Helical polymer with acid / alkali response multiple chiral switching function as well as preparation method and application of helical polymer

Abstract

The invention provides a spiral polymer with an acid / alkali response multiple chiral switching function as well as a preparation method and application of the spiral polymer. The helical polymer is prepared by combining polyacetylene with an acid-base responsive Rhodol structure; under the condition that different acids and alkalis are added, the helical polymer can induce to generate multiple reversible switching chiral optical states. The helical polymer prepared by the technical scheme of the invention can be induced to generate as many as five chiral optical states under the addition of different acids and bases, the switching quantity of the chiral optical states is far higher than that of 2-3 optical chiral states in the prior art, and particularly, the switching reversibility of the chiral states is good.

Description

Technical Field

[0001] The present invention belongs to the technical field of display materials, and in particular relates to a helical polymer with acid / base responsive multiple chiral switching functions, a preparation method and an application thereof. Background Art

[0002] Chiral optical switch materials are materials whose chiral optical absorption properties can undergo reversible changes under external environmental stimulation. Due to these properties, chiral optical switch materials have important applications in optical communications, information encryption, biological probes, and other fields. Existing materials have demonstrated responsiveness to various stimuli, such as acid / base (pH), light, temperature, redox, solvents, ionic additives, and electric fields. However, most currently developed chiral switch materials can only switch between two or three chiral states, resulting in a limited amount of switchable information and hindering their further application in specialized scenarios such as information storage and encryption that require diverse information. Acid / base-responsive chiral switch materials have attracted considerable attention in recent years due to their distinct chiral properties in the protonated and deprotonated states, their ease of structural modification, and their rich array of chiral optical properties. Currently developed acid / base-responsive chiral switch materials generally involve grafting chiral functional groups onto acid-base-responsive functional units, such as derivatives of fluorescein and salicylaldehyde. However, such materials typically have only a single acid / base responsive site and limited chiral conformations, so the number of states of the chiral switch is generally limited to two or three. Furthermore, when applied in scenarios requiring multi-chiral state switching, the reversibility of the switching becomes difficult, such as multi-dimensional information encryption, thus hindering its further development in practical applications. For example, Chinese invention patent CN114442341A discloses an electroresponsive material, device, and preparation method with adjustable circularly polarized luminescence properties. By utilizing the properties of "electroacidic" aniline derivatives and "electroalkaline" benzoquinone derivatives that can reversibly release or extract protons during electrochemical oxidation or reduction, combined with circularly polarized optical switch molecules that respond to both aniline derivatives and benzoquinone derivatives, an electroresponsive material with adjustable circularly polarized luminescence properties under the action of an electric field can be obtained. Chinese invention patent CN111948864A discloses an electrochromic device with an electrical response prepared by using an electrochromic chiral molecule with multiple chiral states. The device is prepared by mixing a fluoran dye containing an aldehyde group and a phenolic hydroxyl group with a chiral amine molecule. The electrochromic chiral molecule includes an intramolecular hydrogen bond structure, and the aldehyde group and the phenolic hydroxyl group are located at adjacent positions on the same benzene ring of the fluoran dye. The device is then used to prepare an electrochromic device with multiple chiral states adjustable under the action of an electric field, and can achieve three chiral states in the visible light band. For example, the Chinese invention patent discloses a side-chain azobenzene polymer gel, its preparation method, and the construction of a chiral light switch. The side-chain azobenzene polymer is prepared into a side-chain azobenzene polymer gel, and its chirality is induced and regulated by circularly polarized light to construct a series of chiral light switches. The invention prepares the side-chain azobenzene polymer into a gel film using supramolecular assembly technology, and then uses circularly polarized light to induce and regulate the chirality of the side-chain azobenzene polymer gel.At the same time, its chirality can be erased and restored using ultraviolet light and heating and cooling treatments, enabling the construction of a chiral optical switch and visual identification of enantiomeric molecules using gel-sol transitions. The chiral optical switching properties provided by the above technologies, whether electrically responsive or optically responsive or acid-base responsive, have certain limitations, generally only being able to switch between two or three states. In particular, the optical switching properties of the materials, such as stability, color state, and reversibility, are less than ideal.

[0003] Based on the above technical problems, the present invention designs a new type of helical polymer by combining polyacetylene with an acid-base responsive Rhodol structure. When used as a chiral switch material, it can achieve a completely reversible chiral switching process and has good stability. Summary of the Invention

[0004] The purpose of the present invention is to overcome the technical problems of the prior art and provide a helical polymer with acid / base responsive multiple chiral switching properties and its preparation method and application, in particular, it can realize the reversible switching of 5-fold chiral optical states, and the state switching has good reversibility.

[0005] To achieve the above objectives, the present invention provides a helical polymer with acid / base responsive multiple chiral switching functions, which is prepared by combining polyacetylene with an acid-base responsive Rhodol structure; the helical polymer can induce multiple reversibly switchable chiral optical states under the addition of different acid and base conditions.

[0006] Preferably, the structural formula of the helical polymer is:

[0007]

[0008] Among them, a:(c+d)=1:0.1~10; c:d=1:0.1~10.

[0009] Preferably, the helical polymer can produce five reversible chiral states under different acid-base induction, including:

[0010] No circular dichroism (CD) signal;

[0011] Under acidic conditions, a negative CD signal appears at the absorption peak around 535-540nm. As the amount of acid added increases, a positive CD signal then appears, and the change in the CD signal is accompanied by a switch in the color of the chiral state from colorless to pink.

[0012] Under alkaline conditions, a positive CD signal appears at the absorption peak around 525-530 nm, and as the amount of base added increases, a negative CD signal then appears. The change in CD signal is accompanied by a switch in the color of the chiral state from colorless to orange.

[0013] The process of switching the chiral state is completely reversible.

[0014] As one of the purposes of the present invention, the synthesis route of the helical polymer with acid / base responsive multiple chiral switch function is as follows:

[0015]

[0016] Wherein, in the above structural formula, b=(c+d), a∶(c+d)=1∶0.1~10; c∶d=1∶0.1~10.

[0017] Based on the above technical solution, the present invention provides a method for preparing the helical polymer having acid / base responsive multiple chiral switch functions, comprising the following steps:

[0018] S1. Synthesis of chiral monomer M1: (R)-(+)-α-methylbenzyl isocyanate and propargylamine are dissolved in a first solvent, mixed, and reacted to obtain a white solid, which is the chiral monomer M1;

[0019] S2.P ab Synthesis of -Boc-U: Achiral monomer M2, chiral monomer M1 and catalyst are dissolved in a second solvent and reacted under nitrogen atmosphere to obtain a yellow product, which is P ab -Boc-U; the structural formula of the achiral monomer M2 is

[0020] S3.P ab Synthesis of -NH2-U: P ab -Boc-U and trifluoroacetic acid are dissolved in a third solvent and stirred to react to obtain a yellow product P ab -NH2-U, during the reaction, a:b=a:(c+d); a:b=a:(c+d)=1:0.1~10; c:d=1:0.1~10.

[0021] S4. Synthesis of Helical Polymers: P ab -NH2-U and Rhodol-CHO are dissolved in the fourth solvent and stirred to react to obtain a red product P ab -Rh-U is the helical polymer; the structural formula of Rhodol-CHO is:

[0022] Preferably, in S1, the first solvent is tetrahydrofuran; (R)-(+)-α-methylbenzyl isocyanate is dissolved in tetrahydrofuran, and a tetrahydrofuran solution containing 1 equivalent of propargylamine is added dropwise at 0°C, and stirred at room temperature until the reaction is completed; the chiral monomer M1 is obtained after extraction, drying, and evaporation.

[0023] Preferably, in S2, the second solvent is chloroform.

[0024] Preferably, the catalyst is Rh + (nbd)[B(C6H6)4] - The addition amount is 1 mol% of the sum of the achiral monomer M2 and the chiral monomer M1; the reaction conditions include a temperature of 20 to 40°C.

[0025] Preferably, in S3, the third solvent is dichloromethane.

[0026] Preferably, the volume ratio of the third solvent to trifluoroacetic acid is 1:1.

[0027] Preferably, in S4, P ab The molar ratio of -NH2-U to Rhodol-CHO is 1:1.5.

[0028] Preferably, the fourth solvent is anhydrous ethanol.

[0029] As another object, the present invention also provides a multi-chirality switch material, comprising at least the helical polymer provided by the above technical solution.

[0030] Preferably, the multi-chirality switch material comprises dissolving the helical polymer and PMMA in a fifth organic solvent to obtain a functional solution, which is the functional chirality switch material.

[0031] Preferably, the fifth organic solvent comprises one of DMSO or acetonitrile.

[0032] Preferably, the mass ratio of the helical polymer to PMMA is 1:10 to 10,000.

[0033] As another object, the present invention further provides a functional film, comprising the multi-chirality switch material provided by the above technical solution coated on the surface of a transparent substrate, and the functional film is obtained after drying.

[0034] Preferably, the functional film exhibits different chiral optical states under different acid and alkali conditions.

[0035] More preferably, the initial state is that there is no circular dichroism (CD) signal; under acidic conditions, a negative CD signal appears at the absorption peak of about 535-540 nm; as the amount of acid added increases, a positive CD signal then appears, and as the CD signal changes, the color of the chiral state switches from colorless to pink; under alkaline conditions, a positive CD signal appears at the absorption peak of about 525-530 nm, and as the amount of base added increases, a negative CD signal then appears, and as the CD signal changes, the color of the chiral state switches from colorless to orange; the process of switching the optical chiral state is completely reversible.

[0036] As another object, the present invention also provides an electrochromic device, at least the multiple chirality switching material provided by the above technical solution.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. Using the technical solution of the present invention, a new type of helical polymer was designed by combining polyacetylene with an acid-base responsive rhodol structure. This helical polymer can induce up to five chiral optical states under the addition of different acids and bases, which is far higher than the 2-3 optical chiral states switched in the existing technology. In particular, the switching of chiral states is reversible.

[0039] 2. Based on the technical solution of the present invention, a helical polymer with acid-base responsive multiple chiral switching characteristics was prepared by introducing a rhodol structure into a helical polymer (polyacetylene). This helical polymer was then doped into polymethyl methacrylate (PMMA), successfully fabricating a functional film with acid-base responsive multiple chiral switching capabilities. The film exhibited reversible switching of five chiral optical states with good reversibility.

[0040] 3. The electrochromic device with acid-base responsive multiple chirality switching function provided by the technical solution of the present invention has the advantages of simple process and easy operation, is suitable for large-scale promotion and utilization, and can save manufacturing costs and reduce the difficulty of the preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 These are the H-NMR spectra and C-NMR spectra of the helical polymer, intermediate, and chiral monomer prepared in Example 1 of the present invention.

[0042] Figure 2a This is a diagram showing the initial state of the functional film in Example 1 of the present invention without circular dichroism (CD) signal.

[0043] Figure 2b and Figure 2cThey are respectively a circular dichroism (CD) signal response change diagram of the acid-base response of the functional film in Example 1 of the present invention and a performance change diagram of the multiple chiral switch.

[0044] Figure 3 Graph showing the color change of the quintuple chiral optical state of the functional film in Example 1 of the present invention. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below with reference to specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, rather than all embodiments. In order to describe concisely, it is impossible for this specification to provide a detailed description of all features of the actual implementation method. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. It should be noted that, unless otherwise defined, the technical terms or scientific terms used in this specification should be known to people in the technical field described in this application.

[0046] The present invention discloses a helical polymer with acid / base responsive multiple chiral switching functions, which is prepared by combining polyacetylene with an acid-base responsive Rhodol structure. The helical polymer can induce the generation of multiple reversibly switchable chiral optical states under the addition of different acid and base conditions.

[0047] Specifically, under acidic conditions, the absorption peak at 539 nm initially exhibited a negative CD signal followed by a positive CD signal as the amount of added acid increased, with the color switching from colorless to a darker pink. Under alkaline conditions, the absorption peak at 528 nm initially exhibited a positive CD signal followed by a negative CD signal as the amount of added base increased, with the color switching from colorless to a darker orange. Under different acid-base induction conditions, the five-fold chiral optical state could be reversibly switched, and this was achieved simply by adjusting the acid-base conditions, with excellent reversibility.

[0048] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the reagents, materials, etc. used in the following examples are all commercially available unless otherwise specified.

[0049] The technical solution of the present invention is described in detail below through specific embodiments.

[0050] Example 1

[0051] This embodiment provides a method for preparing a functional film having acid / base responsive multiple chiral switching properties:

[0052] (1) The synthesis route of polymers with acid / base responsive multiple chiral switching properties is shown in the figure below:

[0053]

[0054] Among them, a:b=a:(c+d)=1:0.1~10; c:d=1:0.1~10.

[0055] The following uses a:b=7:3 as a preferred embodiment to explain in detail the synthesis method of the above polymer and verify the acid / base responsive multiple chiral switching characteristics of the synthesized polymer. The specific operation steps include:

[0056] (i) Synthesis of M1: (R)-(+)-α-Methylbenzyl isocyanate was dissolved in 16 mL of tetrahydrofuran. A solution of 1 equivalent of propargylamine in 16 mL of tetrahydrofuran was added dropwise at 0°C. The reaction solution was stirred at room temperature for 4 hours. After the reaction, the mixture was extracted three times with dichloromethane and deionized water. The organic phase was collected and dried over anhydrous sodium sulfate. The solvent was removed by rotary evaporation to obtain M1 as a white solid.

[0057] (ii)P ab -Synthesis of Boc-U: The achiral monomer M2, chiral monomer M1 (1.5 equivalents) and catalyst Rh+(nbd)[B(C6H6)4]- (1 mol% monomer) were dissolved in 3.2 mL of chloroform and reacted at 30°C in a N2 atmosphere for 6 hours. The resulting yellow solution was precipitated in a large amount of n-hexane. The crude product was washed several times with anhydrous ethanol and dried to obtain the yellow product Pab-Boc-U.

[0058] (iii)P ab Synthesis of -NH2-U: P ab -Boc-U was dissolved in a solution of trifluoroacetic acid and dichloromethane (volume ratio of 1:1) and stirred at room temperature overnight. After the reaction was completed, the solution was precipitated in a large amount of ether and dried to obtain a yellow product Pab-NH2-U.

[0059] (iv)P ab -Rh-U (functional helical polymer) synthesis: P ab -NH2-U and Rhodol-CHO (molar ratio of 1:1.5) were dissolved in anhydrous methanol and stirred at room temperature for 48 hours. After the reaction was completed, the solution was precipitated in a large amount of ether. The crude product was washed several times with anhydrous ethanol and dried to obtain a red product P ab -Rh-U.

[0060] See Figure 1 , when the molar ratio of a to b is 7 to 3, the NMR spectrum. As shown in the figure, by comparing the raw material P 73-NH2-U, Rhodol-CHO and product P 73 -Rh-U NMR spectrum shows that the product has the characteristic hydrogen of both raw materials, such as P 73 -Rh-U has two hydrogens (e+g) in the benzene ring region of the raw material; in addition, in the saturated region, P 73 -Rh-U has both the characteristic hydrogen of N, N-diethyl of Rhodol-CHO and P 73 -NH2-U methyl hydrogen, the above results show that P 73 -Rh-U has been successfully prepared.

[0061] (2) Preparation of functional solution: The helical polymer and PMMA were mixed at a mass ratio of 1:200, dissolved in DMSO as a solvent, and stirred thoroughly at 40°C to obtain a clear and transparent solution.

[0062] (3) Preparation of functional film: After the functional solution is prepared, it is drop-coated or spin-coated on the surface of a transparent glass substrate. After the solution is completely evaporated, the functional film is obtained.

[0063] The prepared functional films exhibit different chiral states under different acid and base conditions.

[0064] like Figure 2a The figure shows the initial state of the functional film without circular dichroism (CD) signal; Figure 2b and Figure 2c The graphs of the circular dichroism (CD) signal response changes of the functional film in response to acid and base and the performance changes of the multiple chiral switches are shown in the figure. As can be seen from the figure, under acidic conditions (adding trifluoroacetic acid), a negative CD signal (P 73 -Rh-U), and then a positive CD signal appeared (P 73 -Rh-U), the process is accompanied by the color switching from colorless to pink; under alkaline conditions (addition of tetrabutylammonium hydroxide), the positive CD signal (P 73 -Rh-U), followed by a negative CD signal (P 73 -Rh-U), which is accompanied by a color change from colorless to orange, Figure 2c It can be seen that under different acid-base induction, the five-fold chiral optical state can be reversibly switched, and it can be achieved by simply adjusting the acid-base conditions, with good reversibility.

[0065] See Figure 3This is a diagram of the acid / base response of the functional film in multiple colors. Under acidic conditions, the color changes from initial colorless to light pink and finally to pink. Under alkaline conditions, the color changes from colorless to light orange and finally to orange, showing three different color changes.

[0066] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any changes, modifications, substitutions, integrations, or parameter changes to these embodiments, which fall within the spirit and principles of the present invention and achieve the same functionality through conventional substitutions, without departing from the principles and spirit of the present invention, fall within the scope of protection of the present invention.

Claims

1. A helical polymer with acid / base responsive multiple chiral switching functions, prepared by combining polyacetylene with an acid-base responsive rhodol structure; the helical polymer can induce multiple reversibly switchable chiral optical states under the addition of different acid or base conditions.

2. The helical polymer having acid / base responsive multiple chiral switching functions according to claim 1, characterized in that: The structural formula of the helical polymer is: Among them, a:(c+d)=1:0.1~10; c:d=1:0.1~10.

3. The helical polymer having acid / base responsive multiple chiral switching functions according to claim 2, characterized in that: The helical polymer can produce five reversible chiral states under different acid-base induction, including: No circular dichroism (CD) signal; Under acidic conditions, a negative CD signal appears at the absorption peak of 535-540 nm. As the amount of acid added increases, a positive CD signal then appears, and the change in the CD signal is accompanied by a switch in the color of the chiral state from colorless to pink. Under alkaline conditions, a positive CD signal appears at the absorption peak position of 525-530 nm, and as the amount of base added increases, a negative CD signal then appears, and the change in CD signal is accompanied by a switch in the color of the chiral state from colorless to orange; The process of switching the chiral state is completely reversible.

4. A method for preparing a helical polymer having acid / base responsive multiple chiral switching functions as claimed in claim 1, characterized in that: The following steps are involved: S1. Synthesis of chiral monomer M1: (R)-(+)-α-methylbenzyl isocyanate and propargylamine are dissolved in a first solvent, mixed, and reacted to obtain a white solid, which is the chiral monomer M1; S2.P ab Synthesis of -Boc-U: Achiral monomer M2, chiral monomer M1 and catalyst are dissolved in a second solvent and reacted under nitrogen atmosphere to obtain a yellow product, which is P ab -Boc-U; the structural formula of the achiral monomer M2 is S3.P ab Synthesis of -NH2-U: P ab -Boc-U and trifluoroacetic acid are dissolved in a third solvent and stirred to react to obtain a yellow product P ab -NH2-U; S4. Synthesis of Helical Polymers: P ab -NH2-U and Rhodol-CHO are dissolved in the fourth solvent and stirred to react to obtain a red product P ab -Rh-U, which is the helical polymer.

5. The preparation method according to claim 4, characterized in that In S1, the first solvent is tetrahydrofuran; (R)-(+)-α-methylbenzyl isocyanate is dissolved in tetrahydrofuran, and a tetrahydrofuran solution containing 1 equivalent of propargylamine is added dropwise at 0°C, and stirred at room temperature until the reaction is complete; after extraction, drying, and evaporation, the chiral monomer M1 is obtained; And / or, in S2, the second solvent is chloroform; the catalyst is Rh + (nbd)[B(C6H6)4] - , the addition amount is 1 mol% of the sum of the achiral monomer M2 and the chiral monomer M1; the reaction conditions include a temperature of 20 to 40°C; And / or, in S3, the third solvent is dichloromethane; the volume ratio of the third solvent to trifluoroacetic acid is 1:1; and / or, in S4, P ab The molar ratio of -NH2-U and Rhodol-CHO is 1:1.5; The fourth solvent is anhydrous ethanol.

6. A multi-chirality switch material, comprising at least the helical polymer according to any one of claims 1 to 3.

7. The multi-chirality switch material according to claim 6, characterized in that: The method comprises dissolving at least the helical polymer and PMMA in a fifth organic solvent to obtain a functional solution, which is the functional chiral switch material; The fifth organic solvent comprises DMSO and / or acetonitrile; The mass ratio of the helical polymer to PMMA is 1:10-10000.

8. A functional film, comprising coating the multi-chirality switch material according to claim 6 or 7 on the surface of a transparent substrate, and obtaining the functional film after drying.

9. The functional film according to claim 8, wherein The functional film exhibits different chiral optical states under different acid and alkali conditions and can be reversibly switched between five chiral optical states of three different colors; Preferably, the initial state is no circular dichroism (CD) signal; under acidic conditions, a negative CD signal appears at the absorption peak of 539 nm; as the amount of acid added increases, a positive CD signal then appears, and as the CD signal changes, the color of the chiral state switches from colorless to pink; Under alkaline conditions, a positive CD signal appears at the absorption peak of 528 nm, and as the amount of base added increases, a negative CD signal then appears. The change in CD signal is accompanied by a switch in the color of the chiral state from colorless to orange. The process of switching the optical chiral state is completely reversible.

10. An electrochromic device comprising at least the multi-chirality switching material according to claim 7 or 8.

Images