CN112409324B

CN112409324B - Visible light controlled perfluoro-substituted dithienyl vinyl compound, preparation and application thereof

Info

Publication number: CN112409324B
Application number: CN202011271951.4A
Authority: CN
Inventors: 李冲; 梅丽君; 朱明强; 曹亦闲
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2020-11-13
Filing date: 2020-11-13
Publication date: 2022-02-11
Anticipated expiration: 2040-11-13
Also published as: CN112409324A

Abstract

The invention belongs to the field of new materials, and particularly relates to a visible light controlled perfluoro-substituted dithienyl ethylene compound, and preparation and application thereof. According to the invention, through modification design of a substituent group on the perfluoro-substituted dithienyl ethylene compound, molecules absorb red shift, the dithienyl ethylene molecular switch driven by full visible light is synthesized, the fatigue resistance is improved, and the material and biological application fields of the photochromic switch are greatly expanded. In a preferred embodiment of the invention the dithienylethylene compound is in CD before and after irradiation with 405nm visible light₂Cl₂The nuclear magnetic hydrogen spectrum in the molecular switch changes, the optical isomerization rate is respectively 96% and 98%, and the triphenylamine disubstituted DTE molecular switch shows ultra-high quasi quantitative conversion capability under the excitation of visible light.

Description

Visible light controlled perfluoro-substituted dithienyl vinyl compound, preparation and application thereof

Technical Field

The invention belongs to the field of new materials, and particularly relates to a visible light controlled perfluoro-substituted dithienyl ethylene compound, and preparation and application thereof.

Background

In recent years, organic photochromic materials are used as a light-operated molecular switch, and have the advantages of being capable of being accurately and reversibly regulated and controlled on a single molecular level due to various physicochemical properties, having the ultrahigh-density information storage potential of nanometer scale and the like, and are rapidly researched and developed in the aspects of optical information electronic elements and biological imaging. The dithienyl ethylene compound has the characteristics of thermal stability, good photobleaching resistance, excellent photochromic performance in a solid medium, simple molecular structure, low synthesis cost, strong chemical designability and the like in a plurality of organic photochromic materials.

However, the conventional dithienyl ethylene optical switch uses destructive ultraviolet light source to trigger the ring-closing reaction, which severely limits the development of the conventional dithienyl ethylene optical switch in practical application. The ultraviolet light source triggers the closed-loop reaction and has the following technical defects:

(1) the ultraviolet light source has strong penetrating power, most of the medium penetrates when the research object is irradiated, and only a small part of energy is utilized, so that resource waste is caused.

(2) Meanwhile, an ultra-high-energy ultraviolet light source excites the light to react, non-radiative transition is increased, a byproduct without photochromic performance is generated, and the fatigue resistance of the molecular switch is reduced.

(3) For researchers, ultraviolet light generally damages cells, is non-selectively absorbed by any chromophore, and rapidly decays in tissues, causing unpredictable and controlled damage.

On the other hand, the dithienylethene photochromic fluorescent molecular switch in the prior art has low fatigue resistance and low open-close ring isomerization rate, and directly influences the further application performance of the switch.

Disclosure of Invention

Aiming at the defects or improvement requirements of the prior art, the invention aims to provide a visible light-regulated perfluoro-substituted dithienylethylene compound, and aims to solve the technical problems of energy waste, low molecular switch fatigue resistance and the like caused by triggering a ring-closing reaction of dithienylethylene by an ultraviolet light source in the prior art.

In order to achieve the above object, the present invention provides a perfluoro-substituted dithienylethylene compound, which is a dithienylethylene compound doubly conjugated and substituted with an arylamine group, and has a structural formula shown as formula (one) or formula (two):

wherein R is₁And R₂Each independently is C1-C10 alkyl, C1-C10 alkyl alcohol or C6-C20 aryl.

Preferably, said R is₁And R₂Each independently is C1-C5 alkyl, C1-C5 alkyl alcohol or C6-C10 aryl.

Preferably, said R is₁And R₂Each independently is methyl, ethyl, propyl, hydroxyethyl, hydroxypropyl, phenyl, tolyl, ethylphenyl, or propylphenyl.

According to another aspect of the present invention, there is provided a process for preparing said dithienylethylene compound using a compound having R in the presence of a catalyst and an organic solvent₁And R₂The aniline group or the aniline-alkynyl group carries out substitution reaction on bromine atoms in the 1, 2-bis (5-bromine-2-methylthiophene-3-yl) perfluoro cyclopentene to obtain the dithienyl ethylene compound.

Preferably, the substitution reaction is carried out under anhydrous and oxygen-free conditions with heating to 80-95 ℃.

Preferably, the catalyst is a palladium catalyst.

According to another aspect of the invention, the application of the perfluoro-substituted dithienylethylene compound in preparing a full visible light-regulated molecular switch material is provided, and the molecular switch material adopts a visible light source to trigger a ring-closing reaction of the molecular switch material.

Preferably, the molecular switching material is a photochromic molecular switching material.

Preferably, the visible light wavelength range is 405-440 nm.

Preferably, the visible light wavelength is 405 nm.

According to another aspect of the present invention, there is provided a fully visible light-regulated perfluoro-substituted dithienyl vinyl molecule switch comprising said dithienyl vinyl compound;

the molecular switch is prepared by carrying out the process of containing R on perfluoro cyclopentene dithienyl ethylene₁And R₂The aniline group or the aniline-alkynyl group is modified in a conjugated way, so that the triggering wavelength of the ring-closing reaction can be red shifted to a visible light area, and the triggering wavelength of the ring-opening reaction is in the visible light area, so that the full visible light regulation and control of the molecular switch photoisomerization reaction are realized.

Preferably, the ring-closing conversion rate of visible light triggering the ring-closing reaction of the molecular switch is higher than 98%.

Through the technical scheme, compared with the prior art, the invention can obtain the following beneficial effects:

(1) according to the invention, through modification design of a substituent group on the perfluoro-substituted dithienyl ethylene compound, molecules absorb red shift, the dithienyl ethylene molecular switch driven by full visible light is synthesized, the fatigue resistance is improved, and the material and biological application fields of the photochromic switch are greatly expanded. In addition, visible light has harmless characteristics, has absolute dominance in the solar spectrum reaching the earth surface, and the ratio of available wave bands to the full spectrum is large, thereby providing infinite possibility for related applications and technologies in the future on energy power.

(2) According to the invention, the perfluorinated cyclopentadithiophene based ethylene DTE is modified by selecting aniline groups or aniline-alkynyl groups with an electron-donating conjugation effect, the performance of the DTE is regulated, the energy gap (Eg) of the molecular switch is reduced, and the absorption red shift of the molecular switch is realized. A series of arylamine group symmetrically-substituted dithienylethylene photochromic compounds are synthesized, and photochromic performance comparison tests under different excitation wavelengths mainly based on UV-Vis absorption and photoswitch dynamics tests under the drive of full visible light are respectively carried out on the compounds, so that visible light response groups with excellent performance are obtained for the construction of a fluorescent molecular switch. Experiments show that the dithienylethylene compounds provided in the preferred embodiments of the present invention are in CD before and after 405nm visible light irradiation₂Cl₂The optical isomerization rate of the nuclear magnetic hydrogen spectrum is respectively 96 percent and 98 percent, the closed-loop isomerization rate is close to 100 percent,the aniline group disubstituted DTE molecular switch shows ultra-high quasi-quantitative conversion capability under the excitation of visible light.

(3) The dithienyl ethylene compound of the invention shows visible light photochromic performance in THF, and has quick response to 405nm visible light. The aniline group substituted dithienyl ethylene photochromic switch has excellent visible light response reversible photochromic performance, can avoid the ultraviolet light source excitation light reaction with over-high energy, increase non-radiative transition, generate a byproduct without photochromic performance and reduce the fatigue resistance of a molecular switch compared with the prior art that a destructive ultraviolet light source triggers a closed loop reaction.

(4) In the preferred embodiment of the invention, linear rigid triple bonds (triphenylamine-alkynyl) are used for increasing a pi conjugated plane and constructing a donor-acceptor (D-A) push-pull electron system, so that the basic state HOMO of a molecular switch can be raised, the energy gap (Eg) is reduced, red shift is absorbed, a dithienyl ethylene unit can be directly excited by visible light to carry out a photocyclization reaction, a group (TPA) with strong electron donating effect can be connected to prolong the pi conjugated system without reducing the excited state electron density of the active center of the photocyclization reaction, the corresponding light response speed is higher, the molar extinction coefficient is larger, and the performance of photochromic molecules is effectively improved.

Drawings

FIG. 1 is a schematic diagram of the synthetic route of a dithienylethylene compound prepared in example 1, example 2 and comparative example 1 of the present invention;

FIG. 2 is a UV absorption spectrum of a dithienylethylene compound DTE-1 prepared in example 1 of the present invention in a tetrahydrofuran solution. FIG. 2 shows (a) the spectrum of DTE-1 prepared in example 1 showing the absorption in tetrahydrofuran solution as a function of the duration of 405nm light; FIG. 2, panel (b), is a graph of the absorption of DTE-1 prepared in example 1 in tetrahydrofuran solution as a function of 621nm light exposure; FIG. 2, content (c) is a comparison of the 365nm and 405nm light absorption light steady-state PSS of DTE-1 prepared in example 1 in tetrahydrofuran solution;

FIG. 3 is a UV absorption spectrum of a dithienylethylene compound DTE-2 prepared in example 2 of the present invention in a tetrahydrofuran solution. FIG. 3 shows the spectrum of DTE-2 prepared in example 2 as a function of the time duration of 405nm light irradiation; FIG. 3, panel (b), is a graph of the absorption of DTE-2 prepared in example 2 in tetrahydrofuran solution as a function of 621nm light exposure; FIG. 3, Contents (c) is a comparison of the 365nm and 405nm light absorption light stable PSS of DTE-2 prepared in example 2 in tetrahydrofuran solution;

FIG. 4 is a UV absorption spectrum of DTE-3, a dithienylethylene compound prepared in comparative example 1 of the present invention, in a tetrahydrofuran solution. FIG. 4 shows (a) the spectrum of DTE-3 absorption in tetrahydrofuran solution as a function of 405nm illumination duration; FIG. 4 (b) is a graph showing the absorption of DTE-3 in tetrahydrofuran solution as a function of 621nm light exposure time; FIG. 4 (c) is a comparison of the 365nm and 405nm absorption light steady state PSS of DTE-3 in tetrahydrofuran solution;

FIG. 5 is a UV absorption spectrum of a dithienylethylene compound prepared in example 3 of the present invention in a tetrahydrofuran solution;

FIG. 6 shows the open-ring absorption contrast of DTE-1 to 3, which are dithienylethylene compounds prepared in example 1, example 2 and comparative example 1 of the present invention, in THF and the absorption contrast when exposed to light at 405nm to PSS. FIG. 6 shows the comparison of absorption of dithienylethylene compounds DTE-1-3 in ring-opened state in THF; FIG. 6 (b) shows the absorption contrast of DTE-1-3 under illumination of 405nm to PSS state;

FIG. 7 shows the nuclear magnetic hydrogen spectra of dithienyl vinyl compounds DTE-1 to 3 prepared in example 1, example 2 and comparative example 1 of the present invention in deuterated dichloromethane with 405nm illumination. FIG. 7 shows (a) the chemical shift region of the methyl group H on the thiophene aromatic ring in the DTE substructure of DTE-1 prepared in example 1 of the present invention; FIG. 7 (b) shows the chemical shift region of methyl H on the thiophene aromatic ring in the DTE substructure of DTE-2 prepared in example 2 of the present invention; FIG. 7 (c) is the chemical shift region of the methyl group H on the thiophene aromatic ring in the DTE substructure of DTE-3 prepared in example 3 of the present invention;

FIG. 8 shows the switching dynamics fit curves of the dithienylethylene compounds DTE-1-2 prepared in examples 1 and 2 of the present invention. FIG. 8 shows (a) the fitting of absorbance at 631nm as a function of 405nm for DTE-1 prepared in example 1 of the present invention; FIG. 8 (b) shows the fitting of absorbance at 631nm as a function of 621nm for DTE-1 prepared in example 1 of the present invention; FIG. 8, panel (c), is a plot of absorbance at 639nm as a function of 405nm for DTE-2 prepared in example 2 of the present invention; FIG. 8, panel (d), shows the absorbance at 639nm as a function of 621nm for DTE-2 prepared in example 2 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The invention provides a visible light controlled perfluoro-substituted dithienyl ethylene compound, which is an arylamine group dual-conjugate-substituted dithienyl ethylene compound and has a structural formula shown as a formula (I) or a formula (II):

As R₁And R₂The C1-C10 alkyl group is preferably a C1-C5 alkyl group, and more preferably a methyl group, an ethyl group or a propyl group.

As R₁And R₂The C1-C10 alkyl alcohol represented by the formula (I) is preferably a C1-C5 alkyl alcohol, more preferably a hydroxyethyl group, a hydroxypropyl group or the like.

As R₁And R₂The aryl group having C6-C20 as represented herein is preferably an aryl group having C6-C10, and more preferably a phenyl group, tolyl group, ethylphenyl group or propylphenyl group.

The invention also provides a preparation method of the dithienyl ethylene compound, which adopts the compound with R in the presence of a catalyst and an organic solvent₁And R₂The aniline group or the aniline-alkynyl group carries out substitution reaction on bromine atoms in 1, 2-bis (5-bromine-2-methylthiophene-3-yl) perfluoro cyclopentene (Br-DTE-Br) to obtain the compoundA dithienylethylene compound.

In some embodiments, the substitution reaction is carried out in the absence of water and oxygen, heated to 80-95 ℃.

In some embodiments, the catalyst is a palladium catalyst.

The invention has R₁And R₂The theoretical reaction molar ratio of the aniline group or the aniline-alkynyl group to Br-DTE-Br is 1:1, and the raw materials can be mixed according to the ratio and then react.

In some examples, Br-DTE-Br was prepared as follows: firstly, 3, 5-dibromo-2-methyl trypan, n-butyl lithium and trimethylchlorosilane are used as raw materials, and 3-bromo-2-methyl-5-trimethylsilyl thiophene is prepared through substitution reaction at the low temperature of-85 to-70 ℃; then 3-bromo-2-methyl-5-trimethylsilyl thiophene, n-butyllithium and perfluorocyclopentene are used as raw materials, and 1, 2-bis (2-methyl-5-trimethylsilyl thiophen-3-yl) perfluorocyclopentene is prepared by reaction at the low temperature of-85 to-70 ℃; and finally, taking 1, 2-bis (2-methyl-5-trimethylsilyl thiophen-3-yl) perfluorocyclopentene anhydrous tetrahydrofuran and NBS as raw materials, and reacting for 16 hours at room temperature in a dark place to obtain a compound, namely the 1, 2-bis (5-bromo-2-methylthiophene-3-yl) perfluorocyclopentene, namely Br-DTE-Br.

A compound of formula (I) is prepared by the following steps:

the compound shown in the formula (II) is prepared by the following steps:

as a comparative example, the present inventors also synthesized R in the compound represented by the formula (II)₁And R₂A compound corresponding to the carbazolyl group and represented by the formula (III):

the invention also provides application of the perfluoro-substituted dithienyl ethylene compound in preparation of a photochromic molecular switch material, and correspondingly provides a visible light-regulated perfluoro-substituted dithienyl ethylene molecular switch which comprises the dithienyl ethylene compound. Therefore, the photochromic performance test result, the density functional theory simulation calculation result and the photochromic switch dynamics test result of the bithienyl ethylene compound regulated and controlled by the full visible light are tested.

In the prior art, the dithienyl ethylene molecular switch adopts ultraviolet light with shorter wavelength to trigger the closed-loop reaction of the dithienyl ethylene molecular switch, and adopts visible light with longer wavelength to trigger the open-loop reaction of the dithienyl ethylene molecular switch, so that the function of the molecular switch is realized. However, the destructive ultraviolet light source triggers the ring-closing reaction, which severely limits the development of the traditional dithienyl ethylene optical switch in practical application. Therefore, the invention modifies aniline groups or aniline alkynyl groups on the perfluoro-substituted dithienyl ethylene compound, and unexpectedly finds that when the compound is used as a molecular switch, closed-loop triggering can be carried out through visible light, the closed-loop conversion rate can reach nearly 100%, and open-loop triggering can also be carried out by adopting visible light, so that the dithienyl ethylene molecular switch driven by full visible light is realized, the fatigue resistance is greatly improved, and the material and biological application fields of the photochromic switch are greatly expanded. In a preferred embodiment of the invention the dithienylethylene compound is in CD before and after irradiation with 405nm visible light₂Cl₂The nuclear magnetic hydrogen spectrum in the molecular switch changes, the optical isomerization rate is respectively 96% and 98%, and the triphenylamine disubstituted DTE molecular switch shows ultra-high quasi quantitative conversion capability under the excitation of visible light.

The following are examples:

example 1

A dithienylethylene compound shown as formula (I), the name of which is abbreviated as 2TPA-DTE, wherein R₁Is composed of

R₂Is composed of

The synthesis path is shown in fig. 1, and comprises the following steps:

under the protection of nitrogen, anhydrous K is quickly added into a double-neck flask₂CO₃4- (diphenylamine) phenylboronic acid pinaster, Br-DTE-Br and redistilled V_{Deionized water}:V_{Ethylene glycol dimethyl ether}Vacuumizing and filling nitrogen for three times, adding a palladium catalyst and a small amount of phase transfer catalyst PTC, stirring and mixing uniformly, ensuring that a reaction system is anhydrous and anaerobic, and heating and reacting for 24 hours at 90 ℃. And after the reaction is finished, cooling to room temperature, washing to be neutral by using distilled water, extracting by using ethyl acetate, carrying out spin drying to obtain a crude product, mixing dichloromethane and petroleum ether to be used as a developing agent, and carrying out chromatographic separation and purification on the crude product by using a silica gel column to obtain a red solid product.¹H NMR(600MHz,CD₂Cl₂)δ(ppm):7.69(d,J＝8.5Hz,4H),7.62-7.58(m,9H),7.43-7.40(m,11H),7.27(d,J＝8.8Hz,4H),6.87(s,2H),2.25(s,6H).MS(m/z):C₅₁H₃₆F₆N₂S₂,854.97。

Example 2

A dithienylethylene compound represented by formula (II), wherein the name is abbreviated as 2(TPA-AC) -DTE, and R₁Is composed of

R₂Is composed of

The synthesis path is shown in fig. 1, and comprises the following steps:

under the protection of nitrogen, quickly pouring Br-DTE-Br, triphenylphosphine, 4-ethynyl triphenylamine, redistilled triethylamine and redistilled tetrahydrofuran into a two-neck flask, and adding Pd (PPh) in the environment of vacuumizing and introducing nitrogen₃)₂Cl₂And copper iodide, carefully and repeatedly pumping nitrogen to remove oxygen, and reacting for 24 hours at 90 ℃. After quenching reaction, extracting reaction liquid by ethyl acetate, washing an organic phase to be neutral by pure water, drying,filtering, spin-drying, and purifying by column chromatography to obtain crude product. 1H NMR (600MHz, CD2Cl2) delta (ppm):7.64-7.55(m,6H),7.42-7.38(m,14H),7.25(d, J ═ 8.8Hz,4H),7.23-7.20(m,4H),6.70(s,2H),2.23(s,6H).13C NMR (151MHz, CD2Cl2) delta ppm:158.6,158,153.6,151.7,148.2,143.2,141.7,139.4,137.3,136.9,135.2,131.7,130.9,128.6,127.7,126.1,125.9,122.6,121.9,120.7,118.0,117.1,107.7,105.9,92.8,86.9,28.4,23.3,15.4,14.5.MS (m/z): C55H36F6N2S2,902.22.

Comparative example 1

A dithienylethylene compound shown as formula (III), the name of which is abbreviated as 2(CA-AC) -DTE. The synthesis path is shown in fig. 1, and comprises the following steps:

adding Br-DTE-Br, triphenylphosphine and 9- (4-ethynylphenyl) carbazole into a double-neck flask, then quickly adding redistilled triethylamine and redistilled tetrahydrofuran, vacuumizing and filling nitrogen, and then adding a catalyst Pd (PPh)₃)₂Cl₂And copper iodide, and vacuumizing again to ensure that the environment is positive pressure of nitrogen, and uniformly stirring and reacting for 24 hours at 90 ℃. After the reaction is finished, extracting the reaction solution by using ethyl acetate, washing by using deionized water, drying by spinning, mixing the ethyl acetate with petroleum ether, adding a small amount of dichloromethane for assisting dissolution, carrying out column chromatography separation on a crude product, recrystallizing the obtained product by using dichloromethane and n-hexane, and drying to obtain colorless solid powder. 1H NMR (600MHz, CD2Cl2) δ (ppm) 8.44(d, J ═ 7.8,2.9Hz,6H),8.10(d, J ═ 8.4Hz,2H),8.07-8.02(m,4H),7.95-7.87(m,6H),7.80-7.68(m,6H),7.66-7.55(m,2H),2.30(s,6H). MS (m/z): C55H32F6N2S2,898.19.

Example 3

A dithienylethylene compound represented by formula (II), the name of which is abbreviated as (DMTPA-AC) -DTE, wherein R₁Is composed of

R₂Is composed of

The synthesis path is shown in fig. 1, and comprises the following steps:

under the protection of nitrogen, Br-DTE-Br, triphenylphosphine, 4, 4' -dimethyltriphenylamine, redistilled triethylamine and redistilled tetrahydrofuran are quickly poured into a two-neck flask, and Pd (PPh) is added under the environment of vacuumizing and introducing nitrogen₃)₂Cl₂And copper iodide, carefully and repeatedly pumping nitrogen to remove oxygen, and reacting for 24 hours at 90 ℃. After quenching reaction, extracting reaction liquid by ethyl acetate, washing an organic phase to be neutral by pure water, drying, filtering, spin-drying, and purifying by column chromatography to obtain a crude product.

Example 4

A dithienylethylene compound represented by formula (II), wherein the name is abbreviated as (MDPA-AC) -DTE, R1 is-CH₃R2 is

The synthesis path is shown in fig. 1, and comprises the following steps:

under the protection of nitrogen, quickly pouring Br-DTE-Br, triphenylphosphine, 4-ethynyl-4-methyldiphenylamine, redistilled triethylamine and redistilled tetrahydrofuran into a two-neck flask, and adding Pd (PPh) in the environment of vacuumizing and introducing nitrogen₃)₂Cl₂And copper iodide, carefully and repeatedly pumping nitrogen to remove oxygen, and reacting for 24 hours at 90 ℃. After quenching reaction, extracting reaction liquid by ethyl acetate, washing an organic phase to be neutral by pure water, drying, filtering, spin-drying, and purifying by column chromatography to obtain a crude product.

The synthetic route of Br-DTE-Br in FIG. 1 is as follows:

and (4) analyzing results:

FIG. 2 is a UV absorption spectrum of a dithienylethylene compound prepared in example 1 of the present invention in a tetrahydrofuran solution. FIG. 2, content a is the spectrum of DTE-1 prepared in example 1 showing the absorption in tetrahydrofuran solution as a function of the duration of 405nm light; FIG. 2, panel b, is a graph of the absorption of DTE-1 prepared in example 1 in tetrahydrofuran solution as a function of 621nm illumination time; FIG. 2, content c, is a graph comparing the 365nm and 405nm light absorption steady-state PSS of DTE-1 prepared in example 1 in tetrahydrofuran solution. When the open-loop DTE-1O (DTE-1O is the open-loop DTE-1) is in a monodisperse form in a tetrahydrofuran solution, the liquid is colorless transparent liquid, the maximum absorption wavelength of the DTE-1O (DTE-1) is 355nm, after excitation of 405nm visible light or 365nm ultraviolet light, a ring-closing reaction of a dithiophene vinyl unit occurs, and the maximum absorption wavelength of the closed-loop DTE-1C (DTE-1 closed-loop) is 631 nm.

FIG. 3 is a UV absorption spectrum of a dithienylethylene compound prepared in example 2 of the present invention in a tetrahydrofuran solution. FIG. 3, content a is the spectrum of DTE-2 prepared in example 2 showing the absorption in tetrahydrofuran solution as a function of the duration of 405nm light; FIG. 3, panel b, is a graph of the absorption of DTE-2 prepared in example 2 in tetrahydrofuran solution as a function of 621nm light exposure time; FIG. 3, content c, is a graph comparing the 365nm and 405nm light absorption steady-state PSS of DTE-2 prepared in example 2 in tetrahydrofuran solution. The DTE-2 molecule contains triple bonds, the delocalized pi conjugated electronic effect is increased, the wavelength of the maximum absorption position of the open/closed ring isomer is red-shifted, the maximum absorption wavelength of the open/closed ring isomer is red-shifted to be near 15nm to 370nm in an open ring state in an ultraviolet region, after the excitation of 405nm visible light or 365nm ultraviolet light, the dithiophene vinyl unit performs a ring-closing reaction, the DTE-2C characteristic absorption is 458nm and 639nm, and a colorless solution is changed into green. DTE-1O-2O containing triphenylamine groups in molecules has extremely high response speed, and when the DTE-1O-2O contains triphenylamine groups in molecules, the DTE-1O-2O has 5-10 s of visible light irradiation at 405nm and 2-5 s of ultraviolet light irradiation, each characteristic absorption peak does not change any more, namely reaches a Photostability (PSS). Under the irradiation of long-wavelength visible light (lambda is more than 500nm), the color of the liquid is changed from green to colorless, and the ultraviolet visible absorption spectrum is also returned to an open-loop state. As can be seen from the comparison of the absorption PSS at the respective wavelengths, the absorbance ratios of DTE-1 and DTE-2 at the maximum absorption wavelength of the light steady state (PSS) reached after the excitation of the 405nm visible light and the 365nm ultraviolet light are respectively 0.96:1 and 1:1, the light conversion rates are almost consistent, and the photochromic performance driven by the visible light is excellent.

FIG. 4 is a UV absorption spectrum of DTE-3, a dithienylethylene compound prepared in comparative example 1 of the present invention, in a tetrahydrofuran solution. FIG. 4, panel a is a graph of the absorption of DTE-3 in tetrahydrofuran solution as a function of time duration with 405nm light; FIG. 4, panel b, is a graph of the absorption of DTE-3 in tetrahydrofuran solution as a function of 621nm illumination duration; FIG. 4c is a graph comparing the light absorption steady-state PSS at 365nm and 405nm of DTE-3 in tetrahydrofuran solution. DTE-3O has low conjugation due to electron donating property and molecular configuration, and the characteristic absorption peak is blue-shifted to 340 nm. DTE-3 has almost no 405nm visible light response photochromic performance, and almost does not generate a new closed-loop isomer characteristic absorption peak after being excited by 405nm visible light. And after 365nm ultraviolet irradiation, DTE-3C (a closed loop state of DTE-3) generates an absorption peak at 612 nm. The absorbance ratio of DTE-3 was only 0.147:1, indicating that dithienylethylene substituted with a carbazole group was less responsive to 405nm visible light.

FIG. 5 is a UV absorption spectrum of a dithienylethylene compound prepared in example 3 of the present invention in a tetrahydrofuran solution. FIG. 5, panel a, is a plot of the absorbance of (DMTPA-AC) -DTE prepared in example 3 (abbreviated as DTE-4) in tetrahydrofuran solution as a function of time duration under 405nm light; FIG. 5, panel b, shows the absorption of DTE-4 prepared in example 3 in tetrahydrofuran as a function of 621nm light exposure. When the open-loop DTE-4O (DTE-4O is the open-loop DTE-4) is in a monodisperse form in a tetrahydrofuran solution, the liquid is colorless transparent liquid, the maximum absorption wavelength of the DTE-4O (DTE-4) is 380nm, after excitation of 405nm visible light or 365nm ultraviolet light, a ring-closing reaction of a dithiophene vinyl unit occurs, and the maximum absorption wavelength of the closed-loop DTE-4C (DTE-4 closed-loop) is 640 nm. The light isomerization rate of the product before and after 405nm visible light irradiation reaches more than 96 percent through calculation.

Density functional theory calculation geometric structures and electron cloud distribution diagram drawing in an open loop state and a closed loop state are carried out on the dithienyl vinyl compounds DTE-1-3 prepared in the example 1, the example 2 and the comparative example 1. The DTE-1-3 compound has a donor-acceptor (D-A) structure, triphenylamine groups (TPA) and carbazole groups (CA) have electron donating difference, and triphenylamine has relatively strong electron donating property. Due to the linear triple bond, the TPA-AC enables the triarylamine substructure and the dithienylethylene group to be in a rigid plane to a greater extent than TPA, and increases the pi-electron conjugation of molecules. After optimizing an electron cloud structure by using ChemBio 3D Ultra14.0 in ChemBio Office 2014, optimizing the HOMO and LUMO orbits of the structure simulation calculation molecules in a Gaussian 09 program by using B3LYP/6-31G (D) as an algorithm basis group. Both the open-loop DTE-1O-3O and the closed-loop DTE-1C-3C have a twisted conformation of the substituent units along the plane of the backbone. The most of HOMO electrons of the open-loop DTE-1O-3O are stretched to a triarylamine electron donating structure, LUMO electrons are distributed on a DTE sub-structure, and the electron cloud distribution of the three dithienylethylene derivatives potentially shows the inherent intramolecular charge transfer characteristic of the (D-A) structure. And the electron clouds of the three closed loop states, namely HOMO and LUMO, are uniformly distributed on the conjugated groups of the dithienylethylene nucleus and the triarylamine electron donor through bonding connection, and the DTE structure in the compound is excited by illumination to be closed, so that electrons extend on the push group and the pull group along the ring structure, the conjugation degree is increased, and the closed loop state product generates a new absorption peak in a visible light region.

FIG. 6 shows the open-ring absorption contrast of DTE-1 to 3, which are dithienylethylene compounds prepared in example 1, example 2 and comparative example 1 of the present invention, in THF and the absorption contrast when exposed to light at 405nm to PSS. FIG. 6, panel a, shows the comparison of absorption of DTE-1-3 in ring-opened state in THF; FIG. 6 b shows the absorption contrast of DTE-1 to DTE-3 in the PSS state under 405nm light. The calculated energy level differences (Eg) of DTE-1O to 3O were 3.29eV, 3.19eV, and 4.17eV, respectively, and the absorption of DTE-1O to 3O was also red-shifted toward a long wavelength by the decrease of the molecular Eg. The Eg of DTE-2O is minimum, and the absorption red shift value is large; the Eg of DTE-3O is maximum, the red shift degree is small, the response performance of 405nm visible light is weak, and the closed loop conversion rate of the PSS state is low. Comparing HOMO energy levels of open-loop compounds DTE-1O and DTE-2O to be-4.98 eV and-4.96 eV respectively, which are obviously lower than-5.50 eV (HOMO energy level of DTE-O), wherein HOMO energy level of DTE-3O is-5.37 eV, which is not much different from DTE, molar extinction coefficient DTE-2O of the open-loop characteristic absorption peak is the largest, and DTE-3O is the smallest; the highest HOMO energy level DTE-1C of the closed-loop product is-4.61 eV, and the maximum absorption molar extinction coefficient of the DTE-1C in the closed-loop state is the maximum in the PSS state. Based on a molecular structure optimized by a Gaussian program obtained by a ground state algorithm, the first excited state energy (S1) of three disubstituted diarylene compounds and the original unsubstituted DTE is continuously calculated in a Gaussian 09 program, and the DTE (3.75eV) > DTE-3O (2.90eV) > DTE-1O (2.78eV) > DTE-2O (2.70 eV). However, the largest derivative of S1 of carbazole-substituted DTE-3O is, so that the 405nm visible light responsiveness of the compound is slightly inferior to that of triphenylamine-substituted DTE-1-2. In addition, the triplet first excited state energy T1 of DTE, TPA and TPA-AC is calculated by taking B3LYP/6-31G (d) as a base set DFT simulation in Gaussian software, and whether triphenylamine groups have the potential as triplet sensitizers of DTE is researched. Calculated DTE T1-2.74 eV, S1-3.75 eV, TPA: t1-3.18 eV, S1-3.93 eV, TPA-AC: t1-2.77 eV and S1-3.68 eV. The triplet sensitizer needs to satisfy the condition 1 that S1 of the sensitizing group is less than S1 of DTE, and S1 of the sensitizing group is converted into light with the same energy, and the wavelength is in the visible light region; 2. t1 of the sensitizing group > T1 of DTE; 3. the difference in the energy levels of the sensitizing group S1 and T1 (Δ EST) is sufficiently small. The wavelengths of the TPA and TPA-AC corresponding to the first excited state energy are 315nm and 336nm, respectively, and it is known that triphenylamine groups do not satisfy the first condition as a triplet sensitizer in this molecular system. Triphenylamine groups are used as electron-donating conjugated groups, the light wavelengths corresponding to the first singlet state excitation state energy of the symmetrically-substituted DTE derivatives DTE-1-2 are 445nm and 458nm respectively, and the light wavelengths are red-shifted to 330nm excitation light required by the non-substituted DTE, so that visible light driven ring-closing reaction can be realized by substituting the triphenylamine for the DTE.

FIG. 7 shows the nuclear magnetic hydrogen spectra of dithienyl vinyl compounds DTE-1 to 3 prepared in example 1, example 2 and comparative example 1 of the present invention in deuterated dichloromethane with 405nm illumination. FIG. 7 shows (a) the chemical shift region of methyl H on the thiophene aromatic ring on the DTE substructure in DTE-1; FIG. 7 (b) is the chemical shift region of methyl H on the thiophene aromatic ring on the DTE substructure in DTE-2; FIG. 7 (c) is a chemical shift region of methyl H on the thiophene aromatic ring on the DTE substructure in DTE-3. Taking DTE-1 as an example, the chemical shift of the methyl group on the DTE-1O thiophene ring in the ring-opened state is 2.25ppm, and the chemical shift thereof after ring-closed state is 2.41 ppm. After the visible light with the wavelength of 405nm is irradiated for 15min, the area of the methyl peak at the position of 2.41ppm on the DTE-1 nuclear magnetic hydrogen spectrum has no increase and change, and the two isomers reach the light steady state (PSS) balance. The DTE-1 closed-loop conversion was 2.41ppm peak area and the integral of the two peaks, 2.25ppm and 2.41ppmThe ratio of the sum of the areas was calculated to give a conversion of 96%. And similarly, respectively calculating the integral area of methyl H on the thiophene group of the DTE-2-3 compound, wherein the conversion rate is 98% when the area integral ratio of DTE-2 at 2.25ppm to 2.45ppm, and the conversion rate is 28% when the area integral ratio of DTE-3 at characteristic chemical shifts of 2.30ppm to 2.54 ppm. This gives the actual yields (. alpha.) of the three compounds converted to the closed ring isomers in the PSS state excited by visible light at 405nm_PSS) The photochemical reaction performance can be measured through the closed-loop conversion rate, and the sensitivity of the photochromic molecules to the response of light with specific wavelength is determined to a certain extent.

FIG. 8 shows the switching dynamics fit curves of the dithienylethylene compounds DTE-1-2 prepared in examples 1 and 2 of the present invention. FIG. 8, content a shows the fitting of absorbance at 631nm as a function of 405nm for DTE-1 prepared in example 1 of the present invention; FIG. 8, panel b, shows the absorbance at 631nm as a function of 621nm for DTE-1 prepared in example 1 of the present invention; FIG. 8, panel c, is a plot of absorbance at 639nm as a function of 405nm for DTE-2 prepared in example 2 of the present invention; FIG. 8, panel d, shows the absorbance at 639nm as a function of 62nm for DTE-2 prepared in example 2 of the present invention. Taking ring-opening disubstituted dithienylethylene derivative DTE-1 as an example, in a THF system, a 405nm visible light is used for illumination to reach a light steady state, and then the light is irradiated back by a long wavelength visible light 621nm, and the change of absorbance caused by the increase of the maximum absorption peak 631nm of DTE-1 along with the illumination time in the two processes is recorded and monitored. And exciting a molecular switch DTE-2 by using 405nm and 621nm visible light with the same irradiation intensity, fully irradiating in the two processes to convert the molecular switch DTE-2 into an isomer as far as possible, and monitoring and recording the absorbance change at 639 nm. Nonlinear exponential fitting of a quasi-first order kinetic equation, the matching relation coefficient R2 is close to 1, and the rate constant keq of the photochromic reversible reaction can be obtained. The equilibrium rate constant keq for the resulting ring closure reaction was calculated: DTE-2-O > DTE-1-O > DTE-3-O.

The dithienyl ethylene compound synthesized by the method shows excellent visible light photochromic performance in THF, uses rigid triple bonds to increase a pi conjugated plane and construct a donor-acceptor (D-A) push-pull electron system to reduce an energy gap (Eg), absorbs red shift, can directly excite the dithienyl ethylene unit to carry out a photocyclization reaction by visible light, and effectively improves the photochromic molecular performance. However, when the dithienyl ethylene molecular switch is synthesized by bi-conjugate substitution of a carbazole group, the photoisomerization rate is only 28%, which is greatly reduced compared with the dithienyl ethylene molecular switch synthesized by bi-conjugate substitution of triphenylamine and triphenylamine-alkynyl (photoisomerization rates are respectively 96% and 98%). The possible reason is that the skeleton structure of N-phenylcarbazole, triphenylamine, is more non-planar and the increase of pi-conjugated structure is less. The larger the conjugated system is, the more the energy gap between the Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO) is reduced, so that the energy gap (calculated energy level difference Eg) of N-phenylcarbazole is not so much reduced compared to triphenylamine structure, so that the degree of red shift of absorption is smaller, resulting in a change in nuclear magnetic hydrogen spectrum in CD2Cl2 before and after irradiation of 405nm visible light, and the 405nm visible light responsivity of carbazole substituted product DTE-3 is inferior to triphenylamine substituted compounds DTE-1 and DTE-2.

DTE-1 and DTE-2 correspond to symmetric substitution of triphenylamine and triphenylamine-alkynyl for DTE respectively, and compared with triphenylamine group (TPA), the TPA-AC has a triarylamine sub-structure and a dithienylethylene group to be in a rigid plane to a greater extent than TPA due to linear triple bonds, so that pi electron conjugation of the molecule is increased, which is probably the reason that DTE-2 containing alkynyl is higher in reversible discoloration performance and photoisomerization rate than DTE-1 containing no alkynyl.

In the compounds of the formulae (I) and (II) according to the invention, the substituent R₁And R₂When in the range of a hydrogen atom, a C1-C10 alkyl group or a C6-C20 aryl group, other than phenyl, such as R₁And R₂When the tolyl group or the methyl group is used as the tolyl group or the methyl group in the embodiment 3 or the embodiment 4, the absorption wavelength is red-shifted by experiments, and the photoisomerization rate before and after the irradiation of the 405nm visible light can reach more than 96 percent by calculation; in addition, for R₁And R₂When the groups are ethyl, ethylphenyl, hydroxyethyl, hydroxypropyl and the like, the corresponding aniline-alkynyl group still has strong electron-donating conjugation effect, and the active range of pi electrons can be enlarged by forming delocalized pi bonds, so that the energy gap between HOMO and LUMO(Eg) decreases and the absorption of the molecular switch is red-shifted. Therefore, it also enables the fluorescence response wavelength of the molecular switch to be red-shifted to the visible region and exhibits excellent visible photochromic properties. The synthetic route can be adjusted according to the technical route.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A visible light controlled perfluoro-substituted dithienyl ethylene compound is characterized in that the compound is a dithienyl ethylene compound which is doubly conjugated and substituted by arylamine groups and has a structural formula shown as a formula (II):

wherein R is₁And R₂Each independently is methyl, ethyl, propyl, hydroxyethyl, hydroxypropyl, phenyl, tolyl, ethylphenyl, or propylphenyl.

2. A process for preparing a dithienylethylene compound as claimed in claim 1, wherein R is used in the presence of a catalyst and an organic solvent₁And R₂The aniline-alkynyl group carries out substitution reaction on bromine atoms in the 1, 2-bis (5-bromine-2-methylthiophene-3-yl) perfluoro cyclopentene to obtain the dithienyl ethylene compound.

3. The method of claim 2, wherein the substitution reaction is carried out in the absence of water and oxygen and heated to 80-95 ℃.

4. The method of claim 2, wherein the catalyst is a palladium catalyst.

5. The use of the perfluoro-substituted dithienylethylene compound of claim 1 in the preparation of a full visible light-regulated molecular switch material, wherein the molecular switch material adopts a visible light source to trigger a ring-closing reaction thereof.

6. Use according to claim 5, wherein the molecular switching material is a photochromic molecular switching material.

7. The use according to claim 5, wherein the visible light wavelength range is 405 to 440 nm.

8. A fully visible light-regulated perfluoro-substituted dithienyl ethylene molecular switch comprising the dithienyl ethylene compound of claim 1;

the molecular switch is prepared by carrying out the process of containing R on perfluoro cyclopentene dithienyl ethylene₁And R₂The aniline-alkynyl group is modified in a conjugated manner, so that the triggering wavelength of the ring-closing reaction can be red shifted to a visible light region, and the triggering wavelength of the ring-opening reaction is in the visible light region, so that the full visible light regulation and control of the molecular switch photoisomerization reaction are realized.