CN114752070A

CN114752070A - Photoresponse intelligent material and preparation method thereof

Info

Publication number: CN114752070A
Application number: CN202210485626.0A
Authority: CN
Inventors: 范丛斌; 蒲守智; 范亭亭; 刘刚; 涂雅怡; 李志坚; 郑春红
Original assignee: Jiangxi Science and Technology Normal University
Current assignee: Jiangxi Science and Technology Normal University
Priority date: 2022-05-06
Filing date: 2022-05-06
Publication date: 2022-07-15
Anticipated expiration: 2042-05-06
Also published as: CN114752070B

Abstract

The invention discloses a photoresponse intelligent material and a preparation method thereof. The material is [ Cd (BCM) ]_0.5(4,4′‑bipy)_0.5]Belonging to the orthorhombic Pnna space group, whose asymmetric unit comprises a crystallographically independent divalent Cd, half of a perfluorodithienyl vinyl formate anion and half of a 4,4' -bipyridine molecule. The compound is prepared by taking perfluoro dithienyl vinyl formic acid and 4,4' -bipyridine as mixed ligands. Photo-responsive smart material of the present application [ Cd (BCM)_0.5(4,4′‑bipy)_0.5]Compared with perfluoro dithienyl vinyl formic acid, the color generation process and the color fading process have better speed, thermal stability and fatigue resistance, and larger application prospect; the distance is significantly minimized and the cyclization and decyclization rates are maximized compared to the same class of complexes. The photoresponse intelligent material can be switched between two discrete states during irradiation, and pure white or blue crystals can be selected according to requirementsNow, the natural blue spar can be well replaced.

Description

Photoresponse intelligent material and preparation method thereof

Technical Field

The invention belongs to the field of photoresponse metal-organic framework compounds, and particularly relates to a photoresponse intelligent material and a preparation method thereof.

Background

The blue natural spar has special magic power and is popular among a plurality of amateurs. First, blue represents a precious color, such as alexandrite, sea vein stone, sapphire, etc., which are all valuable. Blue crystals with colors from sky blue to dark blue are coated in pure white crystals, and the crystals are beautiful and rare; secondly, blue is a curing color system, and blue crystallization is used for the adjuvant treatment of depression and insomnia in foreign countries; thus, sapphire is also known as a healed gemstone. The yield of blue-hair crystals is very rare, only brazil is found with such a field, and the exploitation of this ore is very difficult, because of the beautiful shape and magical efficacy of this stone, its popularity is increasing and the demand is also increasing.

Disclosure of Invention

Aiming at the problems of high price, small quantity, difficult exploitation and the like of blue natural spar, the most fundamental way for solving the shortage of supply is replacement, and the cadmium metal organic framework compound constructed on the basis of a mixed ligand of perfluorodithienyl vinyl formic acid and 4,4' -bipyridine is provided and is a photochromic intelligent material. Compared with diarylene or other published similar complexes, the coordinated cadmium metal organic framework complex has better effect or performance in the aspects of the speed of a color generation process and a fading process, thermal stability, fatigue resistance and the like. Attempts to incorporate the photoresponsive material into processes such as necklaces, earrings, brooches have resulted in both increased product aesthetics and a solution to the problem of energy consumption. The crystal can be switched between two discrete states during irradiation, which indicates that the photophysical properties of the material can be adjusted according to the excitation wavelength, and pure white or blue crystals can be selected to be presented according to requirements. For example, it appears pure white in the absence of light or darkness and blue in the sun. The development of stimuli-responsive materials that undergo changes in their physicochemical properties upon exposure to external light stimuli covers the next generation of advances in the art.

The following technical scheme is adopted specifically:

a light-responsive smart material, wherein the material is [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5]Belonging to the orthorhombic Pnna space group, the asymmetric unit of which comprises a crystallographically independent divalent Cd, half of a perfluorodithienyl vinyl formate anion and half of a 4,4' -bipyridine molecule; in a coordination environment, divalent Cd presents a four-corner bipyramid coordination geometric structure, the vertex is respectively provided by nitrogen atoms of two 4,4' -bipyridyl ligands, the basal plane is formed by four oxygen atoms of four perfluoro-dithienyl vinyl formic acid ligands, wherein the distance of Cd-O bonds is

Distance of Cd-N bond of

The coordination mode of the perfluoro-dithienyl vinyl formate ligand is bidentate bridging mu 4-eta 1: eta 1, the structure of the perfluoro-dithienyl vinyl formate is arranged in an antiparallel conformation, and the distance between two active carbon atoms is

(less than

Indicating [ Cd (BCM)_0.5(4,4′-bipy)_0.5]Optically active); the material is a 3-

node

2,2,8-c connection network, and the topological symbol of the material is {4 }².6¹⁰.8¹⁰.10⁶}{4}²{6}²。

Among them, few reports of 4,4 '-bipyridyl cobalt, copper and zinc complexes and perfluoro dithienyl cobalt formate, copper and zinc complexes have been reported, but a complex assembled by perfluoro dithienyl vinyl formate and 4,4' -bipyridyl as ligands and cadmium as metal ions has not been found so far.

4,4' -bipyridine is a linear double-base rigid ligandThe product has no branched chain, less steric hindrance and better bridging effect. The coordination ability of the transition metal ions and the ammonia atom of the 4,4' -bipyridyl is stronger, and the coordination complexes with various spatial structures can be formed. Mainly comprises a linear shape, a zigzag shape, a step shape, a brick wall shape, a square net, a honeycomb shape, a diamond shape and an octahedron shape. The two pyridine rings can rotate around the carbon-carbon single bond between the two pyridine rings at will, so that the diversity of the space structure of the bridged complex is increased. Due to different structures of the complexes, different complex properties are obtained, and the different complex properties inevitably cause different purposes in application. The photochromism of diarylethene derivatives in the single crystalline phase is controlled by the molecular conformation in the crystal. In the perfluoro-dithienyl vinyl formic acid crystal, two isomers with different photoactivity in an antiparallel conformation and a parallel conformation exist at the same time. In the antiparallel conformation, the distance between the activated carbon atoms C1 and C10 is

Sufficient for the photocyclization reaction to occur in the crystal. In the photo-inactive parallel conformation, the distance between the activated carbon atoms C18 and C27 is

The ratio of antiparallel to parallel conformations is 1:1, so that only 50% of the diarylethene molecules in the crystal can undergo a photochromic reaction.

And [ Cd (BCM)_0.5(4,4′-bipy)_0.5]In the single crystal, the distance between two activated carbon atoms is

The distance between two activated carbon atoms is reduced compared to perfluorodithienyl vinyl formic acid single crystals

Also, 100% of the diarylethene molecules in the crystal can undergo a photochromic reaction.

We handle [ Cd (BCM)_0.5(4,4′-bipy)_0.5]And the other twoThe photoisomerization rates of the same complexes were compared. The cyclization rate constants of the three substances are obtained, and the sizes of the three substances are [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5](8.89×10^-3mol·L^-1·s^-1)，[Zn(BCM)₂(bpfb)](8.37×10^-3mol·L^-1·s^-1),[Zn₂(BCM)₂(4,4′-bipy)](8.07×10^-3mol·L^-1·s^-1). Log (A) under visible light irradiation during the decyclization process₁) Shows a good linear relation with the irradiation time, which indicates that the decyclization process belongs to a first-order reaction, and the reaction rate constants of the decyclization process are [ Cd (BCM) ] from large to small_0.5(4,4′-bipy)_0.5](6.20×10^-2s^-1)，[Zn(BCM)₂(bpfb)](4.19×10^-2s^-1)，[Zn₂(BCM)₂(4,4′-bipy)](4.99×10^-2s^-1). Of the three materials, [ Cd (BCM)_0.5(4,4′-bipy)_0.5]The cyclization reaction rate of (a) is maximal, while the decyclization reaction rate is also maximal, and may be related to the distance between two activated carbon atoms of the perfluorodithienyl vinyl formate ligand in its crystal structure, compared to the other two materials, [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5]Is significantly minimized.

The invention also provides a preparation method of the photoresponse intelligent material, which comprises the following steps:

perfluorodithienyl vinyl formic acid, 4' -bipyridine and Cd (NO)₃)₂·4H₂Dispersing O in a dimethylformamide/ethanol/deionized water solution according to a molar ratio of 1:1:1, wherein the volume ratio of dimethylformamide to ethanol to deionized water is 1.5:0.1:1, heating at 115 ℃ for 72 hours under a sealed condition, and filtering to obtain transparent blocky crystals. Preferably, the transparent bulk crystal is rinsed 3 times with dimethylformamide and ethanol.

The invention has the beneficial effects that:

(1) photo-responsive smart material of the present application [ Cd (BCM)_0.5(4,4′-bipy)_0.5]Compared with perfluor bithienyl vinyl formic acid, the cadmium metal organic frame after coordinationThe frame compound has better speed, thermal stability (the thermal stability is still kept at the high temperature of 350 ℃) and fatigue resistance (the absorption strength is basically not influenced after continuous 25 reversible cycles) in the color generation process and the color fading process, and has wider application prospect.

(2) Photo-responsive smart material [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5]The structure of the perfluorodithienylvinyl formic acid is arranged in an antiparallel conformation, the distance between two activated carbon atoms is less than

And 100% of diarylethene molecules in the crystal can generate photochromic reaction; compared with the same complex, [ Cd (BCM)_0.5(4,4′-bipy)_0.5]Is significantly minimized and its cyclization reaction rate is maximized, while the decyclization reaction rate is also maximized.

(3) Photo-responsive smart material [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5]The crystal can be switched between two discrete states during irradiation, the photophysical properties of the material can be adjusted according to the excitation wavelength, pure white or blue crystal can be selected according to requirements to be presented, and natural blue spar can be well replaced.

Drawings

FIG. 1 is a diagram showing the synthetic scheme of ligand perfluorodithienyl vinyl formate;

FIG. 2 shows [ Cd (BCM)_0.5(4,4′-bipy)_0.5]A synthetic scheme for crystalline materials;

FIG. 3 shows [ Cd (BCM)_0.5(4,4′-bipy)_0.5]The crystal structure of (1);

FIG. 4 shows [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5]Thermogram of (a);

FIG. 5 shows [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5]In the infrared spectrum；

FIG. 6 shows [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5]Powder X-ray diffraction pattern of (a);

FIG. 7 shows [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5]And a solid photochromic plot of a perfluorodithienyl vinyl formate ligand;

FIG. 8 shows [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5]And a photochromic pattern of a perfluorodithienyl vinyl formate ligand in methanol solution;

FIG. 9 shows [ Cd (BCM)_0.5(4,4′-bipy)_0.5]And photoisomerization rate profile of the same complex in methanol saturated solution.

Detailed Description

The concept and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments and the accompanying drawings to fully understand the objects, aspects and effects of the present invention.

Example 1:

(1) synthesis of ligand perfluorodithienyl vinyl formic acid

The synthetic route is shown in figure 1. Accurately weighed 1(15.13g, 120mmol) and placed in a 250mL single-neck flask, 120.0mL glacial acetic acid was added and stirred, and Br was measured using a measuring cylinder₂(9.0mL, 132mmol) was added slowly dropwise over Br over about 2h in an isobaric titration funnel₂Then keeping the reaction for 12h, adding a proper amount of water to stop the reaction after the reaction is finished, and passing through Na₂CO₃Adjusting the reaction liquid to be neutral, adding 120.0mL of multiplied by 3 dichloromethane for extraction, combining organic phases, washing by supersaturated salt solution, drying by anhydrous sodium sulfate, carrying out rotary evaporation under reduced pressure, removing a solvent, carrying out column chromatography by silica gel, separating by eluent which is pure petroleum ether, and obtaining a product 2 which is a light yellow solid (13.02g, yield: 53.57%), and carrying out structural analysis on a target product:¹H NMR(400MHz，DMSO-d₆)δ(ppm)：9.81(s，1H)，8.01(s，1H)，2.47(s，3H)。

accurately weighing 2(3.06g, 15mmol) and adding into 250.0mL single-neck bottle, adding 3.0mL ethylene glycol, p-toluenesulfonic acid (0.056g, 0.03mmol) as catalyst, toluene as solvent, heating to 130 deg.C, maintaining, and introducingH generated in the water passing device₂O is separated out and 3.0mL of H is produced by 10mmol of material₂The general rule of O judges whether the reaction is complete, 3 is an intermediate product, the aldehyde group protection stability is poor, the process is not further purified, and the next reaction is directly carried out after the reaction is finished.

3 was dissolved in 120.0mL of purified anhydrous tetrahydrofuran at a low temperature of-78 ℃ under an argon atmosphere, and placed in a 250.0mL three-necked flask. Injecting n-butyl lithium (7.0mL, 16mmol) through a syringe, continuously adding liquid nitrogen during the reaction to keep reacting at low temperature for 0.75h, weighing perfluorocyclopentene (1.2mL, 9mmol) to be dissolved in 15.0mL refined tetrahydrofuran, dropwise adding the solution into a reaction system through a constant pressure titration funnel to react for 3h, tracking the reaction through TLC detection, adding a proper amount of deionized water to terminate the reaction after the reaction is completed, carrying out reduced pressure rotary evaporation, adding 120.0mL multiplied by 3 dichloromethane to extract, combining organic phases, washing with supersaturated salt water, drying with anhydrous sodium sulfate, carrying out reduced pressure rotary evaporation, taking petroleum ether and ethyl acetate (v: 20:1) as eluents, separating and purifying through a silica gel column, wherein the product is 1.55g of 4 blue oily liquid, and the yield is: 20.23 percent.¹HNMR(400MHz，DMSO-d₆)δ(ppm)：6.79(s，2H)，6.07(s，2H)，3.85(d，4H)，3.75(d，4H)，2.36(s，6H)。

Taking 4(1.5g, 3mmol) to a 250.0mL single-neck flask, dissolving in 120.0mL acetone and 30.0mL water, taking p-toluenesulfonic acid (1.66g, 8.7mmol) as a catalyst, heating to 80 ℃, stirring and refluxing, reacting for 12h, tracing the reaction by TLC detection, after the reaction is completed, carrying out reduced pressure rotary evaporation, adding 120.0mL multiplied by 3 dichloromethane for extraction, combining organic phases, washing with supersaturated sodium chloride, drying with anhydrous sodium sulfate, carrying out reduced pressure rotary evaporation, taking petroleum ether and ethyl acetate (v: v ═ 20:1) as eluent, separating and purifying by silica gel column to obtain 1.12g of 5 blue solid matter, wherein the yield: 88.21 percent.¹HNMR(400MHz，DMSO-d₆)δ(ppm)：9.90(s，1H)，8.12(s，1H)，2.03(s，3H)。

Accurately weighing compound 5(1.12g, 2.64mmol), dissolving in acetone, pouring into a single-neck flask, stirring in ice-water bath environment, gradually dropping Jones reagent until the solution turns orange from blue, and addingChanging to green, detecting and tracking reaction by TLC, after the reaction is finished, carrying out rotary evaporation under reduced pressure, adding trichloromethane and water solution, carrying out suction filtration, and drying in an oven for 5h to obtain 1.13g of 6 light green solid powder with the yield of 91.17%.¹H NMR(400MHz，DMSO-d₆)，δ(ppm)：13.45(s，1H)，7.69(s，1H)，1.97(s，3H)。¹³C NMR(DMSO-d₆，100MHz)，161.85，148.64，135.80，133.16，132.18，124.41。

(2)[Cd(BCM)_0.5(4,4′-bipy)_0.5]Preparation of crystalline materials

The synthetic route is shown in FIG. 2, and the 4, 4-bipyridine ligand is purchased from Tech technologies, Inc. of Yinakai, Beijing. Fluorodithienylvinylformic acid (9.13mg, 0.02mmol), 4-bipyridine (3.12mg, 0.02mmol) and Cd (NO)₃)₂·4H₂O (6.20mg, 0.02mmol) was dispersed in a 2.0mL solution of dimethylformamide/ethanol/deionized water (v: v: v ═ 1.5:0.1:1) and then sealed in a 25.0mL teflon-lined autoclave and heated at 115 ℃ for 72 h. Filtration gave colorless transparent bulk crystals, which were washed 3 times with dimethylformamide and ethanol, in 87.0% yield. Calcd: c₂₇H₁₆CdF₆N₂O₄S₂。C，45.00；H，2.10；N，3.90％。found：C，44.85；H，2.09；N，3.87％。

Example 2:

[Cd(BCM)_0.5(4,4′-bipy)_0.5]experimental profile analysis of crystalline material:

(1) the single crystal data were measured at room temperature using a Bruker SMART APEX II single crystal diffractometer. And refined using the program SHELX-2014 and full matrix least squares, all non-hydrogen atoms being anisotropically refined. During refinement, disordered guest molecules were removed by using the SQUEEZE program in PLATON.

As shown in FIG. 3, it can be seen that [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5]Belongs to the orthorhombic Pnna space group, and the asymmetric unit comprises a crystallographically independent Cd (II), a half perfluorodithienyl vinyl formate anion and a half 4, 4-bipyridine molecule. In the coordination environment, the coordination environment is the environment,cd (II) presents a four-corner bipyramid coordination geometry, the vertex is provided by nitrogen atoms of two 4, 4-bipyridine ligands, the basal plane is formed by four oxygen atoms of four perfluoro-dithienyl vinyl formic acid ligands, wherein the distance of Cd-O bonds is between

Range, distance of Cd-N bond

The perfluorodithienyl vinyl formate ligand only adopts one coordination mode: the bidentate bridge is mu 4-eta 1: eta 1. The structure of perfluorodithienylethenecarboxylic acid is arranged in an antiparallel conformation with the distance between two activated carbon atoms being

Is less than

Indicating [ Cd (BCM)_0.5(4,4′-bipy)_0.5]Has optical activity.

(2) The thermal stability was analyzed using a Netzsch STA 449C thermal analyzer heated from room temperature to 800 ℃ using a heating rate of 20 ℃/min in an air atmosphere. About 4mg of the solid sample was weighed into a ceramic crucible for testing. The results are shown in FIG. 4, and the experiment shows that [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5]The thermogravimetric curve of (a) shows a weight loss of 8.73% before 330 ℃, mainly due to the loss of free solvent molecules in the channels, with the breakdown of the ligands as the temperature increases, the framework structure of the crystals begins to collapse and eventually breaks down into the metal oxide CdO.

(3) Tabletting with dried KBr and recording of perfluorodithienylvinylformic acid and [ Cd (BCM) ]on a Bruker Vertex-70 Fourier transform infrared spectrometer_0.5(4,4′-bipy)_0.5]The wave number range is 4000-400cm^-1An infrared spectrum of (1). As shown in FIG. 5, at a wave number of 3438cm^-1And 1686cm^-1The strong absorption peak can be attributed to perfluoro-dithienyl vinyl formic acid ligandV is_O-HAnd upsilon_C＝OAnd (5) stretching and vibrating. Due to the fact that in [ Cd (BCM)_0.5(4,4′-bipy)_0.5]In the method, the perfluoro-dithienyl vinyl formic acid adopts a bidentate bridging coordination mode, so that the concentration of the perfluoro-dithienyl vinyl formic acid is 1680cm^-1No υ is seen nearby_C＝OA stretching vibration peak.

(4) Powder X-ray diffraction (PXRD) characterization was performed on a Shimadzu Lab Xrd-6100X-ray diffractometer using Cu radiation at room temperature in the 2 θ range of 5-60 ℃ to determine the purity of the sample and whether the crystal structure was altered. [ Cd (BCM)_0.5(4,4′-bipy)_0.5]PXRD results of (1) show the spectrum of the experimental synthetic sample [ Cd (BCM)_0.5(4,4′-bipy)_0.5]-o (red), [ Cd (BCM)_0.5(4,4′-bipy)_0.5]The agreement between-c (black) and PXRD pattern (blue) simulated by Mercury single crystal data (as shown in FIG. 6) is good, which indicates that the synthesized crystal [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5]Has high phase purity, although 2 theta is between 15 and 17 deg.C, [ Cd (BCM)_0.5(4,4′-bipy)_0.5]-o and [ Cd (BCM)_0.5(4,4′-bipy)_0.5]C there is a difference in diffraction peak height, which is suspected to be related to a slight change in the crystallographic plane between open and closed loop. However, the diffraction peak positions were substantially the same, and [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5]The optical cyclization from open to closed loop still maintains its structural integrity.

(5) Assay [ Cd (BCM) using Agilent 8453_0.5(4,4′-bipy)_0.5](FIG. 7a) and perfluorodithienylvinylcarboxylic acid (FIG. 7b) by irradiation with SHG-200 UV lamp and BMH-250 visible lamp. The UV power was set to 1.604X 10 by filtering with a 313nm filter^-4W, visible light power is set to 1.975X 10^- ⁴W is added. Perfluorodithienylvinylformic acid and [ Cd (BCM) ]were carried out at room temperature_0.5(4,4′-bipy)_0.5]Testing photochromic behavior in solid state. First, [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5]O shows a distinct absorption peak at 320nm, and a broad and flat absorption peak at 700nm, which does not belong toCharacteristic peaks of the ring-opened isomers of the diarylethene molecules, which conclusion is confirmed by its photochromic behavior in methanol solution. After 313nm ultraviolet irradiation, a new absorption peak appears at 600nm, the absorption peak at 600nm gradually rises with the prolonging of the irradiation time, and finally reaches saturation, and the color changes from original colorless to blue, which is attributed to the occurrence of a photocyclization reaction and is formed by ring-opening isomers [ Cd (BCM)_0.5(4,4′-bipy)_0.5]O into the closed ring isomer [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5]-c is the structure of. After saturation, visible light (lambda) passes through>500nm) the absorption peak and the color both returned to the initial values, indicating [ Cd (BCM))_0.5(4,4′-bipy)_0.5]Has good photochromic property.

As shown in FIG. 7b, the maximum absorption of the ring-opened isomer (perfluorodithienylethenecarboxylic acid-o) occurred at 320 nm. Under 297nm, a new visible absorption band appeared at 615nm, changing the color from colorless to blue, due to photoisomerization of the ring-opened isomer (perfluorodithienylethenecarboxylic acid-o) to the ring-closed isomer (perfluorodithienylethenecarboxylic acid-c). The absorption spectrum and the color are recovered after the irradiation of visible light (lambda is more than 500nm), which shows that the perfluoro dithienyl vinyl formic acid-c is photoisomerized back to the perfluoro dithienyl vinyl formic acid-o, and an equal absorption point is observed at 350 nm.

(6) Assay [ Cd (BCM) using Agilent 8453_0.5(4,4′-bipy)_0.5](FIG. 8a) and perfluorodithienylethenecarboxylic acid (FIG. 8b) in methanol solution. The concentration of perfluorodithienyl vinyl formic acid is 2X 10^- ⁵mol/L，[Cd(BCM)_0.5(4,4′-bipy)_0.5]Is the saturation concentration. The light irradiation was carried out using an SHG-200 ultraviolet lamp and a BMH-250 visible lamp. The UV power was set to 1.604X 10 with 297nm filter^-4W, visible light power is set to 1.975X 10^-4W is added. The UV absorption band of perfluorodithienylvinylcarboxylic acid-o (20. mu.M) appeared clearly at 250nm, which is attributable to the π - π transition. Then, under the irradiation of 297nm ultraviolet light, the absorption spectrum of the perfluorodithienyl vinyl formic acid is changed remarkably. Occurring at 581nmA new absorption peak, changing the color from colorless to blue, indicates that the ring-opened isomer perfluorodithienylethenecarboxylic acid-o undergoes cyclization reaction to form the ring-closed isomer perfluorodithienylethenecarboxylic acid-c structure (FIG. 8 b). Similarly, [ Cd (BCM)_0.5(4,4′-bipy)_0.5]A clear absorption band at 250nm in methanol solution was shown. Under 297nm uv irradiation, a new absorption band appears at 580nm and the colorless solution turns blue (fig. 8 a). Accordingly, when perfluorodithienylethenecarboxylic acid-c and [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5]C visible light (lambda) for the solution>500nm), their absorption spectra and colors can be restored to the original state. [ Cd (BCM)_0.5(4,4′-bipy)_0.5]The wavelength of maximum absorption in methanol solution is different from that of solid, which may be due to solvent effect or crystal stacking. The above experimental phenomena clearly show that the compounds perfluorodithienylvinylformic acid and [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5]Has reversible and consistent photochromic characteristics. More evidence of [ Cd (BCM)_0.5(4,4′-bipy)_0.5]The photochromic of (a) is derived from a perfluorodithienyl vinyl formate ligand.

(7) Assay [ Cd (BCM) using Agilent 8453_0.5(4,4′-bipy)_0.5]And ultraviolet-visible absorption spectrum of the same complex in methanol saturated solution. By alternately irradiating ultraviolet/visible light, the photoisomerization kinetic rates of the three materials in methanol saturated solution were studied. As shown in FIG. 9a, under 297nm ultraviolet irradiation, it can be clearly seen that the absorbance and the irradiation time show a better linear relationship, and the linear correction factors are all greater than 0.99, which indicates that the photochromic cyclization reaction of the three materials is a zero-order reaction, and the slope is a rate constant, according to the method, the cyclization rate constants of the three materials are obtained, and the sizes of the constants are [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5](8.89×10^-3mol·L^-1·s^-1)，[Zn(BCM)₂(bpfb)](8.37×10^- ³mol·L^-1·s^-1),[Zn₂(BCM)₂(4,4′-bipy)](8.07×10^-3mol·L^-1·s^-1). Under the irradiation of visible light during the decyclization process9b，log(A₁) Shows a good linear relation with the irradiation time, which indicates that the decyclization process belongs to a first-order reaction, and the reaction rate constants of the decyclization process are [ Cd (BCM) ] from large to small_0.5(4,4′-bipy)_0.5](6.20×10^-2s^-1)，[Zn(BCM)₂(bpfb)](4.19×10^-2s^-1)，[Zn₂(BCM)₂(4,4′-bipy)](4.99×10^-2s^-1). Of these three materials, [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5]The cyclization reaction rate of (a) is maximal, while the decyclization reaction rate is also maximal, and may be related to the distance between two activated carbon atoms of the perfluorodithienyl vinyl formate ligand in its crystal structure, compared to the other two materials, [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5]Is significantly minimized.

The above description is only a preferred embodiment of the present invention, and the present invention is not limited to the above embodiment, and the present invention shall fall within the protection scope of the present invention as long as the technical effects of the present invention are achieved by the same means. The invention is capable of other modifications and variations in its technical solution and/or its implementation, within the scope of protection of the invention.

Claims

1. A photo-responsive smart material, wherein the material is [ Cd (BCM) ]_0.5(4,4′-bipy)_0.5]Belonging to the orthorhombic Pnna space group, the asymmetric unit comprises a crystallographically independent divalent Cd, a half perfluorodithienyl vinyl formate anion and a half 4,4' -bipyridine molecule.

2. The photo-responsive smart material of claim 1 wherein in a coordination environment, divalent Cd assumes a four-corner bipyramidal coordination geometry with vertices provided by nitrogen atoms of two 4,4' -bipyridyl ligands, respectively, and basal planes consisting of four oxygen atoms of four perfluorodithienyl vinyl formate ligands.

3. The photo-responsive smart material of claim 2, wherein the distance of the Cd-O bondsIs separated into

Distance of Cd-N bond

4. The optically-responsive smart material of claim 1 wherein the material is a 3-node 2,2,8-c connection network having a topological sign of {4 }².6¹⁰.8¹⁰.10⁶}{4}²{6}²。

5. A method for preparing the light-responsive smart material as claimed in any one of claims 1 to 4, comprising the steps of:

perfluorodithienyl vinyl formic acid, 4' -bipyridine and Cd (NO)₃)₂·4H₂Dispersing O in a dimethylformamide/ethanol/deionized water solution according to a molar ratio of 1:1:1, wherein the volume ratio of dimethylformamide to ethanol to deionized water is 1.5:0.1:1, heating at 115 ℃ for 72 hours under a sealed condition, and filtering to obtain transparent blocky crystals.

6. The production method according to claim 5, wherein the transparent bulk crystal is rinsed 3 times with dimethylformamide and ethanol.