CN112300142A

CN112300142A - Dithienylethylene fluorescent molecular switch regulated and controlled by visible light, and preparation and application thereof

Info

Publication number: CN112300142A
Application number: CN202011269922.4A
Authority: CN
Inventors: 朱明强; 骆鹏飞; 李冲; 熊凯
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: 2021-02-02
Anticipated expiration: 2040-11-13
Also published as: CN112300142B

Abstract

The invention belongs to the field of new materials, and particularly relates to a visible light controlled dithienyl ethylene fluorescent molecular switch, and preparation and application thereof. The dithienyl ethylene derivative takes aniline-alkynyl as a photosensitization group, and Perylene Monoimide (PMI) as a fluorescent group, and comprises a structural unit shown as a formula (I) or a formula (II):

wherein R is₁And R₂Each independently is C1-C10 alkyl, C1-C10 alkyl alcohol or C6-C20 aryl. When the derivative is used as a fluorescent molecular switch, the introduction of the aniline-alkynyl group enables the fluorescence response wavelength of the molecular switch to be red-shifted to a visible light region, and the derivative has good thermal stability and good performanceFatigue resistance, high cyclization rate, high fluorescence on-off ratio and the like.

Description

Dithienylethylene fluorescent molecular switch regulated and controlled by visible light, and preparation and application thereof

Technical Field

The invention belongs to the field of new materials, and particularly relates to a visible light controlled dithienyl ethylene fluorescent molecular switch, and preparation and application thereof.

Background

The dithienyl ethylene fluorescent molecular switch has high fluorescence quantum yield, high fluorescence on-off ratio, good fatigue resistance and thermal stability, and can still keep better optical switch performance in a film, which has great research significance for realizing ultrahigh-density optical storage and super-resolution imaging.

To the first report of a full visible light-regulated diarylethene molecular switch 20 years ago, Lehn and colleagues successfully red-shifted the absorption of DAEs for the first time by introducing two additional thiophene units at the 5-and 5' -positions of dithiophene. Then Irie et al synthesized a class of compounds having perfluorocyclopentadithiophene-based vinyl molecular structure and perylene monoimide structural units, which could be successfully switched between open-loop and closed-loop under 560nm and 405nm alternating irradiation, and had a higher light conversion rate. Other DAE have been reported shortly after to be conjugated with extended pi-conjugated groups at the side, such as carotenoids, but such DAE derivatives have very low ring-splitting quantum yields, a disadvantage that severely limits the practical application of these compound switches.

In 2009, the Branda group demonstrated that near infrared driven isomerization of DAE derivatives could be achieved using lanthanum doped up-converting nanoparticles (UCNPs), and this particular system was not reversible since the two nanoparticles had to be excited with 980nm wavelength light of different intensities, and a film containing two different nanoparticles had to be prepared in the system. The group made in 2010 a reversible photosensitive system of core-shell NaYF4 nanocrystal structure comprising ions doped with Er3+/Yb3+ and Tm3+/Yb3+ in separate continuous layers. By adjusting the intensity of the 980nm laser beam, reversible switching between the two isomers can be achieved.

Irie topic group uses femtosecond laser pulse with half-peak width of 35 femtosecond and Near Infrared (NIR)1.28 μm, and makes diarylethene molecule realize photochromic cyclization and ring cleavage reaction only under one kind of long wavelength excitation through non-resonance high-order multiphoton absorption process, but excitation multiphoton absorption has too high requirement on laser condition, and has limitation to wide practical application and popularization of the method.

The group of the problems of the paddy field and the vermilion recently reports that a series of DTEs which can be excited by full visible light are synthesized by utilizing the IPT (proton transfer) effect of salicylidene Schiff base. Experimental research proves that the system is simultaneously suitable for a polar solvent system and a polymer gel system, and has good application effect. However, the polarity dependence of the system on the solvent and the medium limits further practical applications to a certain extent.

Most of the existing fluorescent molecular switches still respond to ultraviolet light, and because the ultraviolet light energy is higher, the fluorescent molecular switches are not safe for users except for destructiveness to biological molecules. Even the existing fluorescent molecular switch with visible light response generally has the defects of slow fluorescent response, low photocyclization conversion rate, general fluorescence quenching efficiency, poor fatigue resistance and the like.

Disclosure of Invention

Aiming at the defects or improvement requirements of the prior art, the invention aims to provide a dithienyl ethylene fluorescent molecular switch which is regulated and controlled by full visible light and has high fluorescence quenching rate, switching ratio and good fatigue resistance, and aims to solve the problems that the traditional fluorescent molecular switch needs ultraviolet response, the fluorescent switching ratio is low and the like.

In order to achieve the above object, the present invention provides an aniline-alkynyl conjugated modified dithienyl ethylene derivative, which comprises a structural unit represented by formula (i) or formula (ii):

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, phenyl, tolyl, ethylphenyl, propylphenyl, hydroxyethyl, or hydroxypropyl.

According to another aspect of the present invention, there is provided a method for preparing said dithienyl ethylene derivative, comprising the steps of:

(1) 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; then 3-bromo-2-methyl-5-trimethylsilylthiophene, n-butyllithium and perfluorocyclopentene are used as raw materials to react to prepare 1, 2-bis (2-methyl-5-trimethylsilylthiophene-3-yl) perfluorocyclopentene, and finally 1, 2-bis (2-methyl-5-trimethylsilylthiophene-3-yl) perfluorocyclopentene, anhydrous tetrahydrofuran and NBS are used as raw materials to react for 14-18 hours at room temperature in a dark place to obtain a compound, wherein the 1, 2-bis (5-bromo-2-methylthiophene-3-yl) perfluorocyclopentene is Br-DTE-Br.

(2) With Br-DTE-Br, with R₁And R₂Aniline compound of the group and triphenylphosphine are used as main reaction raw materials, triethylamine and tetrahydrofuran are used as solvents, and Pd (PPh) is added under nitrogen atmosphere₃)₂Cl₂And copper iodide to carry R₁And R₂The aniline compound of the group is mono-substituted with Br to give compounds bearing R₁And R₂Aniline groups of the group-AC-DTE-Br; wherein AC represents alkynyl, DTE represents perfluorocyclopentadithiophene ethylene;

(3) will carry R₁And R₂Taking aniline group-AC-DTE-Br and PMI-O-Ph-Borate of the groups as raw materials, and respectively removing Br and Borate groups to obtain a compound containing a structural unit shown in a formula (I); or will carry R₁And R₂Taking aniline groups-AC-DTE-Br and PMI-Borate of the groups as raw materials, and respectively removing Br and Borate groups to obtain a compound containing a structural unit shown in a formula (II); wherein PMI represents perylene monoimide and Borate represents Borate.

According to another aspect of the invention, the application of the dithienyl ethylene derivative in the full visible light-regulated fluorescent molecular switch is provided.

According to another aspect of the invention, a bithienyl ethylene fluorescent molecular switch regulated by full visible light is provided, wherein perylene monoimide is used as a fluorescent group, bithienyl ethylene is used as a photochromic unit, the structure of the fluorescent molecular switch also comprises a photosensitization group, the photosensitization group is an aniline-alkynyl group, and the photosensitization group is in conjugated connection with the photochromic unit bithienyl ethylene;

after the aniline-alkynyl group is introduced for conjugate modification, the trigger wavelength of the ring-closing reaction of the fluorescent molecular switch can be red shifted to a visible light region, and the trigger wavelength of the ring-opening reaction is in the visible light region, so that the full visible light regulation and control of the light isomerization reaction of the dithienyl ethylene fluorescent molecular switch are realized, and the high fluorescence on-off ratio and the fluorescence quenching rate are achieved.

Preferably, the trigger wavelength range is 400-440 nm. The visible light in the waveband replaces ultraviolet light, is applied to practical application such as super-resolution fluorescence imaging, avoids using ultraviolet light, can improve the fatigue resistance of a sample, and avoids irradiation damage to the sample and an operator.

Preferably, the photochromic unit is perfluorocyclopentadithienyl ethylene; the fluorescent molecular switch comprises a structural unit shown as a formula (I) or a formula (II):

According to another aspect of the invention, the fluorescent molecular switch is applied to the field of optical storage or super-resolution imaging.

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

(1) the invention designs a dithienylethylene fluorescent molecular switch taking aniline-alkynyl as a photosensitization group and Perylene Monoimide (PMI) as a fluorescent group, and the introduction of the aniline-alkynyl group enables the fluorescent response wavelength of the molecular switch to be red-shifted to a visible light region and has high fluorescence quenching rate and good fatigue resistance.

(2) After the dithienyl vinyl fluorescent molecular switch provided by the invention is introduced with aniline-alkynyl groups for conjugate modification, the trigger wavelength of the ring-closing reaction can be red-shifted to a visible light region, and the trigger wavelength of the ring-opening reaction is in the visible light region, so that the full visible light regulation and control of the light isomerization reaction of the dithienyl vinyl fluorescent molecular switch are realized, and the dithienyl vinyl fluorescent molecular switch has high fluorescent switch ratio and fluorescent quenching rate; the preferable closed-loop reaction trigger wavelength range is 400-440nm, and the visible light in the band replaces ultraviolet light, so that the method is applied to practical applications such as super-resolution fluorescence imaging, avoids using ultraviolet light, can improve the fatigue resistance of a sample, and avoids irradiation damage to the sample and an operator.

(3) According to the invention, the bithienyl ethylene is subjected to conjugate modification by adopting the aniline-alkynyl group, and compared with two conjugate connecting molecules, the conjugate degree of the visible light sensitive group is increased, so that the photochromic response at 405nm is better; compared with molecules connected with non-conjugation and conjugation, the oxygen-bridged bond non-conjugation connected fluorescent group improves photochromic response speed, increases fluorescent switch contrast, simultaneously keeps independent unit performance, has high fluorescence quenching efficiency and does not interfere with each other.

(4) DTE-PMI-1 (R) represented by the formula (III) provided in a preferred embodiment of the present invention₁And R₂All phenyl) solid film is irradiated by visible light with 405 nm-470 nm, the strong orange-red fluorescence of DTE-PMI-1 in the original ring-opening state is quenched to different degrees in the PSS state, the color is changed from colorless to purple, and the visible light in the wave band can be induced by the visible lightDTE-PMI-1 undergoes an effective ring closure reaction. The 405nm light irradiation can obtain higher and stable fluorescence quenching rate which reaches 98 percent, and can ensure the accuracy of information erasing and writing. And the fluorescent molecular switch is repeatedly and alternately irradiated by 405nm visible light and 621nm visible light, so that the fatigue resistance of the fluorescent molecular switch is good, and the repeatability of writing/erasing of fluorescent information is ensured.

(5) In the preferred embodiment of the invention, three visible light response photochromic DTE groups covalently replace the berth position and the gulf position of a single PMI fluorescent group in a non-conjugated mode through oxygen bridge bonds, so that a visible light sensitive triphenylamine group-dithienyl ethylene-perylene monoimide star triplet 3DTE-PMI (shown as a formula (IV)) is constructed, the visible light sensitive triphenylamine group-dithienyl ethylene-perylene monoimide star triplet 3DTE-PMI has a highly twisted three-dimensional structure, when the visible light response photochromic DTE groups reach the PSS state within 20s under continuous illumination of 405nm, the fluorescence quenching is more than 99.5%, and the fluorescence on-off ratio is as high as 659: 1. Has good reversibility and fatigue resistance, and the absorption and fluorescence of the material do not generate obvious changes after being alternately irradiated for ten times by visible light of 405nm and 621 nm.

(6) In the preferred embodiment of the invention, a multi-substituted fluorescent molecular switch 3DTE-PMI shown in a formula (five) is synthesized. Compared with a single substituted product, the visible light control fluorescence switch in the solid medium is improved by more than 100 times, the switching speed is higher, and the fluorescence information repeated reversible switch of the erasable optical storage model is successfully realized. The method is used for exploring super-resolution fluorescence imaging research, dyeing is carried out on the block copolymer, the block copolymer is self-assembled into micelle, and a reconstructed image with the resolution of 24nm is obtained.

Drawings

FIG. 1 is a schematic diagram of the synthetic route of the fluorescent molecular switch prepared in example 1 of the present invention.

FIG. 2 is a graph showing the change of fluorescence spectra of fluorescent molecular switches obtained by the preparation process of example 1 of the present invention under 488nm excitation light in tetrahydrofuran with the irradiation time of 405nm/621nm and 365nm/621nm light.

FIG. 3 is a graph showing the change of fluorescence spectra of fluorescent molecular switch obtained by the preparation process of example 1 in the irradiation time of light of 405nm/621nm and 365nm/621nm in the excitation light of 488nm in polymethyl methacrylate (PMMA).

FIG. 4 is a graph of fatigue resistance test of the fluorescent molecular switch in THF solution obtained from the preparation process of example 1 of the present invention.

FIG. 5 is a fluorescence kinetic diagram of the fluorescent molecular switch obtained by the preparation process of example 1 of the present invention in polymethyl methacrylate (PMMA) at different wavelengths.

FIG. 6 is a schematic diagram of the synthetic route of the fluorescent molecular switch prepared in example 2 of the present invention.

In FIG. 7, the contents a and b are fluorescence emission spectra of the photostable state (PSS) of the fluorescent molecular switch obtained by the preparation process of example 2 of the present invention in THF and PMMA under 488nm excitation light at 405nm and 365nm illumination, respectively.

FIG. 8 is a schematic diagram of the synthetic route of the fluorescent molecular switch of the comparative example 1 preparation process of the present invention.

FIG. 9, Contents a and b, shows fluorescence emission spectra of photostable state (PSS) of the fluorescent molecular switch obtained by the preparation process of comparative example 1 of the present invention in THF and PMMA in the ring-opened state under 488nm excitation light at 405nm and 365nm illumination.

FIG. 10 is a schematic diagram of the synthetic route of the fluorescent molecular switch prepared in example 3 of the present invention.

FIG. 11 is a graph showing the change of 488nm excitation fluorescence spectrum of the fluorescent molecular switch obtained by the preparation process of example 3 in Tetrahydrofuran (THF) with the irradiation time of 405nm/621nm and 365nm/621nm light.

FIG. 12 is a graph showing the absorption and 488nm fluorescence excitation spectra of the fluorescent molecular switch obtained from the preparation process of example 3 of the invention in PMMA (2 wt%).

FIG. 13 is a graph showing the fatigue resistance of the fluorescent molecular switch in THF solution according to the preparation process of example 3 of the present invention.

FIG. 14 is a fluorescence kinetic diagram of a fluorescent molecular switch obtained by the preparation process of example 3 of the present invention in polymethyl methacrylate (PMMA) at different wavelengths.

FIG. 15 is a 3 DTE-PMI-dyed PSt-b-PEO block copolymer micelle (content a) bright field image, (content b) conventional fluorescence imaging image, (content c) super-resolution fluorescence imaging image and (content d) super-resolution and fluorescence integration image prepared in example 3 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 an aniline-alkynyl conjugated modified dithienyl ethylene derivative, which comprises a structural unit shown as a formula (I) or a formula (II):

wherein R is₁And R₂Each independently is a hydrogen atom, a C1-C10 alkyl group or a C6-C20 aryl group.

The invention also provides the application of the dithienyl ethylene derivative in a fluorescent molecular switch regulated by full visible light. According to the invention, the aniline-alkynyl visible light-sensitive group is introduced, so that the response wavelength of the dithienyl ethylene fluorescent switch is red-shifted to a visible light region, and the defect of ultraviolet response of the traditional fluorescent molecular switch is overcome. The fluorescent molecular switch designed by the invention is based on the aniline-alkynyl structural unit, and has the advantages of visible light response, better thermal stability, good fatigue resistance, high closed-loop conversion rate, high fluorescent switch ratio and the like.

The invention also provides a bithienyl ethylene fluorescent molecular switch regulated by full visible light, wherein the fluorescent molecular switch takes perylene monoimide as a fluorescent group and bithienyl ethylene as a photochromic unit, the structure of the fluorescent molecular switch also comprises a photosensitization group, the photosensitization group is an aniline-alkynyl group, and the photosensitization group is in conjugated connection with the bithienyl ethylene photochromic unit. After the aniline-alkynyl group is introduced for conjugate modification, the absorption wavelength of the ring-closing reaction of the fluorescent molecular switch can be red-shifted to a visible light region, compared with the ultraviolet light excitation in the prior art, the fluorescent molecular switch realizes the visible light controlled photocyclization reaction, and has high fluorescence quenching rate and fluorescence on-off ratio; the ring-closure reaction trigger wavelength range is preferably 400-450nm, and more preferably 400-440 nm.

In some embodiments, the photochromic unit is perfluorocyclopentadithienyl ethylene; the fluorescent molecular switch comprises a structural unit shown as the formula (I) or the formula (II).

In experiments, the dithienylethylene derivative obtained by conjugating and modifying the photochromic unit dithienylethylene by the photo-sensitizing group, conjugating or non-conjugating the fluorescent group Perylene Monoimide (PMI) on the other side of the photochromic unit (DTE), and different photosensitizing groups and different connection modes is used as a fluorescent molecular switch, so that the switch performance difference is large. For example, the bithienyl ethylene is subjected to conjugate modification by the aniline-alkynyl group, and compared with the bithienyl ethylene subjected to conjugate modification by an independent aniline group, the bithienyl ethylene with the aniline group connected by pi electron conjugate extended by a triple bond has better visible light response effect, and the fluorescence contrast of a corresponding fluorescent molecular switch is larger. The dithienylethylene is in non-conjugated connection with the perylene monoimide through the oxygen-bridged bond, and is directly connected with the perylene monoimide, and the corresponding fluorescent molecular switch has a larger fluorescent on-off ratio and a larger fluorescent quenching rate.

In some preferred embodiments, the fluorescent molecular switch has a structural formula as described in any one of formulas (three) to (five):

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

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, propylphenyl group or the like.

As a comparative example, in the example of the present invention, triphenylamine having the same photosensitization function is used to replace triphenylamine-alkynyl for conjugate modification of a photochromic unit dithienylethylene to prepare a compound represented by formula (vi):

when R is in DTE-PMI-1 represented by formula (three), DTE-PMI-2 represented by formula (four) and DTE-PMI-3 represented by formula (six)₁And R₂When the fluorescent dye is phenyl, under the excitation of 405nm visible light in a solid medium, the fluorescent switch ratio DTE-PMI-1(60:1) > DTE-PMI-2(10:1) > DTE-PMI-3(4:1) is higher, and the degree of conjugation of visible light sensitive groups is increased to enable the response of 405nm photochromism to be better by comparing two conjugated connecting molecules (DTE-PMI-1 shown in a formula (III) and DTE-PMI-3 shown in a formula (VI)); compared with molecules (DTE-PMI-1 shown in formula (III) and DTE-PMI-2 shown in formula (IV)) connected with non-conjugation and conjugation, the fluorescent group connected with non-conjugation of the oxygen bridge bond improves the photochromic response speed, increases the contrast ratio of the fluorescent switch, simultaneously keeps the performance of an independent unit, has high fluorescence quenching efficiency and does not interfere with each other.

DTE-PMI-1 (R) represented by the formula (III)₁And R₂All phenyl) solid film is irradiated by visible light of 405 nm-470 nm, the strong orange-red fluorescence of DTE-PMI-1 in the original ring-opening state is quenched to different degrees in the PSS state, the color is changed from colorless to purple, and the visible light in the wave band can induce DTE-PMI-1 to generate effective ring-closing reaction. The 405nm light irradiation can obtain higher and stable fluorescence quenching rate which reaches 98 percent, and can ensure the accuracy of information erasing and writing. And the fluorescent molecular switch is repeatedly and alternately irradiated by 405nm visible light and 621nm visible light, so that the fatigue resistance of the fluorescent molecular switch is good, and the repeatability of writing/erasing of fluorescent information is ensured.

The invention provides a preparation method of a dithienyl ethylene derivative, which comprises the following preparation steps:

(1) 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; then 3-bromo-2-methyl-5-trimethylsilylthiophene, n-butyllithium and perfluorocyclopentene are used as raw materials to react to prepare 1, 2-bis (2-methyl-5-trimethylsilylthiophene-3-yl) perfluorocyclopentene, and finally 1, 2-bis (2-methyl-5-trimethylsilylthiophene-3-yl) perfluorocyclopentene, anhydrous tetrahydrofuran and NBS are used as raw materials to react for 16 hours at room temperature in a dark place to obtain a compound, wherein the 1, 2-bis (5-bromo-2-methylthiophene-3-yl) perfluorocyclopentene is Br-DTE-Br.

(2) With Br-DTE-Br, with R₁And R₂Aniline compound of the group and triphenylphosphine are used as main reaction raw materials, triethylamine and tetrahydrofuran are used as solvents, and Pd (PPh) is added under nitrogen atmosphere₃)₂Cl₂And copper iodide to carry R₁And R₂The aniline compound of the group is mono-substituted with Br to give compounds bearing R₁And R₂Aniline groups of the group-AC-DTE-Br;

(3) will carry R₁And R₂Taking aniline group-AC-DTE-Br and PMI-O-Ph-Borate of the groups as raw materials, and respectively removing Br and Borate groups to obtain a compound containing a structural unit shown in a formula (I); or will carry R₁And R₂The aniline group-AC-DTE-Br and PMI-Borate of the group are used as raw materials, and Br and Borate groups are respectively removed to obtain the compound containing the structural unit shown in the formula (II).

In some embodiments, the Br-DTE-Br is 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 ℃; and then 3-bromo-2-methyl-5-trimethylsilylthiophene, n-butyllithium and perfluorocyclopentene are used as raw materials, 1, 2-bis (2-methyl-5-trimethylsilylthiophene-3-yl) perfluorocyclopentene is prepared by reaction at a low temperature of-85 to-70 ℃, and finally 1, 2-bis (2-methyl-5-trimethylsilylthiophene-3-yl) perfluorocyclopentene, anhydrous tetrahydrofuran and NBS are used as raw materials and are reacted at room temperature in a dark place for 16 hours to obtain a compound, wherein the 1, 2-bis (5-bromo-2-methylthiophene-3-yl) perfluorocyclopentene is Br-DTE-Br.

In some embodiments, the ring has R₁And R₂The aniline group-AC-DTE-Br of the group is prepared according to the following preparation method: with Br-DTE-Br, with R₁And R₂Aniline compound of the group and triphenylphosphine are used as main reaction raw materials, redistilled triethylamine and redistilled tetrahydrofuran are used as solvents, Pd (PPh) is added in the environment of vacuumizing and introducing nitrogen₃)₂Cl₂Reacting with copper iodide at 90 ℃ for 24h, and controlling Br-DTE-Br and the catalyst with R₁And R₂The ratio of aniline compounds of the radicals R₁And R₂The aniline compound of the group is mono-substituted with Br to give compounds bearing R₁And R₂Aniline groups of the group-AC-DTE-Br.

In some embodiments, R₁And R₂When both are phenyl, with R₁And R₂The aniline compound of the group is 4-ethynyltriphenylamine, and the compound obtained by the reaction in the step (2) is TPA-AC-DTE-Br.

In some embodiments, the compound of formula (iii) is prepared by the steps of: with R as PMI-O-Ph-Borate₁And R₂Aniline group-AC-DTE-Br of the group is taken as a main raw material, TBAHS, potassium carbonate, water and toluene are taken as auxiliary reagents, tetrabutylammonium hydrogen sulfate and Pd (PPh) are added in a nitrogen atmosphere₃)₄Reaction at 80 ℃ for 16h to obtain PMI-O-Ph-Borate and a compound with R₁And R₂The aniline group-AC-DTE-Br of the group is stripped of Borate and Br, respectively, to produce the compound of formula (III).

In some embodiments, with R₁And R₂The aniline compound of the group is 4-ethynyltriphenylamine with R₁And R₂The aniline group-AC-DTE-Br of the group is TPA-AC-DTE-Br; the compound shown in the formula (III) is TPA-AC-DTE-Ph-O-PMI.

In some embodiments, the process for preparing the compound of formula (iv) comprises the steps of: with R as PMI-Borate₁And R₂Anilino group of the group-AC-DTE-Br as main raw material, and other reagents including toluene, water, small amount of TBAHS and K₂CO₃Adding catalyst Pd (PPh) in nitrogen atmosphere₃)₄80 ℃ overnight, PMI-Borate and a vector with R₁And R₂Removal of Borate and Br respectively from the aniline group-AC-DTE-Br of the group to give a compound bearing R₁And R₂The aniline group-AC-DTE-PMI of the group is the compound shown in the formula (IV).

In some embodiments, the PMI-Borate preparation comprises the steps of: PMI-Br and pinacol bisborate are taken as raw materials, redistilled 1, 4-dioxane is taken as a solvent, divalent palladium is taken as a catalyst, and the reaction is carried out at 90 ℃ for 16h under a nitrogen environment to remove Br on the PMI-Br so as to generate PMI-Borate.

In some embodiments, PMI-O-Ph-Br is prepared by: mixing PMI-Br with 4-bromophenol and K₂CO₃Then adding N-methyl pyrrolidone, stirring, reacting for 5h at 130 ℃, and removing Br on PMI and hydrogen on 4-bromophenol to generate PMI-O-Ph-Br.

In some embodiments, the PMI-O-Ph-Borate is prepared by: mixing PMI-O-Ph-Br product with pinacol ester of boric acid and potassium acetate, adding anhydrous dioxane as solvent, adding PdCl₂As a catalyst, the reaction was carried out at 90 ℃ for 16 hours under a nitrogen atmosphere to produce PMI-O-Ph-Borate by substitution reaction.

The light reaction isomerization of the dithienyl ethylene photochromic compound is used for regulating and controlling the fluorescence emission of the fluorescent dye group to form a controllable fluorescent molecular switch, and the method is a novel hotspot for researching the organic photochromic compound. Because the dithienyl ethylene photochromic compound has high detection sensitivity and excellent fatigue resistance, the reversible regulation and control of fluorescence under the drive of light has wide application prospect in the aspects of molecular switch semiconductors, optical information storage and biological imaging. Research results show that a fluorescent group cannot be completely quenched by a dithienyl ethylene switch, and in order to improve the speed and contrast of an optical switch and realize real in-situ (in-suit) fluorescence ON/OFF, the perylene monoimide perisite is also used as an active reaction substitution site in the preferred embodiment of the invention, and a plurality of DTEs are used for simultaneous regulation and control. The photochromic performance of dithienylethylene is easily sacrificed in a conjugated connection mode, and when molecules are designed, the interaction between electron clouds after fluorescent groups are connected is coordinated, so that the photochromic performance of visible light responding to DTE groups is maintained. Therefore, in the preferred embodiment of the invention, three visible light response photochromic DTE groups covalently replace the peri-position and the gulf-position of a single PMI fluorescent group in a non-conjugated manner through oxygen bridge bonds, so as to construct a visible light sensitive triphenylamine group-dithienylethene-perylene monoimide star triplet 3DTE-PMI (shown as formula (IV)) which has a highly distorted three-dimensional structure, has strong fluorescence emission in a tetrahydrofuran and PMMA polymer solid film system, can quench over 99 percent of the original fluorescence value under the irradiation of 405nm visible light, realizes a real 'dark state', shows good light resistance, and can realize repeated erasing/writing of optical storage model information and full-visible light high-resolution super-resolution fluorescence imaging of a block copolymer.

Connecting a plurality of DTE groups with excellent visible light response to the gulf position and the berth position of a PMI fluorescent group in the most effective non-conjugated mode to synthesize the multi-substituted fluorescent molecular switch 3DTE-PMI shown in the formula (IV). Compared with a single substituted product, the ratio of the visible light control fluorescence switch in the solid medium is improved by nearly 100 times, which is as high as 659:1, and the switching speed is higher. Fluorescent information repeated reversible switch of the erasable optical storage model is successfully realized. The method is used for exploring super-resolution fluorescence imaging research, dyeing is carried out on the block copolymer, the block copolymer is self-assembled into micelle, and a reconstructed image with the resolution of 24nm is obtained.

When the substituent R in the molecular structure of the formula (III) to the formula (V)₁And R₂In the range of a hydrogen atom, a C1-C10 alkyl group or a C6-C20 aryl group, other than phenyl, e.g. R₁And R₂Is methyl, ethyl, tolyl, ethyl phenyl and other groups, and R is caused by multiple effects due to the fact that alkyl has better electron donating effect relative to benzene ring and the linear conjugate effect of alkynyl-benzene ring₁、R₂The aniline-alkynyl structure can still have visible photosensitization after being changed into other groups. Therefore, the fluorescence response wavelength of the molecular switch can also be red-shifted to the visible region, andhas high fluorescence quenching rate and good fatigue resistance. The synthetic route can be adjusted according to the technical route.

The fluorescent molecular switch provided by the invention has the advantages that the fluorescence response wavelength is red-shifted to a visible light region, and the high fluorescence quenching rate and the good fatigue resistance are achieved. The problems that the traditional fluorescent molecular switch needs ultraviolet response, the fluorescent switch ratio is low and the like are solved, and the excellent fluorescent properties enable the fluorescent molecular switch to have great application values in the aspects of information optical storage, super-resolution imaging and biological detection. When in use, the fluorescent molecular switch is firstly dissolved in a solvent or made into a solid medium, such as a PMMA film. According to the embodiment of the invention, 3DTE-PMI is used for super-resolution fluorescence imaging, and fluorescence imaging is reconstructed through FRC, so that the resolution reaches 24nm, the limitation (>200nm) of the diffraction limit of a conventional optical microscope on the resolution is broken through, the resolution of the conventional fluorescence imaging is improved by 10 times, and the full-visible light super-resolution fluorescence imaging of DTE is realized.

The following are specific examples:

example 1:

a diarylethene fluorescent molecular switch as shown in formula (III), wherein R₁And R₂Is composed of

The name is abbreviated as TPA-AC-DTE-Ph-O-PMI (or DTE-PMI-1), the synthetic route is shown in figure 1, and the method comprises the following steps:

(1) reference is made to the synthesis of Br-DTE-Br (Lichong, Synthesis, Properties and applications of diarylethene fluorescent molecular switches [ D ]. Wuhan, university of science and technology in Huazhong, Wuhan national research center for photoelectricity 2015: 28-32).

(2) Under the protection of nitrogen, Br-DTE-Br (1.5g,4.75mmol), triphenylphosphine (0.015g,0.095mmol), 4-ethynyltriphenylamine (0.77g,4.75mmol), 25mL of redistilled triethylamine and 120mL of redistilled tetrahydrofuran are quickly poured into a 250mL two-neck flask, and Pd (PPh) is added under the condition of vacuumizing and introducing nitrogen₃)₂Cl₂(0.01g,0.238mmol) and copper iodide (0.108g,0.095mmol), carefully exhausting nitrogen and deoxidizing for multiple times, and reacting at 90 ℃ for 24h. After quenching reaction, ethyl acetate extracts reaction liquid, and an organic phase is washed to be neutral by pure water, dried, filtered, dried and purified by column chromatography, so that 1.4g of product TPA-AC-DTE-Br is obtained, and the yield is 33%.

(3) PMI-Br (0.6g,1.04mmol), 4-bromophenol (0.25g,1.6mmol) and K₂CO₃(0.16g,1.76mmol) was mixed with 50mL of N-methylpyrrolidone, stirred well, and heated to 130 ℃ for reaction for 5 h. After cooling to room temperature, the reaction solution was poured into a dilute hydrochloric acid (1M, 100mL) solution, stirred and settled, the precipitate was filtered and washed with distilled water to neutrality, the crude product was eluted with a mixture of dichloromethane/petroleum ether at a ratio of 3:2, and the crude product was separated and purified by column chromatography to obtain 0.38g of red powder (crude product of PMI-O-Ph-Br). In the reaction process, bromine removal side reaction and nucleophilic substitution reaction coexist, the polarities of a side reaction product PMI and a target product PMI-O-Ph-Br are very similar, separation and purification are difficult, the side products are comprehensively considered to have no influence on the next reaction, and the product of the next reaction is obviously different from the polarity of the side products and is easy to separate and purify, so that the next reaction is directly carried out without further purification.

(4) Mixing the crude product (0.38g) in the last step with pinacol bisborate (0.22g,0.88mmol) and potassium acetate (0.14g,0.15mmol) to obtain 20mL of anhydrous dioxane, vacuumizing to remove nitrogen and oxygen, and rapidly adding a small amount of PdCl (palladium catalyst) in nitrogen atmosphere₂(dppf) (20mg,0.03mmol), quenching the reaction after maintaining the temperature of the reaction mixture at 90 ℃ for 16h, using CH₂Cl₂And extracting an organic phase, washing and drying the organic phase, filtering and spin-drying the organic phase, taking a mixed solution of dichloromethane/petroleum ether in a ratio of 3:2 as a developing agent, separating a crude product by silica gel column chromatography, and collecting 0.18g of red powder PMI-O-Ph-Borate, wherein the comprehensive calculation yield is 27%.

(5) Keeping nitrogen atmosphere, adding small amount of TBAHS and K₂CO₃(0.2g,2.15mmoL) was dissolved in 30mL of deionized water, 120mL of toluene was mixed and added to a 500mL two-necked flask followed by PMI-O-Ph-Borate (0.20g,0.29mmoL), TPA-AC-DTE-Br (0.127g,0.29mmoL), two-way calandria was switched to vacuum and nitrogen was charged, and tetrabutylammonium bisulfate (0.010g, 0.043mmoL) and Pd (PPh) were added with stirring directly under liquid nitrogen protection₃)₄(0.019g,0.0215mmol), vacuumizing again, and reacting at 80 deg.C for 16 hr, CH₂Cl₂And (3) extracting, removing the organic solvent by rotary evaporation, separating by column chromatography by using a developing agent V dichloromethane and V petroleum ether as a developing agent 2, and drying in vacuum to obtain 0.29g of red solid, namely the target product TPA-AC-DTE-Ph-O-PMI with the yield of 53%. The product was structurally characterized by 1H NMR (600M, CD2Cl2): δ (ppm)1.21(d, J ═ 7.8Hz,12H),1.93(t, J ═ 9.9Hz,6H),2.37(dt, J1 ═ 9.7, J2 ═ 4.6Hz,2H),6.69(s,2H),6.98-7.00(d, J ═ 8.3Hz,2H),7.07-7.12(s ═ 8.5Hz,8H),7.21-7.24(M,4H),7.26(d, J ═ 9.8Hz,4H),7.31(d, J ═ 8.8Hz,1H),7.36-7.49(M,2H),7.54-7.63(M,1H),7.67(d, 6.5J ═ 8Hz, 8H), 7.59 (M, 7.7.7.8H), 7.57-7.8H, 7.59 (M, 8H), 7.7.7.7.59 (M, 8H), 7.59 (M, 8H), 8H, 8, 1H, 8, 1H.

Preparation of PMMA film: 1g of polymethyl methacrylate was dissolved sufficiently in 10mL of chloroform solution for 1 hour by sonication to prepare a PMMA mother liquor of 100mg/mL, and the solution was allowed to stand overnight. Adding 2mg of the prepared fluorescent molecular switch into 1mL of PMMA mother solution which is completely dissolved to prepare 2mg/mL of fluorescent dye-PMMA-chloroform solution, taking 100uL of the solution on a clean square quartz plate, and spin-coating the solution by using a homogenizer to form a film.

Fig. 2 and fig. 3 are graphs showing the changes of the absorption spectra of the fluorescent molecular switch DTE-PMI-1 obtained by the preparation process of this example in tetrahydrofuran and polymethyl methacrylate, respectively, with the irradiation time lengths of different wavelengths of light. In FIG. 2, the excitation is performed at 488nm in tetrahydrofuran solution (2X 10)^-6M) fluorescence spectrum. The content (a) is the change of fluorescence with the illumination time length of 405nm, and the content b is the change of fluorescence with the illumination time length of 621 nm. The content c is the change of the fluorescence along with the 365nm illumination time length, the content d is the change of the fluorescence along with the 621nm illumination time length, and the illumination intensities of the 405nm/365nm/621nm LEDs are 29.18mW/cm respectively²、3.09mW/cm²、9.36mW/cm². FIG. 3 shows the fluorescence spectrum of DTE-PMI-1 in PMMA (2 wt%) excited at 488 nm. Fluorescence as a function of the duration of 405nm/621nm illumination (content a and content b). The change of fluorescence with the illumination time length of 365nm/621nm (content c and content d), the illumination intensity of the LED at 405nm/365nm/621nm is 29.18mW/cm²、3.09mW/cm²、9.36mW/cm². It can be seen that in the case of the solid polymer (C)PMMA) film, the photochromic rate is obviously slower than that of a solution state, but the fluorescence quenching speed is higher than that of tetrahydrofuran in a molecular dispersion state, the quenching efficiency is higher, after the film is irradiated by 405nm visible light for 55s, the fluorescence is almost completely quenched, the quenching rate is 98.3 percent, while the fluorescence is quenched by the irradiation of the 55s 365nm ultraviolet light for 99.9 percent, and the 405nm fluorescence on-off ratio is 60: 1.

FIG. 4 is a graph of fatigue resistance test of the fluorescent molecular switch in THF solution and PMMA obtained by the preparation process of this example, monitoring DTE-PMI-1 in THF solution (2X 10)^-6M) the absorption at 619nm (content a) and the fluorescence intensity at 594nm under the excitation of 488nm light (content b) are changed along with the alternate irradiation of 405nm (60s) visible light and 621nm (2min) visible light; the absorption at 617nm (content c) and the fluorescence intensity at 619nm (content d) in a PMMA film (2 wt%) were varied with alternating irradiation of visible light at 405nm (50s) and 621nm (4min), and the LED illumination intensities at 405nm/365nm/621nm were 29.18mW/cm²、3.09mW/cm²、9.36mW/cm². After visible light with two wavelengths of 405nm and 621nm is repeatedly and alternately irradiated for 10 circles, the fluorescence loss of the DTE-PMI-1 in a solution and a solid film is less than 5%, and the absorbance of an open/closed loop state is not obviously changed, so that the DTE-PMI-1 has good fluorescence fatigue resistance and good photochromic bistability in a tetrahydrofuran solution and a PMMA polymer solid film.

Fig. 5 is a fluorescence kinetic diagram of the fluorescent molecular switch obtained by the preparation process of this embodiment in polymethyl methacrylate (PMMA) at different wavelengths, and after excitation by light of a wavelength band of 405-450 nm, when originally intense orange fluorescence of DTE-PMI-1 reaches a Photostability (PSS), the solution changes from colorless to transparent to purple, and fluorescence is annihilated by naked eyes at substantially one hundred percent, which indicates that visible light of the wavelength band can efficiently drive the photoisomerization of DTE-PMI-1. Wherein, if the visible light with the wavelength of 405 nm-430 nm is selected as the 'erasing wavelength' of the fluorescence, the DTE-PMI-1 fluorescence is efficiently quenched.

Example 2

A diarylethene fluorescent molecular switch shown as a formula (IV), the name of which is abbreviated as TPA-AC-DTE-PMI (or DTE-PMI-2), whereinR₁And R₂Is composed of

The synthetic route is shown in figure 6 and comprises the following steps:

(1) the synthesis of Br-DTE-Br is described in example 1;

(2) the synthesis of TPA-AC-DTE-Br is described in example 1;

(3) into a 50mL two-necked flask were charged PMI-Br (0.80g,1.42mmol), pinacol bisborate (0.54g,2.2mmol), potassium acetate (0.36g,3.6mmol), and PdCl, a divalent palladium catalyst₂(dppf) (50mg,0.072mmol) and redistilled 1, 4-dioxane (50mL), stirred and mixed evenly, pumped with nitrogen for three times to remove oxygen, heated to 90 ℃ and reacted for 16 h. The reaction solution was quenched, cooled to room temperature, and then quenched with CH₂Cl₂Extracting, mixing organic phases, washing with distilled water for three times, and removing anhydrous MgSO₄After drying, suction filtration is carried out, organic solution is dried by spinning, the crude product is separated and purified by silica gel column chromatography by taking dichloromethane/petroleum ether mixed solution (4:1) as developing agent to obtain red powder 0.83g, and the calculated reaction yield is 94%.

(4) A500 mL two-necked flask was charged with a total of 60mL of toluene and water in a ratio of 4:1 with a small amount of TBAHS and K₂CO₃(0.29g,2.0mmol), PMI-Borate (0.27g,0.40mmol), TPA-AC-DTE-Br (0.21g,0.40mmol), Pd (PPh) was added under nitrogen protection₃)₄(0.019g,0.02mmol) was stirred at a constant speed, evacuated again to remove oxygen, and the temperature was maintained at 80 ℃ overnight. Extracting with distilled water and ethyl acetate, drying, evaporating organic solution, gradient eluting the crude product with column chromatography, and developing with n-hexane and CH as developing agent₂Cl₂The initial ratio of the mixed solution is 7: 3. 0.276g of red powder was obtained in a calculated yield of 59%. 1H NMR (600M, CD2Cl2): δ (ppm)1.21(d, J ═ 6.8Hz,12H),1.29(t, J ═ 6.9Hz,6H),2.78(M, J ═ 6.7Hz,2H),6.9-7.01(M,2H),7.09(M,2H),7.13(M,4H),7.20(s,1H),7.27-7.29(t, J ═ 6.6Hz,5H),7.34-7.35(d, J ═ 8.8Hz,4H),7.45-7.49(t, J ═ 9.8Hz 1H),7.7(s,2H),8.16-8.17(d, J ═ 6.8Hz,1H),8.52(d, J ═ 8.8, 1H), 19.67H, 19H, LC 97.21 (d, J ═ 8, 8H), 19H, 67, 19H, pl ═ 32H).

In FIG. 7, the contents a and b are fluorescence emission spectra of the photostable state (PSS) of the fluorescent molecular switch obtained by the preparation process of example 2 of the present invention in THF and PMMA under 488nm excitation light at 405nm and 365nm illumination, respectively. When the PMMA membrane is irradiated by 405nm visible light or 365nm ultraviolet light, the phenomenon of fluorescence switching of the DTE-PMI-2 in the PMMA membrane is more obvious compared with the corresponding solution state, the fluorescence quenching rate is increased in the light steady state and is increased from 90.7 percent in the THF solution state to 98.6 percent in the PMMA membrane, and the switch ratio is 10:1 under the 405nm light.

Comparative example 1

A diarylethene fluorescent molecular switch shown as a formula (VI), which is abbreviated as TPA-DTE-PMI (or DTE-PMI-3), wherein R₁And R₂Is composed of

The synthetic route is shown in fig. 8, and comprises the following steps:

(1) the procedure for the synthesis of Br-DTE-Br is described in example 1, and for the synthesis of PMI-Borate in example 2.

(2) Under the protection of nitrogen, anhydrous K is quickly added into a 250mL double-mouth flask₂CO₃(0.526g,7.6mmoL), pinacol 4- (diphenylamine) phenylboronate (0.44g, 1.52mmoL), Br-DTE-Br (0.96g,1.52mmoL) and redistilled V_{Deionized water}:V_{Ethylene glycol dimethyl ether}4:1(80mL), vacuumizing and charging nitrogen three times, adding a palladium catalyst (0.088g, 0.152mmoL) and a small amount of phase transfer catalyst PTC (0.05g, 0.152mmoL), stirring and mixing uniformly, ensuring that the reaction system is anhydrous and anaerobic, and heating at 90 ℃ for reaction for 24 hours. After the reaction is finished, cooling to room temperature, washing to be neutral by using distilled water, extracting by using ethyl acetate, obtaining a crude product after spin-drying, mixing dichloromethane and petroleum ether according to the volume ratio of 1:1 to be used as a developing agent, and separating and purifying the crude product by using a silica gel column chromatography to obtain 0.60g of a red solid product TPA-DTE-Br, wherein the yield is 46 percent by calculation.

(3) Anhydrous Na is added₂CO₃(0.22g,2.1mmol), TPA-DTE-Br (0.20g,0.42mmol), PMI-Borate (0.28g,0.42mmol), DME and water were added to a 100mL two-neck flask, and the mixture was stirred at a constant speed while keeping bubbling nitrogen in the reaction solution for 30min to deoxidize. Care is takenPTC (0.01g, 0.042mmoL), Pd (PPh) as a zero-valent palladium catalyst were added rapidly₃)₄(0.02g,0.021mmol), nitrogen is pumped and oxygen is strictly removed. Stirring and heating to 90 ℃, and reacting for 24 h. The product in the organic phase was extracted with ethyl acetate, washed with water over anhydrous MgSO₄After drying, suction filtration and spin drying are carried out, and silica gel chromatography (developing solvent is a mixed solution of normal hexane and dichloromethane with the volume ratio of 4:1) is carried out to purify the red powder to obtain 0.252g, namely TPA-DTE-PMI with the yield of 55 percent. 1H NMR (600M, CD2Cl2): δ (ppm)1.25-1.26(d, J ═ 6.7Hz,12H),2.15-2.30(M,6H),2.85-2.90(d, J ═ 4.3,2H),7.28(s,1H),7.35-7.38(d, J ═ 8.8Hz,2H),7.39-7.40(d, J ═ 6.7Hz,1H),7.45-7.48(t, J ═ 6.8Hz,5H),7.52-7.54(M,1H),7.60-7.72(t, J ═ 8.7Hz, 4H), 7.74-7.79(d, J ═ 6Hz,2H),8.15-8.21(M,2H), 8.8.43-8.8H, 8, 8.8, 8H ═ 8, 8.8, 8H, 8.

In FIG. 9, the contents a and b are fluorescence emission spectra of the fluorescent molecular switch obtained by the preparation process of comparative example 1 of the present invention in THF and PMMA in the ring-opened state under 488nm excitation light and in the light stabilization state (PSS) under 405nm and 365nm illumination, respectively. When the PMMA film is irradiated by 405nm visible light or 365nm ultraviolet light, the phenomenon of fluorescence switching of DTE-PMI-3 in the PMMA film is more obvious when compared with the corresponding solution state, and the fluorescence quenching rate is increased when the PMMA film is in a light steady state and is increased from 73.5 percent in a THF solution to 86.7 percent in the PMMA film; however, under 405nm illumination, the fluorescent molecular on-off ratio is only 4: 1.

Example 3

A diarylethene fluorescent molecular switch shown as formula (V) is abbreviated as (TPA-AC-DTE-Ph-O-PMI)₃PMI, where R₁And R₂Is composed of

The synthesis path is shown in fig. 10, and includes the following steps:

(1) PMI (3.0g,6.6mmol) was dissolved in 180mL of chloroform and placed in a 500mL two-necked flask, 16.5mL of liquid bromine was slowly added via a dropping funnel, the reaction was quenched after heating and refluxing for 6h, cooled to room temperature, and treated with KOH and Na₂SO₃Mixed alkali solution of (3.5g KOH, 2.4g Na)₂SO₃，500mL H₂O) washing the reaction solution for a plurality of times, collecting the organic phase with anhydrous Mg₂SO₄Drying to remove water, performing suction filtration, spin-drying a solvent, performing vacuum drying, and performing silica gel column chromatography separation and purification by using a solution with a mixing ratio of n-hexane to dichloromethane of 3:2 as a developing agent to obtain red solid powder PMI-3Br, wherein the mass is 1.66g, and the yield is as follows: 35 percent.

(2) PMI-3Br (1.44g,2.00mmol), 4-bromophenol (1.4g,8.0mmol) and K were reacted under nitrogen₂CO₃(0.8g,8.0mmol) and N-methylpyrrolidone (60mL) were charged into a 100mL single-neck flask, mixed well with stirring, and refluxed at 130 ℃ for 4 hours. The reaction was quenched and poured slowly into a stirred solution of dilute hydrochloric acid (1M, 500 mL). Filtering the obtained precipitate, washing with distilled water to neutrality, vacuum drying, and purifying with V_{Methylene dichloride}/V_{Petroleum ether}The mixed solution 1:1 was used as a developing solvent and purified by silica gel column chromatography to obtain 0.80g of PMI- (O-Ph-Br) as red powder₃The yield was 37%.

(3) PMI- (O-Ph-Br)₃(0.80g,0.40mmol) and pinacol boronate (1.22g,4.80mmol), anhydrous K₂CO₃(0.60g,6.00mmol) and 1, 4-dioxane (60mL) after deoxygenation and drying are fully stirred, evenly mixed, vacuumized and filled with nitrogen for multiple times, and the catalyst PdCl is rapidly added under the nitrogen flow₂(dppf) (88mg,0.12mmol), followed by evacuation, and heating to 90 ℃ for 16 h. After cooling to room temperature, the reaction solution was treated with CH₂Cl₂Extracting, washing with water for three times, drying with anhydrous magnesium sulfate, suction filtering, and rotary steaming. Using a mixed solution of dichloromethane/n-hexane (4:1) as an eluent, carrying out silica gel column chromatography on the crude product, and finally recrystallizing with a dichloromethane/n-hexane solution to obtain 0.48g of red solid particles PMI- (O-Ph-Borate)₃The yield was 41%.

(4) Under the protection of nitrogen, PMI- (O-Ph-Borate) is quickly added into a 500mL double-mouth flask₃(0.40g,0.25mmol), TPA-AC-DTE-Br (0.54g,0.75mmol), small amounts of TBAHS and K₂CO₃(0.5g,1.25mmol), toluene and water 4:1 in total 60mL, and an appropriate amount of Pd (PPh) added under a nitrogen stream₃)₄(0.042g,0.04mmol), evacuation and nitrogen gas filling three timesEnsuring that the reaction system is free of oxygen, and stirring at a constant speed at 80 ℃ for reaction. Overnight, the organic phase was extracted with ethyl acetate, the solvent was dried by spinning, and the mobile phase was CH₂Cl₂Mixing petroleum ether and ethyl acetate according to the initial volume ratio of 2:6:2, separating the crude product by gradient elution to obtain 0.259g of red target product (TPA-AC-DTE-O-Ph)₃PMI, calculated in 39%.¹H NMR(600MHz,CD₂Cl₂):δ(ppm):7.70-7.65(d,J＝2.4Hz,1H),7.60-7.48(dq,J＝8.4Hz,6H),7.46-7.42(t,J＝2.1Hz,1H),7.35-7.32(d,J＝8.0Hz,6H),7.31-7.26(t,J＝7.9Hz,12H),7.27-7.23(d,J＝6.5Hz,4H),7.20(t,J＝6.7Hz,6H),7.19-7.15(m,2H)7.12-7.07(t,J＝4.6Hz,11H),6.95(d,J＝9.1Hz,6H),2.18(d,J＝8.1Hz,9H),2.14(d,J＝8.8Hz,18H),1.16(m,12H).¹³C NMR(151MHz,CDCl₃):δ(ppm):169.6,157,163.7,159.8,156.9,145.6,152.3,147.7,147.5,146.3,146,145.1,144.2,143.4,142.6,141.8,140.4,139.5,138.9,138.1,137.8,137.3,136.7,135,134.5,133.6,132.9,131.7,130.7,118,128.2,121.5,118.7,116.9,94.9,73.9,26.4,18.4,14.7.MS(MALDI-TOF m/z):[M+1]⁺Calcd.for C₁₅₇H₁₀₂F₁₈N₄O₅S₆,2658.90；found,2657.90.HPLC purity:95.5％。

FIG. 11 is a graph showing the change of the fluorescence spectrum of the fluorescent molecular switch 3DTE-PMI obtained by the preparation process of this example in Tetrahydrofuran (THF) with the irradiation time of light at 405nm/621nm and 365nm/621nm, and FIG. 11 shows the fluorescence spectrum of the fluorescent molecular switch 3DTE-PMI excited by 488nm in THF at 405nm (33.02 mW/cm) in FIG. 11, wherein a, b, c and d are respectively the fluorescence spectrum of the fluorescent molecular switch 3DTE-PMI excited by 488nm in THF at 405nm (33²)、621nm(6.28mW/cm²) And 365nm (8.22 mW/cm)²)、621nm(9.34mW/cm²) Change spectrogram in illumination with concentration of 5 × 10^-6M。

FIG. 12 is a graph of absorption and 488nm fluorescence excitation spectrum of fluorescent molecular switch 3DTE-PMI obtained by the preparation process of this example in PMMA (2 wt%). Absorption of 3DTE-PMI in PMMA (2 wt%) and 488nm excitation fluorescence spectrum. The absorption varied with the duration of 405nm/621nm illumination (content a, content c). Fluorescence varied with the duration of 405nm/621nm illumination (content b, content d). The absorption varied with the duration of 365nm/621nm illumination (content e, content g). FluorescenceThe illumination intensity of the 405nm/365nm/621nm LED is 29.18mW/cm respectively along with the change of the illumination time length of 365nm/621nm (content f, content h)²、3.09mW/cm²、9.36mW/cm²。

It can be seen that a fluorescence on-off ratio of 230:1 was obtained in tetrahydrofuran, quenching 99.3% of the initial fluorescence, showing rapid photo-response capability. Under the same test condition, the 365nm ultraviolet light is used for continuous illumination, the fluorescence on-off ratio reaches 3651:1, the initial-100% fluorescence is almost quenched, and the excellent fluorescence contrast is shown. Continuously illuminating for 20s at 405nm in PMMA to reach PSS state, wherein the fluorescent on-off ratio is 659: 1; the optical property spectrogram of 365nm ultraviolet light illumination under the same test condition is similar to 405nm illumination, and the fluorescence on-off ratio is 1090: 1.

FIG. 13 is a fatigue resistance test chart of the fluorescent molecular switch 3DTE-PMI obtained by the preparation process of this embodiment in a THF solution, and the 3DTE-PMI is subjected to different light alternate irradiation to monitor the absorption at 614nm and the fluorescence intensity at 580nm under 488nm light excitation. Alternatively irradiating at 405nm (40s)/621nm (3min) in THF solution, absorbing/fluorescence (content a/content b); alternate irradiation at 365nm (40s)/621nm (3min), absorption/fluorescence (content c/content d). Absorption/fluorescence (content e/content f) in PMMA film at 405nm (15s)/621nm (6 min); 365nm (60s)/621nm (6min), and absorbs fluorescence (content g/content h). The concentration is 5X 10^-6The illumination intensities of the M, 405nm/365nm/621nm LEDs are 29.18mW/cm respectively²、3.09mW/cm²、9.36mW/cm². Irradiating at 405nm for 40s to obtain (TPA-AC-DTE-O-Ph)₃PMI-C (C represents a closed-loop state) almost completely annihilates fluorescence emission when the maximum absorbance of the PMI-C in a visible light region is more than 90% of that of PSS, and then restores the initial absorbance and the fluorescence emission intensity of an open-loop state after being irradiated for 3min at 621 nm. And 3DTE-PMI shows a small fluorescence loss of less than 3% after several tens of alternate irradiation, and a good fatigue resistance of the compound (TPA-AC-DTE-O-Ph)₃PMI has great advantages in practical optical applications.

Fig. 14 is a fluorescence dynamics diagram of the fluorescent molecular switch obtained by the preparation process of this embodiment in polymethyl methacrylate (PMMA) at different wavelengths, and a PMMA film excited by visible light in a wavelength band of 400nm to 440nm (TPA-AC-DTE-O-Ph)3-PMI has a faster fluorescence switching speed and a larger fluorescence quenching rate, so that the visible light in this wavelength band is used to replace ultraviolet light, and the method is applied to practical applications such as super-resolution fluorescence imaging, and avoids using ultraviolet light, improves fatigue resistance of a sample, and avoids radiation damage to the sample and an operator.

Wherein, the preparation of PMMA film: 1g of polymethyl methacrylate was dissolved sufficiently in 10mL of chloroform solution for 1 hour by sonication to prepare a PMMA mother liquor of 100mg/mL, and the solution was allowed to stand overnight. Adding 2mg of the prepared fluorescent molecular switch into 1mL of PMMA mother solution which is completely dissolved to prepare 2mg/mL of fluorescent dye-PMMA-chloroform solution, taking 100uL of the solution on a clean square quartz plate, and spin-coating the solution by using a homogenizer to form a film.

Example 4

The fluorescent molecular switch prepared in example 3 is used for optical storage.

The visible light regulation photophysical behavior and photochemical property of the 3DTE-PMI in an aggregation state are inspired, theoretically, the fluorescence emission and annihilation of the dithienyl ethylene derivative can represent '1' and '0' of information binary, information recording points enter a single molecule level, each fluorescence switch molecule is a fluorescence information recording point, and the application research of the photochromic compound is further explored.

The fluorescence emission of the open-loop 3DTE-PMI molecule in a PMMA polymer medium is a bright state, the closed-loop molecule greatly quenches fluorescence even to a non-fluorescence state due to a FRET (fluorescence resonance energy transfer) mechanism, and the 3DTE-PMI has the capability of fluorescence switching at the same time due to optically-controlled reversible open-close ring isomerization reaction, so that the optical property test shows that the fluorescence switching ratio of the 3DTE-PMI molecule reaches 659:1 under the irradiation of visible light at 405nm, the photoisomerization conversion rate can reach 77.8%, the bistable fluorescence switching performance can realize the optical storage of high-density and high-precision information, and the accuracy of reading out the fluorescence information by using the visible light at 405nm is ensured.

Preliminarily building a microscopic optical storage model, dripping a PMMA (polymethyl methacrylate) chloroform solution doped with 3DTE-PMI on a quartz glass sheet, placing a mesh optical mask plate right above a sample, and preliminarily building an erasable information storage model with the size of several microns. And (3) emitting orange fluorescence by the sample in the mesh under the illumination of 405nm visible light, continuously exciting for a period of time until the fluorescence in the mesh is almost completely quenched, removing the mesh template, continuously exciting with the 405nm visible light, enabling the sample in the hole on the quartz plate to be in a dark state, enabling the fluorescence to present a pattern with a mesh shape, and further quenching the mesh fluorescence information of the template on the glass plate after continuously irradiating for a period of time, namely erasing the fluorescence information by the illumination of 405 nm. The 3DTE-PMI fluorescent molecular switch has good light stability, and template information on the quartz plate can be repeatedly subjected to multiple times of light writing and light erasing, so that the 3DTE-PMI fluorescent molecular switch has potential application value in the aspects of light storage, anti-counterfeiting display and the like.

Example 5

The fluorescent molecular switch prepared in example 3 is applied to super-resolution imaging.

The 3DTE-PMI can respond quickly under the excitation of 405nm light, most of the 3DTE-PMI is converted into closed-loop molecules, the fluorescence is quenched, the closed-loop 3DTE-PMI-C responds slowly under the excitation of 488nm light, and the molecules which are quenched to fluorescence are randomly lightened. Under the regulation and control of external exciting light, the single fluorescent molecular switch 3DTE-PMI is captured by an optical system to obtain the sparsely lighted fluorescence at different moments, and accords with the super-resolution single-molecule reconstruction imaging principle, so that two visible light laser beams of 405nm and 488nm are selected as working light sources for jointly regulating and controlling the fluorescence of the 3 DTE-PMI.

FIG. 15 shows a 3 DTE-PMI-stained PSt-b-PEO block copolymer micelle (content a) bright field map, (content b) conventional fluorescence imaging map, (content c) super-resolution fluorescence imaging map, and (content d) super-resolution and fluorescence integration map, wherein the scale in the content a, b, and d is 5000nm, and the scale in the content c is 2500 nm.

Conventional imaging and super-resolution imaging of the copolymer micelle fluorescence self-assembled by 3DTE-PMI and PSt-b-PEO were compared (FIG. 15, content b, content c). The fluorescence image is cross-sectionally analyzed by a Gaussian deconvolution method, the local full width at half maximum (FWHM) of the micelle is measured, the minimum full width at half maximum (FWHM) of the conventional fluorescence image is 304nm, a super-resolution reconstructed imaging image of the same area (content c in figure 15) is obtained, the data of the full width at half maximum is 32.7nm, and the imaging resolution is improved by 10 times. The overall resolution of the super-resolution image was calculated as 24.72 ± 0.42nm from a large data fit Fourier Ring Correlation (FRC) curve. The performance of the 3DTE-PMI fluorescent molecular switch in super-resolution imaging application is evaluated in more detail, and in addition, the average photon number which accords with Gaussian distribution is obtained through calculation, which fully indicates that the micelle dyed by the probe has strong enough fluorescence emission. In addition, Scanning Electron Microscopy (SEM) images of PSt-b-PEO micelles showed that the actual size was about 33nm, consistent with the half-width analysis of super-resolution fluorescence imaging. The 3DTE-PMI can be applied to a solid-state luminescent probe with excellent fluorescence performance, the diffraction limit is broken, the resolution of fluorescence imaging of a conventional optical microscope is improved by more than 10 times in situ, and the super-resolution fluorescence imaging characterization of a microstructure below 30nm is realized.

Example 6

The synthesis process comprises the following steps:

(1) for the synthesis of PMI-O-Ph-Br and PMI-O-Ph-Borate, see example 1, (P-toluene)₂Synthesis of (E) -N-Ph-AC-DTE-Br referring to example 1, the starting material 4-ethynyltriphenylamine was replaced with (P-toluene)₂-N-Ph-AC, the other steps being the same.

(2) Keeping nitrogen atmosphere, adding small amount of TBAHS and K₂CO₃(0.2g,2.15mmol) was dissolved in 30mL of deionized water, 120mL of toluene was mixed and added to a 500mL two-necked flask followed by PMI-O-Ph-Borate (0.20g,0.29mmol), (P-toluene)₂-N-Ph-AC-DTE-Br (0.215g,0.29mmoL), switching the double calandria, vacuumizing and charging nitrogen, then directly adding tetrabutylammonium hydrogen sulfate (0.010g, 0.043mmoL) and Pd (PPh) under stirring in the condition of liquid nitrogen protection₃)₄(0.019g,0.0215mmol), vacuumizing again, and reacting at 60 deg.C for 13 hr, CH₂Cl₂Extracting, removing organic solvent by rotary evaporation, separating by column chromatography with developing agent V dichloromethane V petroleum ether (l: 2), and vacuum drying to obtain red solid 0.34g, i.e. target product (P-tolue)ne)₂-N-Ph-AC-DTE-Ph-O-PMI, yield 61%. Under the irradiation of 405nm laser, the closed-loop conversion rate reaches 80%, the fluorescent on-off ratio reaches 52:1, and the photochromic process can be reversibly circulated for many times.

Example 7

The synthesis process comprises the following steps:

(1) for the synthesis of PMI-O-Ph-Br and PMI-O-Ph-Borate, see example 1, (Butyl)₂Synthesis of (E) -N-Ph-AC-DTE-Br in example 1, wherein 4-ethynyltriphenylamine (Butyl) is used as the starting material₂-N-Ph-AC, the other steps being the same.

(2) Keeping nitrogen atmosphere, adding small amount of TBAHS and K₂CO₃(0.2g,2.15mmol) was dissolved in 30mL of deionized water, 120mL of toluene was mixed and added to a 500mL two-necked flask followed by PMI-O-Ph-Borate (0.20g,0.29mmol), (Butyl)₂-N-Ph-AC-DTE-Br (0.196g,0.29mmoL), switching the double calandria, vacuumizing and charging nitrogen, then directly adding tetrabutylammonium hydrogen sulfate (0.010g, 0.043mmoL) and Pd (PPh) under stirring in the condition of liquid nitrogen protection₃)₄(0.019g,0.0215mmol), vacuumizing again, and reacting at 60 deg.C for 13 hr, CH₂Cl₂Extracting, rotary evaporating to remove organic solvent, separating by column chromatography with developing agent V dichloromethane V petroleum ether ═ l:2, and vacuum drying to obtain red solid 0.19g, i.e. target product (Butyl)₂-N-Ph-AC-DTE-Ph-O-PMI, yield 58%. Under the illumination of 405nm, the closed-loop conversion rate exceeds 84%, the fluorescent on-off ratio reaches 36:1, and the fatigue resistance is better.

Example 8

A diarylethene fluorescent molecular switch as shown in formula (V), wherein R₁is-CH₃、R₂Is composed of

The synthesis process comprises the following steps:

(1)PMI-3Br、PMI-(O-Ph-Br)₃、PMI-(O-Ph-Borate)₃see example 3 for synthesis.

(2) Synthesis of (Methyl, Ph) -N-Ph-AC-DTE-Br referring to example 1, the starting material 4-ethynyltriphenylamine was changed to (Methyl, Ph) -N-Ph-AC, and the other steps were the same.

(3) Under the protection of nitrogen, PMI- (O-Ph-Borate) is quickly added into a 500mL double-mouth flask₃(0.40g,0.25mmol), (Methyl, Ph) -N-AC-DTE-Br (0.49g,0.75mmol), small amounts of TBAHS and K₂CO₃(0.5g,1.25mmol), toluene and water 4:1 in total 60mL, and an appropriate amount of Pd (PPh) added under a nitrogen stream₃)₄(0.042g,0.04mmol), vacuumizing and charging nitrogen for three times to ensure that the reaction system is free of oxygen, and stirring at a constant speed at 80 ℃ for reaction. Overnight, the organic phase was extracted with ethyl acetate, the solvent was dried by spinning, and the mobile phase was CH₂Cl₂Mixing the petroleum ether and ethyl acetate according to the initial volume ratio of 2:6:2, and separating the crude product by gradient elution to obtain 0.24g of red target product ((Methyl, Ph) -N-Ph-AC-DTE)₃PMI, calculated in 39%. The closed-loop conversion rate is higher than 78%, the fluorescent switching ratio is as high as 520:1, and the fluorescent material has good fatigue resistance and high fluorescent quantum yield.

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. An aniline-alkynyl conjugated modified dithienyl ethylene derivative is characterized by comprising a structural unit shown as a formula (I) or a formula (II):

2. A dithienylethylene derivative according to claim 1, wherein R is₁And R₂Each independently is C1-C5 alkyl, C1-C5 alkyl alcohol or C6-C10 aryl.

3. A dithienylethylene derivative according to claim 1, wherein R is₁And R₂Each independently is methyl, ethyl, propyl, phenyl, tolyl, ethylphenyl, propylphenyl, hydroxyethyl, or hydroxypropyl.

4. A process for preparing a dithienylethylene derivative according to any of claims 1 to 3, characterized by comprising the steps of:

(1) 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; then 3-bromo-2-methyl-5-trimethylsilylthiophene, n-butyllithium and perfluorocyclopentene are used as raw materials to react to prepare 1, 2-bis (2-methyl-5-trimethylsilylthiophene-3-yl) perfluorocyclopentene, and finally 1, 2-bis (2-methyl-5-trimethylsilylthiophene-3-yl) perfluorocyclopentene, anhydrous tetrahydrofuran and NBS are used as raw materials to react for 14-18 hours at room temperature in a dark place to obtain a compound 1, 2-bis (5-bromo-2-methylthiophene-3-yl) perfluorocyclopentene, namely Br-DTE-Br;

(3) will carry R₁And R₂Taking aniline group-AC-DTE-Br and PMI-O-Ph-Borate of the groups as raw materials, and respectively removing Br and Borate groups to obtain a compound containing a structural unit shown in a formula (I); or will carry R₁And R₂Radical benzeneTaking amine group-AC-DTE-Br and PMI-Borate as raw materials, and respectively removing Br and Borate groups to obtain the compound containing the structural unit shown in the formula (II).

5. Use of a dithienylethylene derivative according to any of claims 1 to 3 in an all visible light modulated fluorescent molecular switch.

6. The bithienyl ethylene fluorescent molecular switch regulated by full visible light is characterized in that perylene monoimide is used as a fluorescent group, bithienyl ethylene is used as a photochromic unit, the structure of the fluorescent molecular switch also comprises a photosensitizing group, the photosensitizing group is an aniline-alkynyl group, and the photosensitizing group is in conjugate connection with the photochromic unit bithienyl ethylene;

the fluorescence molecular switch has the advantages that through introducing the aniline-alkynyl group, the triggering wavelength of the closed-loop reaction can be red shifted to a visible light region, and meanwhile, the triggering wavelength of the open-loop reaction is in the visible light region, so that the full visible light regulation and control of the photoisomerization reaction of the fluorescence molecular switch are realized, and the fluorescence switch ratio and the fluorescence quenching rate of the fluorescence molecular switch are improved; the trigger wavelength range of the ring-closure reaction is preferably 400-440 nm.

7. The fluorescent molecular switch of claim 6, wherein the photochromic unit is perfluorocyclopentadithiophene-based ethylene; the fluorescent molecular switch comprises a structural unit shown as a formula (I) or a formula (II):

wherein R is₁And R₂Each independently is C1-C10 alkyl, C1-C10 alkyl alcohol orAryl of C6-C20.

8. The fluorescent molecular switch of claim 7, wherein R is₁And R₂Each independently is C1-C5 alkyl, C1-C5 alkyl alcohol or C6-C10 aryl.

9. The fluorescent molecular switch of claim 7, wherein R is₁And R₂Each independently is methyl, ethyl, propyl, phenyl, tolyl, ethylphenyl, propylphenyl, hydroxyethyl, or hydroxypropyl.

10. Use of a fluorescent molecular switch according to any of claims 6 to 9 in the field of optical storage or super-resolution imaging.