Oligopolyaniline derivative, preparation method and application thereof in monomolecular switch

Abstract

The invention discloses an oligoaniline derivative, a preparation method and application of the oligoaniline derivative in a monomolecular switch, and the structural formula of the oligoaniline derivative is as follows: # imgabs0 #, wherein Ar is an aromatic group and is selected from any one of benzene ring, pyridine, thiophene and pyrrole; r is an anchoring group and is selected from any one of thioether, sulfuryl and amino; according to the preparation method, 1, 4-dibromobenzene and an amino aromatic compound derivative are used as raw materials, an intermediate is obtained through Buchwald-Harwig reaction, then silver oxide is added, a final product is obtained, the preparation method is simple, the reaction condition is mild, the prepared oligoaniline derivative can achieve reversible switching between a double-free-radical structure and a quinoid structure through regulation and control by additionally adding acid and alkali, and the preparation method is suitable for industrial production. Therefore, the method is applied to construction of switch electronic devices or logic circuits.

Description

Technical Field

[0001] The present invention relates to an oligopolyaniline derivative, a preparation method thereof, and an application thereof in a single-molecule switch, belonging to the technical fields of oligopolyaniline derivatives and single-molecule switches. Background Art

[0002] Single-molecule electronics mainly studies the electrical transport properties of single molecules at the mesoscopic scale and the development of molecular-scale electronic devices. Taking a single molecule as the basic unit of research is of great significance for the miniaturization and performance improvement of electronic devices. A single-molecule switch that has a reversible response to external stimuli and can achieve mutual conversion between two or more stable states is the core of switch-type electronic devices and logic circuits. Among them, molecules containing redox centers can be regulated among multiple redox states through electrochemical oxidation or reduction processes, which is crucial for the research of high-performance molecular switch devices. At present, some organic small molecules have achieved effective regulation of molecular conductance through single-molecule-scale electrochemical oxidation and reduction (Journal of the American Chemical Society, 2014, 136(25), 8867-8870; The Chemical Record, 2021, 21(9), 2411-2429.). However, the current single-molecule switches have problems such as complex molecular design and synthesis, poor reversibility and stability during the regulation of electrical transport properties, and low switching current. The development of single-molecule switches that are simple to synthesize and have high responsiveness and high stability is the research focus and difficulty in the field of molecular switches.

[0003] As a kind of conductive material with multiple redox states, polyaniline has been widely studied at the macroscopic level. By adding external acids and bases, partially oxidized intrinsic polyaniline can achieve efficient reversible switching between a high-conductivity state containing free radicals and a low-conductivity state containing quinoid structures. Therefore, polyaniline can be used as a redox-active material in devices such as batteries, sensors, and electrochromic devices (Polymers, 2021, 13(12), 2003; The Chemical Record, 2023, 24(1), e202300105.). However, polyaniline is prone to decomposition during the redox cycle, and there is currently a lack of systematic research on the influencing mechanism of this decomposition process, which severely limits the optimization of its material properties. Summary of the Invention

[0004] The first object of the present invention is to provide an oligopolyaniline derivative, and its structural formula is as follows:

[0005]

[0006] In the formula:

[0007] Ar is an aromatic group, preferably any one of benzene ring, pyridine, thiophene, and pyrrole;

[0008] R is an anchoring group, preferably any one of thioether, sulfonyl, and amino.

[0009] The object of the second aspect of the present invention is to provide a preparation method of an oligopolyaniline derivative, comprising the following steps:

[0010] (1) 1,4-dibromobenzene reacts with an amino aromatic compound derivative shown in formula (II) to obtain an intermediate (III):

[0011] H2N-Ar-R (II)

[0012]

[0013] (2) Silver oxide reacts with the intermediate (3) to obtain the following final product (IV);

[0014]

[0015] In formulas II-IV:

[0016] Ar is an aromatic group, which is any one of benzene ring, pyridine, thiophene, and pyrrole; R is an anchoring group, which is any one of thioether, sulfonyl, and amino.

[0017] In the preparation method of the present invention, 1,4-dibromobenzene and an amino aromatic compound derivative (II) are used as starting materials, and the intermediate (III) is obtained through the Buchwald-Hartwig reaction, and then silver oxide is added to obtain the final product (IV). The preparation method is simple and the reaction conditions are mild.

[0018] Furthermore, as a preference:

[0019] In step (1), the molar ratio of 1,4-dibromobenzene to the amino aromatic compound derivative is 1-1.2:2.1-2.5, the reaction solvent is toluene, the temperature is 100-120 °C, and the reaction time is 12-24 h.

[0020] In step (1): Tris(dibenzylideneacetone)dipalladium(0) and 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene are added as catalysts. This catalyst system has good solubility in the reaction solvent, and the electron-donating ability of the ligand interacting with palladium contributes to the occurrence of the entire catalytic reaction. Other alternative catalysts are: Tris(dibenzylideneacetone)dipalladium(0) and 1,1'-binaphthalene-2,2'-bis(diphenylphosphine). The molar ratio of 1,4-dibromobenzene to Tris(dibenzylideneacetone)dipalladium(0) is 1:0.05 - 0.10, and the molar ratio of Tris(dibenzylideneacetone)dipalladium(0) to 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene is 1 - 1.2:1.5 - 1.8.

[0021] In step (2), the molar ratio of intermediate (III) to silver oxide is 1 - 1.1:1.5 - 2. The reaction solvent is acetone, the reaction temperature is room temperature, and the reaction time is 2 - 4 h.

[0022] The third aspect of the present invention aims to provide an application of an oligopolyaniline derivative as a single-molecule switch. The oligopolyaniline derivative prepared in the present invention can be reversibly switched between a biradical structure and a quinoid structure by external acid-base regulation, and thus can be applied to the construction of switch-type electronic devices or logic circuits.

[0023] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. Description of the Drawings

[0024] Figure 1 1H-NMR spectrum of product d prepared in Example 1 1 1H-NMR spectrum.

[0025] Figure 2 13C-NMR spectrum of product d prepared in Example 1 13 13C-NMR spectrum.

[0026] Figure 3 1H-NMR spectrum of the biradical molecule e formed during the acid regulation process of product d prepared in Example 1 1 1H-NMR spectrum.

[0027] Figure 4 Cyclic voltammetry (CV) curve of product d prepared in Example 1 at 298 K in dichloromethane (DCM, c ~ 5×10 -3 M, 0.1 M n-Bu4NPF6), scan rate 0.10 V·s -1 .

[0028] Figure 5 UV-visible absorption spectrum of product d prepared in Example 1 in 1,2,4-trichlorobenzene (TCB, c ~ 5×10 -5 M) with acid-base regulation by camphorsulfonic acid (CSA) and triethylamine (TEA).

[0029] Figure 6 The electron spin resonance spectrum (EPR) of the product d prepared in Example 1 in N,N-dimethylformamide (DMF, c~2*10 -3 M) containing 50 molar equivalents of camphorsulfonic acid (CSA).

[0030] Figure 7 The conductivity test result graph of the product d prepared in Example 1 in TCB (c~10 -4 M) with acid-base regulation by camphorsulfonic acid (CSA) and triethylamine (TEA). Detailed implementation manners

[0031] Example 1

[0032] A preparation method of an oligopolyaniline derivative, comprising the following steps:

[0033] (1) Synthesis of intermediate c:

[0034] Add tris(dibenzylideneacetone)dipalladium(0) (0.27 g, 0.3 mmol), 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (0.26 g, 0.45 mmol), and sodium tert-butoxide (2.40 g, 25 mmol) into a 100 mL two-necked flask containing dry toluene (50 mL). After heating to 110 °C under nitrogen protection, add compound a (1.46 g, 10.5 mmol) and compound b (1.18 g, 5.0 mmol), and stir at 110 °C for 24 hours. After the reaction is cooled to room temperature, extract with dichloromethane, collect the organic phase and dry it with anhydrous sodium sulfate. After filtration and rotary evaporation, isolate the crude product of intermediate c to obtain 1.45 g of a red-brown solid with a yield of 82%. The crude product of the synthesized intermediate c is directly used for the next reaction without further purification.

[0035] (2) Synthesis of oligopolyaniline derivative d:

[0036] Add the crude product of intermediate c into a 250 mL single-necked round-bottom flask containing acetone (150 mL). After adding silver oxide (1.74 g, 7.5 mmol), stir at room temperature for 4 hours. Filter the reaction mixture, collect the filtrate and rotary evaporate it, and wash the remaining solid with ethyl acetate and methanol to obtain 0.58 g of a brown solid product d, which is a mixture of E / Z isomers, labeled as OANI, with a yield of 40%.

[0037] Product confirmation:

[0038] 11H NMR (400 MHz, CDCl3, δ / ppm): 7.31 - 7.28 (dd, Z, 4H, J = 8.5 Hz, 2.0 Hz), 7.28 - 7.26 (dd, E, 4H, J = 6.6 Hz, 2.0 Hz), 7.09 (m, Z, 2H), 6.96 - 6.95 (d, E, 4H, J = 2.0 Hz), 6.89 - 6.87 (dd, Z, 4H, J = 8.5 Hz, 2.0 Hz), 6.86 - 6.84 (dd, E, 4H, J = 8.5 Hz, 2.0 Hz), 6.80 - 6.79 (m, Z, 2H), 2.52 (s, Z, 6H), 2.50 (s, E, 6H).

[0039] 13 13C NMR (100 MHz, CDCl3, δ / ppm): 158.6, 158.5, 147.6, 137.8, 136.6, 135.7, 135.6, 127.6, 127.1, 125.2, 124.5, 121.9, 121.8, 16.4, 16.4.

[0040] The reaction equations involved are as follows:

[0041]

[0042] Application Examples

[0043] As shown in the above reaction equations, the product d, i.e., OANI, prepared in Example 1 was used as a single - molecule switch for acid - base regulation. The specific method is as follows: In a 1,2,4 - trichlorobenzene (TCB) solution, OANI with the chemical structure of d interacted with 15 molar equivalents of camphorsulfonic acid (CSA) to obtain a biradical molecule e. Subsequently, by adding 15 molar equivalents of triethylamine (TEA), the biradical molecule e could be reduced to molecule d, thus realizing the acid - base regulation process of the single - molecule switch.

[0044] As Figure 3 shown is the 1 1H - NMR spectrum of the biradical molecule e. It can be seen from Figure 3 that: Due to the paramagnetism of the biradical molecule e, no characteristic peaks are generated in its 1 1H - NMR characterization. The NMR signals in the figure are all solvent peaks, which proves the generation of the biradical molecule e.

[0045] Performance Tests

[0046] The product OANI prepared in Example 1 was respectively subjected to electrochemical oxidation, electrochemical reduction, ultraviolet - visible absorption spectroscopy, electron spin resonance spectroscopy, and single - molecule conductance testing. The specific process is as follows:

[0047] (1) At room temperature (298 K), the cyclic voltammetry (CV) curve of OANI in dichloromethane (DCM, c ~ 5×10 - 3 M, 0.1 M n-Bu4NPF6) was measured with a scan rate of 0.10 V·s -1 , and the results are as Figure 4 shown. Among them, Figure 4 a and Figure 4 b are the CV curves of the electrochemical oxidation and electrochemical reduction processes of the product OANI, respectively.

[0048] From Figure 4 a, it can be seen that the CV curve of the final product OANI generates two pairs of oxidation peaks at 0.69 V and 1.08 V, and the HOMO energy level is calculated to be -5.09 eV. Figure 4 In b, the first reduction potential of the CV curve is -0.88 V, and the LUMO energy level is calculated to be -3.52 eV.

[0049] (2) At room temperature, through the acid-base regulation process with camphorsulfonic acid (CSA) and triethylamine (TEA), the ultraviolet-visible absorption spectrum ( -5 ) of OANI in 1,2,4-trichlorobenzene (TCB, c ~ 5×10 Figure 5 M) was measured: In the TCB solution, OANI with the chemical structure of d interacts with 30 molar equivalents of CSA to obtain the biradical molecule e. Subsequently, by adding 30 molar equivalents of TEA, the biradical molecule e can be reduced to the molecule d, thus realizing the acid-base regulation process of the single-molecule switch, and obtaining the change of the characteristic absorption peak of the OANI molecule during the acid-base regulation process.

[0050] As Figure 5 shown, the ultraviolet-visible absorption spectrum (black) of OANI produces a broad main absorption band at 400 - 600 nm, which belongs to the intramolecular exciton transition. After adding 30 molar equivalents of CSA to obtain the protonated biradical molecule e, the main absorption band of its ultraviolet-visible absorption spectrum (red) appears at 600 - 800 nm, which belongs to the charge transition between the generated radical cation and the π orbital. It can be seen that the acid regulation process of OANI causes a red shift of about 200 nm in the maximum absorption wavelength of the molecule, significantly changing its optical properties. Subsequently, the biradical molecule e interacts with 30 molar equivalents of TEA, and the main absorption band of its ultraviolet-visible absorption spectrum (blue) blue-shifts to 400 - 600 nm, basically coinciding with the characteristic absorption band of OANI, indicating that the acid-base regulation process of the single-molecule switch has good reversibility.

[0051] (3) At room temperature, the electron spin resonance spectrum (EPR) of OANI in N,N-dimethylformamide (DMF, c ∼ 2×10 -3 M) containing 50 molar equivalents of camphorsulfonic acid (CSA) was measured: In the DMF solution, OANI with the chemical structural formula d interacts with 50 molar equivalents of camphorsulfonic acid (CSA) to obtain the biradical molecule e. The test results are as Figure 6 shown:

[0052] Figure 6 The curves in the figure and the inset respectively represent the characteristic EPR signal (g = 2.005) of the biradical molecule e generated after protonation of the end-product molecule and the half-field forbidden transition signal, indicating the existence of spin-coupled biradicals in the biradical molecule e. Further, it shows that the end-product OANI has certain application potential in magnetic materials such as memory storage devices.

[0053] (4) At room temperature, using the scanning tunneling microscope break junction technique (STM-BJ), the single-molecule conductance test of the acid-base regulation process of the product OANI in 1,2,4-trichlorobenzene (TCB, c ∼ 10 -4 M) was carried out: In the TCB solution, OANI with the chemical structural formula d interacts with 15 molar equivalents of camphorsulfonic acid (CSA) to obtain the biradical molecule e. Subsequently, by adding 15 molar equivalents of triethylamine (TEA), the biradical molecule e can be reduced to the molecule d, thus realizing the acid-base regulation process of the single-molecule switch. The test results are as Figure 7 shown:

[0054] Among them Figure 7 a, Figure 7 d are respectively the one-dimensional and two-dimensional conductance histograms of the product OANI, Figure 7 b, 7e are respectively the one-dimensional and two-dimensional conductance histograms of the biradical molecule e obtained after the interaction of the molecule OANI with 15 molar equivalents of CSA, Figure 7 c, 7f are respectively the one-dimensional and two-dimensional conductance histograms of the quinoid structure molecule d obtained after the interaction of the biradical molecule e with 15 molar equivalents of TEA.

[0055] Performing Gaussian fitting on the Figure 7 conductance test results, the conductance value of the product OANI is 10 -4.43 G0, the conductance value of the biradical molecule obtained after acid regulation is 10 -3.68 G0, which is increased by about 0.8 orders of magnitude, indicating that the interaction between the molecule OANI and the acid significantly improves its charge transport performance. Subsequently, an alkali regulation experiment was carried out on the biradical molecule e, and the conductance value of the quinoid structure molecule d obtained was 10 -4.23G0, which is close to the conductance value before the acid-base regulation experiment, indicates the reversibility of the acid-base regulation process of the single-molecule switch, and can be applied to the construction of switch-type electronic devices or logic circuits.

[0056] Summary:

[0057] The present invention provides a method for synthesizing oligopolyaniline derivatives. The preparation conditions are simple. The synthesized oligopolyaniline derivatives can be used as single-molecule switches and can be regulated by adding acid or base, and can achieve reversible switching between the biradical structure and the quinoid structure, so as to be applied to the construction of switch-type electronic devices or logic circuits.

Claims

1. An oligopolyaniline derivative, the structural formula of which is as follows: In the formula: Ar is an aromatic group, selected from any one of benzene ring, pyridine, thiophene, and pyrrole; R is an anchoring group, selected from any one of thioether, sulfonyl, and amino.

2. A preparation method of the oligopolyaniline derivative according to claim 1, comprising the following steps: (1) 1,4-Dibromobenzene reacts with an amino aromatic compound derivative shown in formula (II) to obtain an intermediate (III): H2N-Ar-R (II) (2) Silver oxide reacts with the intermediate (III) to obtain the following final product (IV); In formulas II-IV: Ar is an aromatic group, selected from any one of benzene ring, pyridine, thiophene, and pyrrole; R is an anchoring group, selected from any one of thioether, sulfonyl, and amino.

3. The preparation method of an oligopolyaniline derivative according to claim 2, wherein: In step (1), the molar ratio of 1,4-dibromobenzene to the amino aromatic compound derivative is 1-1.2:2.1-2.

5.

4. The preparation method of an oligopolyaniline derivative according to claim 2, characterized in that: In step (1), the reaction is carried out in the presence of a solvent, and the solvent is toluene.

5. The preparation method of an oligopolyaniline derivative according to claim 2, wherein: In step (1), the reaction temperature is 100-120 °C, and the reaction time is 12-24 h.

6. The preparation method of an oligoaniline derivative according to claim 2, characterized in that: In step (1), the reaction is carried out in the presence of a catalyst, and the catalyst is tris(dibenzylideneacetone)dipalladium and 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene, or tris(dibenzylideneacetone)dipalladium and 1,1'-binaphthalene-2,2'-bis(diphenylphosphine).

7. The preparation method of an oligoaniline derivative according to claim 6, characterized in that: When the catalyst is tris(dibenzylideneacetone)dipalladium and 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene, the molar ratio of 1,4-dibromobenzene to tris(dibenzylideneacetone)dipalladium in the feed is 1:0.05-0.10, and the molar ratio of tris(dibenzylideneacetone)dipalladium to 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene in the feed is 1-1.2:1.5-1.

8.

8. The preparation method of an oligoaniline derivative according to claim 2, characterized in that: In step (2), the molar ratio of the intermediate (III) to silver oxide is 1-1.1:1.5-2.

9. The preparation method of an oligopolyaniline derivative according to claim 2, wherein: In step (2), the reaction is carried out in the presence of a solvent, the solvent is acetone, the reaction temperature is room temperature, and the reaction time is 2-4 h.

10. Use of the oligopolyaniline derivative according to claim 1 as a single-molecule switch, characterized in that: The oligopolyaniline derivative is regulated by adding acid and base externally to achieve reversible switching between the biradical structure and the quinoid structure.

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