LIGHT-STIMULI RESPONSIVE COORDINATION POLYMER, AND PREPARATION AND USE THEREOF

Abstract

The invention provides a light-stimuli responsive coordination polymer, and preparation method and use thereof. The coordination polymer has a chemical formula of [Zn(tkpvb) (Fb).sub.2].sub.n1, wherein Fb represents p-fluorobenzoate, tkpvb represents 1,2,4,5-tetrakis((E)-2-(4-pyridyl)vinyl)benzene, and n=3000-60000; and crystallographic parameters of: (1) crystal system: monoclinic system; (2) space group: C2/c; (3) =28.577(3), b=7.4084(6) , c=22.612(3) , =126.771(2), and V=3834.8(7) .sup.3; (4) Z=4; and (5) F(000)=1720, R.sub.1=0.0440, wR.sub.2=0.1042, and GOF=1.047. The method is simple, and has mild reaction conditions, and fast light conversion rate. The means of light-stimuli responsiveness are non-contact and non-damage type, the volume adjustment is highly accurate, and the whole adjustment process does not require any chemical reagents, and is safe and reliable. Photoactuators can complete a variety of behaviors under the irradiation of ultraviolet light having a wavelength of 365 nm.

Claims

1. A light-stimuli responsive coordination polymer, wherein the coordination polymer is a bright yellow bulk crystal and has a chemical formula of [Zn(tkpvb)(Fb).sub.2].sub.n1, crystallographic parameters of: (1) crystal system: monoclinic system; (2) space group: C2/c; (3) 28.577(3) , b=7.4084(6) , c=22.612(3) , =126.771(2), and V=3834.8(7) .sup.3 (4) Z=4; and (5) F(000)=1720, R.sub.1 0.0440, wR.sub.2=0.1042, and GOF 1.047, wherein Fb represents p-fluorobenzoate, tkpvb represents 1,2,4,5-tetrakis((E)-2-(4-pyridyl)vinyl)benzene, and n1=3000-60000.

2. A method for preparing a light-stimuli responsive coordination polymer according to claim 1, comprising steps of: dissolving zinc nitrate hexahydrate, p-fluorobenzoic acid or a water-soluble salt thereof, and 1,2,4,5-tetrakis((E)-2-(4-pyridyl)vinyl)benzene in a mixed solvent of N,N-dimethylformamide and water, adjusting the pH to 5-6, and reacting to obtain the light-stimuli responsive coordination polymer.

3. The preparation method according to claim 2, wherein the molar ratio of zinc nitrate hexahydrate, p-fluorobenzoic acid or a water-soluble salt thereof and 1,2,4,5-tetrakis((E)-2-(4-pyridyl)vinyl)benzene is 1-2.5: 1-2.5: 1-2.5.

4. The preparation method according to claim 2, wherein the reaction temperature is 120 to 125 C., and the time is 5-12 h.

5. A composite film, comprising a light-stimuli responsive coordination polymer according to claim 1.

6. A method for preparing a composite film according to claim 5, comprising steps of: S1: grinding a light-stimuli responsive coordination polymer, dispersing in a solvent, and drying; S2: adding a substrate, and stirring to obtain a uniform viscous liquid; S3: adding the uniform viscous liquid into a mold, drying, and peeling to obtain the composite film.

7. The method for preparing a composite film according to claim 6, wherein the substrate is selected from the group consisting of PVA, chitosan, polyvinylidene difluoride, polypropylene and any combination thereof.

8. A photoactuator, prepared with a composite film according to claim 5.

9. Use of the light-stimuli responsive coordination polymer according to claim 1 in photoactuation.

10. The use according to claim 9, enabled by irradiation with light of 365 nm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIG. 1 is a schematic diagram showing the synthesis of Compound [Zn(tkpvb)(Fb).sub.2].sub.n1 in Example 1.

[0042] FIG. 2 shows the one-dimensional stacking of Compound [Zn(tkpvb)(Fb).sub.2].sub.n1 in Example 1.

[0043] FIG. 3 shows a X-ray powder diffraction pattern of Compound [Zn(tkpvb)(Fb).sub.2].sub.n1 in Example 1.

[0044] FIG. 4 shows a thermogravimetric analysis profile of Compound [Zn(tkpvb)(Fb).sub.2].sub.n1 in Example 1.

[0045] FIG. 5 is a schematic diagram showing the chemical conversion of Compound [Zn(tkpvb)(Fb).sub.2].sub.n1 into [Zn(poly-bpbpvpcb)(Fb).sub.2].sub.n2 in Example 2.

[0046] FIG. 6 shows the single crystal morphology of [Zn(tkpvb)(Fb).sub.2].sub.n1(a) and [Zn(poly-bpbpvpcb)(Fb).sub.2].sub.n1(b) in Example 2.

[0047] FIG. 7 shows the two-dimensional structure of Compound [Zn(poly-bpbpvpcb)(Fb).sub.2]n.sub.2(CP2) in Example 2.

[0048] FIG. 8 shows a X-ray powder diffraction pattern of Compound [Zn(poly-bpbpvpcb)(Fb).sub.2]n.sub.2(CP2) in Example 2.

[0049] FIG. 9 shows a thermogravimetric analysis profile of Compound [Zn (poly-bpbpvpcb)(Fb).sub.2].sub.n2(CP2) in Example 2.

[0050] FIG. 10 shows a Teflon mold (left) and a mold loaded with a composite film (right) in Example 3.

[0051] FIG. 11 shows an SEM image (upper left) and an EDS mapping images (others) of the composite film in Example 3.

[0052] FIG. 12 shows an X-ray powder diffraction pattern of the composite film 0-PVA in Example 3.

[0053] FIG. 13 schematically shows the photomechanical behavior of the photoactuator 1 in Examples 4 (a-c), 5 (d-f) and 6 (g-h).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0054] The present invention will be further described below with reference to the accompanying drawings and specific examples, so that those skilled in the art can better understand and implement the present invention; however, the present invention is not limited thereto.

Example 1: Preparation of Coordination Polymer [Zn(Tkpvb)(Fb).SUB.2.].SUB.n1

[0055] A mixture of zinc nitrate hexahydrate (297 mg, 0.1 mmol), 1,2,4,5-tetrakis((E)-2-(4-pyridyl)vinyl)benzene (490 mg, 0.1 mmol) and p-fluorobenzoic acid (280 mg, 0.1 mmol) was added to a 25 mL of thick-walled pressure flask. Then 10 mL of a mixed solution of N,N-dimethyl formamide and deionized water at a volume ratio of 2:3 was added, and the system was adjusted to about pH 5 with 0.1 M hydrochloric acid. The flask was sealed, ultrasonically dispersed for 10 min, heated for 8 h in an oven at a temperature programmed to 120 C., and then naturally cooled to room temperature, to obtain a bright yellow lump crystal [Zn (tkpvb) (Fb).sub.2].sub.n1(CP1). The crystal was washed with ethanol, collected, and dried in an oven at 60 C. Yield: 472.8 mg (65%, calculated based on 1,2,4,5-tetrakis((E)-2-(4-pyridyl)vinyl)benzene).

[0056] Elemental analysis (%): C.sub.48H.sub.34F.sub.2N.sub.4O.sub.4Zn; Calculated: C 69.11, H 4.11, N 6.72; Found: C 69.88, H 4.20, N 6.75.

[0057] Infrared spectrum (potassium bromide disc method): 3045 (w), 1610 (w), 1504 (w), 1409 (w), 1362 (s), 1219 (m), 1151 (s), 1025 (w), 857 (m), 780 (m), 629 (m), 620 (s), 536 (s) cm.sup.1.

[0058] The structure of the compound was characterized by single crystal X-ray diffraction, powder X-ray diffraction and thermogravimetric analysis. The crystallographic parameters are listed in Table 1. The X-ray powder diffraction pattern and thermogravimetric analysis profile are shown in FIGS. 3 and 4.

TABLE-US-00001 TABLE 1 Crystallographic parameters of the coordination polymer of Example 1 Compounds CP1 Molecular formula C.sub.48H.sub.34F.sub.2N.sub.4O.sub.4Zn Molecular weight 834.16 Temperature 119.98 Crystal system Monoclinic Space group C2/c a/ 28.577(3) b/ 7.4084(6) c/ 22.612(3) / 90 / 126.771(2) / 90 V/.sup.3 3834.8(7) Dc/g cm.sup.3 1.445 Z 4 (Mo-K)/mm.sup.1 0.704 Total number of 19493 diffraction points Number of independent 4392 diffraction points F(000) 1720 R.sub.1.sup.a 0.0440 wR.sub.2.sup.b 0.1042 GOF.sup.c 1.047

[0059] The compound is monoclinic, and the space group is C2/c. FIG. 1 schematically show the synthesis and the spatial structure of Compound CP1. As can be seen, the central metal ion in the above coordination polymer containing an alkene ligand is Zn.sup.2+, which is coordinated with O in two p-fluorobenzoic acid molecules, and N in two tkpvb ligand molecules. The metal ions are bridged by the tkpvb ligand, and extend to form a one-dimensional chain-like structure as shown in FIG. 2.

Example 2: Preparation of Coordination Polymer [Zn (Poly-Bpbpvpcb) (Fb).SUB.2.].SUB.n2.(CP2)

[0060] At room temperature, a small amount of CP1 crystal was placed on a clean glass slide, and irradiated with an LED light having a wavelength of 500 nm for 30 min while a distance of 2 cm was maintained between the light source and the crystal to obtain a [2+2] cycloaddition product [Zn (poly-bpbpvpcb) (Fb).sub.2].sub.n2(CP2) with a conversion rate of 100%.

[0061] Elemental analysis (%): C.sub.48H.sub.34F.sub.2N.sub.4O.sub.4Zn; Calculated: C 69.11, H 4.11, N 6.72; Found: C 69.10, H 4.15, N 6.73.

[0062] Infrared spectrum (potassium bromide disc method): 2934 (w), 1735 (w), 1431 (w), 1375 (w), 1245 (w), 1143 (w), 1095 (s), 919 (w), 881 (m), 821 (s), 745 (s), 688 (m), 546 (s) cm.sup.1

[0063] The product was tested by single crystal X-ray diffraction. The crystallographic parameters are listed in Table 2. The single-crystal morphology, two-dimensional structure, X-ray diffraction pattern and thermogravimetric analysis profile of the powder are shown in FIGS. 6-9.

TABLE-US-00002 TABLE 2 Crystallographic parameters of the coordination polymer of Example 2 Compounds CP2 Molecular formula C.sub.48H.sub.34F.sub.2N.sub.4O.sub.4Zn Molecular weight 834.16 Temperature 119.99 Crystal system Monoclinic Space group C2/c a/ 28.252(6) b/ 7.392(2) c/ 23.651(5) / 90.00(3) / 125.82(3) / 90.00(3) V/.sup.3 4005(2) Dc/g cm.sup.3 4 Z 1.383 (Mo-K)/mm.sup.1 0.674 Total number of 21661 diffraction points Number of independent 3526 diffraction points F(000) 1720 R1.sup.a 0.1195 wR.sub.2.sup.b 0.2944 GOF.sup.c 1.152

Example 3: Preparation of Composite Film 0-PVA

[0064] CP1 was ground into a uniform powder in a mortar (about 30 minutes), and then 200 mg of the powder was dispersed in 4 mL of ethanol, ultrasonicated for 5 h, and dried at 60 C. 2.25 g of 10% PVA aqueous solution was mixed with the powder and stirred for 12 h to obtain a uniform viscous liquid. Subsequently, the mixed solution was added dropwise to a polytetrafluoroethylene mold having a clean surface dried with nitrogen, and allowed to stand overnight at 80 C. in an oven to remove the remaining solvent. After the solvent was completely evaporated, a free-standing composite film 0-PVA was obtained by peeling from the mold.

[0065] The composite film was analyzed by scanning electron microscopy (SEM), EDS mapping, and X-ray powder diffraction. The SEM image, EDS mapping image, and X-ray powder diffraction pattern are shown in FIGS. 11, and 12.

Example 4: Preparation and Mechanical Behavior Study of Photoactuator 1

[0066] 0-PVA was cut into a strip of 0.5 cm2 cm, to prepare a photoactuator 1 (1-PVA). One end of the photoactuator 1 was fixed with a clip, and the other end was tied with a heavy object. The film was irradiated with an LED light having a wavelength of 365 nm (at a distance of about 2 cm) and the process was recorded with a high-speed camera (1200 frames/s). When exposed to irradiation with light of 365 nm, the photoactuator 1 undergoes backlight bending quickly, with a bending angle up to 45, to lift the heavy object (see FIG. 13).

Example 5: Preparation and Mechanical Behavior Study of Photoactuator 2

[0067] 0-PVA was cut into a strip of 0.5 cm3 cm, and the strip-shaped composite film was fold at an edge (0.5 cm0.5 cm) by an angle of 900 to form a knuckle of a finger for grabbing a heavy object. The film material is a photoactuator 2 (2-PVA). 2-PVA was laid flatly, and illuminated with light having a wavelength of 365 nm at a distance of 5 cm from the above, and the process was recorded with a high-speed camera (1200 frames/s). The finger began to bend, to grab the heavy object underneath (see FIG. 13).

Example 6: Mechanical Behavior Study of Photoactuator 3-PVA

[0068] 0-PVA was cut into a strip of 0.5 cm2 cm. Two cut composite films were crisscrossed and fixed together, at an angle of 90. The film material is a photoactuator 3 (3-PVA). 3-PVA was laid flatly on a flat surface, and a heavy object was placed at a central position. 4-PVA was irradiated with an LED light having a wavelength of 365 nm at a distance of 5 cm from the above (at a distance of about 5 cm) and the process was recorded with a high-speed camera (1200 frames/sec). As shown in FIG. X, when exposed to irradiation with light of 365 nm, four sides of 3-PVA are bent, so the center was arched, similar to the situation where a jack props a heavy object in the center. In this way, 3-PVA can props an object that is 20 times higher than its own weight (see FIG. 13).

[0069] The present invention discloses a method for preparing a coordination polymer and a method for preparing three photoactuators using the coordination polymer as a raw material. Specifically, in the present invention, a photosensitive coordination polymer [Zn(tkpvb)(Fb).sub.2].sub.n1 (CP1) is hydrothermally synthesized at a low temperature (120 C.), which undergoes an [2+2] cycloaddition reaction under irradiation with light having a wavelength of 365 nm. In this process, a photoinduced stress is generated. The photoinduced stress is amplified by preparing a composite film, and then a series of photoactuators 1-PVA, 2-PVA, and 3-PVA are prepared with CP1 as a raw material. The preparation method of the present invention is simple, and has mild reaction conditions, and fast light conversion rate. By introducing non-contact and non-damage light as a driving source, the mechanical behavior of the photoactuator is accurately controlled. The photoactuator is rapidly responsive, and can complete a variety of mechanical behaviors. The control process is simple and easy to operate, and requires no chemical reagents. conforming the concept of green chemistry.

[0070] Obviously, the above-described embodiments are merely examples provided for clarity of description, and are not intended to limit the implementations of the present invention. Other variations or changes can be made by those skilled in the art based on the above description. The embodiments are not exhaustive herein. Obvious variations or changes derived therefrom also fall within the protection scope of the present invention.