A Class of Multiple Stimulus-Responsive Viologen Derivatives, Their Preparation Methods and Applications

Abstract

The present invention belongs to the field of organic optoelectronic functional materials and devices, and discloses a class of multi-stimulus responsive viologen derivatives, which have 4,4'-bipyridine as a skeleton, 1,10-phenanthroline as an N-substituent, and halogen anions and quasi-halogen anions as counter anions; such multi-stimulus responsive viologen derivatives are prepared by introducing 1,10-phenanthroline into a 4,4'-bipyridine skeleton and then performing ion exchange. Such novel multi-stimulus responsive viologen derivatives are highly sensitive to stimuli such as electric fields, light and temperature, and exhibit adjustable absorption and emission properties. Based on their excellent multi-stimulus responsiveness, such viologen derivatives are used as active materials to prepare electrochromic / electroluminescent color-changing devices, photochromic / photoluminescent color-changing devices, and thermochromic / thermoluminescent color-changing devices. Such multi-stimulus responsive viologen derivatives can also be used to prepare anti-counterfeiting inks to achieve their application in the field of anti-counterfeiting.

Description

Technical Field

[0001] The present invention belongs to the field of organic optoelectronic functional materials and devices. More specifically, it relates to a class of multiple stimulus-responsive viologen derivatives, their preparation methods, and their applications in the fields of display and anti-counterfeiting. Background Art

[0002] In recent years, stimulus-responsive materials based on color change phenomena have received extensive attention due to their numerous applications in high-tech fields such as sensors, smart windows, displays, rewritable copy paper, secret writing, and anti-counterfeiting. Among various stimulus-sensitive materials, organic compounds with reversible color changes, such as azobenzene, divinyl, spiropyran, and viologen, have attracted great interest because of their highly designable and controllable geometric structures, convenient and efficient color-changing behaviors, and readable corresponding signals with regeneration and reuse characteristics when responding to external chemical or physical stimuli. Among them, viologen materials have unique properties such as three stable redox states (dicationic state, radical cationic state, and neutral state), good redox reversibility, multiple stimulus responsiveness, and easily modified chemical structures, and have great potential in intelligent technology applications. Viologen materials can be interconverted between three redox states by gaining or losing an electron. The three different redox states have different electronic transitions, resulting in different electronic absorption bands, accompanied by obvious color changes. Based on this, viologen materials can directly exhibit reversible and visible color changes under external stimuli such as pH, temperature, light, potential, and solvent. However, most known viologen materials not only respond only to a single stimulus but also do not have tunable luminescence properties, which greatly limits their applications in the fields of light-emitting display and anti-counterfeiting. Therefore, it is of great significance to construct multiple stimulus-responsive and luminescence-tunable viologen derivatives by using the easily modified chemical structure of viologen to broaden its applications in various fields.

[0003] At present, referring to the patent document with the publication number CN114478505A, an extended π-conjugated viologen derivative with luminescent properties was constructed by introducing a π-bridge into the 4,4'-bipyridine skeleton, or referring to the patent document with the publication number CN105237578A, which is the patent document previously disclosed in this project, a phosphorescent iridium complex was constructed by introducing a viologen derivative as an auxiliary ligand into an iridium complex. Both provided viologen compounds with multiple stimulus responses. However, compared with traditional viologen derivatives, the synthesis of these two types of viologen derivatives is relatively complex and there is no fixed synthesis method, which greatly increases the synthesis difficulty. In addition, the above-mentioned disclosed π-conjugated viologen derivatives only exhibit fluorescence turn-on or fluorescence quenching phenomena, while the above-mentioned disclosed phosphorescent iridium complexes containing viologen units only exhibit phosphorescence turn-on or phosphorescence quenching phenomena. Neither of these two types of viologen derivatives can achieve the mutual conversion of multiple luminescent colors and is not suitable for multicolor intelligent luminescent display. Therefore, by modifying traditional means such as N-substituents and counter anions, constructing viologen derivatives with a simple structure, multiple stimulus responses, and adjustable color and luminescent properties has a positive promoting effect on the field of multifunctional optoelectronic materials and devices. Summary of the Invention

[0004] Aiming at the above existing problems, the present invention aims to provide a class of multiple stimulus-responsive viologen derivatives and their preparation methods, and applying this class of multiple stimulus-responsive viologen derivatives to the fields of display and anti-counterfeiting, showing great application potential in the fields of information display, information storage, information encryption, and security anti-counterfeiting.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] Taking advantage of the easily modifiable chemical structure, rich redox states, and good redox reversibility of viologens, lumophores with rigid structures are modified in the viologen framework to endow viologen derivatives with tunable absorption and emission; by modifying halogen or pseudohalogen anions, viologen derivatives can achieve simultaneous responsiveness to external stimuli such as electric fields, light, and temperature. Moreover, the absorption and emission of viologen derivatives can also be effectively regulated under different voltages, irradiation wavelengths, and temperatures. Specifically, 1,10-phenanthroline with a rigid structure is introduced as an N-substituent into the 4,4'-bipyridine framework respectively, and then ion exchange is carried out to obtain multi-stimuli-responsive viologen derivatives with different halogen and pseudohalogen anions. These viologen derivatives exhibit excellent absorption, emission, and electrochemical properties, and under electrical, optical, and thermal stimuli, good redox reversible reactions occur accompanied by reversible changes in color and luminescence color. By optimizing the device structure, electrochromic / electroluminescent color-changing, photochromic / photoluminescent color-changing, and thermochromic / thermoluminescent color-changing devices are first prepared. Further, the electrochromic / electroluminescent color-changing, photochromic / photoluminescent color-changing, and thermochromic / thermoluminescent color-changing properties of viologen derivatives are applied to the field of security anti-counterfeiting. Such novel multi-stimuli-responsive viologen derivatives have broad application prospects in the fields of information display, information storage, information encryption, and security anti-counterfeiting.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] In the first aspect, the present invention provides a class of novel viologen derivatives phen-Vio[X1X2], and the structural formula is:

[0009]

[0010] Among them, X1 - and X2 - are any one of the following and X1 - and X2 - can be the same: X1 - , X2 - =Cl - , Br - , I - , ClO4 - , BrO3 - , IO3 - , CN - , OCN - , SCN - ;

[0011] Among them, R can be independently selected from cyclic, branched, and straight-chain alkyl chains or ether chains with a positive integer number of carbon atoms.

[0012] Preferably, the chemical formula of the viologen derivative is:

[0013]

[0014] In a second aspect, the present invention provides a method for preparing the above novel viologen derivative, and the preparation method includes the following synthetic route:

[0015]

[0016] The specific steps of the preparation method include: reacting compound 1 with an asymmetric pyridinium salt intermediate 2 to obtain compound 3; performing a nucleophilic substitution reaction on compound 3 and a halide to obtain a viologen derivative phen-Vio[ClX], and finally performing ion exchange with chloride salts, bromide salts, iodide salts, perchlorate salts, bromate salts, iodate salts, cyanide salts, cyanate salts, and cyan sulfate salts respectively to obtain a novel viologen derivative phen-Vio[X1X2].

[0017] As a preferred embodiment, the specific synthesis steps of the above viologen derivative are as follows:

[0018] (1) Preparation of compound 3: Compound 1 and compound 2 are refluxed in a mixed solvent of alcohol and deionized water for 24 to 84 h; cooled to room temperature, the solvent is removed by rotary evaporation, a small amount of alcohol is added to completely dissolve the solid, and then a large amount of ethyl acetate and acetone are added for sedimentation, filtered, and washed three times with a mixed solvent of ethyl acetate and acetone to obtain compound 3;

[0019] (2) Preparation of viologen derivative phen-Vio[ClX]: Compound 4 is reacted with a halide in solvents such as acetonitrile, alcohol, DMSO, and DMF at 40 to 50 °C for 12 to 36 h under a nitrogen atmosphere; after the reaction is completed, the solvent is removed by rotary evaporation, and the residue is washed three times with a mixed solvent of ethyl acetate and acetone to obtain compound phen-Vio[ClX];

[0020] (3) Preparation of viologen derivative phen-Vio[X1X2]: Dissolve compound phen-Vio[ClX] in a benign solvent, add a saturated aqueous solution of any one of chloride salts, bromide salts, iodide salts, perchlorate salts, bromate salts, iodate salts, cyanide salts, cyanate salts, or cyan sulfate salts, and stir at room temperature for 4 to 12 h; after the reaction is completed, filter and recrystallize to obtain viologen derivative phen-Vio[X1X2].

[0021] Thirdly, the present invention also provides the application of the above-mentioned viologen compounds as active materials for various optoelectronic devices; a novel class of viologen derivatives of the present invention not only has rich redox states and good redox reversibility, but also has high sensitivity to various stimuli such as external electric fields, light, and temperature, and can be used as active materials to construct electrochromic / electroluminescent color-changing, photochromic / electroluminescent color-changing, and thermochromic / thermoluminescent color-changing devices. That is, the various optoelectronic devices include electrochromic / electroluminescent color-changing devices, photochromic / electroluminescent color-changing devices, or thermochromic / thermoluminescent color-changing devices.

[0022] Specifically, the application is to use the above-mentioned viologen derivative phen-Vio[X1X2] as an active material, doping an imidazole salt and a polymer electrolyte in a suitable solvent to prepare a homogeneous electrolyte solution at room temperature in air, and assembling it with two conductive electrodes to prepare an optical device, where the suitable solvent is any one of DMF, acetonitrile, DMSO, or acetone; the polymer electrolyte includes any one of polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polymethyl methacrylate (PMMA), polyethylene oxide (PEO), polyacrylonitrile (PAN), polypropylene oxide (PPO), or polyvinylidene chloride (PVDC).

[0023] Preferably, the conductive electrodes are two pieces of ITO glass;

[0024] Preferably, the electrolyte is poly(vinylidene fluoride-co-hexafluoropropylene) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and the mass ratio of poly(vinylidene fluoride-co-hexafluoropropylene), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and Vio-X is set to 8:72:3.

[0025] A novel class of viologen derivatives of the present invention has excellent electrochromic / electroluminescent color-changing, photochromic / electroluminescent color-changing, and thermochromic / thermoluminescent color-changing properties, and can be combined with other energy storage and sensing materials to construct multifunctional energy storage or sensor devices that can display in real time, such as color-changing supercapacitors, color-changing batteries, and color-changing sensors.

[0026] A novel class of viologen derivatives of the present invention has good reversible redox ability and can be used as the negative electrode material in lithium-ion batteries, sodium-ion batteries, or potassium-ion batteries and the anodic electrolyte in redox flow batteries.

[0027] A novel class of viologen derivatives described in the present invention has good redox states and high electrical stimulation sensitivity. Under electrical stimulation, its redox state undergoes reversible changes, resulting in corresponding reversible changes in its resistance state. Therefore, it can be used as an active material for various transistors (such as field-effect transistors, electrochemical transistors) and memories (including memristors) for neuromorphic computing.

[0028] In a fourth aspect, the present invention provides the application of the above-mentioned viologen compound in information anti-counterfeiting.

[0029] The specific application method includes: dissolving phen-Vio[X1X2] in DMF to prepare a phen-Vio[X1X2]-DMF solution with a concentration of 10 mg·mL -1 dissolving polyvinyl alcohol type 124 in deionized water to prepare a PVA-H2O solution with a concentration of 5 mg·mL -1 mixing equal volumes of the phen-Vio[X1X2]-DMF solution and the PVA-H2O solution, and stirring evenly to obtain anti-counterfeiting ink; dissolving polyethylene glycol with a molecular weight of M n = 8000 in dichloromethane to prepare a PEG-DCM solution with a concentration of 90 mg·mL -1 then dropping and coating it on drawing paper, and drying it in a room temperature environment to obtain printing paper as an anti-counterfeiting carrier; using the above anti-counterfeiting ink and the drawing paper coated with the above ethylene glycol as the printing paper, and directly printing with a commercial printer to obtain a print with a preset anti-counterfeiting pattern;

[0030] Irradiating the preset anti-counterfeiting pattern with a 365 nm ultraviolet lamp shows yellowish-green fluorescence that can be recognized and can be recognized by a mobile phone; when exposed to 365 nm ultraviolet light for 10 s, the preset anti-counterfeiting pattern changes from light yellow to green, and its fluorescence changes from bright yellowish-green to dark yellow. At this time, the preset anti-counterfeiting pattern is clearly visible and can be easily recognized. Next, after heating at 75 °C for 2 min, the preset anti-counterfeiting pattern and its luminescence return to the initial unrecognizable state.

[0031] Preferably, the above-mentioned viologen compound is Phen-Vio[ClI].

[0032] The beneficial effects of the present invention are:

[0033] For the color-changing phenomenon of viologen compounds, different color conversions under light, electricity, or thermal stimuli can be easily achieved by regulating the types of their N-substituents or counter anions. However, due to the inherent strong electron-withdrawing ability of viologens, it is difficult to regulate their luminescence properties. Appropriate N-substituents or counter anions must be selected to lower the frontier orbital energy levels of viologen compounds in order to endow them with fluorescence. To achieve the luminescence regulation of viologen compounds, researchers introduced some aromatic groups into the middle of the 4,4'-bipyridine skeleton, or introduced viologen derivatives as auxiliary ligands into iridium complexes to form π-expanded viologen derivatives and phosphorescent iridium complexes with luminescence properties. However, π-expanded viologen derivatives only exhibit fluorescence on→off or fluorescence off→on phenomena, while phosphorescent iridium complexes containing viologen units only exhibit phosphorescence turn-on or phosphorescence quenching phenomena and do not have the mutual conversion of multiple fluorescence colors.

[0034] By introducing a lumophore with a rigid structure as an N-substituent onto 4,4'-bipyridine and then regulating its counter anion, a viologen compound with a lower frontier orbital energy level difference can be obtained, and the mutual conversion of multiple fluorescence colors can be achieved under external stimuli. Therefore, the multiple-stimulus-responsive viologen derivatives provided by the present invention introduce the fluorescent group 1,10-phenanthroline with a rigid structure onto 4,4'-bipyridine, and then obtain novel viologen derivatives with different halogen and pseudohalogen anions through ion exchange. Compared with π-expanded viologen derivatives and phosphorescent iridium complexes, the multiple-stimulus-responsive viologen derivatives provided by the present invention have simple synthesis steps, and are easy to separate and purify, and are suitable for large-scale production. In addition, such novel viologen derivatives have high sensitivity to external stimuli such as electric fields, light, and temperature, and excellent absorption, emission, and electrochemical properties. Moreover, under different voltages, irradiation wavelengths, and temperatures, the absorption (color) and emission (luminescence color) of viologen derivatives can be reversibly converted. Further, by optimizing the device structure, electrochromic / electroluminescent color-changing, photochromic / photoluminescent color-changing, and thermochromic / thermoluminescent color-changing devices were first prepared. Further, the electrochromic / electroluminescent color-changing, photochromic / photoluminescent color-changing, and thermochromic / thermoluminescent color-changing properties of viologen derivatives were applied to the field of security anti-counterfeiting. The viologen derivatives involved in the present invention have simple synthesis steps, can simultaneously achieve color and luminescence color changes under stimuli such as electricity, light, and heat, and can be made into various display and anti-counterfeiting devices, providing strong support for the further development of multifunctional optoelectronic materials and devices. Compared with single-functional devices, such multifunctional devices have multiple driving methods, that is, after adjusting the external voltage, light, or temperature, the device responds by changing the color or luminescence color, and the color change or luminescence color change is applied according to actual needs. In addition, the introduction of the luminescence color-changing property enables viologen-based materials to be applied in fields such as anti-counterfeiting, electronic tags, and optical imaging. Brief Description of the Drawings

[0035] Figure 1 For the UV absorption and emission spectrum tests of phen-Vio[ClI] in Test Example 2;

[0036] Figure 2a For the cyclic voltammetry tests of the solution type of phen-Vio[ClI] in the negative potential direction in Test Example 3;

[0037] Figure 2b For the cyclic voltammetry tests of the solution type of phen-Vio[ClI] in the positive potential direction in Test Example 3;

[0038] Figure 3 For the color and luminescence color change diagrams of the multifunctional device prepared with phen-Vio[ClI] as the active material under different voltage, light, and temperature drives in Test Example 4;

[0039] Figure 4 For the cyclic voltammetry tests of the multifunctional device prepared with phen-Vio[ClI] as the active material in Test Example 5;

[0040] Figure 5a For the absorption spectrum of the phen-Vio[ClI] device under forward voltage in Test Example 6;

[0041] Figure 5b For the absorption spectrum of the phen-Vio[ClI] device under reverse voltage in Test Example 6;

[0042] Figure 5c For the emission spectrum of the phen-Vio[ClI] device under forward voltage in Test Example 6;

[0043] Figure 5d For the emission spectrum of the phen-Vio[ClI] device under reverse voltage in Test Example 6;

[0044] Figure 6a For the absorption spectrum of the phen-Vio[ClI] device under 365 nm light irradiation in Test Example 7;

[0045] Figure 6b For the absorption spectrum of the phen-Vio[ClI] device at 75 °C in Test Example 7;

[0046] Figure 6c For the absorption spectrum of the phen-Vio[ClI] device under 620 nm light irradiation in Test Example 7;

[0047] Figure 6d For the emission spectrum of the phen-Vio[ClI] device under 365 nm light irradiation in Test Example 7;

[0048] Figure 6e To test the emission spectrum of the phen-Vio[ClI] device in Test Example 7 at 75 °C;

[0049] Figure 6f To test the emission spectrum of the phen-Vio[ClI] device under light irradiation at 620 nm in Test Example 7;

[0050] Figure 7 For the demonstration experiment of phen-Vio[ClI] in anti-counterfeiting applications in Test Example 9. Detailed implementation manners

[0051] The following examples further illustrate the content of the present invention, but should not be construed as limiting the present invention. Without departing from the essence of the present invention, modifications and substitutions made to the methods, steps or conditions of the present invention all fall within the scope of the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well-known to those skilled in the art.

[0052] The viologen derivative phen-Vio[X1X2] has multiple redox states, excellent redox reversibility and high sensitivity to external stimuli such as electricity, light and heat. Among them, different phen-Vio[X1X2] have similar synthesis steps, similar photophysical and electrochemical properties, and the following takes phen-Vio[ClI] as an example for detailed description.

[0053] Example 1: Preparation of phen-Vio[ClI]

[0054]

[0055] (1) For the preparation process of Compound 2, please refer to the patent document specifically: Liu Shujuan, Zhuang Yanling, Zhao Qiang, Ren Xiuli. Preparation and application of a class of ionic iridium(III) complexes containing viologen units: ZL202011528123.4[P]. 2021.04.02.

[0056] (2) Preparation of Compound 3: Compound 1 (2.2 mmol, 429 mg) and Compound 2 [1] (2.0 mmol, 786 mg) were refluxed in an 80% ethanol solvent for 24 h; cooled to room temperature, the solvent was removed by rotary evaporation, a small amount of methanol was added to completely dissolve the solid, and then a large amount of a mixed solvent of ethyl acetate and acetone was added for precipitation to obtain Compound 3. Yield: 84%. 1HNMR(400MHz, DMSO-d6) δ 9.65 (d, J = 6.8 Hz, 2H), 9.31 (ddd, J = 12.2, 4.2, 1.4 Hz, 2H), 9.02 - 8.96 (m, 4H), 8.70 (dd, J = 8.0, 1.6 Hz, 1H), 8.66 (s, 1H), 8.23 (dd, J = 4.6, 1.4 Hz, 2H), 8.11 (dd, J = 8.2, 1.4 Hz, 1H), 7.99 (dd, J = 8.0, 4.4 Hz, 1H), 7.89 (dd, J = 8.4, 4.2 Hz, 1H). 13 CNMR(100MHz, DMSO-d6) δ 150.0, 152.8, 151.9, 151.6, 147.5, 145.9, 145.5, 141.4, 138.1, 136.8, 131.1, 126.9, 126.4, 126.3, 125.1, 124.9, 123.9, 122.7。

[0057] (3) Preparation of viologen derivative phen-Vio[ClI]: Compound 4 (1 mmol, 420 mg) and methyl iodide (8.0 mmol, 0.5 mL) were reacted at 43 °C for 24 h in an acetonitrile solvent under a nitrogen atmosphere; after the reaction was completed, the reaction solution was rotary evaporated to remove the unreacted methyl iodide and acetonitrile solvent, and then the solid was washed three times with acetonitrile and dried in vacuo to obtain an orange solid phen-Vio[ClI]. Yield: 82%. 1 HNMR(400MHz, (CD3)2SO) δ = 9.81 (d, J = 7.2 Hz, 2H), 9.38 (d, J = 6.8 Hz, 2H), 9.34 (dd, J = 4.4, 1.6 Hz, 1H), 9.31 (dd, J = 4.4, 1.6 Hz, 1H), 9.13 (d, J = 7.2 Hz, 2H), 8.92 (d, J = 6.8 Hz, 2H), 8.72 (dd, J = 8.4, 1.6 Hz, 1H), 8.67 (s, 1H), 8.11 (dd, J = 8.4, 1.6 Hz, 1H), 8.00 (dd, J = 8.0, 4.4 Hz, 1H), 7.91 (dd, J = 8.4, 4.0 Hz, 1H), 4.50 (s, 3H). 13 CNMR(100MHz, (CD3)2SO) δ = 154.0, 153.0, 152.1, 149.5, 149.1, 148.4, 147.3, 146.8, 139.0, 137.9, 132.1, 128.5, 127.9, 127.8, 127.5, 126.1, 125.8, 125.0, 49.7.

[0058] Test Example 1: UV Absorption and Emission Spectra Test of phen-Vio[ClI]

[0059] In this invention, the spectral test concentration is 10 μM, the test solvent is DMF, and the excitation wavelength is 365 nm. The UV absorption and emission spectra of phen-Vio[ClI] are as Figure 1 shown. phen-Vio[ClI] has a strong absorption at 266 nm, which may be due to the π→π* electronic transition of the pyridine group and the benzene ring. Under the excitation of light at 365 nm, phen-Vio[ClI] exhibits dual emission peaks at 410 nm and 430 nm.

[0060] Test Example 2: Solution-Type Cyclic Voltammetry Test of phen-Vio[ClI]

[0061] The cyclic voltammetry test of phen-Vio[ClI] adopts a three-electrode system. The reference electrode is Ag / AgNO3, the counter electrode is a platinum wire electrode, and the working electrode is a palladium-carbon electrode. The electrolyte is a DMF solution (0.1 M) of tetrabutylammonium hexafluorophosphate. The scanning speed is 50 mV·s -1 . The solution-type cyclic voltammogram of phen-Vio[ClI] is as Figure 2a and 2b shown. As can be seen from Figure 2a , in the negative potential direction, phen-Vio[ClI] has two pairs of reversible redox peaks and two irreversible redox peaks. Among them, the two pairs of reversible redox peaks are attributed to the sequential gain of one electron by two nitrogen atoms on the viologen skeleton to generate its radical cation substance and neutral substance, while the two-step electron loss reduction process of the two nitrogen atoms on 1,10-phenanthroline corresponds to two pairs of irreversible reduction peaks. As can be seen from Figure 2b , in the positive potential direction, phen-Vio[ClI] has two irreversible redox peaks, which are caused by the oxidation reaction of halogen anions.

[0062] Test Example 3: Preparation of Multifunctional Devices

[0063] An electrochromic / electroluminescent color-changing device is prepared at room temperature in air using phen-Vio[ClI] as the electroactive material, two pieces of ITO glass as the conductive electrodes, and poly(vinylidene fluoride-co-hexafluoropropylene) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide as the electrolyte; the mass ratio of poly(vinylidene fluoride-co-hexafluoropropylene), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and phen-Vio[ClI] is 8:72:3.

[0064] The preparation process is as follows: First, at room temperature, the ITO glass is ultrasonically cleaned with deionized water, ethanol, and acetone in sequence for 10 - 30 min, and then dried for later use. Second, at room temperature, two pieces of ITO glass are bonded with ordinary double-sided tape, leaving the required grooves and edges for injecting the electrolyte solution containing phen-Vio[ClI] and electrode clamping. Finally, 40 mg of poly(vinylidene fluoride-co-hexafluoropropylene), 360 mg of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and 15 mg of phen-Vio[ClI] are stirred at 50 °C until completely dissolved in 5 mL of anhydrous DMF. After the reaction, it is cooled to room temperature, and the electrolyte solution is sucked with a 1 mL syringe and injected into the groove of the device, successfully realizing the construction of electrochromic / electroluminescent color-changing, photochromic / electroluminescent color-changing, and thermochromic / electroluminescent color-changing devices.

[0065] Test Example 4: Color and luminescence color change diagrams of the multifunctional device prepared with phen-Vio[ClI] as the active material under different voltage, light, and temperature driving

[0066] The color and luminescence color change diagrams of the multifunctional device prepared with phen-Vio[ClI] as the active material under different voltage, light, and temperature driving are as Figure 3 shown. When no stimuli such as electricity, light, and heat are applied, the phen-Vio[ClI] device is orange and emits yellow light. After applying a voltage of -1.2 to -2.2 V and irradiating with light of 365 nm wavelength, the phen-Vio[ClI] device turns blue and emits orange light. In this state, by applying a reverse voltage of 0 to 1.2 V, light of 620 nm wavelength, and a temperature of 75 °C, the color and luminescence color of the phen-Vio[ClI] device can be restored to the initial state, showing good reversibility.

[0067] Test Example 5: Cyclic voltammetry test of the multifunctional device prepared with phen-Vio[ClI] as the active material

[0068] The cyclic voltammetry test of the phen-Vio[ClI] device adopts a two-electrode system. The alligator clip of the working electrode is clamped on one conductive electrode of the device, and the alligator clips of the counter electrode and reference electrode are clamped on the other conductive electrode of the device to test its cyclic voltammogram at different scan rates. The solution-type cyclic voltammogram of phen-Vio[ClI] is as Figure 4 shown. It can be seen from the figure that the reversible oxidation-reduction peaks near 0 V belong to the oxidation of halogen counter anions. Comparing Figure 2aIt can be seen that the other two pairs of reversible oxidation-reduction peaks are caused by the successive gain of one electron by the viologen skeleton in phen-Vio[ClI] to generate its radical cation substance and neutral substance respectively. Moreover, as the scan rate increases, the oxidation peak and reduction peak shift in the direction of increasing potential respectively and both exhibit good peak shapes, indicating that the device has excellent stability. In addition, the oxidation-reduction potential of the viologen skeleton corresponds to the driving voltage (about ±1.8 V) of the multifunctional device, proving that the electrochromic, electrochemiluminescence color-changing, photochromic, and photoluminescence color-changing properties of phen-Vio[ClI] originate from the reversible oxidation-reduction reaction of the viologen skeleton. Moreover, the two relatively close oxidation-reduction potentials enable the multifunctional device to exhibit only reversible changes between two states.

[0069] Test Example 6: Measurement of Absorption and Emission Curves of phen-Vio[ClI] Device at Different Voltages

[0070] To explore in detail the electrochromic and electrochemiluminescence color-changing phenomena of the above-mentioned phen-Vio[ClI] device, we measured the absorption and emission spectra of the phen-Vio[ClI] device at different voltages. As can be seen from the absorption spectrum, as Figure 5a shown, at 0 V, the device has a broad absorption peak in the range of 300 - 700 nm; as the applied voltage increases from -1.2 V to -2.2 V, two new absorption peaks appear at 500 - 800 nm in the device, which is attributed to the generation of radical cation substance by phen-Vio[ClI] gaining one electron. As Figure 5b shown, when a reverse voltage of 0 - 1.2 V is applied, the absorption spectrum returns to the initial state, indicating the good reversibility of the electrochromism of the device. As can be seen from the emission spectrum, as Figure 5c shown, at 0 V, the device has an emission peak at about 520 nm; Figure 5c shown, as the applied voltage increases from -1.2 V to -2.2 V, the emission peak gradually redshifts to about 590 nm, and the luminescence intensity also gradually decreases, which is also caused by the generation of radical cation substance by phen-Vio[ClI] gaining one electron. Figure 5d shown, when a reverse voltage of 0 - 1.2 V is applied, the emission spectrum returns to the initial state, indicating the good reversibility of the electrochemiluminescence color-changing of the device.

[0071] Test Example 7: Measurement of Absorption and Emission Curves of phen-Vio[ClI] Device under Different Illumination and Temperatures

[0072] To explore in detail the photochromic, photoluminescence color-changing, thermochromic, and thermoluminescence color-changing phenomena of the above-mentioned phen-Vio[ClI] device, we measured the absorption and emission spectra of the phen-Vio[ClI] device under different illumination and temperatures. As can be seen from the absorption spectrum, asFigure 6a As shown, when not irradiated by light, the device has a broad absorption peak at 300 - 700 nm; after irradiating with 365 nm light for 8 min, the absorption curve no longer changes. At this time, as Figure 6a shown, two new absorption peaks appear at 500 - 800 nm in the device, which is attributed to the formation of a radical cation substance by phen-Vio[ClI] gaining one electron. In this state, as Figure 6b shown, heating the device at 75 °C for 2 min or as Figure 6c shown, irradiating the device with 620 nm light for 7 min, its absorption spectrum returns to the initial state, indicating good reversibility of the device's photochromism. From the emission spectrum, as Figure 6d shown, when not irradiated by light, the device has an emission peak at about 520 nm. After irradiating with 365 nm light for 8 min, the emission peak gradually redshifts to about 590 nm, and the emission intensity also gradually decreases. This is also caused by the formation of a radical cation substance by phen-Vio[ClI] gaining one electron. As Figure 6e shown, heating the device at 75 °C for 2 min or as Figure 6f shown, irradiating the device with 620 nm light for 7 min, the absorption spectrum returns to the initial state, indicating good reversibility of the device's photoluminescence color change and thermoluminescence color change.

[0073] Test Example 8: Preparation of Anti-counterfeiting Ink and Printing Paper

[0074] Dissolve 20 mg of Phen-Vio[ClI] in 2 mL of DMF to prepare a Phen-Vio[ClI]-DMF solution with a concentration of 10 mg·mL -1 ; dissolve 75 mg of the polymer polyvinyl alcohol type 124 in 15 mL of deionized water to prepare a PVA-H2O solution with a concentration of 5 mg·mL -1 ; take 1 mL of the Phen-Vio[Cl I]-DMF solution and add it to 1 mL of the PVA-H2O solution, stir evenly to obtain the anti-counterfeiting ink. Dissolve polyethylene glycol (M n = 8000, 1350 mg) in dichloromethane (15 mL) to prepare a PEG-DCM solution with a concentration of 90 mg·mL -1 ; then use a dropper to drop the solution onto A4-sized sketch paper and dry it in a room-temperature environment to obtain the printing paper.

[0075] Test Example 9: Demonstration Experiment of phen-Vio[ClI] in Anti-counterfeiting Application

[0076] Using the mixed solution of phen-Vio[ClI], polyvinyl alcohol and deionized water in Test Example 8 as the ink, and the sketch paper coated with ethylene glycol as the printing paper, various patterns were printed using a commercial printer. As Figure 7 shown, taking the printed QR code as an example, initially, the light yellow QR code could not be recognized by the mobile phone, but it showed yellow-green fluorescence under the irradiation of a 365 nm ultraviolet lamp and could be recognized by the mobile phone. When exposed to 365 nm ultraviolet light for 10 s, the QR code changed from light yellow to green, and its fluorescence changed from bright yellow-green to dark yellow. At this time, the QR code was clearly visible and could be easily recognized by the mobile phone. Next, after heating at 75 °C for 2 min, the QR code and its luminescence returned to the initial state. After irradiation with a 365 nm ultraviolet lamp, the QR code turned green and showed dark yellow emission and could be recognized by the mobile phone again. These results indicate that such novel viologen derivatives can be used in an anti-counterfeiting printing system based on the "write-erase-write" concept, which can not only encrypt and decrypt security and confidential documents, but also reduce the negative impact on the environment caused by paper production and consumption.

Claims

1. A class of multi-stimulus responsive viologen derivatives, characterized in that, The chemical structural formula of the viologen derivative phen-Vio[X1 X2] is as follows: ； Among them, X1 - is Cl - , X2 - is I - ; R is methyl 2. The preparation method of a class of multiple-stimulus-responsive viologen derivatives according to claim 1, characterized in that, The synthetic route of the preparation method is as follows: ； The specific steps of the preparation method include: reacting compound 1 with the asymmetric pyridinium salt intermediate 2 to obtain compound 3; and performing a nucleophilic substitution reaction on compound 3 with an iodide salt to obtain the viologen derivative phen-Vio[X1 X2].

3. The preparation method according to claim 2, characterized in that, The specific synthesis steps of the viologen derivative are as follows: (1) Preparation of compound 3: Compound 1 and compound 2 are refluxed in a mixed solvent of alcohol and deionized water for 24 - 84 h; cooled to room temperature, the solvent is removed by rotary evaporation, a small amount of alcohol is added to completely dissolve the solid, and then a large amount of ethyl acetate and acetone are added for precipitation, filtered, and washed three times with a mixed solvent of ethyl acetate and acetone to obtain compound 3; (2) Preparation of the viologen derivative phen-Vio[X1 X2]: Compound 3 reacts with an iodide salt in an atmosphere of nitrogen in solvents of acetonitrile, alcohol, DMSO, and DMF at 40 - 50 °C for 12 - 36 h; after the reaction is completed, the solvent is removed by rotary evaporation, and the product is washed three times with a mixed solvent of ethyl acetate and acetone to obtain compound phen-Vio[X1 X2].

4. Application of the viologen derivative according to claim 1 as an active material for various optoelectronic devices, wherein the various optoelectronic devices include electrochromic / electroluminescent color-changing devices, photochromic / photoluminescent color-changing devices, or thermochromic / thermoluminescent color-changing devices.

5. The application according to claim 4, characterized in that, The application includes: using the above-mentioned viologen derivative phen-Vio[X1X2] as an active material, doping an imidazolium salt and a polymer electrolyte in a suitable solvent to prepare a homogeneous electrolyte solution at room temperature in air, and assembling it with two conductive electrodes to prepare an optical device, wherein the suitable solvent is any one of DMF, acetonitrile, DMSO, or acetone; the polymer electrolyte is any one of polyvinylidene fluoride, vinylidene fluoride - hexafluoropropylene copolymer, polymethyl methacrylate, polyethylene oxide, polyacrylonitrile, polypropylene oxide, or polyvinylidene chloride.

6. The application according to claim 5, characterized in that The conductive electrodes are two pieces of ITO glass.

7. The application according to claim 5, characterized in that, The electrolyte is poly(vinylidene fluoride - co - hexafluoropropylene) and 1 - ethyl - 3 - methylimidazolium bis(trifluoromethylsulfonyl)imide, and the mass ratio of poly(vinylidene fluoride - co - hexafluoropropylene), 1 - ethyl - 3 - methylimidazolium bis(trifluoromethylsulfonyl)imide, and Vio - X is set to 8 : 72 :

3.

8. Application of the viologen derivative according to claim 1 as an information anti - counterfeiting material.

9. The application according to claim 8, wherein The specific application methods include: dissolving phen-Vio[X1 X2] in DMF to prepare a phen-Vio[X1 X2]-DMF solution with a concentration of 10 mg·mL -1 ; dissolving polyvinyl alcohol type 124 in deionized water to prepare a PVA-H2O solution with a concentration of 5 mg·mL -1 ; mixing equal volumes of the phen-Vio[X1 X2]-DMF solution and the PVA-H2O solution, and stirring evenly to obtain the anti-counterfeiting ink; dissolving polyethylene glycol with a molecular weight of M n = 8000 in dichloromethane to prepare a PEG-DCM solution with a concentration of 90 mg·mL -1 ; then dropping and coating it on drawing paper, and drying it in a room temperature environment to obtain printing paper as the anti-counterfeiting carrier; using the above anti-counterfeiting ink and using the drawing paper coated with the above polyethylene glycol as the printing paper, and directly printing with a commercial printer to obtain a print of a preset anti-counterfeiting pattern; irradiating the preset anti-counterfeiting pattern with a 365 nm ultraviolet lamp, and a recognizable yellow-green fluorescence can be displayed and can be recognized by a mobile phone; when exposed to 365 nm ultraviolet light for 10 s, the preset anti-counterfeiting pattern changes from light yellow to green, and its fluorescence changes from bright yellow-green to dark yellow. At this time, the preset anti-counterfeiting pattern is clearly visible and can be easily recognized; next, after heating at 75 °C for 2 min, the preset anti-counterfeiting pattern and its luminescence return to the initial unrecognizable state.

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