * in the middle represents the half-wave potential E 1 / 2 . Fig.10It is revealed that the five benzotriazine free radical compounds prepared by the present invention all have reversible redox behavior. According to the formula, the HOMO energy levels of the five compounds are calculated to be -4.43, -4.59, -4.56, -4.53 and -4.46 eV respectively; the LUMO energy levels are -3.61, -3.62, -3.60, -3.60 and -3.54 eV respectively. For semiconductor devices, the smaller the HOMO energy level difference between the work function of the electrode and the active layer, the easier it is for the valence electrons to transition and thus transmit current. For organic free radicals, the smaller the energy gap difference, the easier it is to excite electrons from the valence band to the conduction band, thereby increasing the intrinsic carrier concentration, and finally the molecules in the active layer of the device are more likely to cause circuit conduction. Therefore, the five benzotriazine free radical compounds prepared by the present invention can be used in electronic devices.

[0154] (2) Energy level information

[0155] The energy level information of the five benzotriazine free radical compounds prepared by the present invention is shown in Table 1.

[0156] Table 1 Energy level information of benzotriazine free radical compounds

[0157]

[0158] Note:

[0159] The energy barriers between the HOMO energy level of BPP-NMe2, BPP-NO2, BPP-CN, BPP-F, and BPP-OCH3 and the ITO work function (4.8 eV) are 0.37 eV, 0.21 eV, 0.24 eV, 0.27 eV, and 0.34 eV, respectively, which are lower than the energy barriers between their respective LUMO energy levels and the A1 work function (4.28 eV), which are 0.67 eV, 0.66 eV, 0.68 eV, 0.68 eV, and 0.74 eV, respectively. This indicates that hole injection from ITO to the HOMO energy level is much easier than electron injection from A1 to the LUMO energy level. This indicates that the five benzotriazine free radical compounds prepared by the present invention are all p-type materials, and hole conduction is dominant during the use of organic memory devices.

[0160] (III) Thermogravimetric analysis (TGA)

[0161] The thermal properties of the BPP-NO2, BPP-CN, BPP-F, and BPP-OCH3 benzotriazine free radical compounds prepared by the present invention were tested by thermogravimetric analysis (TGA) under nitrogen atmosphere. The results are as follows: Fig.11All compounds showed good thermal stability, and the thermal decomposition temperatures (5% weight loss temperature) were 295°C, 355°C, 295°C, and 403°C, respectively. This shows that the benzotriazine free radical compounds prepared by the present invention can withstand thermal deterioration in storage devices and have a wide range of applications in practical applications.

[0162] (IV) Magnetic characterization (ESR characterization)

[0163] The quartz plate was ultrasonically treated with acetone, isopropanol, anhydrous ethanol and water for 20 minutes respectively, and then the quartz plate was blown dry with nitrogen. The five benzotriazine free radical compounds prepared by the present invention were prepared into 2 mg / mL solutions (all with dichloromethane as solvent) and dropped on the quartz plate respectively. After evaporation at room temperature, the ESR signal of the obtained film was tested. The results are as follows Fig.12 shown.

[0164] It can be seen from the figure that the five benzotriazine free radical compounds prepared in the present invention are all magnetic at room temperature, and the magnetic properties of their films are weakened as the temperature decreases.

[0165] Example 13: Preparation of organic memristor

[0166] In this embodiment, an organic memristor is prepared. The device includes three layers, which are a substrate layer, an organic active layer and a top electrode layer from bottom to top. The schematic diagram of the structure is shown in FIG. Fig.13 As shown, the substrate layer is ITO glass, and the top electrode layer is an aluminum electrode evaporated by a thermal evaporator. The steps for preparing an organic memristor device are as follows:

[0167] S1: Preparation of organic active layer

[0168] The five benzotriazine free radical compounds BPP-R were uniformly prepared into 0.2wt% solutions, and the solvents used for the five benzotriazine free radical compounds BPP-R are shown in Table 2. The ITO glass with a size of 1.5×1.5cm and the cover glass with a size of 2×2cm (as a scraper) were ultrasonically vibrated for 20min using detergent water, ultrapure water, and isopropanol in turn, and blown dry with N2. The clean ITO glass was treated with plasma for 600s, and the power was set to 45W, which can remove the hydrocarbons attached to the ITO surface, making the ITO surface more lyophilic, so that the compound solution can form a crystal film on the ITO surface. Then, a scraper was used to prepare a thin film of the ITO glass and the prepared BPP-R solution to obtain a thin film, i.e., the active layer of the organic memristor device (the sample stage needs to be corrected with a spirit level before scraping. The scraping height was set to 100 μm, and the scraping speed was found to be optimal at 10 μm / s to 20 μm / s based on the evaporation rate of different sample solvents. The angle between the scraper and the substrate was fixed at 45 degrees. The above are the best scraping conditions explored).

[0169] Table 2 Solvent ratios used in BPP-R

[0170]

[0171] S2: Preparation of organic memristors

[0172] Paste the electrode mask and the film and put them into the evaporation apparatus. Set the aluminum electrode evaporation thickness to 100nm. The evaporation conditions are as follows: -4 Under the vacuum condition of Pa, the evaporation rate is The result is an organic memristor.

[0173] Example 14 Performance test of organic memristor device

[0174] (1) Characterization of polarization morphology of active layer

[0175] The polarized morphology of the thin films of five benzotriazine free radical compound molecules is shown in Figure 2. Fig.14 As shown, except for the BPP-NMe2 film, the crystal morphology of the films prepared by other molecules is roughly composed of the stacking of elongated nanoscale single crystals.

[0176] (2) Polarized light morphology characterization and XRD diffraction characterization of active layer

[0177] The thin film XRD diffraction patterns and GIWAXS patterns of the four benzotriazine free radical compound molecules BPP-F, BPP-NO2, BPP-CN, and BPP-OCH3 are shown in Fig.15 As shown in the figure, the interplanar spacing of the four compound crystal films can be seen. Taking BPP-F as an example, according to one-dimensional XRD, it is not difficult to see that the molecule has two diffraction peaks, one strong and one weak. When 2θ = 6.28°, the interplanar spacing is larger. When 2θ = 12.62°, the interplanar spacing is The two diffraction peaks may be due to the conformational inversion between the benzene rings, and the two diffraction peaks are basically 2 times the relationship, indicating that the molecules have a good stacking level. In addition, in order to more comprehensively understand the stacking mode of the molecules after film formation, we tested the grazing incidence wide-angle X-ray scattering (GIWAXS) of BPP-R molecules to explore the effect of molecular stacking mode on carrier transport from a microscopic perspective. Fig.15 GIWAXS spectrum combined with Fig.14 It can be inferred from the polarized morphology image of the film that BPP-F has the best crystallinity and forms a long-range ordered crystal morphology. The other three molecules also form a good crystal morphology, which belongs to short-range order.

[0178] The XRD patterns of the four films all have sharp diffraction peaks, indicating that the benzotriazine free radical compounds prepared by the present invention can self-assemble into highly ordered crystalline films. Since the crystallinity of the film plays a vital role in the transmission of charges, the above experimental results may have a great impact on its storage behavior.

[0179] (3) IV characteristics test

[0180] The device performance was tested using Keithley 4200A-CVIV MULTI-SWITCH. The scan range was a closed loop scan between -5 V and 5 V. Starting from 0 V, the step size was 10 mV and gradually increased to 5 V, then gradually decreased to -5 V with the same step size, and then increased to 0 V with the same step size. The current value during this period was recorded to depict the IV characteristics.

[0181] like Fig.16 The IV characteristic curve of the sample is shown. It can be seen that the ITO / BPP-R / A1 device undergoes a process from "off" to "on" and from "on" to "off" under the cyclic scanning of positive voltage and negative voltage, and the switching ratio is about 10 to 100. For the BPP-R memristor substituted with electron-withdrawing groups, its threshold voltage is distributed in the range of 1 to 2V. It can be judged that due to the existence of the electron-withdrawing effect, the frontier orbital energy level of the BPP-R-type molecule is pulled from the original BTBT core and Blatter core distribution to the benzene ring at the C3 site of the Blatter core, which has a certain degree of influence on the transmission of carriers between molecules with conjugated structures, and the increase in the energy gap difference also increases the turn-on voltage of the memristor to a certain extent. On the contrary, the threshold voltage of the BPP-R-based memristor substituted with electron-donating groups is mainly distributed within 1V, which is consistent with the expected electronic effect of electron-donating / electron-withdrawing groups. The stability test of the above device confirms that it has good device stability.

[0182] The above results indicate that the present invention utilizes a sandwich-structured organic memristor prepared based on organic small molecule materials to successfully achieve the design and regulation of the Blatter radical end groups to form FLASH-type electrical storage behavior. The device is simple to prepare, has high film quality, and exhibits good stability under high temperature conditions, confirming the application research prospects of Blatter radicals in the field of organic memristive devices.

[0183] Example 15: Preparation of organic artificial synapses

[0184] The steps of the preparation method of the organic artificial synaptic device described in this embodiment are the same as the steps of the preparation method of the organic memristor in Example 13, wherein the compounds BPP-F and BPP-OCH3 are prepared into an organic artificial synaptic device, and the signal transmission schematic diagram thereof is shown in FIG. Fig.17shown.

[0185] Example 16 Organic artificial synapse performance test

[0186] (1) IV characteristics test

[0187] The performance of the device was tested using Keithley 4200A-CVIV MULTI-SWITCH.

[0188] like Fig.18 The IV characteristic curve of the sample is shown in the figure. It can be seen that the BPP-OCH3 memristor device exhibits the hysteresis curve characteristics of artificial synaptic characteristics during the bias voltage scanning process of 0 to 0.2V in the positive direction and 0 to -0.2V in the negative direction, that is, under the stimulation of continuous voltage, the device current exhibits a gradual enhancement / inhibition characteristic, while the BPP-F exhibits related characteristics during the bias voltage scanning process of 0 to 1V in the positive direction and 0 to -1V in the negative direction. This once again shows that the BPP-OCH3 memristor with a low threshold voltage has a lower operating voltage, which is in line with the low energy consumption characteristics of biological synapses.

[0189] (2) Synaptic plasticity experiments of organic artificial synapses

[0190] The performance of the device was tested using Keithley 4200A-CVIV MULTI-SWITCH. The synaptic plasticity of the artificial synapse includes short-term synaptic plasticity and long-term synaptic plasticity.

[0191] like Fig.19 (a) and (e) show the double pulse facilitation (PPF) characteristic curves of the sample. It can be seen that the PPF behavior of the memristor is widely present in artificial synaptic devices. Pulse stimulation at different time intervals has a certain influence on the PPF behavior. As one of the important signs of synaptic short-term plasticity, double pulse facilitation (PPF) reflects the characteristic performance of the current of artificial synapses under continuous pulse voltage stimulation. PPF reflects that after the synaptic device is stimulated by two consecutive pulses, the second postsynaptic current (EPSC) peak is higher than the first EPSC peak. Fig.19(b) and (f) show the short-term synaptic plasticity (STP) characteristic curves of the samples. Short-term synaptic plasticity is regarded as one of the important features in synaptic simulation. It represents the excitatory / inhibitory current in biological synapses, that is, after the presynaptic membrane receives external stimulation, it will release neurotransmitters and transmit them to the postsynaptic membrane through the synaptic cleft. At this time, the chemical signal is converted into an electrical signal, thereby causing the response action potential of the postsynaptic membrane. Here, we will use the metal A1 electrode layer and the ITO electrode layer in the BPP-R memristor as the presynaptic membrane and the postsynaptic membrane respectively, while BPP-F and BPP-OCH3 will act as the synaptic cleft. By applying a pulse voltage to the top electrode Al, the current change will be generated due to the release of the signal. This also further reflects the potential of memristive devices in short-term synaptic plasticity.

[0192] like Fig.19 (c), (d), (g) and (h) show the long-term synaptic plasticity (LTP) characteristic curves of the samples. LTP is a signal formed through repeated memory training behavior on the basis of a short time course, so it can become a permanent memory. The process from STP to LTP is also called "experience learning". After multiple STP simulations, the BPP-F memristor and the BPP-OCH3 memristor showed effective long-term prominent plasticity under pulse voltages of 1.2V and 0.8V, respectively. It is worth noting that this is different from the threshold voltage of the artificial synaptic characteristic curves of the BPP-F and BPP-OCH3 memristors measured by DC voltage, which may be because short-term pulse stimulation requires a higher voltage to stimulate the device.

[0193] The above results indicate that the present invention has successfully achieved a preliminary simulation of artificial synaptic plasticity by using a sandwich-structured artificial synaptic device prepared based on organic small molecule materials. This will be conducive to the next step of exploring the mechanism of action of Blatter free radical derivatives in the field of artificial synapses, and lay a good foundation for better applications in brain-like learning, computing, and other aspects.

[0194] The above embodiments are intended to illustrate the essential content of the present invention, but are not intended to limit the protection scope of the present invention. Those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and protection scope of the technical solution of the present invention.

Claims

1. A benzotriazine free radical compound, characterized in that: The structural formula is shown in Formula 1: Wherein, R is selected from any one of dimethylamino, nitro, cyano, fluoro or methoxy.

2. The method for preparing the benzotriazine free radical compound according to claim 1, characterized in that: The following steps are involved: S1: Compound A and compound B are added to tetrahydrofuran and mixed evenly, and then triethylamine is added, and the mixture is heated under reflux at 75°C to 85°C for 12h to 36h to separate the intermediate product; S2: dissolving the intermediate product obtained in step S1 in dichloromethane, adding 1,8-diazabicyclo[5.4.0]undec-7-ene and palladium-carbon powder, stirring to react, filtering and collecting the filtrate after the reaction, separating and purifying the filtrate to obtain a benzotriazine free radical compound as shown in Formula 1; The overall reaction process is expressed as: Wherein, R is selected from any one of dimethylamino, nitro, cyano, fluoro or methoxy.

3. The preparation method according to claim 2, characterized in that: In the step S1, the molar ratio of compound A to compound B is (2-3):1; the molar ratio of triethylamine to compound A is (1-3):

1.

4. The preparation method according to claim 3, characterized in that: After the reaction in step S1 is completed, the reaction solution is cooled to room temperature, filtered and the filtrate is collected; the filtrate is purified by silica gel column chromatography, eluted with ethyl acetate / petroleum ether in a volume ratio of 1:30, the eluate is collected, and the eluate is evaporated under reduced pressure to remove the solvent to obtain an intermediate product.

5. The preparation method according to claim 2, characterized in that: In the step S2, the molar ratio of 1,8-diazabicyclo[5.4.0]undec-7-ene to compound A is 1:(1-2), and the molar ratio of palladium carbon powder to compound A is 1:(5-12).

6. The preparation method according to claim 5, characterized in that: After the reaction in step S2 is completed, the reaction solution is filtered through diatomaceous earth, and the filtrate is purified by chromatography on a silica gel column, eluted with ethyl acetate / n-hexane in a volume ratio of (1:30) to (1:20), the eluate is collected, and the solvent is removed by evaporation under reduced pressure, and further purified to obtain the target product compound.

7. The preparation method according to claim 2, characterized in that: The compound A is prepared by the following method: Compound C and triphenylphosphine are added to acetonitrile, and then carbon tetrachloride is added, and the mixture is stirred at room temperature for reaction; after the reaction is completed, the mixture is filtered, and the filtrate is separated and purified to obtain compound A; wherein the structural formula of compound C is selected from any one of formula c-1, formula c-2, formula c-3, formula c-4, and formula c-5: The molar ratio of the compound C to triphenylphosphine is 1:(1-2), and the molar ratio of the carbon tetrachloride to the compound C is (1-2):

1.

8. The preparation method according to claim 7, characterized in that: The compound C is obtained by amidation reaction of compound D and compound E; wherein the structural formula of the compound D is selected from any one of formula d-1, formula d-2, formula d-3, formula d-4 or formula d-5, and the structural formula of compound E is shown in formula e:

9. Use of the benzotriazine free radical compound according to claim 1 in the preparation of magnetic materials or electronic devices.

10. The use according to claim 9, characterized in that: The electronic device is an organic memristor or an artificial synapse, and its structure includes a substrate layer, an organic active layer and a top electrode layer; the organic active layer is prepared from any one of the benzotriazine free radical compounds described in claim 1.

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