Transparent-red changing viologen derivative as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of electrochromic materials, and discloses a transparent-red changing viologen derivative as well as a preparation method and application thereof. The preparation method of the transparent-red changing viologen derivative comprises the following steps: reacting 1, 2-bis (4-pyridyl) ethylene, a bromine substitute 1 and a solvent to obtain an intermediate product; reacting the intermediate product, a bromine substitute 2 and a solvent to obtain an intermediate; and mixing the intermediate, halogen-containing salt and water, and reacting to obtain the transparent-red variable viologen derivative. The obtained transparent-red changing viologen derivative shows reversible electrochemical oxidation-reduction properties, meanwhile, shows high contrast ratio and has good electrochromic performance, the synthesis method of the viologen derivative is simple, the yield is high, the color range of viologen compounds is enriched, and the application prospect is wide. The method has potential application prospects in the field of electrochromism.

Description

Technical Field

[0001] The invention relates to the technical field of electrochromic materials, and in particular to a transparent-red changing viologen derivative and a preparation method and application thereof. Background Art

[0002] Electrochromism refers to the reversible change of the optical properties (absorption, reflectivity and transmittance) of a material under different voltages, which is manifested as a reversible change in the color of the material on a macro scale. Electrochromism technology has a very broad application prospect and has been applied to smart windows, anti-glare rearview mirrors for cars, electronic paper and military camouflage.

[0003] Viologen (1,1'-disubstituted-4,4'-bipyridine) is a common organic small molecule compound with a bipyridine molecular structure. It shows obvious color changes under voltage drive, has good optical contrast, high coloring efficiency and redox stability. As an organic photoelectric functional material, it is widely used in the field of electrochromism. As an electron-deficient material, the transfer of electrons within the molecule causes the color change of viologens, which specifically includes three different states, namely neutral state, monovalent cationic state and divalent cationic state. Viologen shows different colors in different states. Among them, the divalent cationic state is the stable state of viologens. Because there is no photocharge transfer caused by anions, the viologens in this state are highly transparent and do not show color. When under negative voltage, the viologens compound first obtains an electron, begins to be reduced and colored; after obtaining two electrons, the viologens compound is completely reduced and shows another color.

[0004] At present, viologens in the reduced state generally appear purple and blue, with relatively single color types. Studies have found that the color display of viologens is related to the type of substituents. By modifying the N position of viologens and inserting a conjugated structure in the middle of the bipyridine ring of viologens, a variety of different colors can be obtained, and the rich color range is conducive to the expansion of the application field of viologens.

[0005] Therefore, it is of great significance to study and obtain a transparent-red changing viologen derivative with obvious color contrast and good electrochromic performance and a preparation method thereof. Summary of the invention

[0006] In view of this, the present invention provides a transparent-red changing viologen derivative and its preparation method and application, the purpose of which is to solve the problems of existing viologen compounds showing a single color, unclear contrast and poor electrochromic performance.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] The present invention provides a transparent-red-changing viologen derivative, the structural formula of the transparent-red-changing viologen derivative is shown in Formula I:

[0009]

[0010] Among them, X- is I-, Br - 、Cl-、ClO4 - 、BF4 - PF6 - or TFSI-;

[0011] The R1 and R2 are independently C1-C50 chain alkyl, C1-C50 cycloalkyl, C1-C50 polycycloalkyl, C1-C50 heterocycloalkyl, C1-C50 aryl, C1-C50 alkaryl, C1-C50 aralkyl, C1-C50 alkoxy, C1-C50 alkenyl or C1-C50 alkynyl.

[0012] The present invention also provides a method for preparing the transparent-red-changing viologen derivative, comprising the following steps:

[0013] (1) reacting 1,2-di(4-pyridyl)ethylene, bromine-substituted product 1 and a solvent to obtain an intermediate product;

[0014] (2) reacting the intermediate product, the bromine-substituted product 2 and a solvent to obtain an intermediate;

[0015] (3) The intermediate, the halogen-containing salt and water are mixed and reacted to obtain a viologen derivative that changes from transparent to red.

[0016] Preferably, the bromine substituent 1 and the bromine substituent 2 are independently one or more of C1-C50 chain alkyl bromides, C1-C50 cycloalkyl bromides, C1-C50 polycyclic alkyl bromides, C1-C50 heterocyclic alkyl bromides, C1-C50 aryl bromides, C1-C50 alkylaryl bromides, C1-C50 aralkyl bromides, C1-C50 alkoxy bromides, C1-C50 alkenyl bromides and C1-C50 alkynyl bromides.

[0017] Preferably, the solvent in step (1) and step (2) is acetonitrile;

[0018] In step (1), the ratio of 1,2-di(4-pyridyl)ethylene to the solvent is 1 g:9-13 mL;

[0019] In step (2), the ratio of the intermediate product to the solvent is 1 g: 5 to 13 mL.

[0020] Preferably, the molar ratio of the 1,2-di(4-pyridyl)ethylene to the bromine substituted product 1 is 1:3-5;

[0021] The molar ratio of the intermediate product to the bromine-substituted product 2 is 1:3-5.

[0022] Preferably, the reaction temperature in step (1) is 65 to 90° C., and the reaction time is 10 to 30 hours;

[0023] The reaction temperature in step (2) is 65-90° C., and the reaction time is 10-30 h.

[0024] Preferably, the halogen-containing salt in step (3) includes iodine salt, bromide salt, chloride salt, perchlorate salt, fluoroborate salt, hexafluorophosphate salt or bis(trifluoromethanesulfonyl)imide salt.

[0025] Preferably, in step (3), the molar ratio of the intermediate to the halogen-containing salt is 2.5-3.5:6; and the dosage ratio of the intermediate to water is 1 g:60-82 mL.

[0026] Preferably, the reaction in step (3) is carried out in an ultrasonic environment, the reaction time is 10 to 20 minutes, and the ultrasonic power is 260 to 340W.

[0027] The present invention also provides application of the transparent-red changing viologen derivative in electrochromic materials.

[0028] It can be seen from the above technical solutions that, compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The present invention synthesizes a novel electrochromic material of a viologen derivative by modifying the N position of viologen and inserting a conjugated structure in the middle of the bipyridine ring of viologen. The electrochromic material of the viologen derivative prepared by the present invention is in a highly transparent state in a neutral state. When an external voltage is applied to -0.5V, the absorption peak value rises significantly and is red in a reduced state; and when the voltage is reduced, the color gradually changes from red to a transparent state.

[0030] (2) The transparent-red changing viologen derivative of the present invention exhibits reversible electrochemical redox properties and, at the same time, exhibits a high contrast ratio and has good electrochromic performance.

[0031] (3) The synthesis method of the transparent-red changing viologen derivative of the present invention is simple and has a high yield, which enriches the color range of viologen compounds and has potential application prospects in the field of electrochromism. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0033] Figure 1 Cyclic voltammetry curves of Application Example 1 at different scanning speeds;

[0034] Figure 2 The UV-visible absorption spectra of Application Example 1 at different voltages;

[0035] Figure 3 Cyclic voltammetry curves of Application Example 2 at different scanning speeds;

[0036] Figure 4 The UV-visible absorption spectra of Application Example 2 at different voltages;

[0037] Figure 5 Cyclic voltammetry curves of Application Example 3 at different scanning speeds;

[0038] Figure 6 The UV-visible absorption spectra of Application Example 3 at different voltages. DETAILED DESCRIPTION

[0039] The present invention provides a transparent-red-changing viologen derivative, the structural formula of the transparent-red-changing viologen derivative is shown in Formula I:

[0040]

[0041] Among them, X - For I - Br - , Cl - 、ClO4 - 、BF4 - PF6 - or TFSI - ;

[0042] The R1 and R2 are independently C1-C50 chain alkyl, C1-C50 cycloalkyl, C1-C50 polycycloalkyl, C1-C50 heterocycloalkyl, C1-C50 aryl, C1-C50 alkaryl, C1-C50 aralkyl, C1-C50 alkoxy, C1-C50 alkenyl or C1-C50 alkynyl.

[0043] The present invention also provides a method for preparing the transparent-red-changing viologen derivative, comprising the following steps:

[0044] (1) reacting 1,2-di(4-pyridyl)ethylene, bromine-substituted product 1 and a solvent to obtain an intermediate product;

[0045] (2) reacting the intermediate product, the bromine-substituted product 2 and a solvent to obtain an intermediate;

[0046] (3) The intermediate, the halogen-containing salt and water are mixed and reacted to obtain a viologen derivative that changes from transparent to red.

[0047] In the present invention, the bromine substituted product 1 and the bromine substituted product 2 are preferably independently one or more of C1-C50 chain alkyl bromides, C1-C50 cycloalkyl bromides, C1-C50 polycyclic alkyl bromides, C1-C50 heterocyclic alkyl bromides, C1-C50 aryl bromides, C1-C50 alkylaryl bromides, C1-C50 aralkyl bromides, C1-C50 alkoxy bromides, C1-C50 alkenyl bromides and C1-C50 alkynyl bromides.

[0048] In the present invention, the solvent in step (1) and step (2) is preferably acetonitrile;

[0049] In step (1), the ratio of 1,2-di(4-pyridyl)ethylene to the solvent is preferably 1 g:9-13 mL, more preferably 1 g:9.5-12 mL, and more preferably 1 g:10-11 mL;

[0050] In step (2), the ratio of the intermediate product to the solvent is preferably 1 g: 5 to 13 mL, more preferably 1 g: 6 to 12 mL, and even more preferably 1 g: 8 to 10 mL.

[0051] In the present invention, the molar ratio of the 1,2-di(4-pyridyl)ethylene to the bromine-substituted product 1 is preferably 1:3-5, more preferably 1:3.5-4.5, and more preferably 1:3.8-4;

[0052] The molar ratio of the intermediate product to the bromine-substituted product 2 is preferably 1:3-5, more preferably 1:3.5-4.5, and even more preferably 1:3.8-4.

[0053] In the present invention, the reaction temperature in step (1) is preferably 65 to 90° C., more preferably 68 to 85° C., more preferably 70 to 80° C., and the reaction time is preferably 10 to 30 h, more preferably 15 to 25 h, more preferably 18 to 22 h;

[0054] The reaction temperature in step (2) is preferably 65 to 90° C., more preferably 68 to 85° C., more preferably 70 to 80° C., and the reaction time is preferably 10 to 30 h, more preferably 15 to 25 h, more preferably 18 to 22 h.

[0055] In the present invention, the reaction temperature in step (1) determines the yield of the intermediate product. When the reaction temperature is higher than 90°C, 1,2-di(4-pyridyl)ethylene and the bromine substituent 1 will undergo dibromo substitution to produce a dibromo substituent, thereby reducing the yield of the intermediate product, thereby affecting the yield of the intermediate and ultimately affecting the yield of the viologen derivative.

[0056] In the present invention, when the bromine substituted product 1 is the same as the bromine substituted product 2, step (1) and step (2) are preferably: reacting 1,2-di(4-pyridyl)ethylene, the bromine substituted product and a solvent to obtain an intermediate; wherein the amount ratio of 1,2-di(4-pyridyl)ethylene to the solvent is preferably 1 g:11 to 13 mL, more preferably 1 g:11.5 to 12.5 mL, more preferably 1 g:12 to 12.2 mL, and the molar ratio of the 1,2-di(4-pyridyl)ethylene to the bromine substituted product is preferably 1:3 to 5, more preferably 1:3.5~4.5, more preferably 1:3.8~4, the reaction temperature is preferably 65~90°C, more preferably 70~85°C, more preferably 75~80°C, the reaction time is preferably 10~15h, more preferably 11~14h, more preferably 12~13h; when the reaction temperature is less than 65°C, 1,2-di(4-pyridyl)ethylene and the bromide will undergo monobromo substitution to produce a monobromo substitution product, thereby resulting in a decrease in the yield of the intermediate, thereby affecting the yield of the transparent-red change viologen derivative.

[0057] In the present invention, after the reaction in step (1) is completed, post-treatment is performed to obtain an intermediate product, and the post-treatment is to place the obtained substance in a rotary evaporator after the reaction is completed, evaporate the solvent to obtain a solid, and wash and dry the solid in sequence; wherein the temperature of the rotary evaporator is preferably 55-65°C, more preferably 57-63°C, more preferably 60-62°C, the rotary evaporation time is preferably 8-12min, more preferably 9-11min, more preferably 10min, the washing reagent is preferably ether, the number of washings is preferably 3-5 times, more preferably 4 times, and the drying time is preferably 22-26h, more preferably 23-25h, more preferably 24h.

[0058] In the present invention, after the reaction in step (2) is completed, post-treatment is performed to obtain an intermediate, and the post-treatment is to separate, wash and dry the obtained substance in sequence after the reaction is completed; wherein, separation is preferably performed by vacuum filtration, the washing reagent is preferably acetonitrile or acetone, the number of washings is preferably 3 to 5 times, more preferably 4 times, and the drying time is preferably 22 to 26 hours, more preferably 23 to 25 hours, and more preferably 24 hours.

[0059] In the present invention, the halogen-containing salt in step (3) preferably includes iodine salt, bromide salt, chloride salt, perchlorate salt, fluoroborate salt, hexafluorophosphate salt or bis(trifluoromethanesulfonyl)imide salt.

[0060] In the present invention, the molar ratio of the intermediate to the halogen-containing salt in step (3) is preferably 2.5 to 3.5:6, more preferably 2.6 to 3.2:6, and more preferably 2.8 to 3:6; the amount ratio of the intermediate to water is preferably 1 g:60 to 82 mL, more preferably 1 g:65 to 78 mL, and more preferably 1 g:70 to 75 mL.

[0061] In the present invention, the reaction in step (3) is preferably carried out in an ultrasonic environment, the reaction time is preferably 10 to 20 min, more preferably 12 to 18 min, more preferably 14 to 16 min, and the ultrasonic power is preferably 260 to 340 W, more preferably 270 to 330 W, more preferably 280 to 300 W.

[0062] In the present invention, after the reaction in step (3) is completed, post-treatment is performed to obtain a transparent-red violacein derivative, and the post-treatment is to separate, wash and dry the obtained substance in sequence after the reaction is completed; wherein, separation is preferably performed by vacuum filtration, the washing reagent is preferably water, the number of washings is preferably 3 to 5 times, more preferably 4 times, and the drying time is preferably 22 to 26 hours, more preferably 23 to 25 hours, and more preferably 24 hours.

[0063] The present invention also provides application of the transparent-red changing viologen derivative in electrochromic materials.

[0064] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0065] Example 1

[0066] Prepare a transparent-red-changing viologen derivative as shown in formula II;

[0067]

[0068] 30 mmol of 1,2-di(4-pyridyl)ethylene, 90 mmol of bromopropane and 50 mL of acetonitrile were mixed and refluxed at 65°C for 12 h. After the reaction was completed, the obtained substance was placed in a rotary evaporator and rotary evaporated at 60°C for 10 min to remove the acetonitrile. The remaining solid was then washed with ether for 3 times, and the obtained solid was dried for 24 h to obtain the intermediate product represented by formula III, with a yield of 75.9%;

[0069]

[0070] 30 mmol of the intermediate product, 90 mmol of 1-bromo-3-methylbutane and 50 mL of acetonitrile were mixed and refluxed at 80°C for 12 h. After the reaction was completed, the obtained product was separated by vacuum filtration to obtain a brown-yellow solid. The obtained solid was washed with acetone for 3 times and then dried for 24 h to obtain the intermediate of formula IV with a yield of 83.2%;

[0071]

[0072] 2.5 mmol of the intermediate, 6 mmol of lithium bis(trifluoromethanesulfonyl)imide and 80 mL of water were mixed and placed in an ultrasonic cleaner for ultrasonication at a frequency of 300 W for 10 min. After the reaction was completed, the product was separated by vacuum filtration to obtain a white solid. The solid was washed three times with water and then dried for 24 hours to obtain a transparent-red viologen derivative shown in formula II, with a yield of 79%.

[0073] Example 2

[0074] Prepare a transparent-red-changing viologen derivative as shown in Formula V;

[0075]

[0076]

[0077] 30 mmol of 1,2-di(4-pyridyl)ethylene, 90 mmol of methyl bromide and 50 mL of acetonitrile were mixed and refluxed at 65°C for 12 h. After the reaction was completed, the obtained substance was placed in a rotary evaporator and rotary evaporated at 60°C for 10 min to remove the acetonitrile. The remaining solid was then washed with ether for 3 times, and the obtained solid was dried for 24 h to obtain the intermediate product represented by formula VI, with a yield of 80.9%;

[0078]

[0079] 30 mmol of the intermediate product, 90 mmol of n-butyl bromide and 50 mL of acetonitrile were mixed and refluxed at 80°C for 12 h. After the reaction was completed, the obtained product was separated by vacuum filtration to obtain a brown-yellow solid. The obtained solid was washed with acetone for 3 times and then dried for 24 h to obtain the intermediate represented by formula VII. The yield was 81.5%;

[0080]

[0081] 2.5 mmol of the intermediate, 6 mmol of lithium perchlorate and 80 mL of water were mixed and placed in an ultrasonic cleaner for ultrasonication at a frequency of 300 W for 10 min. After the reaction was completed, the product was separated by vacuum filtration to obtain a white solid. The solid was washed three times with water and then dried for 24 hours to obtain a transparent-red violacein derivative shown in formula V, with a yield of 76%.

[0082] Example 3

[0083] Prepare a transparent-red-changing viologen derivative as shown in Formula VIII;

[0084]

[0085] 30 mmol of 1,2-di(4-pyridyl)ethylene, 90 mmol of benzyl bromide and 50 mL of acetonitrile were mixed and refluxed at 80° C. for 12 h. After the reaction was completed, the obtained product was separated by vacuum filtration to obtain a brown-yellow solid. The obtained solid was washed with acetone for 3 times and then dried for 24 h to obtain the intermediate represented by formula IX with a yield of 82.7%;

[0086]

[0087] 2.5 mmol of the intermediate, 6 mmol of potassium hexafluorophosphate and 80 mL of water were mixed and placed in an ultrasonic cleaner for ultrasonication at a frequency of 300 W for 10 min. After the reaction was completed, the product was separated by vacuum filtration to obtain a white solid. The solid was washed three times with water and then dried for 24 hours to obtain a transparent-red violacein derivative shown in formula VIII with a yield of 84%.

[0088] Example 4

[0089] The “80° C. reflux for 12 h” in Example 3 was modified to “70° C. reflux for 12 h”. The other steps were the same as in Example 3. The yield of the intermediate represented by Formula IX was calculated to be 70.2%.

[0090] Example 5

[0091] The “80° C. reflux for 12 h” in Example 3 was modified to “75° C. reflux for 12 h”, and the other steps were the same as in Example 3. The yield of the intermediate represented by Formula IX was calculated to be 75.2%.

[0092] Example 6

[0093] The step "mix 2.5 mmol of the intermediate, 6 mmol of lithium bis(trifluoromethanesulfonyl)imide and 80 mL of water" in Example 1 was modified to "mix 2.5 mmol of the intermediate, 5 mmol of lithium bis(trifluoromethanesulfonyl)imide and 80 mL of water", and the other steps were the same as in Example 1. The yield of the transparent-red-changing viologen derivative shown in Formula II was calculated to be 73.2%.

[0094] Example 7

[0095] The step "mix 2.5 mmol of the intermediate, 6 mmol of lithium perchlorate and 80 mL of water" in Example 2 was modified to "mix 2.5 mmol of the intermediate, 5 mmol of lithium perchlorate and 80 mL of water", and the other steps were the same as in Example 2. The yield of the transparent-red-changing viologen derivative shown in Formula V was calculated to be 76.5%.

[0096] Example 8

[0097] The phrase "mix 2.5 mmol of the intermediate, 6 mmol of potassium hexafluorophosphate and 80 mL of water" in Example 3 was modified to "mix 2.5 mmol of the intermediate, 5 mmol of potassium hexafluorophosphate and 80 mL of water", and the other steps were the same as in Example 3. The yield of the transparent-red-changing viologen derivative shown in Formula VIII was calculated to be 71.2%.

[0098] Example 9

[0099] 30 mmol of 1,2-di(4-pyridyl)ethylene, 90 mmol of bromoethane and 50 mL of acetonitrile were mixed and refluxed at 65°C for 12 h. After the reaction was completed, the obtained substance was placed in a rotary evaporator and rotary evaporated at 60°C for 10 min to remove the acetonitrile. The remaining solid was then washed with ether for 3 times, and the obtained solid was dried for 24 h to obtain an intermediate product.

[0100] 30 mmol of the intermediate product, 90 mmol of methyl bromide and 50 mL of acetonitrile were mixed and refluxed at 80°C for 12 h. After the reaction was completed, the obtained product was separated by vacuum filtration to obtain a brown-yellow solid. The obtained solid was washed three times with acetone and then dried for 24 h to obtain an intermediate.

[0101] 2.5 mmol of the intermediate, 6 mmol of potassium hexafluorophosphate and 80 mL of water were mixed and placed in an ultrasonic cleaner at a frequency of 300 W for 10 min. After the reaction was completed, the product was separated by vacuum filtration to obtain a white solid. The solid was washed three times with water and then dried for 24 hours to obtain a transparent-red violacein derivative with a yield of 72.8%.

[0102] Example 10

[0103] 30 mmol 1,2-di(4-pyridyl)ethylene, 90 mmol 1-bromo-3-methyl-2-butene and 50 mL acetonitrile were mixed and refluxed at 80°C for 12 h. After the reaction was completed, the obtained product was separated by vacuum filtration to obtain a brown-yellow solid. The obtained solid was washed with acetone for 3 times and then dried for 24 h to obtain an intermediate.

[0104] 2.5 mmol of the intermediate, 6 mmol of lithium bis(trifluoromethanesulfonyl)imide and 80 mL of water were mixed and placed in an ultrasonic cleaner for ultrasonication at a frequency of 300 W for 10 min. After the reaction was completed, the product was separated by vacuum filtration to obtain a white solid. The solid was washed three times with water and then dried for 24 hours to obtain a transparent-red viologen derivative with a yield of 83.2%.

[0105] Embodiment 11

[0106] 30 mmol 1,2-di(4-pyridyl)ethylene, 90 mmol bromopropane and 50 mL acetonitrile were mixed and refluxed at 80°C for 12 h. After the reaction was completed, the obtained product was separated by vacuum filtration to obtain a brown-yellow solid. The obtained solid was washed three times with acetone and then dried for 24 h to obtain an intermediate.

[0107] 2.5 mmol of the intermediate, 6 mmol of potassium hexafluorophosphate and 80 mL of water were mixed and placed in an ultrasonic cleaner at a frequency of 300 W for 10 min. After the reaction was completed, the product was separated by vacuum filtration to obtain a white solid. The solid was washed three times with water and then dried for 24 hours to obtain a transparent-red violacein derivative with a yield of 84.2%.

[0108] Example 12

[0109] 30 mmol of 1,2-di(4-pyridyl)ethylene, 90 mmol of n-butyl bromide and 50 mL of acetonitrile were mixed and refluxed at 65°C for 12 h. After the reaction was completed, the obtained substance was placed in a rotary evaporator and rotary evaporated at 60°C for 10 min to remove the acetonitrile. The remaining solid was then washed with ether for 3 times, and the obtained solid was dried for 24 h to obtain an intermediate product.

[0110] 30 mmol of the intermediate product, 90 mmol of bromopropane and 50 mL of acetonitrile were mixed and refluxed at 80°C for 12 h. After the reaction was completed, the obtained product was separated by vacuum filtration to obtain a brown-yellow solid. The obtained solid was washed three times with acetone and then dried for 24 h to obtain an intermediate.

[0111] 2.5 mmol of the intermediate, 6 mmol of potassium hexafluorophosphate and 80 mL of water were mixed and placed in an ultrasonic cleaner for ultrasonication at a frequency of 300 W for 10 min. After the reaction was completed, the product was separated by vacuum filtration to obtain a white solid. The solid was washed three times with water and then dried for 24 hours to obtain a transparent-red violacein derivative with a yield of 72.5%.

[0112] Embodiment 13

[0113] 30 mmol of 1,2-di(4-pyridyl)ethylene, 90 mmol of 3-bromopropylene and 50 mL of acetonitrile were mixed and refluxed at 65°C for 12 h. After the reaction was completed, the obtained substance was placed in a rotary evaporator and rotary evaporated at 60°C for 10 min to remove the acetonitrile. The remaining solid was then washed with ether for 3 times, and the obtained solid was dried for 24 h to obtain an intermediate product.

[0114] 30 mmol of the intermediate product, 90 mmol of bromopropane and 50 mL of acetonitrile were mixed and refluxed at 80°C for 12 h. After the reaction was completed, the obtained product was separated by vacuum filtration to obtain a brown-yellow solid. The obtained solid was washed three times with acetone and then dried for 24 h to obtain an intermediate.

[0115] 2.5 mmol of the intermediate, 6 mmol of lithium perchlorate and 80 mL of water were mixed and placed in an ultrasonic cleaner for ultrasonication at a frequency of 300 W for 10 min. After the reaction was completed, the product was separated by vacuum filtration to obtain a white solid. The solid was washed three times with water and then dried for 24 h to obtain a transparent-red violacein derivative with a yield of 70.5%.

[0116] Embodiment 14

[0117] 30 mmol of 1,2-di(4-pyridyl)ethylene, 90 mmol of 3-bromopropylene and 50 mL of acetonitrile were mixed and refluxed at 80°C for 12 h. After the reaction was completed, the obtained product was separated by vacuum filtration to obtain a brown-yellow solid. The obtained solid was washed three times with acetone and then dried for 24 h to obtain an intermediate.

[0118] 2.5 mmol of the intermediate, 6 mmol of lithium perchlorate and 80 mL of water were mixed and placed in an ultrasonic cleaner for ultrasonication at a frequency of 300 W for 10 min. After the reaction was completed, the product was separated by vacuum filtration to obtain a white solid. The solid was washed three times with water and then dried for 24 hours to obtain a transparent-red violacein derivative with a yield of 82.3%.

[0119] Embodiment 15

[0120] 30 mmol 1,2-di(4-pyridyl)ethylene, 90 mmol 1-bromodecane and 50 mL acetonitrile were mixed and refluxed at 80°C for 12 h. After the reaction was completed, the obtained product was separated by vacuum filtration to obtain a brown-yellow solid. The obtained solid was washed three times with acetone and then dried for 24 h to obtain an intermediate.

[0121] 2.5 mmol of the intermediate, 6 mmol of lithium bis(trifluoromethanesulfonyl)imide and 80 mL of water were mixed and placed in an ultrasonic cleaner for ultrasonication at a frequency of 300 W for 10 min. After the reaction was completed, the product was separated by vacuum filtration to obtain a white solid. The solid was washed three times with water and then dried for 24 hours to obtain a transparent-red viologen derivative with a yield of 81.4%.

[0122] Example 16

[0123] 30 mmol 1,2-di(4-pyridyl)ethylene, 90 mmol 1-bromooctadecane and 50 mL acetonitrile were mixed and refluxed at 80°C for 12 h. After the reaction was completed, the obtained product was separated by vacuum filtration to obtain a brown-yellow solid. The obtained solid was washed with acetone for 3 times and then dried for 24 h to obtain an intermediate.

[0124] 2.5 mmol of the intermediate, 6 mmol of potassium hexafluorophosphate and 80 mL of water were mixed and placed in an ultrasonic cleaner at a frequency of 300 W for 10 min. After the reaction was completed, the product was separated by vacuum filtration to obtain a white solid. The solid was washed three times with water and then dried for 24 hours to obtain a transparent-red violacein derivative with a yield of 82.4%.

[0125] Embodiment 17

[0126] 30 mmol 1,2-di(4-pyridyl)ethylene, 90 mmol 1-bromohexane and 50 mL acetonitrile were mixed and refluxed at 65°C for 12 h. After the reaction was completed, the obtained substance was placed in a rotary evaporator and rotary evaporated at 60°C for 10 min to remove the acetonitrile. The remaining solid was then washed with ether for 3 times, and the obtained solid was dried for 24 h to obtain an intermediate product.

[0127] 30 mmol of the intermediate product, 90 mmol of 2-bromohexane and 50 mL of acetonitrile were mixed and refluxed at 80° C. for 12 h. After the reaction was completed, the obtained product was separated by vacuum filtration to obtain a brown-yellow solid. The obtained solid was washed three times with acetone and then dried for 24 h to obtain an intermediate.

[0128] 2.5 mmol of the intermediate, 6 mmol of lithium bis(trifluoromethanesulfonyl)imide and 80 mL of water were mixed and placed in an ultrasonic cleaner for ultrasonication at a frequency of 300 W for 10 min. After the reaction was completed, the product was separated by vacuum filtration to obtain a white solid. The solid was washed three times with water and then dried for 24 hours to obtain a transparent-red violacein derivative with a yield of 75.4%.

[0129] Embodiment 18

[0130] 30 mmol 1,2-di(4-pyridyl)ethylene, 90 mmol 1-bromohexane and 50 mL acetonitrile were mixed and refluxed at 80°C for 12 h. After the reaction was completed, the obtained product was separated by vacuum filtration to obtain a brown-yellow solid. The obtained solid was washed three times with acetone and then dried for 24 h to obtain an intermediate.

[0131] 2.5 mmol of the intermediate, 6 mmol of lithium perchlorate and 80 mL of water were mixed and placed in an ultrasonic cleaner at a frequency of 300 W for 10 min. After the reaction was completed, the product was separated by vacuum filtration to obtain a white solid. The solid was washed three times with water and then dried for 24 hours to obtain a transparent-red violacein derivative with a yield of 85.6%.

[0132] Embodiment 19

[0133] 30 mmol 1,2-di(4-pyridyl)ethylene, 90 mmol methyl bromide and 50 mL acetonitrile were mixed and refluxed at 80°C for 12 h. After the reaction was completed, the obtained product was separated by vacuum filtration to obtain a brown-yellow solid. The obtained solid was washed three times with acetone and then dried for 24 h to obtain an intermediate.

[0134] 2.5 mmol of the intermediate, 6 mmol of lithium perchlorate and 80 mL of water were mixed and placed in an ultrasonic cleaner at a frequency of 300 W for 10 min. After the reaction was completed, the product was separated by vacuum filtration to obtain a white solid. The solid was washed three times with water and then dried for 24 hours to obtain a transparent-red violacein derivative with a yield of 82.2%.

[0135] Comparative Example 1

[0136] The “reflux at 80° C. for 12 h” in Example 3 was modified to “reflux at 60° C. for 12 h”. The other steps were the same as in Example 3. The yield of the intermediate represented by Formula IX was calculated to be 30.5%.

[0137] Comparative Example 2

[0138] The step "mix 2.5 mmol of the intermediate, 6 mmol of lithium bis(trifluoromethanesulfonyl)imide and 80 mL of water" in Example 1 was modified to "mix 2.5 mmol of the intermediate, 4 mmol of lithium bis(trifluoromethanesulfonyl)imide and 80 mL of water", and the other steps were the same as those in Example 1. The yield of the transparent-red-changing viologen derivative shown in Formula II was calculated to be 55.3%.

[0139] Comparative Example 3

[0140] The step "mix 2.5 mmol of the intermediate, 6 mmol of lithium bis(trifluoromethanesulfonyl)imide and 80 mL of water" in Example 1 was modified to "mix 2.5 mmol of the intermediate, 3 mmol of lithium bis(trifluoromethanesulfonyl)imide and 80 mL of water", and the other steps were the same as in Example 1. The yield of the transparent-red-changing viologen derivative shown in Formula II was calculated to be 45.6%.

[0141] Comparative Example 4

[0142] The step "mix 2.5 mmol of the intermediate, 6 mmol of lithium perchlorate and 80 mL of water" in Example 2 was modified to "mix 2.5 mmol of the intermediate, 4 mmol of lithium perchlorate and 80 mL of water", and the other steps were the same as in Example 2. The yield of the transparent-red-changing viologen derivative shown in Formula V was calculated to be 40.1%.

[0143] Comparative Example 5

[0144] The step "mix 2.5 mmol of the intermediate, 6 mmol of lithium perchlorate and 80 mL of water" in Example 2 was modified to "mix 2.5 mmol of the intermediate, 3 mmol of lithium perchlorate and 80 mL of water", and the other steps were the same as in Example 2. The yield of the transparent-red-changing viologen derivative shown in Formula V was calculated to be 35.6%.

[0145] Comparative Example 6

[0146] The step "mix 2.5 mmol of the intermediate, 6 mmol of potassium hexafluorophosphate and 80 mL of water" in Example 3 was modified to "mix 2.5 mmol of the intermediate, 4 mmol of potassium hexafluorophosphate and 80 mL of water", and the other steps were the same as those in Example 3. The yield of the transparent-red-changing viologen derivative shown in Formula VIII was calculated to be 56.8%.

[0147] Comparative Example 7

[0148] The step "mix 2.5 mmol of the intermediate, 6 mmol of potassium hexafluorophosphate and 80 mL of water" in Example 3 was modified to "mix 2.5 mmol of the intermediate, 3 mmol of potassium hexafluorophosphate and 80 mL of water", and the other steps were the same as in Example 3. The yield of the transparent-red-changing viologen derivative shown in Formula VIII was calculated to be 45.2%.

[0149] By comparing the yields of the transparent-red-changing viologen derivatives obtained in Example 1, Example 4, Example 5 and Comparative Example 1, it can be seen that when the reaction temperature is 70-80°C, the yield of the intermediate is greater than 70%, and the by-products are less. When the reaction temperature drops to 60°C, 1,2-di(4-pyridyl)ethylene reacts with benzyl bromide to undergo monosubstitution, resulting in a significant reduction in the yield of the intermediate, and the yield of the intermediate is greatly affected by temperature. In the preparation method of the viologen derivative provided by the present invention, the yield of the intermediate product shown in Formula IX will further affect the yield of the transparent-red-changing viologen derivative in the subsequent steps. Therefore, as a key factor in the reaction, accurately controlling the reaction temperature of 1,2-di(4-pyridyl)ethylene and the bromide is particularly important for preparing intermediates and final product viologen derivatives.

[0150] By comparing the yields of the transparent-red-changing viologen derivatives obtained in Example 1, Example 6 and Comparative Examples 2-3, it can be seen that when the lithium bistrifluoromethanesulfonyl imide is greatly excessive, the yield of the transparent-red-changing viologen derivative is greater than 70%, and when the lithium bistrifluoromethanesulfonyl imide feed is reduced, the yield of the transparent-red-changing viologen derivative is greatly reduced. It can be seen that the preparation of the transparent-red-changing viologen derivative is greatly affected by the feed ratio, and accurately controlling the feed ratio of the intermediate and the halogen-containing salt is particularly important for the preparation of the yield of the transparent-red-changing viologen derivative.

[0151] By comparing the yields of the transparent-red-changing viologen derivatives obtained in Example 2, Example 7 and Comparative Examples 4-5, it can be seen that when lithium perchlorate is greatly in excess, the yield of the transparent-red-changing viologen derivative is greater than 50%, and when the lithium perchlorate feed is reduced, the yield of the transparent-red-changing viologen derivative is greatly reduced. It can be seen that the preparation of the transparent-red-changing viologen derivative is greatly affected by the feed ratio, and accurately controlling the feed ratio of the intermediate and the halogen-containing salt is particularly important for the preparation of the yield of the transparent-red-changing viologen derivative.

[0152] By comparing the yields of the transparent-red-changing viologen derivatives obtained in Example 3, Example 8 and Comparative Examples 6-7, it can be seen that when potassium hexafluorophosphate is greatly excessive, the yield of the transparent-red-changing viologen derivative is greater than 70%, and when the potassium hexafluorophosphate feed is reduced, the yield of the transparent-red-changing viologen derivative is greatly reduced. It can be seen that the preparation of the transparent-red-changing viologen derivative is greatly affected by the feed ratio, and accurately controlling the feed ratio of the intermediate and the halogen-containing salt is particularly important for the preparation of the yield of the transparent-red-changing viologen derivative.

[0153] Application Example 1

[0154] A propylene carbonate solution of tetrabutylammonium hexafluorophosphate with a concentration of 0.1 mol / L was used as a supporting electrolyte, and the transparent-red-changing viologen derivative obtained in Example 1 was added to the supporting electrolyte to obtain an electrolyte with a transparent-red-changing viologen derivative concentration of 0.005 mol / L;

[0155] ITO conductive glass is used as a working electrode, a Pt sheet is used as a counter electrode, and Ag / AgCl is used as a reference electrode to form a three-electrode system, and the obtained electrolyte is used as the electrolyte of the three-electrode system.

[0156] Cyclic voltammetry test:

[0157] The three-electrode system was subjected to cyclic voltammetry test at different voltages. The cyclic voltammetry test voltage was -1.3 to 0 V. The scanning speeds were 0.01 V / s, 0.025 V / s, 0.05 V / s, and 0.1 V / s, respectively. The test results are shown in FIG. Figure 1 shown.

[0158] Application Example 1 Cyclic voltammetry curves at different scanning speeds are shown in Figure 1 As shown. Figure 1 It can be seen that the redox property of the transparent-red viologen derivative obtained in Example 1 is reversible and diffusion-controlled, and has good reversible redox activity.

[0159] UV absorption spectrum test:

[0160] The ultraviolet absorption spectrum of the above three-electrode system was tested by using an electrochemical workstation-ultraviolet visible spectrophotometer. The ultraviolet absorption spectrum test voltage was 0-1.2V. The test results are as follows: Figure 2 shown.

[0161] Application Example 1: UV-visible absorption spectra at different voltages Figure 2 As shown. Figure 2It can be seen that the viologen derivative is colorless and transparent in the neutral state, and the absorption peak increases with the increase of the applied negative voltage, and appears red in the reduced state; and when the voltage is reduced, the color gradually changes from red to transparent, and this cycle is repeated, showing good electrochromic properties.

[0162] Application Example 2

[0163] A propylene carbonate solution of tetrabutylammonium hexafluorophosphate with a concentration of 0.1 mol / L was used as a supporting electrolyte, and the transparent-red-changing viologen derivative obtained in Example 2 was added to the supporting electrolyte to obtain an electrolyte with a transparent-red-changing viologen derivative concentration of 0.005 mol / L;

[0164] ITO conductive glass is used as a working electrode, a Pt sheet is used as a counter electrode, and Ag / AgCl is used as a reference electrode to form a three-electrode system, and the obtained electrolyte is used as the electrolyte of the three-electrode system.

[0165] Cyclic voltammetry test:

[0166] The three-electrode system was subjected to cyclic voltammetry test at different voltages. The cyclic voltammetry test voltage was -1.3 to 0 V. The scanning speeds were 0.01 V / s, 0.025 V / s, 0.05 V / s, and 0.1 V / s, respectively. The test results are shown in FIG. Figure 3 shown.

[0167] Application Example 2 Cyclic voltammetry curves at different scanning speeds are as follows Figure 3 As shown. Figure 3 It can be seen that the redox property of the transparent-red viologen derivative obtained in Example 2 is reversible and diffusion-controlled, and has good reversible redox activity.

[0168] UV absorption spectrum test:

[0169] The ultraviolet absorption spectrum of the above three-electrode system was tested by using an electrochemical workstation-ultraviolet visible spectrophotometer. The ultraviolet absorption spectrum test voltage was 0-1.2V. The test results are as follows: Figure 4 shown.

[0170] Application Example 2: UV-Vis absorption spectra at different voltages Figure 4 As shown. Figure 4 It can be seen that the viologen derivative is colorless and transparent in the neutral state, and the absorption peak increases with the increase of the applied negative voltage, and appears red in the reduced state; and when the voltage is reduced, the color gradually changes from red to transparent, and this cycle is repeated, showing good electrochromic properties.

[0171] Application Example 3

[0172] A propylene carbonate solution of tetrabutylammonium hexafluorophosphate with a concentration of 0.1 mol / L was used as a supporting electrolyte, and the transparent-red-changing viologen derivative obtained in Example 3 was added to the supporting electrolyte to obtain an electrolyte with a transparent-red-changing viologen derivative concentration of 0.005 mol / L;

[0173] ITO conductive glass is used as a working electrode, a Pt sheet is used as a counter electrode, and Ag / AgCl is used as a reference electrode to form a three-electrode system, and the obtained electrolyte is used as the electrolyte of the three-electrode system.

[0174] Cyclic voltammetry test:

[0175] The three-electrode system was subjected to cyclic voltammetry test at different voltages. The cyclic voltammetry test voltage was -1.3 to 0 V. The scanning speeds were 0.01 V / s, 0.025 V / s, 0.05 V / s, and 0.1 V / s, respectively. The test results are shown in FIG. Figure 5 shown.

[0176] Application Example 3 Cyclic voltammetry curves at different scanning speeds are as follows Figure 5 As shown. Figure 5 It can be seen that the redox property of the transparent-red viologen derivative obtained in Example 3 is reversible and diffusion-controlled, and has good reversible redox activity.

[0177] UV absorption spectrum test:

[0178] The ultraviolet absorption spectrum of the above three-electrode system was tested by using an electrochemical workstation-ultraviolet visible spectrophotometer. The ultraviolet absorption spectrum test voltage was 0-1.2V. The test results are as follows: Figure 6 shown.

[0179] Application Example 3 UV-Vis absorption spectra at different voltages are shown in the figure below: Figure 6 As shown. Figure 6 It can be seen that the viologen derivative is colorless and transparent in the neutral state, and the absorption peak increases with the increase of the applied negative voltage, and appears red in the reduced state; and when the voltage is reduced, the color gradually changes from red to transparent, and this cycle is repeated, showing good electrochromic properties.

[0180] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A transparent-red viologen derivative, characterized in that: The structural formula of the transparent-red viologen derivative is shown in Formula I: Among them, X - For I - Br - 、Cl-、ClO4 - 、BF4 - PF6 - or TFSI - ; The R1 and R2 are independently C1-C50 chain alkyl, C1-C50 cycloalkyl, C1-C50 polycycloalkyl, C1-C50 heterocycloalkyl, C1-C50 aryl, C1-C50 alkaryl, C1-C50 aralkyl, C1-C50 alkoxy, C1-C50 alkenyl or C1-C50 alkynyl.

2. The method for preparing a transparent-red-changing viologen derivative according to claim 1, characterized in that: The steps include: (1) reacting 1,2-di(4-pyridyl)ethylene, bromine-substituted product 1 and a solvent to obtain an intermediate product; (2) reacting the intermediate product, the bromine-substituted product 2 and a solvent to obtain an intermediate; (3) The intermediate, the halogen-containing salt and water are mixed and reacted to obtain a viologen derivative that changes from transparent to red.

3. The method for preparing a transparent-red-changing viologen derivative according to claim 2, characterized in that: The bromine substituted product 1 and the bromine substituted product 2 are independently one or more of a C1-C50 chain alkyl bromide, a C1-C50 cycloalkyl bromide, a C1-C50 polycyclic alkyl bromide, a C1-C50 heterocyclic alkyl bromide, a C1-C50 aryl bromide, a C1-C50 alkylaryl bromide, a C1-C50 aralkyl bromide, a C1-C50 alkoxy bromide, a C1-C50 alkenyl bromide and a C1-C50 alkynyl bromide.

4. The method for preparing a transparent-red-changing viologen derivative according to claim 3, characterized in that: The solvent in step (1) and step (2) is acetonitrile; In step (1), the ratio of 1,2-di(4-pyridyl)ethylene to the solvent is 1 g:9-13 mL; In step (2), the ratio of the intermediate product to the solvent is 1 g: 5 to 13 mL.

5. The method for preparing a transparent-red-changing viologen derivative according to claim 2, characterized in that: The molar ratio of the 1,2-di(4-pyridyl)ethylene to the bromine substitution product 1 is 1:3-5; The molar ratio of the intermediate product to the bromine-substituted product 2 is 1:3-5.

6. The method for preparing a transparent-red-changing viologen derivative according to claim 3 or 4, characterized in that: The reaction temperature in step (1) is 65-90° C. and the reaction time is 10-30 h; The reaction temperature in step (2) is 65-90° C., and the reaction time is 10-30 h.

7. The method for preparing a transparent-red-changing viologen derivative according to claim 6, characterized in that: The halogen-containing salt in step (3) includes iodine salt, bromide salt, chloride salt, perchlorate salt, fluoroborate salt, hexafluorophosphate salt or bis(trifluoromethanesulfonyl)imide salt.

8. The method for preparing a transparent-red-changing viologen derivative according to claim 2, characterized in that: The molar ratio of the intermediate to the halogen-containing salt in step (3) is 2.5-3.5:6; the dosage ratio of the intermediate to water is 1 g: 60-82 mL.

9. The method for preparing a transparent-red-changing viologen derivative according to claim 8, characterized in that: The reaction in step (3) is carried out in an ultrasonic environment, the reaction time is 10 to 20 minutes, and the ultrasonic power is 260 to 340W.

10. Use of the transparent-red changing viologen derivative according to claim 1 in electrochromic materials.

Images