Chiral molecule, chiral molecule device, preparation method and circularly polarized light detection application

Abstract

The invention relates to the technical field of molecular optoelectronic devices, and particularly discloses a chiral molecule, a chiral molecule device, a preparation method and circularly polarized light detection application. Wherein the chiral molecule is a functional molecule which contains a chiral center and has a D-A-D structure type, and the chiral molecule device comprises a silicon substrate, an aluminum oxide dielectric layer, a metal electrode, a graphene point electrode and an RE-PDI molecule and is applied to circular polarized light detection. The invention designs and synthesizes a functional molecule RE-PDI which contains a chiral center and has a D-A-D structure type, and the functional molecule RE-PDI is assembled between graphene point electrodes with nano gaps through a chemical decoupling method. By using the distinguishing response of RE-PDI molecules to different types of circularly polarized light, distinguishing detection and dynamic periodic adjustable response to left-handed and right-handed circularly polarized light can be stably realized.

Description

Technical Field

[0001] The present invention relates to the technical field of molecular optoelectronic devices, and in particular to a chiral molecule, a chiral molecular device, a preparation method and circularly polarized light detection application. Background Art

[0002] Circularly polarized light is a relatively common polarization state of light, and has a wide range of applications in optical communications, biomedical research, environmental monitoring, and image sensing. In recent years, circularly polarized light detectors that can detect the polarization of light have attracted the attention of researchers at home and abroad due to their wide application prospects in biosensing, quantum optics, polarization-enhanced imaging, microfluidics, and encrypted optical communications. The core of realizing these applications is to prepare photodetectors that can distinguish between left-handed (L-CPL) and right-handed (R-CPL) circularly polarized light. The Chinese invention patent with application publication number CN119403352A discloses a tunable polarized photon source based on perovskite quantum dots and a preparation method thereof, which uses chiral molecules with adjustable chirality, introduces tunable chiral molecules, injects spin-polarized electron holes, and makes them compound-polarize in the central perovskite quantum dots, and can control the chiral structure switch by irradiating light of different wavelengths. The current circularly polarized light detector usually needs to be realized by combining inorganic photodetectors and polarization optical elements. Such devices are not suitable for miniaturization and integration or low-cost preparation.

[0003] Single-molecule devices developed in the field of molecular electronics have become a research hotspot in the semiconductor industry, leading the next generation of functional, miniaturized, and highly integrated semiconductor products because they can use nanotechnology to realize devices based on single molecules as the core. However, circularly polarized light detection devices based on chiral single-molecule materials are still in the initial exploration stage. Chiral molecular devices can use the controllability of molecular structure and the uniqueness of optoelectronic properties to provide a feasible material basis for the development of a chiral single-molecule circularly polarized light detection device that is sensitive to response, can distinguish between left-handed and right-handed circularly polarized light, and can dynamically switch detection. Summary of the invention

[0004] The present invention aims to solve the above problems. To this end, the present invention provides a chiral molecule, a chiral molecular device, a preparation method and circularly polarized light detection application. The chiral molecular device based on the photoinduced charge transfer effect utilizes the interaction between the chiral molecule and circularly polarized light, and regulates the electrical properties of the molecule through photoinduced charge transfer and excited state charge trap effect. The present invention designs and synthesizes a functional molecule RE-PDI containing a chiral center and having a "DAD" (Donor-Acceptor-Donor) structure type, and assembles it between nano-gap graphene point electrodes by chemical decoupling. By utilizing the differential response of molecules to different types of circularly polarized light, a control system is constructed, which can stably realize the differential detection of left-handed and right-handed circularly polarized light and the dynamically periodic controllable response, providing a new research direction and application idea for photoelectric control and detection technology and miniaturization of functional chips.

[0005] The present invention provides a chiral molecule, and the technical solution adopted is as follows: containing a chiral center and having a "DAD" structure, named RE-PDI molecule, the structure is as follows: .

[0006] The present invention also provides a chiral molecular device, which adopts the following technical solution: including: a silicon substrate, an aluminum oxide dielectric layer, a metal electrode, a graphene point electrode and a RE-PDI molecule, wherein the RE-PDI molecule is connected to the graphene point electrode, the graphene point electrode is connected to the metal electrode, the graphene point electrode and the metal electrode are located on the aluminum oxide dielectric layer, and the aluminum oxide dielectric layer is located on the silicon substrate.

[0007] Furthermore, the thickness of the aluminum oxide dielectric layer is 30 to 40 nm, the thickness of the metal electrode is 68 to 90 nm, and the graphene dot electrode is a single layer.

[0008] The present invention also provides a method for preparing a chiral molecular device, and the technical scheme adopted is as follows: for preparing the above-mentioned chiral molecular device, the method comprises the following steps: Step 1: preparing an aluminum oxide dielectric layer on a silicon substrate; Step 2: preparing a graphene dielectric layer on the aluminum oxide dielectric layer, and preparing a metal electrode on the graphene dielectric layer; Step 3: constructing a graphene point electrode using a graphene dielectric layer; Step 4: Self-assemble a single RE-PDI molecule with a graphene dot electrode to obtain a chiral molecular device.

[0009] Further, in step 4, the RE-PDI molecule is placed in a three-necked flask, dichloromethane and trifluoroacetic acid are added, and the reaction is carried out for more than 2 hours under a nitrogen atmosphere; the trifluoroacetic acid is removed by sodium hydroxide extraction, and the remaining solution after the trifluoroacetic acid is removed is transferred to an eggplant-shaped bottle; the remaining solution is subjected to rotary evaporation to obtain the RE-PDI molecule without the protective group; the RE-PDI molecule without the protective group is placed in a nitrogen atmosphere by ventilation operation, 10 ml of anhydrous pyridine is drawn with a syringe, injected into the eggplant-shaped bottle, and dissolved to obtain a pyridine solution of the RE-PDI molecule without the protective group. The graphene point electrode is placed in a two-necked flask, and a sufficient amount of 1-(3-dimethylaminopropyl)-3-2-ethylcarbodiimide hydrochloride and the pyridine solution of the RE-PDI molecule without the protective group are added to the two-necked flask, and the reaction is carried out for more than 48 hours in a nitrogen atmosphere to obtain a chiral molecular device.

[0010] Furthermore, in step 1, a photoresist is spin-coated on a silicon substrate (silicon wafer), and chromium with a thickness of 6 to 9 nm and gold with a thickness of 30 to 35 nm are photolithographed and evaporated to obtain a lead electrode; photoresist is spin-coated on the lead electrode again, and a gate is photolithographed to obtain a bottom gate; a 30 to 40 nm aluminum film is plated on the surface of the bottom gate by vacuum thermal evaporation, and the bottom gate is then immersed in an acetone solution to remove the resist.

[0011] Furthermore, in step 2, a single-layer graphene is obtained on a copper foil by chemical vapor deposition; PMMA is spin-coated on the single-layer graphene, and excess graphene and PMMA on the back of the copper foil are removed by oxygen plasma etching to obtain PMMA-single-layer graphene-copper foil; the PMMA-single-layer graphene-copper foil is cut into small pieces, and the copper foil is dissolved by ferric chloride solution to obtain a PMMA-single-layer graphene film; the PMMA-single-layer graphene film is transferred to the alumina dielectric layer, left to stand, dried, and debonded. Strips are photoetched on the graphene dielectric layer, and excess single-layer graphene is removed by oxygen plasma etching to obtain a negative film with graphene strips; electrodes are photoetched on the negative film, and 8 to 10 nm chromium and 60 to 80 nm gold are evaporated to obtain metal electrodes on the graphene dielectric layer.

[0012] Furthermore, in step 3, a dotted line with a length of 150 nm and a width of 5 nm is etched on the graphene dielectric layer by electron beam exposure, and then a graphene nanogap point electrode array is obtained by oxygen plasma etching and electrical burning, wherein the graphene nanogap point electrode array includes a plurality of paired graphene point electrodes.

[0013] The present invention also provides an application of a chiral molecular device, and the adopted technical solution is as follows: the chiral molecular device is applied in circularly polarized light detection.

[0014] Furthermore, the chiral molecular device is applied to the femtosecond laser optical path for switchable circularly polarized light detection, and the working process is as follows: The femtosecond pulse laser generator generates femtosecond linearly polarized laser light, which is then emitted through the first reflector and reaches the beam splitter to generate two linearly polarized laser light. After the first linear polarized laser is converted into a linear polarized laser of a first specific wavelength by the second multifunctional optical parametric amplifier, it reaches the second quarter wave plate and is converted into left-handed circularly polarized light with a specific wavelength. The left-handed circularly polarized light enters the photoelectric coupled detection station and irradiates the chiral molecular device located inside the photoelectric coupled detection station. The second linear polarized laser first passes through the first multifunctional optical parametric amplifier to become a linear polarized laser of a second specific wavelength, and then is delayed by the time delay controller and reaches the first quarter wave plate to become right-handed circularly polarized light with a specific wavelength. The right-handed circularly polarized light enters the photoelectric coupled detection station and irradiates the chiral molecular device located inside the photoelectric coupled detection station. One of the first multifunctional optical parametric amplifier and the second multifunctional optical parametric amplifier is in the operating mode, while the other is in the shut-down mode.

[0015] The above one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: 1. The present invention designs a RE-PDI molecule with a chiral center and a "DAD" structure. Due to the introduction of the chiral center, it responds differently to left-handed and right-handed circularly polarized light. Under light induction, the strong electron-withdrawing group and the electron-donating structure of the molecule interact to produce charge separation. The groups inside the molecule also induce an excited state charge trap effect due to energy level mismatch, ensuring that the molecule responds differently to circularly polarized light within a small energy range to obtain two different situations of charge separation and capture, and a relatively stable current signal will be generated in each situation.

[0016] 2. The chiral molecular device of the present invention is prepared based on graphene single-molecule field-effect transistors, with a mature device preparation process. The prepared single-molecule device has 169 pairs of graphene dot electrodes, achieving significant miniaturization of the device size and showing extremely high integration. This feature provides a new idea for the miniaturization and high-density integration of functional chips.

[0017] 3. The chiral molecular device of the present invention is used in circularly polarized light detection. By combining a femtosecond pulse laser generator, a multifunctional optical parametric amplifier, a time delay controller, and a quarter-wave plate for rational design of the optical path, the following effects can be achieved: first, the same light beam is divided into two optical paths through a beam splitter, and then the two beams are converted into left-handed circularly polarized light and right-handed circularly polarized light by placing a quarter-wave plate, and introduced into the optoelectronic detection station for testing; second, the left-handed circularly polarized light and right-handed circularly polarized light with time control can be generated by combining the working and shutdown modes of the multifunctional optical parametric amplifier placed on the two split light paths, and act independently on the optoelectronic detection station, which ensures that the two circularly polarized lights can act periodically and independently on the optoelectronic detection station. In addition, the two circularly polarized lights can be dynamically switched by programming the working and shutdown modes of the multifunctional optical parametric amplifier; third, the addition of the time delay controller can control the time interval of the optical path system from left-handed light irradiation to right-handed light irradiation at up to femtosecond level within one switching cycle.

[0018] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is the circular dichroism spectrum of RE-PDI molecule provided by the present invention.

[0021] Figure 2 It is a three-dimensional schematic diagram of the chiral molecular device provided by the present invention.

[0022] Figure 3 This is a femtosecond laser optical path diagram for switchable circularly polarized light detection provided by the present invention.

[0023] Figure 4 It is a characteristic curve diagram of the current variation with gate voltage of the chiral molecular device provided by the present invention under the irradiation of left-handed circularly polarized light and right-handed circularly polarized light.

[0024] Figure 5 It is a current-time characteristic curve diagram recorded when the chiral molecular device provided by the present invention is irradiated by dynamic switching between left-handed circularly polarized light and right-handed circularly polarized light.

[0025] Figure 6It is a schematic diagram of the charge transfer process of the RE-PDI molecule provided by the present invention under the irradiation of different circularly polarized lights.

[0026] Reference numerals: 101. silicon substrate; 201. alumina dielectric layer; 301. metal electrode; 401. graphene dot electrode; 501. RE-PDI molecule; 1. femtosecond pulse laser generator; 2. first reflector; 3. beam splitter; 4. first multifunctional optical parametric amplifier; 5. time delay controller; 6. second reflector; 7. third reflector; 8. first quarter wave plate; 9. second multifunctional optical parametric amplifier; 10. fourth reflector; 11. second quarter wave plate; 12. fifth reflector; 13. sixth reflector; 14. seventh reflector; 15. eighth reflector; 16. chiral molecular device. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0028] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0029] Combine the following Figures 1 to 6 The present invention is further described in detail, and a chiral molecule, a chiral molecule device, a preparation method and circularly polarized light detection application of the present invention are described: In this embodiment, a chiral molecule is provided, which is a functional molecule containing a chiral center and having a "DAD" structure type, named RE-PDI molecule, and has the following structure: .

[0030] The center of the RE-PDI molecule is a perylene diimide (PDI) structure, which is formed by the combination of a perylene group and an imide group. It is a highly conjugated planar aromatic system with strong electron absorption ability, acting as an electron-withdrawing group. An anthraquinone derivative group (RE) is introduced into the side group of the perylene diimide structure by alkyl chain bridging. The anthraquinone derivative group also has a photoinduced charge transfer effect and has strong electron-withdrawing characteristics. It also plays an excited state charge defect capture role under photoinduction. By introducing a chiral center, the perylene diimide structure and the anthraquinone derivative group introduced by the bridge are coupled as a basic unit that distinguishes between left-handed and right-handed circularly polarized light. The perylene diimide structure and the anthraquinone derivative group introduced by the bridge act as an "acceptor" as an electron-withdrawing center. The amino groups on the left and right ends of the molecule have two functions: 1. Reacting with the carboxyl group at the end of the graphene to form an amide bond, the molecule is connected in the gap of the graphene to form a single molecule junction; 2. The amino groups at both ends are themselves strong electron-pushing groups. Although the electron-donating effect becomes weaker after the amide bond is formed, it still acts as an electron "donor".

[0031] When irradiated with left-handed circularly polarized light, RE-PDI molecules will produce a photoinduced charge transfer effect, which will excite the charges in the ground state to the triplet excited state, resulting in charge separation. After the excited state is formed, the various groups in the molecule will further produce an excited state charge trap effect due to the energy level mismatch, resulting in charge separation and capture. Under right-handed circularly polarized light, due to the coupling effect of the chiral center, a photoinduced charge transfer different from the previous one is produced. At this time, the PDI group and anthraquinone derivative group that are already in the excited state still undergo an excited state charge trap effect due to the energy level mismatch of the various groups in the molecule, thereby exhibiting different charge transfer situations.

[0032] In this embodiment, a method for preparing a RE-PDI molecule is also provided, comprising the following steps: S1: Synthesis of compound 2 Under nitrogen atmosphere, compound 1 (100 mmol), iodine (5 mmol) and sulfuric acid (98%, 450 ml) were added to a three-necked flask and stirred at room temperature for 2 h. The mixture temperature was raised to 80 °C, bromine (150 mmol) was added dropwise within 1 h, and the mixture was reacted at 80 °C for 16 h, then cooled to room temperature, and the mixture was slowly poured into 3 L of ice water to obtain a precipitate, which was filtered to obtain a crude product, which was further separated by column chromatography to obtain compound 2.

[0033] 1 HNMR(500MHz,CDCl3)δ8.67(s,1H),8.50(d, J =8.2Hz,1H),8.42(dd, J=18.5,8.4Hz,2H),8.08(dd, J =11.9,8.2Hz,2H),8.03(d, J =8.2Hz,1H). 13 CNMR(125MHz, CDCl3)δ164.78,164.68,163.85,133.83,133.13,131.99,131.29,131.00,129.55,129.37,129.31,12 9.29,129.21,129.09,127.69,125.95,124.20,123.96,122.00,121.82,121.62,121.45,117.99.(TOF-ESI+)(m / z)C 24 H7BrO6471.22.

[0034] S2: Synthesis of compound 5 The autoclave was cleaned with carbon monoxide three times, and Rh(acac)(CO)2 (0.0125 mmol), compound 4 (0.025 mmol) and 10 mL toluene were added. CO:H2 gas with a pressure ratio of 1:1 was added, and the pressure was increased to 25 atmospheres, and the reaction was carried out at 25 °C for 16 hours. The pressure was reduced to normal pressure, and 5 ml of a toluene solution of compound 3 (6.25 mmol) was added, and the pressure was increased to 25 atmospheres again, and the reaction was carried out at 45 °C for 48 hours. After the reaction was completed, the pressure was reduced and the room temperature was restored. The solvent was spin-dried to obtain a crude product, and compound 5 was separated by a chiral column.

[0035] 1 HNMR(500MHz, CDCl3)δ9.68(dq,J=7.7,1.1Hz,1H),7.26–7.20(m,2H),7.09(dt,J=7.5,1.0Hz,2H),3.71(p,J=7.1 Hz,1H),3.41(td,J=4.8,1.3Hz,2H),2.72(tt,J=7.4,1.1Hz,2H),2.15–2.06(m,1H),1.45(dd,J=6.9,1.1Hz,3H). 13 CNMR(125MHz, CDCl3)δ200.30,140.78,139.43,129.12,128.30,52.31,34.41,33.86,32.41,15.22.(TOF-ESI+)(m / z)C 12 H 15 BrO255.16.

[0036] S3: Synthesis of compound 7 Under nitrogen atmosphere, a mixture of compound 6 (100 mmol) and compound 5 (125 mmol) was heated in nitrobenzene (200 mL) at 140 °C for 18 h in a two-necked flask, then cooled to room temperature, hexane was added, filtered and washed with hexane several times to obtain a solid crude product, which was further purified by column chromatography to obtain compound 7.

[0037] 1 HNMR(500MHz, CDCl3)δ8.27(d,J=9.2Hz,1H),8.10(ddd,J=14.0,6.0,3.4Hz,2H),7.87–7.78(m,3H),7.30–7.24(m,2H),7.08(dt,J=7.8,1 .1Hz,2H),4.40(qt,J=5.9,1.0Hz,1H),3.41(td,J=4.8,1.3Hz,2H),2.72(tt,J=7.5,1.2Hz,2H),2.11(tt,J=7.3,4.7Hz,2H),1.61(s,1H). 13 CNMR (125MHz, CDCl3) δ183.83,182.73,160.54,141.93,140.77,139.09,136.37,134.10,134.03,133.47,133.0 8,128.91,128.75,127.70,127.61,127.16,126.78,122.66,118.59,43.68,34.41,33.86,32.41,20.40.(m / z)C 26 H 21 BrN2O2473.37.

[0038] S4: Synthesis of compound 8 Under nitrogen atmosphere, NiI2 (50 mmol), 5,5′-dimethyl-2,2′-bipyridine (50 mmol), n-Bu4NBr (50 mmol) and zinc powder (75 mmol) were added to a three-necked flask. Then anhydrous DMA (200 ml) was added, and compound 7 (50 mmol) and compound 2 (60 mmol) were added in sequence after stirring. Stir at room temperature for 24 h. After the reaction was completed, ethyl acetate was added, and the mixture was extracted with water. The obtained organic layer was dried over anhydrous sodium sulfate, distilled under reduced pressure, and then further purified by column chromatography to obtain compound 8.

[0039] 1HNMR(500MHz, CDCl3)δ8.47(d,J=8.2Hz,1H),8.44(dd,J=8.3,3.8Hz,2H),8.27(d,J=9.2Hz, 1H),8.12(dd,J=6.0,3.4Hz,1H),8.12–8.05(m,3H),8.02(d,J=8.2Hz,1H),7.87–7.78(m,3H ),7.38(s,1H),7.27(dt,J=8.3,1.1Hz,2H),7.05(dt,J=7.9,1.0Hz,2H),4.44–4.36(m,1H), 3.05(td,J=8.3,2.6Hz,2H),2.67(tt,J=8.0,1.0Hz,2H),1.83(p,J=8.2Hz,2H),1.61(s,2H). 13 CNMR(125MHz, CDCl3)δ183.83,182.73,165.41,164.80,164.65,160.54,141.93,141.44,140.64,139.09, 136.37,134.10,134.03,133.47,133.29,133.08,133.04,132.27,131.39,131.35,130.54,129.32,129.29 ,128.93,128.75,128.32,127.70,127.61,127.59,127.16,126.78,126.40,126.11,124.28,124.01,123.9 9,122.66,122.54,122.50,122.16,120.43,118.59,43.68,35.84,33.81,30.29,20.40.(TOF-ESI+)(m / z)C 50 H 28 N2O8784.78.

[0040] S5: Synthesis of compound 10 Under nitrogen atmosphere, imidazole (150 g) was heated to 90 °C and compound 8 (20 mmol) was dissolved in imidazole, followed by the addition of compound 9 (44 mmol), the mixture was heated to 180 °C, and stirred for 4 h. After the reaction was completed, it was cooled to room temperature, 100 mL of water was added to quench the reaction, and then 700 mL of HCl was added to acidify. The mixture was further stirred for 12 h, filtered to obtain a solid, and the solid was washed with distilled water until neutral. The crude product was further purified by column chromatography to obtain compound 10.

[0041] 1 HNMR(500MHz, CDCl3)δ8.59(d,J=8.6Hz,1H),8.55(dd,J=8.6,2.9Hz,2H),8.27(d,J=9.2Hz,1H ),8.15–8.09(m,2H),8.12–8.03(m,4H),7.87–7.78(m,3H),7.48–7.42(m,4H),7.38(s,1H),7. 30–7.23(m,5H),7.05(dt,J=7.9,1.0Hz,2H),5.89–5.79(m,2H),4.41(q,J=5.6Hz,1H),3.00(t ,J=8.3Hz,2H),2.67(tt,J=8.0,1.0Hz,2H),1.87–1.79(m,2H),1.64(s,3H),1.64–1.58(m,6H). 13 CNMR(125MHz, CDCl3)δ183.83,182.73,168.68,163.46,163.43,163.31,160.54,141.93,141.44,141.25,141.17,139.33,139.09,136.3 7,134.10,134.03,133.47,133.08,132.72,132.36,131.36,131.35,131.33,130.64,130.39,130.11,130.02,129.08,128.93,128.88,1 28.75,128.51,128.49,128.48,127.74,127.72,127.70,127.61,127.16,127.06,126.78,126.71,125.05,125.03,124.56,124.06,123. 74,123.66,122.66,121.81,121.34,121.29,118.59,54.48,54.39,43.65,35.85,33.10,30.33,20.40,19.11,19.05.(TOF-ESI+)(m / z)C 66 H 44 Br2N4O61148.91.

[0042] S6: Synthesis of compound 12 Under nitrogen atmosphere, compound 10 (10 mmol), compound 11 (10 mmol), K2CO3 (10 mmol), and Pd(PPh3)4 (0.2 mmol) were added to a two-necked flask. 110 ml of a mixture of toluene: water = 5:1 was added via a syringe, heated to 110 °C, and refluxed for 30 h. After cooling to room temperature, the reaction mixture was poured into water and extracted three times with dichloromethane (50 ml), the organic layer was dried over anhydrous sodium sulfate, and the solvent was removed. The crude product was purified by silica gel column chromatography to obtain compound 12.

[0043] 1 HNMR(500MHz, CDCl3)δ8.62–8.52(m,1H),8.27(d,J=9.2Hz,0H),8.15–8.02(m,3H),7.87–7.78(m,2H),7.54 (tt,J=9.0,1.5Hz,4H),7.28(ddd,J=7.8,4.9,0.8Hz,3H),7.20(dt,J=8.1,1.1Hz,2H),7.05(dt,J=7.8,1.0 Hz,1H),5.84(dtdd,J=11.0,8.3,6.9,1.1Hz,1H),5.20(t,J=4.9Hz,1H),4.44–4.36(m,0H),3.17(td,J=5.6 ,4.8Hz,2H),3.00(t,J=8.3Hz,1H),2.66(dtt,J=9.8,7.8,1.0Hz,3H),1.87–1.77(m,3H),1.65–1.58(m,4H). 13CNMR (125MHz, CDCl3) δ184.36,183.11,168.80,164.60,164.46,161.60,156.50,142.44,142.34,142.29,142.01,141.56,141.12,139. 28,138.81,138.78,137.60,134.21,134.19,133.57,133.44,133.33,133.08,133.00,132.90,130.95,130.29,129.39,128.98,128.41 ,128.22,128.10,127.66,127.64,127.48,127.46,127.42,127.31,126.36,125.48,125.40,124.60,124.23,124.09,123.94,123.82,1 23.38,121.48,118.84,79.55,52.93,52.78,43.38,40.22,35.91,33.59,33.26,29.80,29.66,28.30,21.98,19.55.(TOF-ESI+)(m / z)C 94 H 84 N6O 10 1456.62.

[0044] S7: Synthesis of compound 13 Under nitrogen atmosphere, compound 12 (5 mmol) and 20 mL of 50% TFA in DCM solution were added to a two-necked flask and stirred at room temperature for 2 h. After the reaction was completed, saturated sodium bicarbonate solution was added for extraction and repeated washing until it became neutral. The collected organic layer was evaporated to remove the solvent to obtain compound 13 (RE-PDI molecule).

[0045] 1HNMR(500MHz,CDCl3)δ8.55(dd,J=8.6,2.9Hz,1H),8.15–8.02(m,2H),7.87–7.79(m,1H),7.58–7.50(m,4H),7.28(ddd,J=7.8,4.9,0.8Hz,3H),7.20(dt,J=8.1,1.1Hz,2H),7.05(dt,J=7.8,1.0Hz,1H),5.84(dtdd,J=10.8,8.3,6.9,1.1Hz,1H),4.40(q,J=5.8Hz,0H),3.00(t,J=8.3Hz,1H),2.77(tt,J=6.3,5.3Hz,2H),2.66(dtt,J=9.6,7.6,1.0Hz,3H),1.87–1.77(m,3H),1.62(dd,J=13.5,6.7Hz,5H). 13 CNMR(125MHz,CDCl3)δ13CNMR(125MHz,CommonNMRSolvents)δ183.83,182.73,168.68,163.46,163.43,163.31,160.54,142.41,142.35,141.93,141.76,141.75,141.44,139.33,139.26,139.25,139.09,138.80,138.78,136.37,134.10,134.03,133.47,133.08,132.72,132.17,130.64,130.31,130.11,129.93,129.30,129.26,129.22,129.08,128.93,128.88,128.75,128.16,128.14,128.11,127.74,127.72,127.70,127.61,127.39,127.34,127.29,127.16,127.12,127.10,127.09,127.06,126.78,126.71,125.05,125.03,124.46,124.06,123.75,123.65,122.66,121.81,118.59,54.48,54.38,43.68,41.73,41.70,35.85,33.90,33.10,33.06,30.33,20.40,19.11,19.05.(TOF-ESI+)(m / z)C 84 H 68 N6O61256.52。

[0046] In this embodiment, the circular dichroism spectrum of the synthesized RE-PDI molecule is detected, which specifically includes the following steps: First, start the circular dichroism spectrometer and preheat it to room temperature. While the machine is preheating, take 10 ml of methanol and place it in a small beaker. Take an appropriate amount of the synthesized RE-PDI molecule and dissolve it in the methanol solution to prepare a solution sample to be tested. The sample is placed in an ultrasonic cleaner and ultrasonically oscillated for 3 minutes to fully dissolve the molecule in methanol. Add a blank sample of the same methanol solvent to the sample cell for blank calibration to eliminate the influence of the system background. Measure the CD signal of the buffer solution without the sample to ensure that the recorded CD spectrum is not affected by the solvent. Then inject the sample solution into the quartz cuvette, taking care to avoid bubbles. Set the wavelength to measure the CD signal of the sample in the range of 250-550 nm, subtract the background signal from the CD signal of the sample, and obtain the net CD spectrum data. Finally, use SELCON3 software to process the obtained data and draw a curve.

[0047] like Figure 1 As shown, the CD spectrum shows that the RE-PDI molecule designed in this embodiment has obvious left-handed and right-handed circularly polarized light differentiated absorption in the wavelength range of 300-550 nm, that is, in the near-ultraviolet and visible spectral regions, verifying the basic design concept that the introduction of the chiral center will affect the differentiated response of this molecule to left-handed and right-handed circularly polarized light.

[0048] In addition, a strong positive peak appears at a wavelength of about 400 nm, indicating that the charge transfer within the RE-PDI molecule absorbs left-handed circularly polarized light more strongly at this wavelength. A strong negative peak appears at a wavelength of about 350 nm, indicating that the charge transfer within the RE-PDI molecule absorbs right-handed circularly polarized light more strongly at this wavelength. The characteristic wavelength provides data support for the specific wavelength selected for the subsequent design of the femtosecond laser circular polarization detection optical path.

[0049] In this embodiment, a chiral molecular device is also provided, such as Figure 2 As shown, it includes: silicon substrate 101, aluminum oxide dielectric layer 201, metal electrode 301, graphene point electrode 401 and RE-PDI molecule 501, RE-PDI molecule 501 is connected to graphene point electrode 401, graphene point electrode 401 is connected to metal electrode 301, graphene point electrode 401 and metal electrode 301 are located on aluminum oxide dielectric layer 201, and aluminum oxide dielectric layer 201 is located on silicon substrate 101. The thickness of aluminum oxide dielectric layer 201 is 30-40 nm, the thickness of metal electrode 301 is 68-90 nm, and graphene point electrode 401 is a single layer.

[0050] In this embodiment, a method for preparing a chiral molecular device is also provided, which is used to prepare the chiral molecular device, comprising the following steps: Step 1: Prepare an aluminum oxide dielectric layer on a silicon substrate.

[0051] Spin-coat photoresist on a silicon wafer (silicon substrate) with a size of 1 cm×1 cm, place a mask on the spin-coated silicon wafer for photolithography using a photolithography machine, and then transfer the photolithographically processed silicon wafer to a vacuum thermal evaporation chamber to evaporate chromium with a thickness of 6 to 9 nm and gold with a thickness of 30 to 35 nm to obtain a lead electrode; spin-coat photoresist on the lead electrode again and place it on the stage of the photolithography machine, replace the mask to perform photolithography of the gate, and obtain a bottom gate; plate a 30 to 40 nm aluminum film on the surface of the bottom gate by vacuum thermal evaporation on the silicon wafer on which the bottom gate is prepared, and then immerse the bottom gate in an acetone solution to remove the glue to obtain an aluminum oxide dielectric layer.

[0052] Step 2: Prepare a graphene dielectric layer on the aluminum oxide dielectric layer, and prepare a metal electrode on the graphene dielectric layer.

[0053] A single-layer graphene was obtained on a clean copper foil by chemical vapor deposition; methyl methacrylate (950 PMMA) was spin-coated on the single-layer graphene, and then the single-layer graphene was placed on a heating platform at 180°C for 2 min. The copper foil was etched with oxygen plasma for 3s to remove excess PMMA and graphene on the back, thereby obtaining PMMA-single-layer graphene-copper foil. Next, the PMMA-single-layer graphene-copper foil is cut into small pieces, transferred to a ferric chloride solution, and the copper foil is dissolved to obtain a PMMA-single-layer graphene film; the PMMA-single-layer graphene film is soaked in a hydrochloric acid solution, an aqueous solution, and a potassium hydroxide solution, and then transferred to an alumina dielectric layer, and the graphene dielectric layer is obtained after standing, drying, and degumming; strips are photoetched on the graphene dielectric layer, and excess single-layer graphene is similarly removed by oxygen plasma etching to obtain a film having graphene strips; electrodes are photoetched on the film, and 8 to 10 nm chromium and 60 to 80 nm gold are evaporated to obtain metal electrodes.

[0054] Step 3: Construct graphene dot electrodes using the graphene dielectric layer.

[0055] Spin-coat photoresist on the negative film with graphene strips after photolithography, and use a customized strip mask to photolithograph the graphene strips. After exposure and development, leave the strip-shaped photoresist to protect part of the graphene, and then perform another 5 s oxygen plasma etching, and the remaining exposed graphene is removed by the oxygen plasma etching process; then soak in acetone to remove the photoresist to obtain a negative film with a central graphene strip; use thermal evaporation to successively evaporate 8-10 nm chromium and 60-80 nm gold on the negative film, soak in acetone to remove the photoresist, and obtain a graphene array electrode. Electron beam exposure is used to etch a dotted line with a length of 150 nm and a width of 5 nm on the graphene array electrode, and then it is developed by methyl isobutyl ketone (MIBK) diluted with isopropyl alcohol (MIBK: isopropyl alcohol = 1:3), and fixed by isopropyl alcohol, and then by oxygen plasma etching and electrical burnout method to obtain a graphene nano-gap point electrode array. In this embodiment, the graphene nanogap point electrode array includes 169 pairs of graphene point electrodes, that is, 338 graphene point electrodes.

[0056] Step 4: Self-assemble a single RE-PDI molecule with a graphene dot electrode to obtain a chiral molecular device.

[0057] Take the RE-PDI molecule and place it in a three-necked flask, inject 5 ml of dichloromethane and 0.5 ml of trifluoroacetic acid to react for 2 h in a nitrogen atmosphere, remove the trifluoroacetic acid by sodium hydroxide extraction, and transfer the solution to an eggplant-shaped bottle; the solution is subjected to rotary evaporation to obtain the RE-PDI molecule without the protective group; the molecule is placed in a nitrogen atmosphere by ventilation operation, and 10 ml of anhydrous pyridine is drawn with a syringe and injected into the eggplant-shaped bottle to dissolve the RE-PDI molecule. The graphene nanogap point electrode array is placed in a three-necked flask, and a sufficient amount of 1-(3-dimethylaminopropyl)-3-2-ethylcarbodiimide hydrochloride and the pyridine solution of the RE-PDI molecule without the protective group are added to the three-necked flask, and reacted for more than 48 h in a nitrogen atmosphere, and the device is taken out from the two-necked flask, and rinsed with deionized water and ethanol three times respectively, and the surface is dried with nitrogen for standby use to obtain a chiral molecular device. Among them, the molecular junction of the chiral molecular device is obtained by forming an amide covalent bond between the –NH2 at the bottom of the RE-PDI molecule and the –COOH at the end of the graphene point electrode.

[0058] The present invention also provides an application of a chiral molecular device, and the adopted technical solution is as follows: the chiral molecular device is applied in circularly polarized light detection.

[0059] Chiral molecular devices are used in femtosecond laser light paths that can switch circularly polarized light detection, such as Figure 3 As shown, the working process is: The femtosecond pulse laser generator 1 generates femtosecond linearly polarized laser light. After being emitted, the laser light reaches the beam splitter 3 through the first reflector 2 to generate two linearly polarized laser lights (first linearly polarized laser light and second linearly polarized laser light).

[0060] After the first linearly polarized laser passes through the second multifunctional optical parametric amplifier 9 and becomes a linearly polarized laser of the first specific wavelength, it reaches the second quarter-wave plate 11 through the fourth reflector 10 (the fast axis of the second quarter-wave plate is rotated 45° clockwise relative to the incident linearly polarized light of the first specific wavelength). At this time, the linearly polarized laser of the first specific wavelength becomes left-handed circularly polarized light with a specific wavelength. The left-handed circularly polarized light continues to propagate forward through the fifth reflector 12, the sixth reflector 13, the seventh reflector 14, and the eighth reflector 15 to enter the optoelectronic detection station and irradiate the chiral molecular device 16 located inside the optoelectronic detection station.

[0061] The second linearly polarized laser first passes through the first multifunctional optical parametric amplifier 4 to become a linearly polarized laser of a second specific wavelength, then passes through the time delay controller 5 with a delay time τ, and then passes through the second reflector 6 and the third reflector 7 to reach the first quarter wave plate 8 (the fast axis of the first quarter wave plate is rotated 45° counterclockwise relative to the incident linearly polarized light of the second specific wavelength), and becomes right-handed circularly polarized light with a specific wavelength. The right-handed circularly polarized light continues to advance through the set optical path, passes through the seventh reflector 14 and the eighth reflector 15 to enter the optoelectronic detection station, and irradiates the chiral molecular device 16 located inside the optoelectronic detection station.

[0062] It is particularly noted that the generation of left-handed circularly polarized light and right-handed circularly polarized light with specific wavelengths is mainly controlled by the first multifunctional optical parametric amplifier 4 and the second multifunctional optical parametric amplifier 9, respectively. The two multifunctional optical parametric amplifiers have two working states that can be controlled by a computer program: one is the working mode, and the other is the shutdown mode. In the working mode, the function of the multifunctional optical parametric amplifier is to amplify the incident light signal and output a beam of outgoing light with a specific wavelength using the built-in adjustable filter. In the shutdown mode, the incident light cannot continue to propagate forward through this device. The single action state of L-CPL is based on the first multifunctional optical parametric amplifier 4 in the above-mentioned optical path system being in the shutdown mode and the second multifunctional optical parametric amplifier 9 being in the working mode. Similarly, the single action state of R-CPL is based on the second multifunctional optical parametric amplifier 9 in the above-mentioned optical path system being in the shutdown mode and the first multifunctional optical parametric amplifier 4 being in the working mode.

[0063] In this embodiment, the computer control program is first used to set the second multifunctional optical parametric amplifier 9 to the working mode and select the wavelength of the output light to be 400 nm, and the first multifunctional optical parametric amplifier 4 to the shutdown mode. After turning on the femtosecond pulse laser generator 1, the photoelectric detection station is introduced to irradiate the chiral molecular device 16 with an L-CPL with a wavelength of 400 nm. Thereafter, the current signal of the chiral molecular device 16 is measured on the photoelectric detection station by changing the gate voltage. Subsequently, the computer control program is set to set the first multifunctional optical parametric amplifier 4 to the working mode and select the wavelength of the output light to be 350 nm, and the second multifunctional optical parametric amplifier 9 to the shutdown mode. After turning on the femtosecond pulse laser generator 1, the photoelectric detection station is introduced to irradiate the chiral molecular device 16 with an R-CPL with a wavelength of 350 nm. Similarly, the current signal of the chiral molecular device 16 is measured on the photoelectric detection station by changing the gate voltage. The test results are as follows. Figure 4 As shown, the chiral molecular device based on the photoinduced charge transfer effect prepared in this embodiment has a distinct response to left-handed circularly polarized light and right-handed circularly polarized light under different gate voltages. The selective response of the device to L / R-CPL is characterized by the asymmetry factor, and the specific formula is as follows: .

[0064] in, Indicates the current value measured at L-CPL, Indicates the current value measured at R-CPL, Represents the asymmetry factor. The above formula is used to calculate the chiral molecular device when the gate voltage is -4V. The value of is 1.61, indicating that the chiral molecular device prepared in the example has excellent application value as a photodetector for distinguishing different types of circularly polarized light.

[0065] The dynamic switchable detection application and femtosecond-level control of circularly polarized light in the femtosecond laser optical path of switchable circularly polarized light detection is realized based on the time control of the coordinated matching of the working and shutdown modes of two multifunctional optical parametric amplifiers by a computer program. The periodic control program is set so that the second multifunctional optical parametric amplifier is first in the shutdown state, and the first multifunctional optical parametric amplifier enters the working mode (the working time is set to 2s) after receiving the incident linearly polarized laser and then immediately switches to the shutdown mode. When the first multifunctional optical parametric amplifier switches to the shutdown mode, the second multifunctional optical parametric amplifier immediately enters the working mode (the working time is set to 2s) and then switches to the shutdown mode. Figure 5The data collection results successfully verified the dynamic switchable detection of circularly polarized light, and the chiral molecular device based on the photoinduced charge transfer effect prepared in this embodiment showed a relatively stable current signal under each different circularly polarized light irradiation state, which also verified that the chiral molecular device based on the photoinduced charge transfer effect prepared by the invention has excellent stability when used as a photoelectric device for distinguishing and detecting different types of circularly polarized light.

[0066] like Figure 6 As shown in the figure, when L-CPL is irradiated on the chiral molecular device, the anthraquinone derivative group absorbs photon energy and changes from the ground state to the excited state, that is, the charge transitions from the HOMO (Highest Occupied Molecular Orbital) energy level to the LUMO (Lowest Unoccupied Molecular Orbital) energy level. At this time, the charge in the excited state will produce the transfer of excited state charge (excited state charge trap capture effect) due to the energy level mismatch between the LUMO energy level of the anthraquinone derivative group and the PDI group. The excited state charge is transferred from the LUMO energy level of the anthraquinone derivative group to the triplet excited T1 energy level generated by the PDI group. When R-CPL is irradiated on the chiral molecular device, the charge at the T1 energy level in the PDI group coupled to the chiral center absorbs the absorbed photon energy and transitions to the T2 energy level. Subsequently, the excited state charge at the T2 energy level will be transferred and captured again due to the mismatch between the LUMO energy level of the anthraquinone derivative group and the T2 energy level, and then transferred to the LUMO energy level of the anthraquinone derivative group. The different current signal changes of the two processes are transmitted by the single molecule junction-graphene source electrode-probe to the photoelectric detection station for reading.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A chiral molecule, characterized in that: Contains a chiral center and has a "DAD" structure, the structure is as follows: 。 2. A chiral molecular device, characterized in that: include: A silicon substrate, an aluminum oxide dielectric layer, a metal electrode, a graphene point electrode and a RE-PDI molecule, wherein the RE-PDI molecule is a chiral molecule as described in claim 1, the RE-PDI molecule is connected to the graphene point electrode, the graphene point electrode is connected to the metal electrode, the graphene point electrode and the metal electrode are located on the aluminum oxide dielectric layer, and the aluminum oxide dielectric layer is located on the silicon substrate.

3. A chiral molecular device according to claim 2, characterized in that: The thickness of the aluminum oxide dielectric layer is 30-40 nm, the thickness of the metal electrode is 68-90 nm, the graphene dot electrode is a single layer, and the number of the RE-PDI molecule is one.

4. A method for preparing a chiral molecular device, characterized in that: The method for preparing a chiral molecular device according to claim 2 or 3 comprises the following steps: Step 1: preparing an aluminum oxide dielectric layer on a silicon substrate; Step 2: preparing a graphene dielectric layer on the aluminum oxide dielectric layer, and preparing a metal electrode on the graphene dielectric layer; Step 3: constructing a graphene point electrode using a graphene dielectric layer; Step 4: Self-assemble a single RE-PDI molecule with a graphene dot electrode to obtain a chiral molecular device.

5. The method for preparing a chiral molecular device according to claim 4, characterized in that: In step 4, take the RE-PDI molecule, add dichloromethane and trifluoroacetic acid, and react for more than 2 hours under a nitrogen atmosphere; the remaining solution after removing the trifluoroacetic acid is subjected to rotary evaporation to obtain the RE-PDI molecule without the protecting group; the RE-PDI molecule without the protecting group is placed in a nitrogen atmosphere, and anhydrous pyridine is added to obtain a pyridine solution of the RE-PDI molecule without the protecting group; the graphene dot electrode, 1-(3-dimethylaminopropyl)-3-2-ethylcarbodiimide hydrochloride and the pyridine solution of the RE-PDI molecule without the protecting group are reacted in a nitrogen atmosphere for more than 48 hours to obtain a chiral molecular device.

6. The method for preparing a chiral molecular device according to claim 4, characterized in that: In step 1, photoresist is spin-coated on a silicon substrate, and chromium and gold with a thickness of 6 to 9 nm and 30 to 35 nm are photolithographed and evaporated to obtain a lead electrode; photoresist is spin-coated on the lead electrode again, and a gate is photolithographed to obtain a bottom gate; a 30 to 40 nm aluminum film is plated on the surface of the bottom gate by vacuum thermal evaporation, and then the bottom gate is debonded.

7. The method for preparing a chiral molecular device according to claim 4, characterized in that: In step 2, PMMA-single-layer graphene-copper foil is prepared, and copper foil is dissolved by ferric chloride solution to obtain PMMA-single-layer graphene film; the PMMA-single-layer graphene film is transferred to the alumina dielectric layer, left to stand, dried, and debonded; strips are photoetched on the graphene dielectric layer, and excess single-layer graphene is removed to obtain a film with graphene strips; electrodes are photoetched on the film, and 8-10 nm chromium and 60-80 nm gold are evaporated to obtain metal electrodes on the graphene dielectric layer.

8. The method for preparing a chiral molecular device according to claim 4, characterized in that: In step 3, a dotted line is etched on the graphene dielectric layer, and then a graphene point electrode is obtained by oxygen plasma etching and electrical burning.

9. An application of a chiral molecular device, characterized in that: The chiral molecular device described in claim 2 or 3 is used in circularly polarized light detection.

10. The use of a chiral molecular device as claimed in claim 9, characterized in that: Chiral molecular devices are used in femtosecond laser optical paths that can switch circularly polarized light detection. The working process is: The femtosecond pulse laser generator generates femtosecond linearly polarized laser light, which is then emitted through the first reflector and reaches the beam splitter to generate two linearly polarized laser light. After the first linear polarized laser is converted into a linear polarized laser of a first specific wavelength by the second multifunctional optical parametric amplifier, it reaches the second quarter wave plate and is converted into left-handed circularly polarized light with a specific wavelength. The left-handed circularly polarized light enters the photoelectric coupled detection station and irradiates the chiral molecular device located inside the photoelectric coupled detection station. The second linear polarized laser first passes through the first multifunctional optical parametric amplifier to become a linear polarized laser of a second specific wavelength, and then is delayed by the time delay controller and reaches the first quarter wave plate to become right-handed circularly polarized light with a specific wavelength. The right-handed circularly polarized light enters the photoelectric coupled detection station and irradiates the chiral molecular device located inside the photoelectric coupled detection station. One of the first multifunctional optical parametric amplifier and the second multifunctional optical parametric amplifier is in the operating mode, while the other is in the shut-down mode.

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