Preparation method of spatially conjugated organic molecules based on bis-hexaphenylbenzene anchoring group and application of spatially conjugated organic molecules in field of organic monomolecular wires
By introducing sterically conjugated organic molecules of bishexophenylbenzene anchoring groups into single-molecular wires, combining valence bond conjugation and spatial conjugation characteristics, the problem of insufficient conductivity of single-molecular wires is solved, and high and stable conductivity is achieved.
Patent Information
- Application Number
- CN202510058311.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-14
- Publication Date
- 2025-04-29
AI Technical Summary
In the prior art, the conductivity of a single molecule wire is affected by insufficient valence bond conjugation and reverse ring current, resulting in poor conductivity and lack of an effective spatial conjugation platform.
Multiple conductive channels are constructed by using scattered conjugated organic molecules based on bishexophenylbenzene anchoring groups, combining valence bond conjugation and spatial conjugation characteristics.
High and stable conductivity performance is achieved, the low conductivity phenomenon caused by insufficient valence bond conjugation is compensated, and new insights are provided for anchoring units of single-molecular conductors.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of organic electronics, and particularly relates to the preparation of spatially conjugated organic molecules based on hexaphenylbenzene anchoring groups and their application in the field of organic optoelectronics. Background Art
[0002] The preparation process of integrated circuits in the semiconductor industry has been developed in a top-down manner according to Moore's Law. The preparation of smaller components through silicon-based micromachining technology has reached a bottleneck. Molecular electronics has attracted much attention because of its potential to break through the inherent limitations of silicon-based electronics. Molecular wires, as the basic components of molecular electronics, are responsible for charge transfer and electronic communication between different components at the molecular level. They are currently a research hotspot in the field of multidisciplinary intersections, and organic molecular wires are an indispensable part of them. The conjugated structure directly affects the energy level structure, chemical stability and thermal stability of organic molecules, and also affects the photophysical properties, carrier transport properties and processing properties of optoelectronic devices, and has a decisive influence on the stability of the device. Therefore, the regulation of the conjugated structure is an indispensable and important link in the design of organic optoelectronic materials.
[0003] Molecular electronics has attracted extensive attention due to its potential to break through the inherent limitations of silicon-based electronics. Single-molecule wires are the basic elements of molecular electronics, responsible for charge transport and electronic communication between different components at the molecular level. In addition to the electrode-molecule interface, the internal electronic structure and geometry of the molecule play a decisive role in the overall performance of the molecular wire in the metal-molecule-metal junction. Therefore, exploring robust single-molecule wires with ideal conformations and unique electronic effects remains a huge challenge to achieve high and stable conductance. To date, the molecular cores of artificial single-molecule wires widely studied in the literature are mainly limited to rod-shaped organic molecules and organometallic molecules through bond π conjugation, in which a high density of delocalized π electrons facilitates charge transport through the molecular backbone. This through-bond conjugation usually refers to the direct connection of aliphatic and aromatic units with carbon-carbon single, double or triple bonds composed of sp, sp2 or sp3 carbon frameworks. Another type of interesting single-molecule wires that has just emerged is based on non-covalent spatial conjugation, in which the π electrons are spatially distributed in the interplanar regions of closely stacked aromatic rings and can be used for charge transport. When two chromophores or aromatic rings are arranged close enough and their electron density distributions overlap, they will form a conjugation involving through-space and Long-Coulomb (dipole-dipole) interactions. This unique spatial conduction mode has attracted increasing attention and has shown important significance in various systems, including redox processes in biological complexes, electronic signaling in DNA molecules, carrier transport in organic electronics and photovoltaics, etc. However, compared with through-bond single-molecule wires, the exploration of through-space single-molecule wires is far from enough, which may be due to the lack of suitable organic platforms with strong through-space conjugation.
[0004] Single-molecule junctions are a popular platform for studying molecular electronics. To this end, there have been numerous demonstrations of single-molecule electron transport properties. In order to count the molecular conductance that may occur in the junction at room temperature, one of the most widely used experimental techniques for studying single-molecule junctions is the scanning tunneling microscopy-broken junction (STM-BJ) method. In this method, the properties of single-molecule junctions are measured while increasing the electrode separation to promote the formation, evolution and rupture of the junction. Therefore, each measurement samples the progression of many different conformations. This method has been previously used for the covalent binding of rigid molecules to electrodes. It provides a platform to elucidate the properties of distance-dependent electronic interactions, such as van der Waals (vdW) forces. In order to be able to improve the conductivity of organic molecules and meet the requirements of industrial applications, the present invention provides conjugated organic molecules based on hexaphenylbenzene anchor groups with simultaneous valence conjugation and steric conjugation. Summary of the invention
[0005] In order to overcome the shortcomings and deficiencies of the above-mentioned prior art, the primary purpose of the present invention is to provide a spatially conjugated organic molecule based on a double hexaphenylbenzene anchoring group and a preparation method thereof. The spatially conjugated organic molecule based on a double hexaphenylbenzene anchoring group of the present invention has the characteristics of spatial conjugation and valence bond conjugation, has multiple conductive channels, and the hexaphenylbenzenes at both ends are anchored to gold electrodes through van der Waals forces to construct molecular wires, providing a new insight into a new type of double anchoring group.
[0006] Another object of the present invention is to provide the application of the spatially conjugated organic molecules based on the double hexaphenylbenzene anchoring group, and the application of the spatially conjugated organic molecules based on the double hexaphenylbenzene anchoring group in the field of organic molecular wires.
[0007] The purpose of the present invention is achieved based on the following technical solutions:
[0008] A spatially conjugated organic molecule based on a double hexaphenylbenzene anchoring group, the structure of which is shown in Formula I-II:
[0009]
[0010] To achieve the above object, the present invention provides the following technical solution: a preparation and application of a spatially conjugated organic molecule based on a double hexaphenylbenzene anchoring group, wherein the preparation method comprises the following steps:
[0011] The compound 4-bromotolane and tetraphenylcyclopentadienone were mixed, added to phenyl ether, and added to a single-mouth round-bottom flask. The mixture was heated for 8 hours. After cooling to room temperature, the mixture was poured into water and extracted with dichloromethane three times. The combined organic layer was washed with saturated sodium bicarbonate and water in sequence, and then dried over anhydrous magnesium sulfate. After filtration, the solvent was evaporated under reduced pressure, and the crude product was purified by silica gel column chromatography using petroleum ether: dichloromethane as the eluent to obtain 4-bromo-3',4',5',6'-tetraphenyl-1,1':2',1''-terphenyl. The compound 4-bromo-3',4',5',6'-tetraphenyl-1,1':2',1''-terphenyl, acetyl dicarboxylic acid, bistriphenylphosphine palladium dichloride, 1,4-bis(diphenylphosphino)butane and 1,8-diazabicyclo[5.4.0]undecene-7-ene were added to a double-mouth round-bottom flask. The reaction flask was evacuated under vacuum, flushed with dry nitrogen three times, and then triethylamine was added. The reaction mixture was refluxed for 24 hours. After cooling to room temperature, the mixture was poured into water and extracted with dichloromethane three times. The combined organic layers were dried over anhydrous magnesium sulfate. After filtration, the solvent was evaporated under reduced pressure, and the crude product was purified by silica gel column chromatography using petroleum ether and dichloromethane as eluents to obtain the product DHPB
[0012] A spatially conjugated organic molecule based on a double hexaphenylbenzene anchoring group synthesized by the present invention not only has a traditional valence bond conjugated structure, but also has a spatial conjugation effect. The molecular anchoring group with an intramolecular π-π stacking structure enables electrons to be transmitted not only along the valence bond conjugation channel, but also along the spatial conjugation channel, and has multiple conductance channels, which effectively compensates for the low conductivity phenomenon caused by insufficient valence bond conjugation of the molecule, and designs a new anchoring group hexaphenylbenzene, which is anchored to the gold electrode through the van der Waals force of hexaphenylbenzene and the gold electrode at both ends, providing new insights for regulating the charge transfer performance of the single molecule wire. The spatially conjugated organic molecule of the present invention is easy to prepare, has excellent conductivity, and is a building block of a molecular wire with good prospects.
[0013] Compared with the prior art, the present invention has the following advantages and beneficial effects:
[0014] In addition to the electrode-molecule interface, the internal electronic structure and geometric structure of the molecule play a decisive role in the overall performance of the molecular wire in the metal-molecule-metal junction. Therefore, exploring a strong single-molecule wire with an ideal conformation and unique electronic effect is still a huge challenge to achieve high and stable conductivity. The traditional valence bond conjugated molecular wire of the through-bond transmission is affected by the reverse ring current and has poor molecular conductivity. The spatial conjugated organic molecule based on the hexaphenylbenzene anchoring group prepared in the present invention has the characteristics of valence bond conjugation and spatial conjugation, providing multiple conductive channels. The preparation method of the present invention is widely applicable and provides new insights into the anchoring unit of the single-molecule wire. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 is the normalized absorption spectrum of DHPB in THF solution (10 μM).
[0016] Figure 2 One-dimensional conductance map of DHPB (A) and two-dimensional conductance-displacement histogram of DHPB (B).
[0017] Figure 3 Two-dimensional histogram of normalized flicker noise power and average conductance for DHPB.
[0018] Figure 4 The optimized structure and torsion angle information of DHPB.
[0019] Figure 5 Illustration of the frontier molecular orbitals of HOMO-2, HOMO-1, HOMO, LUMO, LUMO+1 and LUMO+2 of DHPB determined at the M06-2X / 6-311G (d, p) level of theory.
[0020] Figure 6 Optimized geometry of the junction for calculating the transmittance of DHPB (A), calculated transmission curve of DHPB (B), and characteristic channels of selected snapshots of gold molecule-gold single molecule junction (GMG-SMJ) of DHPB (C).
[0021] Figure 7 This is the high-resolution MALDI-TOF spectrum of DHPB [MALDI-TOF, m / z: 1090.40 (Calcd1090.45).]. DETAILED DESCRIPTION
[0022] The present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.
[0023] Example 1 Preparation of a novel spatially conjugated organic single-molecule wire [DHPB] based on a double hexaphenylbenzene anchoring group
[0024]
[0025] The synthetic route is as follows:
[0026]
[0027] (1) All chemicals and reagents were purchased from commercial sources and used without further purification. All reagents and drugs were sealed and not handled before use.
[0028] (2) Mix 4-bromotolane (1.00 g, 2.60 mmol) and tetraphenylcyclopentadienone (0.73 g, 2.86 mmol), add to 10 mL of phenyl ether, and add to a 25 mL single-necked round-bottom flask. o C for 8 hours. After cooling to room temperature, the mixture was poured into water and extracted with dichloromethane three times. The combined organic layer was washed with saturated sodium bicarbonate and water in sequence, and then dried over anhydrous magnesium sulfate. After filtration, the solvent was evaporated under reduced pressure, and the crude product was purified by silica gel column chromatography using petroleum ether: dichloromethane (5:1, v:v) as the eluent to obtain 1.46 g of white solid product 3 in a yield of 92%. 1 H NMR (500 MHz, CDCl 3 ) δ 6.98 (d, J = 8.25 Hz, 2H), 6.88–6.80 (m, 25H), 6.70 (d, J= 8.40 Hz, 2H). 13 C NMR (125 MHz, CDCl 3 ) δ 140.80, 140.61, 140.56, 140.52,140.39, 140.32, 139.81, 139.07, 133.14, 131.46, 129.92, 126.95, 126.75,125.57, 125.40, 119.56.
[0029] (3) Compound 3 (1.30 g, 2.10 mmol), butynedioic acid (0.13 g, 1.05 mmol), bistriphenylphosphine palladium dichloride (0.08 g, 0.01 mmol), 1,4-bis(diphenylphosphino)butane (DPPB) (0.05 g, 0.01 mmol) and 1,8-diazabicyclo[5.4.0]undecene-7-ene (DBU) (0.33 g, 2.10 mmol) were added to a 250 mL two-necked round-bottom flask. The reaction flask was evacuated under vacuum, flushed with dry nitrogen three times, and then 80 mL of triethylamine was added. The reaction mixture was refluxed for 24 hours. After cooling to room temperature, the mixture was poured into water and extracted three times with dichloromethane. The combined organic layers were dried over anhydrous magnesium sulfate. After filtration, the solvent was evaporated under reduced pressure, and the crude product was purified by silica gel column chromatography using petroleum ether: dichloromethane (3:1, v:v) as eluent to obtain 0.75 g of white solid product DHPB in a yield of 33%. 1 H NMR (500 MHz, CDCl 3) δ 6.92 (d,J = 8.35 Hz, 4H), 6.85–6.79 (m, 50H), 6.74 (d, J = 8.35 Hz, 4H). 13 C NMR (125MHz, CDCl 3 ) δ 140.57, 140.49, 140.39, 140.30, 131.50, 131.45, 130.00, 127.12,126.87, 126.73, 125.52, 125.37. MALDI-TOF, m / z: 1090.40 (Calcd 1090.45).
[0030] Example 2 Preparation of a novel spatially conjugated organic single-molecule wire [DHPB-Ph] based on hexaphenylbenzene
[0031]
[0032] The synthetic route is as follows:
[0033]
[0034] (1) The synthesis of intermediate 3 is the same as that of Example 1.
[0035] (2) The synthesis of DHPB-Ph was carried out in the same manner as in Example 1. Compound 3 (1.30 g, 2.10 mmol), terephthalic acid (0.17 g, 1.05 mmol), bistriphenylphosphine palladium dichloride (0.10 g, 0.01 mmol), 1,4-bis(diphenylphosphino)butane (DPPB) (0.06 g, 0.01 mmol) and 1,8-diazabicyclo[5.4.0]undecene-7-ene (DBU) (0.41 g, 2.10 mmol) were added to a 250 mL two-necked round-bottom flask. The reaction flask was evacuated under vacuum, flushed with dry nitrogen three times, and then 80 mL of triethylamine was added. The reaction mixture was refluxed for 24 hours. After cooling to room temperature, the mixture was poured into water and extracted three times with dichloromethane. The combined organic layers were dried over anhydrous magnesium sulfate. After filtration, the solvent was evaporated under reduced pressure, and the crude product was purified by silica gel column chromatography using petroleum ether: dichloromethane (3:1, v:v) as eluent to obtain 0.50 g of white solid product DHPB with a yield of 21%. 1 H NMR (500 MHz, CDCl 3) δ 7.60-7.52 (m, 10H), 7.45-7.42 (t, J = 15.35 Hz, 3H), 7.35-7.32 (t, J = 14.80 Hz, 2H), 7.18 (d, J = 6.35 Hz, 3H), 6.91–6.85(m, 48H). 13 C NMR (125 MHz, CDCl 3 ) δ 140.88, 140.74, 140.70, 140.53, 140.50,139.86, 139.76, 136.87, 132.04, 131.58, 131.57, 128.91, 127.43, 127.38,127.13, 127.11, 126.82, 126.73, 125.39, 125.34, 125.11.
[0036] Example 3 Determination of molecular conductance based on scanning tunneling microscopy-broken junction (STM-BJ) technology
[0037] Figure 1 The optical properties of the molecules were measured in dilute tetrahydrofuran (THF) solutions. Figure 2 A is the one-dimensional conductivity diagram of DHPB molecule. It can be seen from the one-dimensional conductivity diagram that the conductivity peak of DHPB is located at 10 -5.22 G 0 , Figure 2 B is the two-dimensional conductivity diagram of the DHPB molecule. It can be seen from the figure that there is an obvious intensity cloud in the two-dimensional diagram of the DHPB molecule, indicating that in most of the splitting processes, molecular junctions are formed as the gold electrode breaks and stretches.
[0038] Example 4 Flicker Noise Analysis
[0039] Figure 3 is the two-dimensional noise-conductance intensity statistical diagram of DHPB molecules. According to previous reports, the proportional factor of noise power G 1.0 indicates full through-bond transmission, while G 2.0 It indicates through-space transmission. From the figure, we can see that the noise power proportionality factor of the DHPB molecule is G 2.0 , the noise power of DHPB reveals that it has high spatial conjugation, and spatial conjugation plays a vital role in charge transport.
[0040] Example 5 Molecular structure and frontier orbital analysis
[0041] In order to reveal the molecular valence conformation and charge transport properties of the electrode based on hexaphenylbenzene through spatial conjugation, theoretical simulations including density functional theory using Gaussian 16 and Transiesta function of Siesta software were employed. Figure 4 - Figure 5 As shown, the six annular phenyl groups of DHPB exhibit a face-to-face configuration around the central benzene, with a dihedral angle of about 70°. o , indicating that they have strong annular through-space conjugation, the electron distribution between the peripheral benzene rings dominates the frontier orbitals, and the molecular orbitals are distributed throughout the molecular skeleton, indicating more efficient charge transfer through space conjugation.
[0042] Example 6 Optimization of molecular device structure and quantum transport simulation analysis
[0043] The device model of the molecular junction formed by DHPB was optimized, such as Figure 6 As shown in A, the through-space conjugation of hexaphenylbenzene was successfully connected to the gold tip, and the distance between the gold tip and the central benzene ring of hexaphenylbenzene was 2.468Å. Figure 6 As shown in B, the zero-bias transmission spectrum shows that the LUMO of the optimized molecular junction formed by DHPB dominates the charge transport, indicating that the electrode-molecule bond constructed by the spatially conjugated bihexaphenylbenzene anchor molecule has a significant impact on the model of the transport model. In addition, quantum transport simulations were performed by Siesta software with nonequilibrium Green's function (NEGF) to elucidate the molecular conductance, as shown in Figure 6 The results of the molecular projected self-consistent Hamiltonians (MPSHs) shown in C–D show that both the LUMO and HOMO of DHPB are located on one of the electrons.
[0044] The above data show that the present invention synthesized a series of novel spatially conjugated organic molecules based on the double hexaphenylbenzene anchoring group and applied them to organic single-molecule wires. This type of organic molecule not only has a valence bond conjugated structure, but also has a spatial conjugated structure. The transmission channels of these two carriers work synergistically, thereby obtaining an organic single-molecule wire with good conductivity and simple molecular structure.
[0045] 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 applications of the present invention. It should therefore be understood that the exemplary embodiments may be modified and other arrangements may be designed without departing from the spirit and scope of the present invention as defined by the appended claims.
Claims
1. A class of spatially conjugated organic molecules based on hexaphenylbenzene anchoring groups, whose characteristic structure As shown below I-II: 。 2. The spatially conjugated organic molecule based on the hexaphenylbenzene anchoring group according to claim 1, characterized in that: The spatially conjugated organic molecule based on the hexaphenylbenzene anchoring group of the present invention constructs a stable multi-transmission channel single-molecule device containing the hexaphenylbenzene anchoring group, has the characteristics of spatial conjugation and valence bond conjugation, and has multiple transmission channels.
3. The use of the spatially conjugated organic molecules based on the hexaphenylbenzene anchoring group in organic single-molecule wires according to claims 1-2, characterized in that: Au-hexaphenylbenzene-π-bridge-hexaphenylbenzene-Au single-molecule wire constructed using STM-BJ technology.