Detection method for supermolecular chirality of amplified interface monomolecular film

Abstract

The invention relates to a detection method for supermolecular chirality of an amplified interface monomolecular film, belongs to the field of supermolecular chirality, and solves the problems of inaccurate chirality detection and difficult quantitative characterization of supermolecular chirality when an in-situ second-order nonlinear optical method is used for detecting an interface monomolecular film with small chirality in the prior art. The invention discloses a method for detecting supermolecular chirality of an amplified interface monomolecular film. The method comprises the following steps: S1, dissolving chiral molecules in a volatile solvent to obtain a sample solution; s2, respectively spreading the sample solution on the surface of pure water and the surface of the protonated achiral molecule solution, and after the solvent is completely volatilized, self-assembling chiral molecules on an interface to form a monomolecular film; s3, detecting an SHG signal of the monomolecular film in situ, and quantitatively characterizing the supramolecular chirality of the monomolecular film; and S4, detecting an SFG signal of the monomolecular film in situ, and judging the group chirality and molecular assembly mechanism of the monomolecular film. The method for amplifying and quantitatively characterizing the supermolecule chirality of the monomolecular film is simple and easy to operate.

Description

Technical Field

[0001] The present invention relates to the field of supramolecular chirality, and in particular to a method for detecting supramolecular chirality of an amplified interface monomolecular film. Background Art

[0002] Detecting the supramolecular chirality of monolayers formed by in situ self-assembly of chiral molecules at the air / liquid interface is of great significance for understanding the origin of chirality, the function of biomembranes, and the development of novel functional materials. Traditional linear optical methods for characterizing chirality, such as circular dichroism spectroscopy, vibrational circular dichroism spectroscopy, optical rotation dispersion, and Raman spectroscopy, can effectively distinguish between left-handed and right-handed enantiomers and are highly sensitive to the stereochemical properties of molecules. However, due to their limited sensitivity, these methods are not suitable for in situ detection of supramolecular chirality in interfacial monolayers.

[0003] In situ second-order nonlinear optical methods, such as second harmonic generation (SHG) and sum frequency spectroscopy (SFG), are ideal techniques for in situ probing the supramolecular chirality and structure of monolayers self-assembled at gas / liquid interfaces due to their inherent selectivity and sensitivity to gas / liquid interfaces and chirality. However, when using SHG and / or SFG, which are sensitive to interfaces and chirality, to in situ probe the supramolecular chirality of monolayers at interfaces, the chirality is often too small to be accurately detected. Furthermore, due to the small chirality, traditional in situ second-order nonlinear optical methods are unable to quantitatively characterize the strength, type, group chirality, and various parameters involved in the molecular assembly mechanism.

[0004] Therefore, it is urgent to develop a detection method to amplify the supramolecular chirality of interfacial monolayers and quantitatively characterize their supramolecular chirality. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a method for detecting the supramolecular chirality of an amplified interfacial monolayer to solve at least one of the following technical problems: the existing in situ second-order nonlinear optical method is inaccurate in detecting chirality when detecting interfacial monolayers with smaller chirality, and it is difficult to quantitatively characterize one or more of the strength, chirality type, group chirality, and molecular assembly mechanism of the supramolecular chirality of the interfacial monolayer.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] The present invention provides a method for detecting supramolecular chirality of an amplified interfacial monolayer, comprising the following steps:

[0008] Step S1, dissolving the chiral molecule in a volatile solvent to obtain a sample solution;

[0009] Step S2: spreading the sample solution on the surface of pure water and the surface of the protonated achiral molecule solution, respectively, and after the solvent is completely evaporated, the chiral molecules self-assemble at the interface to form a monolayer;

[0010] Step S3, in situ detecting the second harmonic generation (SHG) signal of the monolayer to quantitatively characterize the supramolecular chirality of the monolayer;

[0011] Step S4: in situ detecting the sum frequency vibration spectrum (SFG) signal of the monolayer to determine the chirality of the monolayer groups and / or the co-assembly mechanism of the chiral molecules and the protonated achiral molecules.

[0012] Furthermore, step S3 includes the following steps:

[0013] Step S31: Calculating the chiral excess DCE value according to the SHG signal;

[0014] Step S32: quantitatively characterizing the supramolecular chirality of the monolayers spread on the pure water surface and the protonated achiral molecular solution surface by SHG signals and DCE values;

[0015] Step S33: determining the chiral magnification of the monolayer by comparing the SHG signals and DCE values of the monolayer spread on the pure water surface and the surface of the protonated achiral molecular solution.

[0016] Furthermore, step S32 includes the following steps:

[0017] Step S321: Determine the source of the chiral SHG signal based on the sign of the DCE value;

[0018] Step S322: quantitatively characterize the supramolecular chirality of the monolayer according to the DCE value.

[0019] Furthermore, the protonated achiral molecular solution is a achiral molecular solution with a pH value less than 4.

[0020] Furthermore, the achiral molecule is a porphyrin molecule with a negatively charged group under acidic conditions, including but not limited to at least one of tetrakis(4-sulfophenyl)porphyrin (TPPS), di(4-sulfophenyl)porphyrin, tris(4-sulfophenyl)porphyrin, tetrakis(4-carboxyphenyl)porphyrin, and di(4-carboxyphenyl)porphyrin.

[0021] Furthermore, the chiral molecule is an amphiphilic chiral molecule, including but not limited to 4-pyridylpropionic acid-L-glutamine derivatives ( L -P-PPG), 3-(4-pyridyl) acrylic acid-L / D-glutamine derivative ( L / D -P-PAG), 3-(2-pyridyl) acrylic acid-L / D-glutamine derivative ( L / D-O-PAG), 3-(3-pyridyl) acrylic acid-L-glutamine derivative ( L -M-PAG).

[0022] Furthermore, the concentration of the sample solution is 0.1 mM to 1.0 mM.

[0023] Furthermore, in step S3 , the positive or negative sign of DCE represents the type of supramolecular chirality of the monolayer; and the absolute value of DCE represents the strength of the supramolecular chirality of the monolayer.

[0024] Furthermore, in step S3, the second harmonic SHG technique for detecting the second harmonic SHG signal of the monolayer is a second harmonic linear dichroism SHG-LD method with S-polarization detection.

[0025] Furthermore, in step S4, the sum frequency vibrational spectroscopy (SFG) technology for detecting the sum frequency vibrational spectroscopy (SFG) signal of the monolayer includes an SFG method of SPP polarization detection and an SFG method of (s+mp)-(s-mp) polarization detection.

[0026] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0027] 1. The present invention provides a simple and easy-to-use method for amplifying the supramolecular chirality of interfacial monolayers. This method requires only spreading chiral molecules on the surface of a protonated achiral solution. The achiral molecules (e.g., TPPS) are readily available commercial reagents. The protonated achiral solution is obtained by adjusting the pH of the achiral solution to <4 by adding dilute hydrochloric acid. When the supramolecular chirality of the monolayer formed by self-assembly of chiral molecules on the surface of pure water is relatively weak, this method can be used to co-assemble the chirality of the monolayer with protonated achiral molecules, effectively amplifying the chirality of the monolayer.

[0028] 2. The present invention provides a method for detecting the amplified supramolecular chirality of an interfacial monolayer. The method combines the method for amplifying the supramolecular chirality of an interfacial monolayer with second harmonic generation (SHG) technology to in situ detect the SHG signal of a monolayer self-assembled on a pure water surface and a protonated achiral molecular solution surface, and calculate the chiral excess (DCE) value. Based on the SHG signal and the DCE value, the supramolecular chirality of the monolayer can be quickly and accurately quantitatively characterized, for example, one or more parameters including chirality type, magnitude of supramolecular chirality, and chirality amplification factor.

[0029] 3. The present invention provides a method for detecting the amplified supramolecular chirality of interfacial monolayers. This method combines the method for amplifying supramolecular chirality of interfacial monolayers with sum frequency vibrational spectroscopy (SFG) technology to in situ detect SFG signals, such as SPP spectroscopy and (S+mp)-(S-mp) spectroscopy, of monolayers self-assembled on pure water surfaces and protonated achiral molecular solutions. This method can quickly and accurately determine the group chirality of the monolayer and / or the co-assembly mechanism of chiral molecules and protonated achiral molecules.

[0030] 4. The present invention provides a detection method for amplifying the supramolecular chirality of interfacial monolayers, which significantly amplifies the supramolecular chirality of interfacial monolayers formed by self-assembly of chiral molecules with different molecular structures. By using in situ second-order nonlinear optical methods, the strength of the supramolecular chirality of interfacial monolayers can be quantitatively characterized, and the group chirality of the monolayers and the co-assembly mechanism of chiral molecules and protonated achiral molecules can be determined. The present invention provides a method for amplifying the supramolecular chirality of monolayers, which is easy to operate, reveals the molecular mechanism of chirality transfer and amplification, and provides a theoretical and material basis for the construction of new functional chiral materials. It is of great significance for the research on the precise construction of multi-level chiral materials, and is expected to provide core technical support for the fields of chiral science, nanoscience, medicine and chiral optoelectronic functional materials.

[0031] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0033] Figure 1 The chiral molecular structure diagram and the protonated TPPS molecular structure diagram used in the embodiments of the present invention;

[0034] Figure 2 This is a second harmonic generation (SHG) spectrum of the S-polarization detection of a monolayer spread on a pure water surface in an embodiment of the present invention;

[0035] Figure 3 This is a second harmonic generation (SHG) spectrum of the monolayer spread on the surface of the pH 2.5 TPPS solution in an embodiment of the present invention detected by S-polarization;

[0036] Figure 4Statistical graph of the ratio of the DCE value and the SHG signal of the monolayer before and after the assembly of the chiral molecule and TPPS according to the embodiment of the present invention;

[0037] Figure 5 The surface of pure water and pH 2.5 TPPS solution in the embodiment of the present invention is spread L -P-PAG monolayer and L -Sum frequency vibration (SFG) spectrum of P-PPG monolayer detected by SPP polarization;

[0038] Figure 6 In the embodiment of the present invention, (a) is the surface of pure water spread L -P-PAG monolayer and L -P-PPG monolayer (s+mp)-(s-mp) polarization detection sum frequency vibration (SFG) spectrum; (b) is the pure water surface spread in the embodiment of the present invention L -M-PAG monolayer and L -O-PAG monolayer (s+mp)-(s-mp) polarization detection sum frequency vibration (SFG) spectrum; (c) and (d) are the surface spread of pH2.5 TPPS solution in the embodiment of the present invention. L -P-PAG monolayer and L -(s+mp)-(s-mp) polarization-detected sum frequency vibration (SFG) spectrum of P-PPG monolayer;

[0039] Figure 7 Schematic diagram of the molecular structure and molecular assembly mode of a monolayer formed by self-assembly of chiral molecules at a gas-liquid interface in an embodiment of the present invention;

[0040] Figure 8 The molecular structures of other achiral molecules that can be used to amplify the supramolecular chirality of monolayers in the present invention, namely, di(4-sulfophenyl)porphyrin, tri(4-sulfophenyl)porphyrin, tetra(4-carboxyphenyl)porphyrin, and di(4-carboxyphenyl)porphyrin;

[0041] Figure 9 For other chiral molecules in the present invention, namely glutamic acid derivatives L / D -G12, L / D -GAn, a tyrosine derivative L / D -TyrC18, a tryptophan derivative L / D -Molecular structure diagram of TrpC18. DETAILED DESCRIPTION

[0042] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0043] The present invention provides a method for detecting the amplified supramolecular chirality of an interfacial monolayer, which utilizes co-assembly of chiral molecules and protonated achiral molecules to amplify the supramolecular chirality of the interfacial monolayer. The detection method comprises the following steps:

[0044] Step S1: dissolving a chiral molecule in a volatile solvent to obtain a sample solution.

[0045] In one possible design, the chiral molecule is an amphiphilic chiral molecule; an amphiphilic chiral molecule has a hydrophilic head and a hydrophobic tail, the hydrophilic head is generally composed of polar groups such as amide, choline, and amine salt, while the hydrophobic tail is generally composed of a long fatty chain.

[0046] It should be noted that the amphiphilic chiral molecule can be selected as needed; optionally, the amphiphilic chiral molecule includes but is not limited to chiral amine molecules that are positively charged under acidic conditions, amino acids that are positively charged under acidic conditions, and amino acid derivatives (for example: glutamic acid, glutamic acid derivatives, tyrosine derivatives, tryptophan derivatives, etc.).

[0047] For example, the chiral molecule is a 4-pyridylpropionic acid-L-glutamine derivative ( L -P-PPG), 3-(4-pyridyl) acrylic acid-L / D-glutamine derivative ( L / D -P-PAG), 3-(2-pyridyl) acrylic acid-L / D-glutamine derivative ( L / D -O-PAG), 3-(3-pyridyl) acrylic acid-L-glutamine derivative ( L -M-PAG) or more.

[0048] from Figure 1 It can be seen that the six chiral molecules have similar structures, all containing a pyridine ring, a glutamine group and a long hydrophobic alkyl chain; the amide group of the chiral molecule has electron-donating ability; only L The pyridine ring and glutamine group of the -P-PPG molecule are connected by a -CC- bond, and L / D -P-PAG, L / D -O-PAG and L The pyridine ring and glutamine group of the -M-PAG molecule are connected by a -C=C- bond; L / D -P-PAG, L / D -O-PAG and L The difference between -M-PAG is that the N substitution position on the pyridine ring is different, namely para, ortho and meta substitution.

[0049] For example, the chiral molecule can be a glutamic acid derivative L / D -G12 molecule, L / D -GAn molecule, a tyrosine derivative L / D -TyrC18 molecule, a tryptophan derivative L / D -One or more of the TrpC18 molecules, see Figure 9 .

[0050] Optionally, a volatile solvent can be selected as needed, including but not limited to chloroform, a mixed solution of chloroform and methanol, toluene, and cyclohexane; wherein the volume ratio of the mixed solution of chloroform and methanol can be set according to different chiral molecules, as long as the chiral molecules can be completely dissolved; the selection of a volatile solvent will neither affect the molecular assembly nor the detection signals of the second harmonic generation (SHG) and sum frequency vibration spectroscopy (SFG).

[0051] In one possible design, when the chiral molecule cannot be dissolved in a volatile solvent at room temperature, it can be dissolved by heating to 40°C to 50°C.

[0052] Preferably, the sample solution has a concentration of 0.1mM to 1.0mM; more preferably, the sample solution has a concentration of 0.5mM. mM represents millimoles per liter, and 1mM is 0.001mol / l. Selecting this preferred concentration ensures uniform distribution of the sample solution on the liquid surface and reduces perturbations to the assembly of chiral molecules during spreading of the sample solution. Perturbations here can be understood as requiring dropwise spreading using a microinjector, meaning that subsequently added chiral molecules may affect previously spread molecules. Furthermore, this preferred concentration requires a smaller amount of sample to be tested, making it more suitable for difficult-to-obtain samples, such as biological samples.

[0053] Step S2: Spread the sample solution on the surface of pure water and the surface of the protonated achiral molecule solution respectively. After the solvent is completely evaporated, the chiral molecules self-assemble at the interface to form a monolayer.

[0054] Specifically, using the Langmuir-Blodgget (LB) film technique, appropriate amounts of sample solution are spread onto the surface of pure water and a protonated achiral molecular solution. After the solvent evaporates completely, the chiral molecules self-assemble at the air-liquid interface to form a monolayer of supramolecular assemblies. The Langmuir-Blodgget (LB) film technique is a technique for constructing organic, ordered, ultrathin molecular films.

[0055] It should be noted that the protonated achiral molecular solution is a achiral molecular solution with a pH <4.

[0056] It is understandable that in a solution with pH < 4, achiral molecules will transform into a protonated state. The protonated achiral molecules can co-assemble with chiral molecules through non-covalent interactions (such as π-π stacking, electrostatic interactions, hydrogen bonds, and van der Waals interactions, etc.), ensuring that the supramolecular chirality of the monolayer formed by the self-assembly of chiral molecules at the gas-liquid interface can be amplified; since the co-assembled molecules are achiral, the amplified chirality comes from the monolayer formed by the self-assembly of chiral molecules, that is, the interfacial chirality of the monolayer.

[0057] Preferably, the achiral molecule is a porphyrin molecule with a negatively charged group under acidic conditions, including but not limited to at least one of tetrakis(4-sulfophenyl)porphyrin (TPPS), bis(4-sulfophenyl)porphyrin, tris(4-sulfophenyl)porphyrin, tetrakis(4-carboxyphenyl)porphyrin, bis(4-carboxyphenyl)porphyrin; more preferably, the achiral molecule is tetrakis(4-sulfophenyl)porphyrin (TPPS); using these molecules can enhance the electrostatic and π-π interactions between molecules, thereby promoting the assembly between molecules and chiral amplification; the molecular structural formula can be seen in Figure 1 and Figure 8 .

[0058] From Figure 1 it can be seen that the protonated TPPS molecule contains four negatively charged sulfonic acid groups, four benzene rings, and a positively charged porphyrin ring; the conformation of the protonated TPPS molecule is saddle-shaped, and the porphyrin ring and benzene ring are nearly planar. The sulfonic acid group of the TPPS molecule forms an electrostatic interaction with the amide group of the chiral molecule, and the benzene ring or porphyrin ring of the TPPS molecule forms a π-π interaction with the pyridine ring of the chiral molecule; through these non-covalent interactions, it can promote the co-assembly of protonated TPPS molecules and chiral molecules, ensuring that the supramolecular chirality of the monolayer formed by the self-assembly of chiral molecules at the interface can be amplified.

[0059] In a possible design, the acidity and alkalinity of the achiral molecule solution are adjusted by adding dilute hydrochloric acid to make its pH < 4;示例性地, the dilute hydrochloric acid solution can be obtained by diluting the commercial 37% hydrochloric acid solution, and the pH range can be detected using a pH meter or pH test paper to ensure that pH < 4.

[0060] Preferably, the pH of the achiral molecule solution satisfies 2 < pH < 4; when the pH of the achiral molecule solution is less than 4, the protonated achiral molecules can effectively assemble with chiral molecules and amplify chirality, without reaching a lower pH. A larger amount of dilute hydrochloric acid is required for a lower pH, and it takes a longer time.

[0061] Preferably, the time required for the complete volatilization of the solvent is 15 minutes to 25 minutes.

[0062] It should be noted that the amount of sample solution is such that the state of the assembled monolayer is between the liquid expansion phase and the condensed phase; the specific amount of sample solution added can be obtained based on the membrane pressure curve of the chiral molecule on the pure water surface.

[0063] Step S3: using the second harmonic generation (SHG) technique to in situ detect the second harmonic generation (SHG) signal of the monolayer to quantitatively characterize the supramolecular chirality of the monolayer;

[0064] The specific steps include:

[0065] Step S31: Calculating the chiral excess DCE value according to the SHG signal;

[0066] Preferably, the second harmonic generation (SHG) technique is a second harmonic generation linear dichroism (SHG-LD) method with S-polarization detection;

[0067] Specifically, there are three methods for detecting interface chirality using second harmonic generation (SHG): second harmonic optical rotational dispersion (SHG-ORD), second harmonic circular dichroism (SHG-CD), and second harmonic linear dichroism (SHG-LD). Among these three methods, the SHG-LD method is the simplest, most direct, and most sensitive in measuring the chiral structure of the membrane. Furthermore, compared to the SHG-LD method with P-polarization detection, the sensitivity of S-polarization detection of chirality is higher than that of P-polarization. The SHG technology with S-polarization detection is surface selective and very sensitive to chirality, and can detect trace samples (10 -13 ~10 -11 mol) chirality, which is very suitable for quantitatively characterizing the supramolecular chirality size and chirality type of monolayers.

[0068] The SHG method with S-polarization detection is used to detect the supramolecular chirality of the monolayer formed by self-assembly at the gas-liquid interface. This is done by measuring the intensity of the outgoing doubled frequency light of a specific polarization as a function of the polarization angle of the incident fundamental frequency light (S-polarization curve). Based on the S-polarization curve, the chiral excess DCE value, an important physical parameter describing the chiral state of the interface, can be obtained. The DCE value is obtained by calculating the intensity difference between the second harmonic generation (SHG) intensity corresponding to S-polarization detection when the incident fundamental frequency light polarization angle is 135° and 45°. The specific calculation formula is as follows (1):

[0069]

[0070] In formula (1), I 135° , I 45° are the SHG signal intensities when the polarization angle of the incident fundamental frequency light is 135° and 45° respectively. 135° , I 45° The value of is obtained by fitting using formula (2):

[0071] I s ∝|χ eff，45° ssin2α+χ eff，chiral cos 2 α| 2 (2)

[0072] In formula (2), α is the polarization angle of the incident fundamental frequency light, χ eff，45°s is the effective second-order nonlinear susceptibility of the 45°-in / s-out polarization combination, χ eff，chiral is the effective second-order nonlinear susceptibility of the chiral term.

[0073] It should be noted that since the SHG signal intensity actually detected is the comprehensive result within the entire range of the incident light spot, DCE can effectively reflect the statistical average of the relative excess degree of chirality of the supramolecular chirality of the monolayer in the corresponding area.

[0074] Step S32: quantitatively characterizing the supramolecular chirality of the monolayers spread on the pure water surface and the protonated achiral molecular solution surface by using SHG signals and DCE values; specifically comprising the following steps:

[0075] Step S321: Determine the source of the chiral SHG signal based on the sign of the DCE value;

[0076] It can be understood that DCE is an important parameter for quantitatively describing the chirality of the interface. The sign (positive or negative) of DCE represents the type of supramolecular chirality of the monolayer. When the sign of DCE is opposite, the supramolecular chiral state of the monolayer is opposite.

[0077] Specifically, based on the positive and negative signs of the DCE values of the monolayer spread on the pure water surface obtained in step S31, and because the DCE signs of the monolayers formed by the self-assembly of mirror-image chiral molecules at the gas-liquid interface are opposite, it is determined that the chiral SHG signal originates from the monolayer.

[0078] Illustratively, chiral molecules that are mirror images of each other (e.g., L -P-PAG and D -P-PAG, L -O-PAG and D The DCE signs of the monolayer formed by the self-assembly of α-P-Ag (P-O-PAG) at the air-liquid interface are opposite, which confirms that the chiral SHG signal comes from the monolayer.

[0079] Preferably, the chiral SHG signal is an S-polarization detected chiral SHG signal.

[0080] Step S322: quantitatively characterizing the supramolecular chirality of the monolayer based on the DCE value to determine whether the chiral molecules are co-assembled with the protonated achiral molecules;

[0081] It is understood that DCE is an important parameter for quantitatively describing interfacial chirality, and the absolute value of DCE represents the relative strength of the monolayer's supramolecular chirality. The greater the supramolecular chirality of the monolayer (i.e., the higher the degree of asymmetry), the larger the absolute value of DCE; the smaller the supramolecular chirality of the monolayer (i.e., the lower the degree of asymmetry), the smaller the absolute value of DCE.

[0082] Specifically, the supramolecular chirality of the monolayers of chiral molecules spread on the pure water surface and the protonated achiral molecule solution surface can be quantitatively obtained by measuring the absolute value of DEC of the monolayers spread on the pure water surface and the protonated achiral molecule solution surface.

[0083] Furthermore, the chiral SHG signal of the monolayer formed by self-assembly of chiral molecules on the pure water surface is weak, and the absolute value of DCE is small; the chiral SHG signal of the monolayer formed by co-assembly of chiral molecules on the surface of protonated achiral molecular solution is enhanced, and the absolute value of DCE increases, indicating that the chiral molecules and protonated achiral molecules are co-assembled, and the supramolecular chirality of the monolayer is amplified.

[0084] Preferably, the protonated achiral molecule solution is a TPPS solution with a pH <4.

[0085] For example, for a pure water surface, DCE D-O-PAG =0.15, for the TPPS solution surface at pH=2.5, DCE D-O-PAG / TPPS =-1.59; thus determining the chiral molecule D The supramolecular chirality of the monolayer of -O-PAG spread on the surface of TPPS solution at pH = 2.5 is greater than that on the surface of pure water. D -O-PAG was co-assembled with TPPS molecules, thereby amplifying the supramolecular chirality.

[0086] Step S33, determining the chiral magnification of the monolayer by comparing the SHG signals and DCE values of the monolayer spread on the pure water surface and the surface of the protonated achiral molecular solution;

[0087] Specifically, the absolute value of the DCE value is taken to calculate the amplification factor, and the maximum value of the SHG signal after assembly is divided by the maximum value of the SHG signal before assembly to obtain the amplification factor of the SHG signal. According to the numerical value of the amplification factor, the degree of chiral amplification of the monolayer can be quantitatively characterized.

[0088] Preferably, the protonated achiral molecule solution is a TPPS solution with a pH <4.

[0089] For example, for a pure water surface, D-The maximum value of SHG signal of O-PAG is 31, DCE D-O-PAG =0.15, for the TPPS solution surface with pH=2.5, D -The maximum value of SHG signal of O-PAG is 2637, DCE D-O-PAG / TPPS =-1.59; thus, it is determined that the chiral molecule D After co-assembly of -O-PAG and TPPS, the DCE value and SHG signal of the monolayer were amplified, with the DCE value amplification factor of 10.6 and the SHG signal amplification factor of 85.0.

[0090] Step S4: using sum frequency vibrational spectroscopy (SFG) technology to in situ detect the sum frequency vibrational spectroscopy (SFG) signal of the monolayer to determine the group chirality of the monolayer and / or the co-assembly mechanism of the chiral molecules and the protonated achiral molecules.

[0091] It can be understood that the principle of sum frequency vibration spectroscopy (SFG) technology is: in the process of "sum frequency generation", a beam of visible light with a frequency of ω1 and a beam of infrared light with a frequency of ω2 act on the interface at the same time, generating a sum frequency signal with a frequency equal to the sum of the frequencies of the two beams (ω1+ω2). As a second-order nonlinear optical method, sum frequency vibration spectroscopy (SFG) has high interface selectivity and sensitivity to non-centrosymmetric medium surfaces, that is, only the molecules in the interface layer (the interface layer is usually one to several layers thick) contribute to the sum frequency signal. Moreover, sum frequency vibration spectroscopy (SFG) is very sensitive to chirality and can detect trace samples (10 -13 ~10 -11 mol) chirality.

[0092] Specifically, the sum frequency vibration spectroscopy (SFG) technique is used to detect the group chirality of the monolayer formed by self-assembly of chiral molecules and chiral molecules with similar structures on the pure water surface, as well as the group chirality of the monolayer formed by co-assembly of these two chiral molecules and protonated achiral molecules. This can determine the source of the chirality of the monolayer co-assembled with the protonated achiral molecules and the mechanism by which the chirality of the monolayer is amplified by co-assembly with achiral molecules.

[0093] Preferably, the above-mentioned sum frequency vibrational spectroscopy (SFG) technology includes an SFG method of SPP polarization detection and an SFG method of (s+mp)-(s-mp) polarization detection.

[0094] It should be noted that in the SPP spectrum, the position of the peak represents the chirality of the corresponding group, and in the (s+mp)-(s-mp) spectrum, the sign of the peak (positive or negative) represents the chiral type of the group.

[0095] Preferably, the protonated achiral molecule is a TPPS solution with a pH < 4.

[0096] In one possible design, the DCE values of the monolayers formed by coassembly of chiral molecules and protonated achiral molecules have opposite signs before and after coassembly, indicating that the chirality of the DCE values of the monolayers before and after coassembly differs. This difference in chirality suggests that the chirality of the groups in the monolayers formed by self-assembly of chiral molecules differs. Chiral SFG spectroscopy can further confirm the chirality of the groups in the monolayers formed by self-assembly of chiral molecules. Therefore, coassembly with protonated achiral molecules allows for in situ determination of the chirality of the groups in the monolayers formed by self-assembly of chiral molecules.

[0097] The technical solution of the present invention is further described in detail below with reference to specific embodiments.

[0098] Example 1

[0099] Step S1: chiral molecules L -P-PPG as an example, L -P-PPG was dissolved in chloroform to prepare a sample solution with a concentration of 0.5 mM;

[0100] Step S2: Using Langmuir-Blodgget (LB) membrane technology, a circular sample cell with a diameter of 7 cm was used to add 32 μL of 0.5 mM sample solution, and the sample solution was spread on the surface of pure water. The solvent was completely evaporated for 15 minutes, and the chiral molecules were detected. L -P-PPG self-assembles into a monolayer at the air-pure water interface;

[0101] Using the Langmuir-Blodgget (LB) membrane technique, a circular sample cell with a diameter of 7 cm was used. 32 μL of 0.5 mM sample solution was added and spread on the surface of the pH 2.5 TPPS solution. The chiral molecules were then allowed to evaporate completely after 15 minutes. L -P-PPG self-assembles into a monolayer at the air-pH 2.5 TPPS solution interface;

[0102] Step S3: Using the SHG technique with S-polarization detection, in situ detection of the chiral molecules self-assembled on the pure water surface L -SHG signal of P-PPG monolayer, such as Figure 2 ;

[0103] In-situ detection of SHG using S-polarization detection L -SHG signal of the monolayer formed by co-assembly of P-PPG and TPPS, such as Figure 3 ;

[0104] By fitting the S-polarization curve spectrum, the pure water surface L DCE of monolayers formed by self-assembly of -P-PPGL-P-PPG =0, pH2.5 TPPS solution surface L DCE of monolayers formed by self-assembly of -P-PPG L-P-PPG / TPPS =1.91; Compared with pure water surface, pH2.5 TPPS solution surface L The DCE value and SHG signal of the monolayer formed by self-assembly of -P-PPG increased significantly, indicating that L -The supramolecular chirality of the monolayer formed by self-assembly of P-PPG is amplified, and L -P-PPG was co-assembled with TPPS molecules.

[0105] because L -P-PPG monolayer DCE and SHG signals are almost zero, so DCE L-P-PPG = 0.01 to approximate the amplification factor of DCE; in order to clearly compare the amplification factors of DCE and SHG signals, Figure 4 In Example 1 L -P-PPG monolayer DCE amplification factor is reduced by 10 times, and SHG signal amplification factor is reduced by 13.6 times. Figure 4 It can be seen that L After co-assembly of -P-PPG and TPPS, L -P-PPG monolayer DCE value and SHG signal are amplified, the amplification factor is: DCE value amplification factor: 191.0 ( L -P-PPG), SHG signal amplification factor: 1360.0( L -P-PPG).

[0106] Example 2

[0107] Step S1: chiral molecules L -P-PAG as an example, L -P-PAG was dissolved in chloroform to prepare a sample solution with a concentration of 0.5 mM;

[0108] Step S2: Using Langmuir-Blodgget (LB) membrane technology, a circular sample cell with a diameter of 7 cm was used, 35 μL of 0.5 mM sample solution was added, and the sample solution was spread on the surface of pure water. The solvent was completely evaporated for 15 minutes, and the chiral molecules were detected. L -P-PAG self-assembles into a monolayer at the air-pure water interface;

[0109] Using the Langmuir-Blodgget (LB) membrane technique, a circular sample cell with a diameter of 7 cm was used. 35 μL of 0.5 mM sample solution was added and spread on the surface of the pH 2.5 TPPS solution. The chiral molecules were then allowed to evaporate completely after 15 minutes. L -P-PAG self-assembles into a monolayer at the air-pH2.5 TPPS interface;

[0110] Step S3: Using the SHG technique with S-polarization detection, in situ detection of the chiral molecules self-assembled on the pure water surface L -SHG signal of P-PAG monolayer, such as Figure 2 ;

[0111] In-situ detection of SHG using S-polarization detection L -SHG signal of the monolayer formed by co-assembly of P-PAG and TPPS, such as Figure 3 ;

[0112] By fitting the S-polarization curve spectrum, the pure water surface L DCE of the monolayer formed by self-assembly of -P-PAG L-P-PAG =0.54, pH2.5 TPPS solution surface L DCE of the monolayer formed by self-assembly of -P-PAG L-P-PAG / TPPS=-0.87; Compared with pure water surface, pH2.5 TPPS solution surface L -P-PAG self-assembled monolayers showed a significant increase in DCE value and SHG signal, indicating that L -The supramolecular chirality of the monolayer formed by P-PAG self-assembly is amplified, and L -P-PAG was co-assembled with TPPS molecules.

[0113] from Figure 4 It can be seen that L After the assembly of P-PAG and TPPS, L -P-PAG monolayer DCE value and SHG signal are amplified, the amplification factor is: DCE value amplification factor: 1.6 ( L -P-PAG), SHG signal amplification factor: 7.1( L -P-PAG).

[0114] Step S4: Using sum frequency spectroscopy (SFG) technology, in situ detect the SFG signal of the monolayer self-assembled at the gas-liquid interface of Example 1 and Example 2, and determine L -P-PPG and L -Group chirality of P-PAG monolayers, and L-P-PPG and L -P-PAG and TPPS co-assembly mechanism.

[0115] (a) In-situ detection

[0116] In situ detection of the surface of pure water and pH 2.5 TPPS solution L -P-PAG monolayer and L -P-PPG monolayer SPP polarization detection sum frequency vibration spectrum, such as Figure 5 ;

[0117] In situ detection of pure water surface spreading L -P-PAG monolayer and L -P-PPG monolayer (s+mp)-(s-mp) polarization detection sum frequency vibration spectrum, such as Figure 6 (a); In situ detection of pH 2.5TPPS solution surface spreading L -P-PAG monolayer and L -P-PPG monolayer (s+mp)-(s-mp) polarization detection sum frequency vibration spectrum, such as Figure 6 (c) and Figure 6 (d); Symbols are experimental data, and solid lines are fitted data.

[0118] (b) Group chirality and co-assembly mechanism:

[0119] from Figure 5 The pure water surface SPP spectrum shown can be seen, for L -P-PAG monolayer, located at ~1553cm -1 The peak belongs to Amide II band. Located at ~1584cm -1 , ~1597cm -1 The peaks belong to the symmetric stretching vibration of the pyridine ring A1 mode v 8a and v 1+6a Located at ~1622cm -1 The peak belongs to the vibration of the C=C double bond of the pyridine ring and the vinyl group. Located at ~1633cm -1 , ~1639cm -1 and ~1652cm -1 The peak belongs to the AmideⅠ band of the amide group. L -P-PPG monolayer, located at ~1630cm -1 The weak peak belongs to the Amide I band of the amide group; located at ~1608cm -1 The peak belongs to the symmetric stretching vibration of the pyridine ring A1 mode v 1+6a . L-P-PPG monolayer is located at ~1639cm -1 The peak at ∼1633 cm represents a looser, smaller, and more disordered antiparallel β-sheet-like structure formed by amide groups. -1 The peak at represents the longer, larger, and stronger antiparallel β-sheet-like structure formed by the amide groups; L -P-PPG monolayer does not have an antiparallel β-sheet-like structure. In addition, the pure water interface L The chiral SFG signals of the pyridine ring and amide group of the -P-PPG monolayer are weak, but L The chiral SFG signals of the amide group and pyridine ring of the -P-PAG monolayer are stronger. This is because L -P-PAG molecules have stronger π-π stacking between pyridine rings and stronger intermolecular hydrogen bonding between amide groups. The β-sheet structure present in the chiral assembly will produce large SHG and SFG activities. L -P-PPG monolayer does not have an antiparallel β-sheet-like structure. L -P-PAG monolayer has an antiparallel β-sheet-like structure, so L -The DCE value of P-PPG monolayer is zero. L -P-PAG monolayer has a DCE value of 0.54, and L The DCE value of -P-PAG monolayer comes from the chirality of the amide group.

[0120] from Figure 5 The SPP spectrum of the pH2.5 TPPS solution surface shows that, at the pH2.5 TPPS solution surface, L -P-PAG and L -P-PPG monolayer has similar SFG spectral line shape. L -P-PAG and L The SFG signals of the two monolayers are shown in Figure 2, and the peak positions of the two monolayers are the same, which are located at 1475 cm -1 ,~1485cm -1 , 1493cm -1 ,~1524cm -1 ,~1536cm -1 ,~1560cm -1 , ~1589cm -1 The chiral peaks belong to v(C α C m), porphyrin skeleton vibration v(por), benzene ring vibration v(ph), v(C α C β ), v(C β C β ), v(C α C m ), v(C β C β ) / v(C α C m ), v(C α C m ) / v as (C α C β ) and benzene ring vibration v(ph). This shows L -P-PAG, L -P-PPG molecules are co-assembled with TPPS molecules to form L -P-PAG / TPPS, L -P-PPG / TPPS monolayer, and the chiral SFG signals of the co-assembled monolayer all come from TPPS molecules. L -P-PAG, L -P-PPG molecules are co-assembled with TPPS molecules, and chiral molecules ( L -P-PAG, L -P-PPG) is transferred to the TPPS molecules, thereby amplifying the supramolecular chirality of the monolayer. L A clear peak at ∼1633 cm was detected in the monolayer formed by co-assembly of P-PAG and TPPS. -1 peak, which indicates that L -P-PAG / TPPS co-assembly still exists L -P-PAG self-assembles to form an antiparallel β-sheet-like structure. Due to the existence of this antiparallel β-sheet-like structure, it is confirmed that the TPPS molecule and L During the co-assembly process of -P-PAG molecules, TPPS molecules only interact with L The π-conjugated groups (pyridine ring and vinyl ring) of -P-PAG are co-assembled without disrupting the hydrogen bonding interactions between the amide groups.

[0121] from Figure 6 (a) shows the (s+mp)-(s-mp) spectrum of pure water surface. L -P-PAG and L The AmideⅠ bands of the amide group of the -P-PPG molecule are all negative peaks, indicating that L -P-PAG and LThe chirality of the amide groups of the -P-PPG molecules is consistent. Since the chirality of the two molecules is consistent, the chirality of the amide groups should be derived from the chirality of the chiral carbon. L The symmetric stretching vibration peak of the pyridine ring detected on the surface of the -P-PPG monolayer is ~1608cm -1 is a negative peak; L -C=C- vibration peak of pyridine ring of P-PAG monolayer is 1622 cm -1 It is a positive peak, indicating L -P-PPG and L The chirality of the pyridine ring of -P-PAG is opposite, and the chirality of the pyridine ring comes from the structural chirality generated by asymmetric stacking.

[0122] from Figure 6 (c) and Figure 6 (d) shows the (s+mp)-(s-mp) spectrum of the pH 2.5 TPPS solution surface. L -P-PAG / TPPS and L -Sulfonic acid group of TPPS molecule in P-PPG / TPPS assembly (~1170cm -1 ,~1231cm -1 ), benzene ring (~1493cm -1 ) and porphyrin ring (~1485cm -1 ) is mirror-symmetrical. It is worth noting that L -P-PAG / TPPS and L The chiral peak symbols of the porphyrin ring and benzene ring of the TPPS molecule in the -P-PPG / TPPS assembly are respectively L -P-PAG and L The chiral peaks of the pyridine ring of -P-PPG are consistent. This once again shows that the TPPS molecule L -P-PAG and L -P-PPG co-assembles through π-π stacking interactions between the pyridine rings. Therefore, it can be proposed at the molecular level that L -P-PAG or L -P-PPG and TPPS co-assembly process chirality transfer and amplification mechanism. L -P-PAG or L When the -P-PPG molecules spread on the surface of the air / pH 2.5 TPPS solution, the protonated TPPS molecules adsorb on the surface through π-π stacking interactions. L -P-PAG or L -P-PPG monolayer film, and L -P-PAG or L-P-PPG's π-conjugated group co-assembly. This co-assembly process dominated by π-π stacking interaction determines that the chiral peak sign of TPPS is consistent with the chiral peak sign of the π-conjugated group (pyridine ring) in the chiral molecule. L -P-PAG / TPPS and L In the P-PPG / TPPS co-assembly, the porphyrin ring and benzene ring of TPPS exhibit mirror-symmetrical chiral peaks. L The DCE value of -P-PAG / TPPS monolayer (-0.87) is the same as L -P-PPG / TPPS monolayer DCE value (1.91) has the opposite sign. Figure 6 (a) It can be seen that L The chiral peaks of the pyridine ring and amide group of the -P-PAG molecule have opposite signs. Figure 5 From the analysis, we can see that L The DCE value of the -P-PAG monolayer is derived from the chirality of the amide group. L -P-PAG / TPPS, L The chiral SFG signals of the -P-PPG / TPPS co-assembled monolayer all come from the TPPS molecules, and the chiral peak sign of TPPS is consistent with the chiral peak sign of the pyridine ring. L -DCE value (-0.87) of P-PAG / TPPS co-assembled monolayer L The DCE value of -P-PAG monolayer (0.54) has the opposite sign.

[0123] Example 3

[0124] Step S1: chiral molecules D -P-PAG as an example, D -P-PAG was dissolved in chloroform to prepare a sample solution with a concentration of 0.5 mM;

[0125] Step S2: Using Langmuir-Blodgget (LB) membrane technology, a circular sample cell with a diameter of 7 cm was used, 35 μL of 0.5 mM sample solution was added, and the sample solution was spread on the surface of pure water. The solvent was completely evaporated for 15 minutes, and the chiral molecules were detected. D -P-PAG self-assembles into a monolayer at the air-pure water interface;

[0126] Using the Langmuir-Blodgget (LB) membrane technique, a circular sample cell with a diameter of 7 cm was used. 35 μL of 0.5 mM sample solution was added and spread on the surface of the pH 2.5 TPPS solution. The chiral molecules were then allowed to evaporate completely after 15 minutes. D-P-PAG self-assembles into a monolayer at the air-pH2.5 TPPS interface;

[0127] Step S3: Using the SHG technique with S-polarization detection, in situ detection of the chiral molecules self-assembled on the pure water surface D -SHG signal of P-PAG monolayer, such as Figure 2 ;

[0128] In-situ detection of SHG using S-polarization detection D -SHG signal of the monolayer formed by co-assembly of P-PAG and TPPS, such as Figure 3 ;

[0129] By fitting the S-polarization curve spectrum, the pure water surface D DCE of the monolayer formed by self-assembly of -P-PAG D-P-PAG =-0.42, pH 2.5 TPPS solution surface D DCE of the monolayer formed by self-assembly of -P-PAG D-P-PAG / TPPS =0.52; Compared with pure water surface, pH2.5 TPPS solution surface D -P-PAG self-assembled monolayers showed a significant increase in DCE value and SHG signal, indicating that D -The supramolecular chirality of the monolayer formed by P-PAG self-assembly is amplified, and D -P-PAG was co-assembled with TPPS molecules.

[0130] from Figure 4 It can be seen that D After co-assembly of -P-PAG and TPPS, D -P-PAG monolayer DCE value and SHG signal are amplified, the amplification factor is: DCE value amplification factor: 1.2 ( D -P-PAG), SHG signal amplification factor: 13.7( D -P-PAG).

[0131] Example 4

[0132] Step S1: chiral molecules L -O-PAG as an example, L -O-PAG was dissolved in chloroform to prepare a sample solution with a concentration of 0.5 mM;

[0133] Step S2: Using Langmuir-Blodgget (LB) membrane technology, a circular sample cell with a diameter of 7 cm was used to add 27 μL of 0.5 mM sample solution, and the sample solution was spread on the surface of pure water. The solvent was completely evaporated for 15 minutes, and the chiral molecules were detected.L -O-PAG self-assembles at the air-pure water interface to form a monolayer;

[0134] Using the Langmuir-Blodgget (LB) membrane technique, a circular sample cell with a diameter of 7 cm was used. 27 μL of 0.5 mM sample solution was added and spread on the surface of the pH 2.5 TPPS solution. The chiral molecules were then allowed to evaporate completely after 15 minutes. L -O-PAG self-assembles into a monolayer at the air-pH2.5 TPPS interface;

[0135] Step S3: Using the SHG technique with S-polarization detection, in situ detection of the chiral molecules self-assembled on the pure water surface L -O-PAG monolayer SHG signal, such as Figure 2 ;

[0136] In-situ detection of SHG using S-polarization detection L -O-PAG and TPPS co-assembled monolayer SHG signal, such as Figure 3 ;

[0137] By fitting the S-polarization curve spectrum, the pure water surface L DCE of monolayers formed by self-assembly of -O-PAG L-O-PAG =-0.42, pH 2.5 TPPS solution surface L DCE of monolayers formed by self-assembly of -O-PAG L-O-PAG / TPPS =1.33; Compared with pure water surface, pH2.5 TPPS solution surface L The DCE value and SHG signal of the monolayer formed by self-assembly of -O-PAG increased significantly, indicating that L -O-PAG self-assembled monolayers have amplified supramolecular chirality, and L -O-PAG was co-assembled with TPPS molecules.

[0138] from Figure 4 It can be seen that L After the assembly of -O-PAG and TPPS, L The DCE value and SHG signal of the -O-PAG monolayer are amplified, and the amplification factor is: DCE value amplification factor: 3.2 ( L -O-PAG), SHG signal amplification factor: 69.5( L -O-PAG).

[0139] Example 5

[0140] Step S1: chiral molecules D-O-PAG as an example, D -O-PAG was dissolved in chloroform to prepare a sample solution with a concentration of 0.5 mM;

[0141] Step S2: Using Langmuir-Blodgget (LB) membrane technology, a circular sample cell with a diameter of 7 cm was used to add 27 μL of 0.5 mM sample solution, and the sample solution was spread on the surface of pure water. The solvent was completely evaporated for 15 minutes, and the chiral molecules were detected. D -O-PAG self-assembles at the air-pure water interface to form a monolayer;

[0142] Using the Langmuir-Blodgget (LB) membrane technique, a circular sample cell with a diameter of 7 cm was used. 27 μL of 0.5 mM sample solution was added and spread on the surface of the pH 2.5 TPPS solution. The chiral molecules were then allowed to evaporate completely after 15 minutes. D -O-PAG self-assembles into a monolayer at the air-pH2.5 TPPS interface;

[0143] Step S3: Using the SHG technique with S-polarization detection, in situ detection of the chiral molecules self-assembled on the pure water surface D -O-PAG monolayer SHG signal, such as Figure 2 ;

[0144] In-situ detection of SHG using S-polarization detection D -O-PAG and TPPS co-assembled monolayer SHG signal, such as Figure 3 ;

[0145] By fitting the S-polarization curve spectrum, the pure water surface D DCE of monolayers formed by self-assembly of -O-PAG D-O-PAG =0.15, pH2.5 TPPS solution surface D DCE of monolayers formed by self-assembly of -O-PAG D-O-PAG / TPPS =-1.59; Compared with pure water surface, pH2.5 TPPS solution surface D The DCE value and SHG signal of the monolayer formed by self-assembly of -O-PAG increased significantly, indicating that D -O-PAG self-assembled monolayers have amplified supramolecular chirality, and D -O-PAG was co-assembled with TPPS molecules.

[0146] from Figure 4 It can be seen that D After the assembly of -O-PAG and TPPS, DThe DCE value and SHG signal of the -O-PAG monolayer were amplified, and the amplification factor was: DCE value amplification factor: 10.6 ( D -O-PAG), SHG signal amplification factor: 85.0( D -O-PAG).

[0147] Example 6

[0148] Step S1: chiral molecules L -M-PAG as an example, L -M-PAG was dissolved in chloroform to prepare a sample solution with a concentration of 0.5 mM;

[0149] Step S2: Using Langmuir-Blodgget (LB) membrane technology, a circular sample cell with a diameter of 7 cm was used to add 30 μL of 0.5 mM sample solution, and the sample solution was spread on the surface of pure water. The solvent was completely evaporated for 15 minutes, and the chiral molecules were detected. L -M-PAG self-assembles into a monolayer at the air-pure water interface;

[0150] Using the Langmuir-Blodgget (LB) membrane technique, a circular sample cell with a diameter of 7 cm was used. 30 μL of 0.5 mM sample solution was added and spread on the surface of the pH 2.5 TPPS solution. The chiral molecules were then allowed to evaporate completely after 15 minutes. L -M-PAG self-assembles into a monolayer at the air-pH2.5 TPPS interface;

[0151] Step S3: Using the SHG technique with S-polarization detection, in situ detection of the chiral molecules self-assembled on the pure water surface L -SHG signal of M-PAG monolayer, such as Figure 2 ;

[0152] In-situ detection of SHG using S-polarization detection L -SHG signal of the monolayer formed by co-assembly of M-PAG and TPPS, such as Figure 3 ;

[0153] By fitting the S-polarization curve spectrum, the pure water surface L DCE of monolayers formed by self-assembly of -M-PAG L-M-PAG =-0.20, pH 2.5 TPPS solution surface L DCE of monolayers formed by self-assembly of -M-PAG L-M-PAG / TPPS =1.89; Compared with pure water surface, pH2.5 TPPS solution surface LThe DCE value and SHG signal of the monolayer formed by self-assembly of -M-PAG increased significantly, indicating that L -The supramolecular chirality of the monolayers formed by self-assembly of M-PAG is amplified, and L -M-PAG was co-assembled with TPPS molecules.

[0154] In order to clearly compare the DCE and SHG signal amplification factors, Figure 4 In Example 6 L The SHG signal amplification factor of the -M-PAG monolayer is reduced by 1.64 times. Figure 4 It can be seen that L -After M-PAG and TPPS are assembled, L -M-PAG monolayer DCE value and SHG signal are amplified; the amplification factor is: DCE value amplification factor: 9.5 ( L -M-PAG), SHG signal amplification factor: 164.0 ( L -M-PAG).

[0155] Step S4: Using sum frequency spectroscopy (SFG) technology, in situ detect the SFG signals of the self-assembled monolayers of Example 4 and Example 6, and determine L -O-PAG and L -Group chirality of M-PAG monolayer, L -O-PAG and L -M-PAG and TPPS co-assembly mechanism.

[0156] (a) In-situ detection

[0157] In situ detection of pure water surface spreading L -O-PAG monolayer and L -M-PAG monolayer (s+mp)-(s-mp) polarization detection sum frequency vibration spectrum, such as Figure 6 (b).

[0158] (b) Group chirality and co-assembly mechanism:

[0159] from Figure 6 (b) It can be seen that L -O-PAG and L The chiral peak symbols of the amide group of the M-PAG molecule and the -C=C- of the pyridine ring and L -P-PAG molecules are consistent, and the chiral peak sign of the pyridine ring is opposite to the chiral peak sign of the amide group. Figure 2 show L -DCE value of O-PAG monolayer (-0.42) sign, LThe DCE value (-0.20) of -M-PAG monolayer has the same sign as L -The DCE value (0.54) of the P-PAG monolayer has the opposite sign. L -O-PAG and L The DCE value of -M-PAG monolayer is derived from the chirality of the pyridine ring. L -O-PAG / TPPS and L The DCE values of the M-PAG / TPPS co-assembled monolayers are all positive, which indicates that L -O-PAG, L -M-PAG and TPPS are co-assembled through the electrostatic interaction between amino and sulfonic acid groups, and the chirality of TPPS comes from the amide group, i.e. L -O-PAG / TPPS and L The DCE value of the -M-PAG / TPPS co-assembled monolayer originates from the chirality of the amide group.

[0160] refer to Figure 7 According to the above analysis, the chiral SHG signal of the monolayer formed by self-assembly of chiral molecules on the surface of pure water is weak, and the DCE value is small; the chiral SHG signal of the monolayer formed by co-assembly of chiral molecules and TPPS on the surface of TPPS solution (pH < 4) is enhanced, and the DCE value is increased, which indicates that the supramolecular chirality of the monolayer is amplified. By using chiral SFG spectroscopy to detect the group chirality of chiral molecules, it is found that through the π-π stacking between the pyridine ring and the benzene ring, L -P-PPG and L -P-PAG molecules and TPPS molecules transfer chirality and co-assemble, thereby amplifying the supramolecular chirality of the monolayer. L -O-PAG and L -M-PAG molecules, through the electrostatic interaction between amide groups and sulfonic acid groups, carry out chirality transfer and co-assembly with TPPS molecules, thereby amplifying the supramolecular chirality of the monolayer. L -P-PPG molecules and L -P-PAG has opposite chirality of pyridine ring, therefore, Figure 7 The pyridine rings of the two molecules are mirror-symmetrical. L -O-PAG molecules and L -M-PAG amide groups undergo electrostatic interactions, indicating that the head groups of these two molecules are relatively L The head group of the -P-PAG molecule is more tilted relative to the interface normal, which is Figure 7 In addition, Figure 7 The saddle-shaped conformation of the protonated TPPS molecule is also shown in FIG.

[0161] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for detecting supramolecular chirality of an amplified interfacial monolayer, characterized in that: The steps include: Step S1, dissolving the chiral molecule in a volatile solvent to obtain a sample solution; Step S2: spreading the sample solution on the surface of pure water and the surface of the protonated achiral molecule solution, respectively, and after the solvent is completely evaporated, the chiral molecules self-assemble at the interface to form a monolayer; Step S3, in situ detecting the second harmonic generation (SHG) signal of the monolayer to quantitatively characterize the supramolecular chirality of the monolayer; Step S4: in situ detecting the sum frequency vibration spectrum (SFG) signal of the monolayer to determine the chirality of the monolayer groups and / or the co-assembly mechanism of the chiral molecules and the protonated achiral molecules.

2. The method for detecting supramolecular chirality of an amplified interfacial monolayer according to claim 1, wherein: Step S3 includes the following steps: Step S31: Calculating the chiral excess DCE value according to the SHG signal; Step S32: quantitatively characterizing the supramolecular chirality of the monolayers spread on the pure water surface and the protonated achiral molecular solution surface by SHG signals and DCE values; Step S33: determining the chiral magnification of the monolayer by comparing the SHG signals and DCE values of the monolayer spread on the pure water surface and the surface of the protonated achiral molecular solution.

3. The method for detecting supramolecular chirality of an amplified interfacial monolayer according to claim 2, wherein: Step S32 includes the following steps: Step S321: Determine the source of the chiral SHG signal based on the sign of the DCE value; Step S322: quantitatively characterize the supramolecular chirality of the monolayer according to the DCE value.

4. The method for detecting supramolecular chirality of an amplified interfacial monolayer according to claim 1, wherein: The protonated achiral molecular solution is a achiral molecular solution with a pH value less than 4.

5. The method for detecting supramolecular chirality of an amplified interfacial monolayer according to claim 1, wherein: The achiral molecule is a porphyrin molecule with a negatively charged group under acidic conditions, including but not limited to at least one of tetrakis(4-sulfophenyl)porphyrin (TPPS), di(4-sulfophenyl)porphyrin, tris(4-sulfophenyl)porphyrin, tetrakis(4-carboxyphenyl)porphyrin, and di(4-carboxyphenyl)porphyrin.

6. The method for detecting supramolecular chirality of an amplified interfacial monolayer according to claim 1, wherein: The chiral molecule is an amphiphilic chiral molecule, including but not limited to 4-pyridylpropionic acid-L-glutamine derivatives ( L -P-PPG), 3-(4-pyridyl) acrylic acid-L / D-glutamine derivative ( L / D -P-PAG), 3-(2-pyridyl) acrylic acid-L / D-glutamine derivative ( L / D -O-PAG), 3-(3-pyridyl) acrylic acid-L-glutamine derivative ( L -M-PAG).

7. The method for detecting supramolecular chirality of an amplified interfacial monolayer according to claim 1, wherein: The concentration of the sample solution is 0.1 mM to 1.0 mM.

8. The method for detecting supramolecular chirality of an amplified interfacial monolayer according to claim 2, wherein: In step S3 , the positive or negative sign of DCE represents the type of supramolecular chirality of the monolayer; the absolute value of DCE represents the strength of the supramolecular chirality of the monolayer.

9. The method for detecting supramolecular chirality of an amplified interfacial monolayer according to claim 1, wherein: In step S3 , the second harmonic SHG technique for detecting the second harmonic SHG signal of the monolayer is a second harmonic linear dichroism SHG-LD method with S-polarization detection.

10. The method for detecting supramolecular chirality of an amplified interfacial monolayer according to claim 1, wherein: In step S4 , the sum frequency vibrational spectroscopy (SFG) technology for detecting the sum frequency vibrational spectroscopy (SFG) signal of the monolayer includes an SFG method of SPP polarization detection and an SFG method of (s+mp)-(s-mp) polarization detection.

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