Chiral Molecules, Chiral Molecular Devices, Preparation Methods, and Applications in Circularly Polarized Light Detection

Abstract

The present invention relates to the technical field of molecular optoelectronic devices, and specifically discloses a chiral molecule, a chiral molecular device, a preparation method thereof, and an application in circularly polarized light detection. Among them, the chiral molecule is a functional molecule containing a chiral center and having a "D-A-D" structural type. The chiral molecular device includes: a silicon substrate, an aluminum oxide dielectric layer, a metal electrode, a graphene dot electrode, and an RE-PDI molecule, which is applied in circularly polarized light detection. The present invention designs and synthesizes a functional molecule RE-PDI containing a chiral center and having a "D-A-D" structural type, and assembles it between the graphene dot electrodes with a nanogap by a chemical decoupling method. By utilizing the differential response of the RE-PDI molecule to different types of circularly polarized light, the differential detection of left-handed and right-handed circularly polarized light and the dynamically periodic adjustable response can be stably achieved.

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 thereof, and an application for circularly polarized light detection. Background Art

[0002] Circularly polarized light is a relatively common state of light polarization and has wide applications in fields such as optical communication, biomedical research, environmental monitoring, and image sensing. In recent years, circularly polarized light detectors capable of detecting the polarization of light have attracted the attention of researchers at home and abroad due to their broad application prospects in fields such as biosensing, quantum optics, polarization-enhanced imaging, microfluidics, and encrypted optical communication. The core of realizing these applications is to prepare a photodetector that can distinguish left-handed (L-CPL) and right-handed (R-CPL) circularly polarized light. The Chinese invention patent with the application publication number CN119403352A discloses a tunable polarization photon source based on perovskite quantum dots and a preparation method thereof. By using a chiral molecule with tunable chirality, spin-polarized electron holes are injected, and they recombine in the central perovskite quantum dot to emit polarized light. The helical chiral structure switch can be controlled by irradiating with light of different wavelengths. Currently, circularly polarized light detectors usually need to be combined with inorganic photodetectors and polarization optical elements to achieve, and such devices are not suitable for miniaturization, integration, or low-cost preparation.

[0003] Single-molecule devices developed in the field of molecular electronics have become a research hotspot for the semiconductor industry to lead the next generation of functional, miniaturized, and highly integrated semiconductor products because they can use nanotechnology to realize devices with a single molecule as the core. However, currently, circularly polarized light detection devices based on chiral single-molecule materials are still in the initial exploration stage. Chiral molecular devices can utilize the controllability of the molecular structure and the uniqueness in optoelectronic properties to provide a realizable material basis for developing a chiral single-molecule circularly polarized light detection device with sensitive response, distinguishable detection of left-handed and right-handed circularly polarized light, and dynamic switching 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 thereof, and a 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 to regulate the electrical properties of the molecule through photoinduced charge transfer and excited state charge trapping effects. The present invention designs and synthesizes a functional molecule RE-PDI containing a chiral center and having a "D-A-D" (Donor-Acceptor-Donor) structural type, and assembles it between the graphene dot electrodes with a nano-gap by a chemical decoupling method. By utilizing the differential response of the molecule to different types of circularly polarized light, a regulation system is constructed, which can stably achieve the discrimination detection of left-handed and right-handed circularly polarized light and the dynamically periodic adjustable response, providing a new research direction and application idea for optoelectronic regulation and detection technology and the miniaturization of functional chips.

[0005] The present invention provides a chiral molecule, and the technical solution adopted is as follows: It contains a chiral center and has a "D-A-D" structure, named RE-PDI molecule, and the structure is as follows:

[0006] 。

[0007] The present invention also provides a chiral molecular device, and the technical solution adopted is as follows: It includes: a silicon substrate, an alumina dielectric layer, a metal electrode, a graphene dot electrode, and an RE-PDI molecule. The RE-PDI molecule is connected to the graphene dot electrode, the graphene dot electrode is connected to the metal electrode, the graphene dot electrode and the metal electrode are located on the alumina dielectric layer, and the alumina dielectric layer is located on the silicon substrate.

[0008] Further, the thickness of the alumina dielectric layer is 30 - 40 nm, the thickness of the metal electrode is 68 - 90 nm, and the graphene dot electrode is a single layer.

[0009] The present invention also provides a preparation method of a chiral molecular device, and the technical solution adopted is as follows: It is used to prepare the above-mentioned chiral molecular device, and includes the following steps:

[0010] Step 1: Prepare an alumina dielectric layer on the silicon substrate;

[0011] Step 2: Prepare a graphene dielectric layer on the alumina dielectric layer, and prepare a metal electrode on the graphene dielectric layer;

[0012] Step 3: Utilize the graphene dielectric layer to construct a graphene dot electrode;

[0013] Step 4: Self-assemble a single RE-PDI molecule with the graphene dot electrode to obtain a chiral molecular device.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] Further, the chiral molecular device is applied to the femtosecond laser optical path for switchable circularly polarized light detection. The working process is as follows:

[0020] The femtosecond pulsed laser generator generates femtosecond linearly polarized laser. After the laser exits, it reaches the beam splitter through the first mirror, generating two linearly polarized lasers.

[0021] After the first linearly polarized laser passes through the second multifunctional optical parametric amplifier and becomes linearly polarized laser with a first specific wavelength, it reaches the second quarter-wave plate and becomes left-handed circularly polarized light with a specific wavelength. The left-handed circularly polarized light enters the optoelectronic combined detection platform and irradiates on the chiral molecular device located inside the optoelectronic combined detection platform.

[0022] The second linearly polarized laser first passes through the first multifunctional optical parametric amplifier and becomes linearly polarized laser with a second specific wavelength, and then is delayed by the time delay controller and reaches the first quarter-wave plate, becoming right-handed circularly polarized light with a specific wavelength. The right-handed circularly polarized light enters the optoelectronic combined detection platform and irradiates on the chiral molecular device located inside the optoelectronic combined detection platform.

[0023] One of the first multifunctional optical parametric amplifier and the second multifunctional optical parametric amplifier is in the working mode, and the other is in the off mode.

[0024] One or more of the above technical solutions in the embodiments of the present invention have at least one of the following technical effects:

[0025] 1. The present invention designs an RE-PDI molecule with a chiral center and a "D-A-D" structure. Due to the introduction of the chiral center, it has a differential response 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 generate charge separation. There will also be an excited-state charge trap effect induced by the energy level mismatch between the groups inside the molecule, ensuring that the molecule differentially responds to circularly polarized light within a small energy range to obtain two different situations of charge separation and capture, and each situation will generate a relatively stable current signal.

[0026] 2. The chiral molecular device of the present invention is prepared based on a graphene single-molecule field-effect transistor, and has a mature device preparation process. The prepared single-molecule device has 169 pairs of graphene dot electrodes, realizing a significant miniaturization of the device size and showing extremely high integration. This characteristic provides a new idea for the miniaturization and high-density integration of functional chips.

[0027] 3. The chiral molecular device of the present invention is applied in circularly polarized light detection. Through a rational design of the optical path by combining a femtosecond pulsed laser generator, a multifunctional optical parametric amplifier, a time delay controller, and a quarter-wave plate, the following functions can be achieved: First, a single beam is split into two optical paths by a beam splitter, and then the two beams of light are respectively converted into left-handed circularly polarized light and right-handed circularly polarized light by placing a quarter-wave plate and introduced into the optoelectronic combined detection platform for testing; Second, the working and off modes of the multifunctional optical parametric amplifiers placed on the two splitting optical paths can be combined to generate left-handed circularly polarized light and right-handed circularly polarized light with time control and act independently on the optoelectronic combined detection platform. This ensures that the two circularly polarized lights can act independently on the optoelectronic combined detection platform periodically. In addition, dynamic switching between the two circularly polarized lights can be achieved by programming the working and off modes of the multifunctional optical parametric amplifier; Third, the addition of the time delay controller can control the time interval for the optical path system to switch from left-handed light irradiation to right-handed light irradiation within a switching cycle up to the femtosecond level.

[0028] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0030] Figure 1 It is the circular dichroism spectrum of the RE-PDI molecule provided by the present invention.

[0031] Figure 2 It is the three-dimensional schematic diagram of the chiral molecular device provided by the present invention.

[0032] Figure 3 It is the femtosecond laser optical path diagram for switchable circularly polarized light detection provided by the present invention.

[0033] Figure 4 It is the characteristic curve of the current varying with the gate voltage of the chiral molecular device provided by the present invention under left-handed circularly polarized light and right-handed circularly polarized light irradiation.

[0034] Figure 5 It is the current-time characteristic curve recorded when the chiral molecular device provided by the present invention is irradiated under dynamic switching between left-handed circularly polarized light and right-handed circularly polarized light.

[0035] Figure 6It is a schematic diagram of the charge transfer process of the RE-PDI molecule provided by the present invention under different circularly polarized light irradiations.

[0036] Reference numerals:

[0037] 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 mirror; 3, beam splitter; 4, first multifunctional optical parametric amplifier; 5, time delay controller; 6, second mirror; 7, third mirror; 8, first quarter-wave plate; 9, second multifunctional optical parametric amplifier; 10, fourth mirror; 11, second quarter-wave plate; 12, fifth mirror; 13, sixth mirror; 14, seventh mirror; 15, eighth mirror; 16, chiral molecular device. Specific embodiments

[0038] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts fall within the protection scope 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.

[0039] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments 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 can be combined in any one or more embodiments or examples in a suitable manner. In addition, without conflict, those skilled in the art can combine the different embodiments or examples described in this specification and the features of the different embodiments or examples.

[0040] The following will further elaborate on the present invention in conjunction with Figures 1 to 6 to describe a chiral molecule, a chiral molecular device, and a preparation method and circularly polarized light detection application of the present invention:

[0041] In this embodiment, a chiral molecule is provided, which is a functional molecule containing a chiral center and having a "D-A-D" structural type, named the RE-PDI molecule, and its structure is as follows:

[0042] .

[0043] The center of the RE-PDI molecule is a perylene diimide (PDI) structure 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 and acts as an electron-withdrawing group. An anthraquinone-derived group (RE) is introduced into the side group of the perylene diimide structure by means of an alkyl chain bridge. The anthraquinone-derived group also has a photoinduced charge transfer effect and strong electron-withdrawing characteristics, and it also plays an excited-state charge defect capture role under photoinduction. By introducing a chiral center, the overall structure composed of the perylene diimide structure and the anthraquinone-derived group introduced by bridging is coupled, making it a basic unit for differentiating the response to left-handed and right-handed circularly polarized light. The overall structure composed of the perylene diimide structure and the anthraquinone-derived group introduced by bridging acts as an electron-withdrawing center to play the role of a "receptor". The amino groups at both ends of the molecule have two functions: 1. React with the carboxyl groups at the ends of graphene to form amide bonds, connecting the molecule in the gaps of graphene to form a single-molecule junction; 2. The amino groups at both ends are themselves strong electron-donating groups. Although the electron-donating effect becomes weaker after the formation of amide bonds, they still act as electron "donors".

[0044] Under the irradiation of left-handed circularly polarized light, the RE-PDI molecule will produce a photoinduced charge transfer effect, exciting the charges in the ground state to the triplet excited state for charge separation. After the formation of the excited state, due to the energy level mismatch of each part of the group within the molecule, an excited-state charge trap effect will further occur, resulting in charge separation and capture. Under the irradiation of right-handed circularly polarized light, due to the coupling effect of the chiral center, a photoinduced charge transfer different from the former will occur, and at this time, for the PDI group and the anthraquinone-derived group that are already in the excited state, an excited-state charge trap effect still occurs due to the energy level mismatch of each part of the group within the molecule, thus showing different charge transfer situations.

[0045] In this embodiment, a preparation method of the RE-PDI molecule is also provided, including the following steps:

[0046] S1: Synthesis of compound 2

[0047]

[0048] Under a nitrogen atmosphere, 100 mmol of compound 1, 5 mmol of iodine, and 450 ml of sulfuric acid (98%) were added to a three-necked flask and stirred at room temperature for 2 h. The temperature of the mixture was raised to 80 °C, and 150 mmol of bromine was added dropwise within 1 h. The reaction was carried out at 80 °C for 16 h, and then cooled to room temperature. The mixture was slowly poured into 3 L of ice water to obtain a precipitate, which was filtered to obtain a crude product, and further separated by column chromatography to obtain compound 2.

[0049] 1 HNMR(500MHz,CDCl 3)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,CDCl 3 )δ164.78,164.68,163.85,133.83,133.13,131.99,131.29,131.00,129.55,129.37,129.31,129.29,129.21,129.09,127.69,125.95,124.20,123.96,122.00,121.82,121.62,121.45,117.99.(TOF-ESI+)(m / z)C 24 H 7 BrO 6 471.22。

[0050] S2: Synthesis of Compound 5

[0051]

[0052] The high-pressure reactor was cleaned with carbon monoxide three times, and Rh(acac)(CO) 2 (0.0125 mmol), Compound 4 (0.025 mmol) and 10 mL of toluene were added. A gas with a CO:H 2 pressure ratio of 1:1 was added, and the pressure was increased to 25 atmospheres. The reaction was carried out at 25 °C for 16 h. The pressure was reduced to atmospheric pressure, 5 ml of a toluene solution of Compound 3 (6.25 mmol) was added, and the pressure was increased to 25 atmospheres again. The reaction was carried out at 45 °C for 48 h. After the reaction was completed, the pressure was reduced and the temperature was restored to room temperature. The solvent was evaporated to dryness to obtain the crude product, and Compound 5 was obtained by separation through a chiral column.

[0053] 1 HNMR(500MHz,CDCl 3 )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=7.1Hz,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). 13CNMR(125MHz,CDCl 3 )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。

[0054] S3: Synthesis of Compound 7

[0055]

[0056] Under a nitrogen atmosphere, a mixture of compound 6 (100 mmol) and compound 5 (125 mmol) in a two-necked flask was heated at 140 °C for 18 h in nitrobenzene (200 mL), then cooled to room temperature, hexane was added, and the mixture was filtered and washed several times with hexane. The solid crude product was further purified by column chromatography to obtain compound 7.

[0057] 1 HNMR(500MHz,CDCl 3 )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,CDCl 3 )δ183.83,182.73,160.54,141.93,140.77,139.09,136.37,134.10,134.03,133.47,133.08,128.91,128.75,127.70,127.61,127.16,126.78,122.66,118.59,43.68,34.41,33.86,32.41,20.40.(m / z)C 26 H 21 BrN 2 O 2 473.37。

[0058] S4: Synthesis of Compound 8

[0059]

[0060] Under a nitrogen atmosphere, NiI 2 (50 mmol), 5,5′-dimethyl-2,2′-bipyridine (50 mmol), n-Bu 4 NBr (50 mmol) and zinc powder (75 mmol) were added to a three-necked flask. Then anhydrous DMA (200 ml) was added, and after stirring, compound 7 (50 mmol) and compound 2 (60 mmol) were added successively. 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.

[0061] 1 HNMR(500MHz,CDCl 3 ) δ 8.47 (d, J = 8.2 Hz, 1H), 8.44 (dd, J = 8.3, 3.8 Hz, 2H), 8.27 (d, J = 9.2 Hz, 1H), 8.12 (dd, J = 6.0, 3.4 Hz, 1H), 8.12–8.05 (m, 3H), 8.02 (d, J = 8.2 Hz, 1H), 7.87–7.78 (m, 3H), 7.38 (s, 1H), 7.27 (dt, J = 8.3, 1.1 Hz, 2H), 7.05 (dt, J = 7.9, 1.0 Hz, 2H), 4.44–4.36 (m, 1H), 3.05 (td, J = 8.3, 2.6 Hz, 2H), 2.67 (tt, J = 8.0, 1.0 Hz, 2H), 1.83 (p, J = 8.2 Hz, 2H), 1.61 (s, 2H). 13 CNMR(125MHz,CDCl 3 ) δ 183.83, 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, 123.99, 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)C50 H 28 N 2 O 8 784.78。

[0062] S5: Synthesis of Compound 10

[0063]

[0064] Under a nitrogen atmosphere, imidazole (150 g) was heated to 90 °C and Compound 8 (20 mmol) was dissolved in imidazole. Subsequently, Compound 9 (44 mmol) was added, and 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 for acidification. The mixture was further stirred for 12 h, and the solid was filtered out. The solid was washed with distilled water until neutral. The obtained crude product was further purified by column chromatography to obtain Compound 10.

[0065] 1 HNMR(500MHz,CDCl 3 )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,CDCl 3)δ183.83,182.73,168.68,163.46,163.43,163.31,160.54,141.93,141.44,141.25,141.17,139.33,139.09,136.37,134.10,134.03,133.47,133.08,132.72,132.36,131.36,131.35,131.33,130.64,130.39,130.11,130.02,129.08,128.93,128.88,128.75,128.51,128.49,128.48,127.74,127.72,127.70,127.61,127.16,127.06,126.78,126.71,125.05,125.03,124.56,124.06,123.74,123.66,122.66,121.81,121.34,121.29,118.59,54.48,54.39,43.65,35.85,33.10,30.33,20.40,19.11,19.05.(TOF-ESI+)(m / z)C 66 H 44 Br 2 N 4 O 6 1148.91。

[0066] S6: Synthesis of Compound 12

[0067]

[0068] Under a nitrogen atmosphere, add Compound 10 (10 mmol), Compound 11 (10 mmol), K 2 CO 3 (10 mmol), Pd(PPh 3 ) 4 (0.2 mmol) into a two-necked flask. Add 110 ml of a toluene:water = 5:1 mixture through a syringe, heat to 110 °C, and reflux for 30 h. After cooling to room temperature, pour the reaction mixture into water and extract three times with dichloromethane (50 ml). Dry the organic layer with anhydrous sodium sulfate and remove the solvent. Purify the resulting crude product by silica gel column chromatography to obtain Compound 12.

[0069] 1 HNMR(500MHz,CDCl 3)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=7.8,1.0Hz,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). 13 C NMR(125MHz,CDCl 3 )δ184.36,183.11,168.80,164.60,164.46,161.60,156.50,142.44,142.34,142.29,142.01,141.56,141.12,139.28,138.81,138.78,137.60,134.21,134.19,133.57,133.44,133.33,133.08,133.00,132.90,130.95,130.29,129.39,128.98,128.41,128.22,128.10,127.66,127.64,127.48,127.46,127.42,127.31,126.36,125.48,125.40,124.60,124.23,124.09,123.94,123.82,123.38,121.48,118.84,79.55,52.93,52.78,43.38,40.22,35.91,33.59,33.26,29.80,29.66,28.30,21.98,19.55.(TOF-ESI+)(m / z)C 94 H 84 N 6 O 10 1456.62。

[0070] S7: Synthesis of Compound 13

[0071]

[0072] Under a nitrogen atmosphere, compound 12 (5 mmol) and a DCM solution of 20 mL of 50% TFA 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, and extraction was carried out, followed by repeated washing until neutral. The collected organic layer was rotary evaporated to remove the solvent, and compound 13 (RE-PDI molecule) was obtained.

[0073] 1 HNMR(500MHz,CDCl 3 )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,CDCl 3)δ13C NMR(125 MHz, Common NMR Solvents) δ 183.83, 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 N 6 O 6 1256.52。

[0074] In this example, the synthesized RE-PDI molecules were detected by circular dichroism spectroscopy, which specifically included the following steps:

[0075] 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 molecules and dissolve them in the methanol solution to prepare a sample solution for measurement. Place this sample in an ultrasonic cleaner and ultrasonically oscillate it for 3 min to fully dissolve the molecules 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 without the sample to ensure that the recorded CD spectrum is not affected by the solvent. Then inject the sample solution into a quartz cuvette, taking care to avoid air bubbles. Set the wavelength range to measure the CD signal of the sample from 250 - 550 nm, subtract the background signal from the CD signal of the sample to obtain the net CD spectral data. Finally, use the SELCON3 software to process the obtained data and plot the curve.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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:

[0080] Step 1: Prepare an aluminum oxide dielectric layer on a silicon substrate.

[0081] 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.

[0082] Step 2: Prepare a graphene dielectric layer on the aluminum oxide dielectric layer, and prepare a metal electrode on the graphene dielectric layer.

[0083] A single-layer graphene is obtained on a clean copper foil by chemical vapor deposition; polymethyl methacrylate (950 PMMA) is spin-coated on the single-layer graphene, and then it is placed on a heating stage at 180 °C for baking the glue for 2 min. The excess PMMA and graphene on the back are removed by oxygen plasma etching the copper foil for 3 s to obtain PMMA-single-layer graphene-copper foil. Next, the PMMA-single-layer graphene-copper foil is cut into small pieces and transferred to a ferric chloride solution to dissolve the copper foil, obtaining a PMMA-single-layer graphene film; the PMMA-single-layer graphene film is soaked in hydrochloric acid solution, aqueous solution and potassium hydroxide solution, and then transferred to an alumina dielectric layer, left standing, dried, and the glue is removed to obtain a graphene dielectric layer; photolithographic strips are carried out on the graphene dielectric layer, and similarly, the excess single-layer graphene is removed by oxygen plasma etching to obtain a negative film with graphene strips; electrodes are photolithographed on the negative film, and 8-10 nm of chromium and 60-80 nm of gold are evaporated to obtain metal electrodes.

[0084] Step 3: Use the graphene dielectric layer to construct graphene dot electrodes.

[0085] Photoresist is spin-coated on the negative film with graphene strips after photolithographing the electrodes. Using a customized strip mask template, graphene strips are photolithographed. After exposure and development, the strip-shaped photoresist remains to protect part of the graphene. It is then subjected to oxygen plasma etching for another 5 s, and the remaining exposed graphene is removed by the oxygen plasma etching process; next, the photoresist is removed by soaking in acetone to obtain a negative film with a central graphene strip; 8-10 nm of chromium and 60-80 nm of gold are successively evaporated on the negative film by thermal evaporation, and the photoresist is removed by soaking in acetone to obtain a graphene array electrode. On the graphene array electrode, a dotted line with a length of 150 nm and a width of 5 nm is etched by electron beam exposure, developed with methyl isobutyl ketone (MIBK) diluted with isopropyl alcohol (MIBK:isopropyl alcohol = 1:3), fixed with isopropyl alcohol, and then obtained by oxygen plasma etching and electro-burning method to obtain a graphene nano-gap dot electrode array. In this embodiment, the graphene nano-gap dot electrode array includes 169 pairs of paired graphene dot electrodes, that is, 338 graphene dot electrodes.

[0086] Step 4: Self-assemble a single RE-PDI molecule with the graphene dot electrode to obtain a chiral molecular device.

[0087] Place the RE-PDI molecule in a three-necked flask, inject 5 ml of dichloromethane and 0.5 ml of trifluoroacetic acid, and react for 2 h under a nitrogen atmosphere. Remove trifluoroacetic acid by extraction with sodium hydroxide, and transfer the solution to a round-bottomed flask. Rotavaporize the solution to obtain the RE-PDI molecule with the protecting group removed. Through gas exchange operation, make the molecule in a nitrogen atmosphere, and use a syringe to draw 10 ml of anhydrous pyridine and inject it into the round-bottomed flask to dissolve the RE-PDI molecule. Place the graphene nano-gap point electrode array in a three-necked flask, add sufficient 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and the pyridine solution of the RE-PDI molecule with the protecting group removed, and react for more than 48 h in a nitrogen atmosphere. Take out the device from the two-necked flask, rinse it three times with deionized water and ethanol respectively, and dry the surface with nitrogen for standby to obtain the chiral molecular device. Among them, the molecular junction of the chiral molecular device is obtained by forming an amide covalent bond connection between –NH at the bottom end of the RE-PDI molecule 2 and –COOH at the end of the graphene dot electrode.

[0088] The present invention also provides an application of the chiral molecular device, and the technical solution adopted is as follows: The above-mentioned chiral molecular device is applied to circularly polarized light detection.

[0089] The chiral molecular device is applied to the femtosecond laser optical path for switchable circularly polarized light detection, such as Figure 3 shown, and the working process is as follows:

[0090] The femtosecond pulsed laser generator 1 generates femtosecond linearly polarized laser. After the laser exits, it reaches the beam splitter 3 through the first mirror 2, generating two linearly polarized lasers (the first linearly polarized laser and the second linearly polarized laser).

[0091] After the first linearly polarized laser passes through the second multifunctional optical parametric amplifier 9 and becomes a linearly polarized laser with a first specific wavelength, it then reaches the second quarter-wave plate 11 through the fourth mirror 10 (the fast axis of the second quarter-wave plate rotates 45° clockwise relative to the incident linearly polarized light with the first specific wavelength). At this time, the linearly polarized laser with the first specific wavelength becomes a left-handed circularly polarized light with a specific wavelength. The left-handed circularly polarized light continues to propagate forward through the fifth mirror 12, the sixth mirror 13, the seventh mirror 14, and the eighth mirror 15 and enters the optoelectronic combined detection platform, and irradiates on the chiral molecular device 16 located inside the optoelectronic combined detection platform.

[0092] The second linearly polarized laser first passes through the first multifunctional optical parametric amplifier 4 to become a linearly polarized laser with a second specific wavelength, then is delayed by a time delay controller 5 for a time τ, and then reaches the first quarter-wave plate 8 through the second mirror 6 and the third mirror 7 (the fast axis of the first quarter-wave plate rotates counterclockwise by 45° relative to the incident linearly polarized light with the second specific wavelength), becoming a 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 mirror 14 and the eighth mirror 15, enters the optoelectronic combined detection platform, and irradiates on the chiral molecular device 16 located inside the optoelectronic combined detection platform.

[0093] It should be specifically noted that the generation of left-handed circularly polarized light (L-CPL) and right-handed circularly polarized light (R-CPL) 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 off mode. In the working mode, the function of the multifunctional optical parametric amplifier is to amplify the incident optical signal and output a beam of outgoing light with a specific wavelength by using the built-in adjustable filter. In the off mode, the incident light cannot continue to propagate forward through this device. The separate action state of L-CPL is based on the fact that the first multifunctional optical parametric amplifier 4 is in the off mode and the second multifunctional optical parametric amplifier 9 is in the working mode in the above optical path system. Similarly, the separate action state of R-CPL is based on the fact that the second multifunctional optical parametric amplifier 9 is in the off mode and the first multifunctional optical parametric amplifier 4 is in the working mode in the above optical path system.

[0094] In this embodiment, first, the computer control program is used to set the second multifunctional optical parametric amplifier 9 to the working mode and select the output light wavelength to be 400 nm, and the first multifunctional optical parametric amplifier 4 to the off mode. After the femtosecond pulse laser generator 1 is turned on, L-CPL with a wavelength of 400 nm that irradiates on the chiral molecular device 16 is introduced into the optoelectronic combined detection platform. Then, the current signal of the chiral molecular device 16 is measured by changing the gate voltage on the optoelectronic combined detection platform. Subsequently, the computer control program is set so that the first multifunctional optical parametric amplifier 4 is in the working mode and the output light wavelength is selected to be 350 nm, and the second multifunctional optical parametric amplifier 9 is in the off mode. After the femtosecond pulse laser generator 1 is turned on, R-CPL with a wavelength of 350 nm that irradiates on the chiral molecular device 16 is introduced into the optoelectronic combined detection platform. Similarly, the current signal of the chiral molecular device 16 is measured by changing the gate voltage on the optoelectronic combined detection platform. The test results are as Figure 4 shown. The chiral molecular device based on the photoinduced charge transfer effect prepared in this embodiment has significantly different responses to left-handed circularly polarized light and right-handed circularly polarized light under different applied gate voltages. According to the asymmetry factor, the selective response of the device to L / R-CPL is characterized, and the specific formula is as follows:

[0095] 。

[0096] Among them, represents the measured current value when L-CPL, represents the measured current value when R-CPL, represents the asymmetry factor. By calculating with the above formula, when the gate voltage of the chiral molecular device is -4V, the value of is 1.61, indicating that the chiral molecular device prepared in the embodiment has excellent application value as a photodetector for distinguishing different types of circularly polarized light.

[0097] The dynamic switchable detection application of circularly polarized light and femtosecond-level control in the femtosecond laser optical path for switchable circularly polarized light detection are realized based on the time control of the coordinated matching of the working and off modes of two multifunctional optical parametric amplifiers by a computer program. The periodic control program is set such that the second multifunctional optical parametric amplifier is first in the off state. After the first multifunctional optical parametric amplifier receives the incident linearly polarized laser and enters the working mode (the working time is set to 2 s), it immediately switches to the off mode. At the same time as the first multifunctional optical parametric amplifier switches to the off mode, the second multifunctional optical parametric amplifier immediately enters the working mode (the working time is set to 2 s) and then switches to the off mode. Figure 5 The data acquisition results successfully verify the dynamic switchable detection of circularly polarized light, and the chiral molecular device prepared in this embodiment based on the photoinduced charge transfer effect exhibits relatively stable current signals under each different circularly polarized light irradiation state, which also verifies the excellent stability of the chiral molecular device prepared by the invention as an optoelectronic device for distinguishing and detecting different types of circularly polarized light.

[0098] Such as Figure 6 shown, when L-CPL irradiates the chiral molecular device, the anthraquinone-derived group absorbs photon energy and changes from the ground state to the excited state, that is, charge transfer occurs from the HOMO (Highest Occupied Molecular Orbital) energy level to the LUMO (Lowest Unoccupied Molecular Orbital) energy level. At this time, due to the energy level mismatch between the LUMO energy level of the anthraquinone-derived group and the PDI group, the excited-state charge transfer (excited-state charge trap capture effect) of the excited-state charge occurs, and the charge in the excited state transfers from the LUMO energy level of the anthraquinone-derived group to the triplet excited state T generated by the PDI group 1 energy level. When R-CPL irradiates the chiral molecular device, the charge on the T 1 energy level in the PDI group coupled with the chiral center absorbs photon energy and jumps to T 2Energy level, subsequently, located at T 2 The excited-state charges at the energy level will again undergo transfer capture of the excited-state charges due to the mismatch between the LUMO energy level of the anthraquinone-derived group and the T 2 energy level, and then transfer to the LUMO energy level of the anthraquinone-derived group. The different current signal changes of the two processes are transmitted from the single-molecule junction - graphene source electrode - probe to the optoelectronic combined detection platform for reading.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various 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, place the RE-PDI molecule in a nitrogen atmosphere, add anhydrous pyridine to obtain a pyridine solution of the RE-PDI molecule; react the graphene dot electrode, 1-(3-dimethylaminopropyl)-3-2-ethylcarbodiimide hydrochloride and the pyridine solution of the RE-PDI molecule 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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