Preparation method, performance research and application of imidazole-based organic molecules

Abstract

The invention belongs to the technical field of monomolecular organic electronics, and discloses a preparation method, performance research and application of imidazole-based organic molecules. On the basis of imidazole organic molecules, methylthio is used as an anchoring group, and the imidazole organic molecules have the following structure: # imgabs0 #. The methylthio anchoring groups are introduced into the unique conjugated structure and two ends of the imidazole molecules, and under certain conditions, the molecules change from a single molecular system to a bimolecular system, so that the molecular weight is increased, and the molecular weight is increased. And the conductivity value, the molecular pulling length and other corresponding characteristics can also change correspondingly. Due to the fact that free ions in imidazole molecules can react with adjacent molecules to a certain extent under specific conditions, the imidazole molecules can serve as molecular devices related to molecular switches and the like to be applied in monomolecular devices, and the imidazole molecules can also be used for information storage and encryption due to the performance of response under the specific conditions. Therefore, the molecule has a good application prospect in the field of organic single-molecule wires.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic electronics, and particularly relates to the preparation of organic single molecules based on an imidazole skeleton conjugated structure and their application in the field of organic optoelectronics. Background Art

[0002] From the birth of the silicon vacuum tube in 1904 to the present day, electronics has evolved from vacuum electronics to solid-state electronics, and finally to microelectronics, forming very large-scale integrated circuits. With the advancement of technology, the size of our electronic devices has continued to decrease, while their functionality has continued to increase, leading to a continuous decrease in the size of the chips within these devices. According to Moore's Law, proposed in 1965 by Gordon Earle Moore, one of the founders of Intel, the number of circuits integrated into an integrated circuit doubles approximately every two years.

[0003] Due to the quantum tunneling effect, semiconductor manufacturing has certain limitations. According to forecasts, the semiconductor manufacturing limit is 3 nm. As transistors continue to shrink in the traditional silicon-based semiconductor industry, Moore's Law will soon come to an end. Instead, electronic components composed of molecules may emerge, giving rise to molecular electronics. As the name suggests, the field of molecular electronics studies molecules at the molecular level, focusing on synthesizing molecules, fabricating molecular electronic devices, and measuring their electrical properties. Compared to silicon-based electronic devices, molecular devices offer significant performance advantages due to their higher integration density. Furthermore, molecular devices are easily synthesized in large quantities, which will significantly reduce device production costs and enhance their competitive advantage. Molecular devices can also form functional components such as wires, switches, rectifiers, memory devices, and diodes in traditional electronic devices.

[0004] For example, single molecules that respond to light can be used as devices such as molecular switches. Single-molecule photoresponse refers to the detectable changes in molecular structure or properties in response to light stimulation at the single-molecule level. This change can be a change in molecular conformation, a transition in electronic state, or the formation and breaking of chemical bonds. Photoresponsive molecules usually contain specific photosensitive groups, such as azobenzene and spiropyran. These groups undergo photochemical reactions after absorbing light of a specific wavelength, thereby triggering structural changes in the entire molecule. For example, the azobenzene group will transform from a trans structure to a cis structure under ultraviolet light, and will revert to a trans structure under visible light.

[0005] In order to be applicable to molecular devices of various organic molecules and meet the requirements of industrial applications, the present invention provides a conjugated organic molecule based on an imidazole skeleton that can transform from a single-molecule system to a bimolecular system under certain conditions. Under these conditions, there will be a significant change in molecular conductivity. The change in the conductivity value of the molecule can be applied to corresponding molecular devices, which is of great significance in single-molecule devices. Summary of the Invention

[0006] To address these issues, an organic molecule based on a conjugated imidazole skeleton was designed and synthesized. A thiomethyl group was used as an anchoring group to better form a molecular bond with a gold electrode. Under certain conditions, a series of changes in the molecular structure of this organic molecule, based on a conjugated imidazole skeleton, lead to changes in the conjugated system within the molecule. Consequently, the molecule's electrical conductivity also changes.

[0007] The purpose of the present invention is to provide applications of organic molecules based on imidazole skeleton conjugation. The conjugated structure based on imidazole skeleton has applications in the field of organic molecular devices.

[0008] The purpose of the present invention is achieved based on the following technical solutions:

[0009] A spatially conjugated organic molecule based on an imidazole skeleton, the structure of which is shown in the figure:

[0010]

[0011] To achieve the above objectives, the present invention provides the following technical solution: a preparation and application of an organic molecule based on an imidazole skeleton conjugation, wherein the preparation method comprises the following steps: adding 1-[4-(methylthio)phenyl]-2-phenyl-1,2-ethanedione, 4-(methylmercapto)benzaldehyde, and ammonium acetate into a two-necked round-bottom flask; evacuating the flask three times, injecting acetic acid under a nitrogen atmosphere, and refluxing the flask; after cooling to room temperature, purifying the resulting crude product by passing it through a silica gel column using ethyl acetate and dichloromethane as eluents to separate and obtain the target product.

[0012] The present invention synthesizes an imidazole-based conjugated organic molecule with a stable valence bond conjugation structure. Under certain conditions, the molecule's structure changes from a unimolecular system to a bimolecular system. This change in conjugation also alters its electrical conductivity. The imidazole-based conjugated organic molecule is easy to prepare and exhibits excellent electrical conductivity and stability, making it a promising building block for molecular devices.

[0013] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0014] Traditional molecular backbones of valence-bonded conjugated molecular wires offer relatively stable electrical conductivity, but they haven't been widely used in various devices. However, under specific conditions, this molecule transforms from a single-molecule system to a bimolecular system, simultaneously altering properties such as conductivity and molecular pull-off length. Therefore, this molecule can be used in single-molecule devices as a molecular switch and other devices, demonstrating promising research prospects for its application in molecular devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 (A) is the absorption spectrum of IMD in THF solution; (B) is the emission spectrum of IMD in THF solution, and the spectra have been normalized.

[0016] Figure 2 HOMO-LUMO spatial distribution diagram of IMD molecules.

[0017] Figure 3 (A) is the one-dimensional conductance map of IMD in trichlorobenzene solution; (B) is the two-dimensional conductance map of IMD in trichlorobenzene solution.

[0018] Figure 4 This is the molecular step length distribution diagram after the formation of the molecular junction in the scanning tunneling microscope splitting technique of IMD.

[0019] Figure 5 This is the H NMR spectrum of the intermediate product compound 3.

[0020] Figure 6 This is the H NMR spectrum of the target product IMD molecule. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings so that those skilled in the art can better understand the advantages and features of the present invention and thus more clearly define the scope of protection of the present invention. The embodiments described in the present invention are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative work shall fall within the scope of protection of the present invention.

[0022] Example 1: Preparation of organic single-molecule wire IMD based on imidazole skeleton conjugated structure

[0023]

[0024] The synthetic route is as follows:

[0025]

[0026] Synthesis route of IMD

[0027] The compounds phenylacetylene, 4-bromothioanisole, and 4-(methylmercapto)benzaldehyde were purchased from Energy Chemical (Shanghai). All reagents and drugs were sealed and not processed before use. All other chemicals and reagents were purchased from commercial sources and used without further purification.

[0028] Synthesis of 1-(Methylthio)-4-(2-phenylethynyl)-benzene (3): Compound 1 (1.02 g), compound 2 (2.03 g), bis(triphenylphosphine)palladium dichloride (0.7019 g), and copper iodide (0.0950 g) were added to a 250 mL two-necked round-bottom flask. The mixture was evacuated three times, and 40 mL of triethylamine was injected under nitrogen. The reaction was refluxed for 18 h. After cooling to room temperature, the crude product was purified on a silica gel column using petroleum ether and dichloromethane as eluents (v / v = 10 / 1). A light yellow solid product (0.8 g) was obtained with a yield of 35.66%. 1 H NMR (500 MHz, CDCl3): δ 7.55 (d, J = 6.1 Hz, 2H), 7.47(d, J = 8.2 Hz, 2H), 7.37 (d, J = 6.2 Hz, 2H), 7.23 (d, J = 8.2 Hz, 2H), 2.53(s, 3H).

[0029] Synthesis of 1-[4-(methylthio)phenyl]-2-phenyl-1,2-ethanedione (4): Rinse the stirring bar and place it in a clean 250 mL reaction flask. Then weigh tetraethylammonium bromide (1.6900 g), sodium bicarbonate (0.8550 g), and potassium permanganate (2.1160 g) into the reaction flask. Add 40 mL of water to dissolve the three solids. Then, weigh dichloromethane (20 mL) into a beaker and weigh the intermediate product C (1.0000 g) into the beaker to dissolve. Then, transfer the solution in the beaker to the reaction flask. The reaction was allowed to proceed at room temperature and pressure for 24 hours. After the reaction was completed, 1 mol / L hydrochloric acid (2 mL) was added to remove the potassium permanganate that had not yet reacted. When no solid precipitated, the reaction was stopped and the crude product was purified by silica gel column using dichloromethane as the eluent. Pure product D was obtained.

[0030] Synthesis of IMD: Intermediate 4 (0.2600 g), substance 5 (0.4638 g), and ammonium acetate (1.1740 g) were weighed separately and added to a 100 mL two-necked round-bottom flask. The mixture was evacuated three times. Acetic acid (20 mL) was added under nitrogen and refluxed for 8 hours. The crude product was purified on a silica gel column using ethyl acetate and dichloromethane as eluents (v / v = 1 / 10). IMD was isolated as a white solid (0.291 g) in a yield of 74.89%. 1 H NMR (500 MHz, DMSO): δ 12.63 (s, 1H), 8.03 (s,2H), 7.42 (d, J = 75.5 Hz, 11H), 2.52 (d, J = 12.9 Hz, 6H).

[0031] Example 2: Absorption spectroscopy characterization of imidazole skeleton conjugated organic molecules IMD

[0032] Figure 1 A and Figure 1 B shows the absorption and emission spectra of IMD obtained in Examples 1 and 2 in THF. The figure shows that the maximum absorption peak wavelength of IMD in THF is 326 nm, and the maximum emission wavelength is 395 nm. The ordinates in this figure are normalized.

[0033] Example 3: HOMO-LUMO spatial distribution of IMD molecules

[0034] from Figure 2 The HOMO-LUMO distribution of the IMD molecule reveals the approximate electron cloud distribution of the molecule. The HOMO electron cloud is concentrated on the benzene ring connected to the -SH3, while the LUMO electron cloud is concentrated on the imidazole molecule. The torsion angles of the three benzene rings connected to the imidazole ring are 7.64°, 28.17°, and 36.71°, respectively.

[0035] Example 4: Single molecule conductance measurement

[0036] Figure 3 A is the one-dimensional conductivity diagram of the IMD molecule and Figure 3 B is the two-dimensional conductivity of the IMD molecule, Figure 4is the step length distribution diagram. As can be seen from Figure B, there are obvious intensity clouds in the two-dimensional diagrams of the three molecules, indicating that in most of the splitting processes, molecular junctions are formed as the gold electrode breaks and stretches. From the step length distribution diagram, it can be found that the pulling length of the IMD molecular junction is 0.45 nm. Considering that there is a 0.5 nm rebound during the stretching process of the gold electrode, the molecular junction length after addition is 0.95 nm, which is consistent with the distance between the two sulfur atoms. This proves that the molecular junction is formed by the connection between the sulfur atom on the mercaptomethyl group and the gold electrode, and the measured conductivity data is reliable. From the one-dimensional conductivity diagram, it can be seen that the conductivity peak of the IMD molecule is located at 10 -3.95 G0.

[0037] The above data demonstrate that the present invention has synthesized a series of novel organic molecules based on an imidazole conjugated backbone and applied them to organic single-molecule conductors. These molecules exhibit stable molecular conductivity. Under certain conditions, these molecules react with adjacent molecules, transforming from a single-molecule system to a bimolecular system, with a corresponding change in conductivity and other properties. Therefore, these molecules have promising applications in organic single-molecule devices.

[0038] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and performance of the present invention. It should therefore be understood that modifications can be made to the illustrative embodiments and that other arrangements can be devised without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims

1. A class of Au-S-π-bridge-S-Au single-molecule wires constructed using STM-BJ technology based on imidazole skeleton conjugated organic molecules, whose characteristic structure As shown below: .

2. The conjugated organic molecule based on an imidazole skeleton according to claim 1, characterized in that: The imidazole skeleton-based conjugated organic molecule is used to construct a stable single-molecule device containing an anchoring group. Under certain conditions, its structure changes from a single-molecule system to a bimolecular system; this feature gives it good application prospects in single-molecule devices.

3. The organic molecule based on the imidazole conjugated skeleton structure according to claim 1, characterized in that: Applications in organic single-molecule wires.

Images