COMPOSITE POLYMER FILM MATERIAL BASED ON TUNGSTEN/COPPER/SULFUR CLUSTER COMPOUND, PREPARATION METHOD AND USE THEREOF IN THIRD-ORDER NONLINEAR OPTICS

Abstract

The invention provides a composite polymer film material based on a tungsten/copper/sulfur cluster compound, a preparation method and use thereof. The cluster compound has a chemical formula of: [RWS.sub.3Cu.sub.2(L.sup.a)].sub.n(M).sub.n, wherein R is tris(3,5-dimethylpyrazolyl)hydroborate, tris(pyrazolyl)hydroborate, or pentamethylcyclopentadienyl; L.sup.a has a structural formula of:

##STR00001## when M is perrhenate, n is 4; and when M is triflate, n is 6. The synthesis process of the cluster compound is simple and controllable. A tetrahedral and an octahedral tungsten/copper/sulfur cluster compound that are good third-order nonlinear optical (NLO) active species are selectively synthesized by using different cuprous salts. Composite polymer films of various layers are prepared by spin coating. Such films, as flexible, portable and easy-to-process solid materials, are applicable to third-order NLO devices. With increasing layers in the film, the third-order NLO response is gradually enhanced, and is 3-4 orders of magnitude higher than a solution containing the cluster compound.

Claims

1. A polyhedral tungsten/copper/sulfur cluster compound, having a chemical formula of: [RWS.sub.3Cu.sub.2(L.sup.a)].sub.n(M).sub.n, wherein R is tris(3,5-dimethylpyrazolyl) hydroborate, tris(pyrazolyl)hydroborate, or pentamethylcyclopentadienyl; L.sup.a has a structural formula of: ##STR00002## M is selected from triflate and perrhenate, in which when M is ReO.sub.4.sup.?, n is 4; and when M is OTf.sup.?, n is 6.

2. A method for preparing a polyhedral tungsten/copper/sulfur cluster compound according to claim 1, comprises steps of: adding a metal sulfur-containing synthon [Et.sub.4N][RWS.sub.3], a ligand L and a cuprous salt to a solvent mixture, reacting with stirring, subjecting the reaction solution to solid-liquid separation, collecting the filtrate, and diffusing with a diffusing agent, to precipitate the polyhedral tungsten/copper/sulfur cluster compound.

3. The method according to claim 2, wherein the molar ratio of the metal sulfur-containing synthon [Et.sub.4N][RWS.sub.3], the ligand L and the cuprous salt is (1-1.5):(1-1.5):(2-2.5).

4. The method according to claim 2, wherein the cuprous salt is selected from [Cu(CH.sub.3CN).sub.4]ReO.sub.4, and [Cu(CH.sub.3CN).sub.4]OTf.

5. A composite polymer film material, comprising the polyhedral tungsten/copper/sulfur cluster compound according to claim 1.

6. A method for preparing a composite polymer film material according to claim 5, comprises steps of: adding a solution of a polyhedral tungsten/copper/sulfur cluster compound to a high molecular polymer solution, mixing uniformly, spin coating the obtained liquid onto a substrate, and thermally treating, to obtain the composite polymer film material.

7. The method according to claim 6, wherein the high molecular polymer is selected from the group consisting of polyvinyl alcohol, polymethyl methacrylate, polyimide, polyacrylic alcohol and any combination thereof.

8. The method according to claim 6, wherein the high molecular polymer solution has a concentration of 5.0?10.sup.?4-1.0?10.sup.?3 mol/L; and the concentration of the solution of the polyhedral tungsten/copper/sulfur cluster compound is 1.6?10.sup.?3-4.0?10.sup.?3 mol/L.

9. The method according to claim 6, wherein the composite polymer film material comprises no less than 2 layers.

10. Use of the composite polymer film material according to claim 5 in the preparation of a third-order nonlinear optical material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] To make the disclosure of the present invention more comprehensible, the present invention will be further described in detail by way of specific embodiments of the present invention with reference the accompanying drawings, in which:

[0026] FIG. 1 is a schematic diagram showing the assembly of [1](ReO.sub.4).sub.4 and [2](OTf).sub.6 in Examples 1 and 2;

[0027] FIG. 2 schematically shows the crystal structure of [1](ReO.sub.4).sub.4 in Example 1;

[0028] FIG. 3 schematically shows the crystal structure of [2](OTf).sub.6 in Example 2;

[0029] FIG. 4 shows the third-order NLO response of DMF solutions of [1](ReO.sub.4).sub.4 and [2](OTf).sub.6 under open-aperture test conditions in Example 3, in which FIG. 4a is a Z-scan scattergram of DMF solutions of [1](ReO.sub.4).sub.4 and [2](OTf).sub.6 under open-aperture test conditions, and FIG. 4b is a histogram showing the third-order NLO parameters (minimum normalized transmittance T.sub.min and effective nonlinear absorption coefficient ?) of DMF solutions of [1](ReO.sub.4).sub.4 and [2](OTf).sub.6;

[0030] FIG. 5 is a schematic diagram showing the preparation process of [1](ReO.sub.4).sub.4@PVA and [2](OTf).sub.6@PVA composite polymer films in Example 4;

[0031] FIG. 6 shows the third-order NLO response of [1](ReO.sub.4).sub.4@PVA and [2](OTf).sub.6@PVA composite polymer films spin-coated to have different layers under open-aperture test conditions in Example 5, in which FIG. 6a is a Z-scan scattergram of [1](ReO.sub.4).sub.4@PVA composite polymer films spin-coated to have 2, 4, 6, 8, 10 and 12 layers under open-aperture test conditions, FIG. 6b is a Z-scan scattergram of [2](OTf).sub.6@PVA composite polymer films spin-coated to have 2, 4, 6, 8, 10 and 12 layers under open-aperture test conditions, FIG. 6c is a histogram showing the third-order NLO parameters (minimum normalized transmittance T.sub.min and effective nonlinear absorption coefficient ?) of [1](ReO.sub.4).sub.4@PVA composite polymer films, and FIG. 6d is a histogram showing the third-order NLO parameters (minimum normalized transmittance T.sub.min and effective nonlinear absorption coefficient ?) of [2](OTf).sub.6@PVA composite polymer films.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] 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 Tetrahedral Tungsten/Copper/Sulfur Cluster Compound [1](ReO.SUB.4.).SUB.4

[0033] At room temperature, a metal sulfur-containing synthon [Et.sub.4N][Tp*WS.sub.3] (0.071 g, 0.10 mmol), a cuprous salt [Cu(CH.sub.3CN).sub.4]ReO.sub.4 (0.096 g, 0.20 mmol) and a ligand L (0.020 g, 0.10 mmol) were dissolved in a solvent mixture of dichloromethane/acetonitrile (40 mL/10 mL), and magnetically stirred for about six hours. After the reaction, the reaction solution was filtered and a dark-red filtrate was obtained. The filtrate was placed in a glass tube, and 25 mL of ether was covered on the top of the filtrate by diffusion method. After one week, a long, black-red crystal [1](ReO.sub.4).sub.4 was precipitated on the tube wall. The crystal was collected, washed thoroughly with ether, and finally dried in a constant temperature oven at 60? C. Yield: 0.335 g (83%, based on [Et.sub.4N][Tp*WS.sub.3])

[0034] Element analysis (%): C.sub.116H.sub.120B.sub.4Cu.sub.8N.sub.32O.sub.16Re.sub.4S.sub.12W.sub.4 (M.W.=4634.91), Calculated: C, 30.06; H, 2.61; N, 9.67%; Found: 30.33; H, 2.87; N, 9.51%.

[0035] Infrared spectrum (potassium bromide disk method): 3446 (s), 2962 (w), 2922 (w), 2852 (w), 2555 (w), 2181 (w), 1608 (s), 1544 (s), 1495 (w), 1449 (m), 1415 (s), 1384 (w), 1355 (s), 1214 (s), 1112 (w), 1065 (m), 1038 (m), 982 (w), 910 (vs), 856 (m), 825 (m), 790 (w), 692 (w), 642 (w), 544 (w) cm.sup.?1.

[0036] Electrospray ionization mass spectrometry (ESI-TOF MS): m/z=1294.5472 ({[1](ReO.sub.4)}.sup.3+ calculated: 1294.6398), 2067.0724 ({[1](ReO.sub.4).sub.2}.sup.2+ calculated: 2066.9229).

[0037] .sup.1H NMR spectrum (600 MHz, CD.sub.3CN, ppm): ? 8.72 (d, J=6 Hz, 8H), 8.09 (s, 8H), 7.75 (d, J=6 Hz, 16H), 6.31 (s, 4H), 6.21 (s, 4H), 5.78 (s, 4H), 3.09 (s, 12H), 2.79 (s, 12H), 2.72 (s, 12H), 2.70 (s, 12H), 2.30 (s, 12H), 1.88 (s, 12H).

[0038] The assembly process is shown in FIG. 1 below. The product was tested by X-ray single crystal diffraction. The crystallographic parameters are listed in Table 1. The cation skeleton structure of the tetrahedral tungsten/copper/sulfur cluster compound [1](ReO.sub.4).sub.4 is shown in FIG. 2.

TABLE-US-00001 TABLE 1 Crystallographic parameters of cluster compound [1](ReO.sub.4).sub.4 Compound [1](ReO.sub.4).sub.4 Molecular formula C.sub.116H.sub.120B.sub.4Cu.sub.8N.sub.32O.sub.16Re.sub.4S.sub.12W.sub.4 Molecular weight 4634.91 Crystal system Triclinic crystal system Space group P1 a/? 18.4637(19) b/? 19.203(2) c/? 23.928(3) ?/? 92.015(3) ?/? 102.688(4) ?/? 90.308(3) V/?.sup.3 8270.6(15) D.sub.c/g cm.sup.?3 1.861 Z 2 ? (MoK?)/mm.sup.?1 6.897 Total number of diffraction points 85432 Number of independent 37519 diffraction points F(000) 4416.0 R.sub.1.sup.a 0.0774 wR.sub.2.sup.b 0.1912 GOF.sup.c 1.028

[0039] The data shows that the tetrahedral tungsten/copper/sulfur cluster compound [Tp*WS.sub.3Cu.sub.2(L.sup.a)].sub.4(ReO.sub.4).sub.4, that is, [1](ReO.sub.4).sub.4, is successfully obtained in this example.

EXAMPLE 2

Preparation of Octahedral Tungsten/Copper/Sulfur Cluster Compound [2](OTf).SUB.6

[0040] At room temperature, a metal sulfur-containing synthon [Et.sub.4N][Tp*WS.sub.3] (0.071 g, 0.10 mmol), a cuprous salt [Cu(CH.sub.3CN).sub.4]OTf (0.075 g, 0.20 mmol) and a ligand L (0.020 g, 0.10 mmol) were dissolved in a solvent mixture of dichloromethane/acetonitrile (40 mL/10 mL), and magnetically stirred for about six hours. After the reaction, the reaction solution was filtered and a dark-red filtrate was obtained. The filtrate was placed in a glass tube, and 25 mL of ether was covered on the top of the filtrate by diffusion method. After one week, a black-red hexagonal flake-like crystal [2](OTf).sub.6 was precipitated on the tube wall. The crystal was collected, washed thoroughly with ether, and finally dried in a constant temperature oven at 60? C. Yield: 0.536 g (78%, based on [Et.sub.4N][Tp*WS.sub.3]).

[0041] The assembly process is shown in FIG. 1 below. [2](OTf).sub.6 was characterized by X-ray single crystal diffraction, elemental analysis, infrared spectroscopy, electrospray ionization mass spectrometry and nuclear magnetic resonance spectroscopy. The specific process is as follows.

TABLE-US-00002 TABLE 2 Crystallographic parameters of cluster compound [2](OTf).sub.6 Compound [2](OTf).sub.6 Molecular formula C.sub.180H.sub.180B.sub.6Cu.sub.12F.sub.18N.sub.48O.sub.18S.sub.24W.sub.6 Molecular weight 6345.59 Crystal system Trigonal system Space group R3 a/? 20.1017(7) b/? 20.1017(7) c/? 71.799(5) ?/? 90 ?/? 90 ?/? 120 V/?.sup.3 25125(2) D.sub.c/g cm.sup.?3 1.258 Z 3 ? (MoK?)/mm.sup.?1 2.999 Total number of diffraction 294150 points Number of independent 12890 diffraction points F(000) 9324.0 R.sub.1.sup.a 0.0854 wR.sub.2.sup.b 0.2107 GOF.sup.c 1.188

[0042] Element analysis (%): C.sub.180H.sub.180B.sub.6CU.sub.12F.sub.18N.sub.48O.sub.18S.sub.24W.sub.6 (M.W.=6345.59), Calculated: C, 34.07; H, 2.86; N, 10.59%; Found: C, 33.89; H, 2.99; N, 10.44%.

[0043] Infrared spectrum (potassium bromide disk method): 3439 (s), 2968 (m), 2926 (m), 2558 (w), 2185 (w), 1610 (s), 1544 (s), 1496 (w), 1448 (m), 1416 (s), 1384 (w), 1354 (s), 1279 (s), 1260 (s), 1218 (m), 1159 (m), 1065 (m), 1030 (s), 981 (w), 857 (m), 815 (m), 693 (w), 638 (s), 517 (w) cm.sup.?1.

[0044] Electrospray ionization mass spectrometry (ESI-TOF MS): m/z=1119.9339 ({[2](OTf)}.sup.5+ calculated: 1119.9840), 1437.1539 ({[2](OTf).sub.2}.sup.4+ calculated: 1437.2180).

[0045] .sup.1H NMR spectrum (600 MHz, d.sub.6-DMSO, ppm): ? 8.95 (d, J=6 Hz, 12H), 8.54-8.40 (m, 24H), 7.88 (m, 12H), 6.27 (s, 12H), 5.83 (s, 6H), 2.65 (s, 54H), 2.26 (s, 27H), 1.79 (d, J=12 Hz, 27H).

[0046] The data shows that the octahedral tungsten/copper/sulfur cluster compound [Tp*WS.sub.3Cu.sub.2(L.sup.a)].sub.6(OTf).sub.6, that is, [2](OTf).sub.6, is successfully obtained in this example. The cation skeleton structure of the octahedral tungsten/copper/sulfur cluster compound [2](OTf).sub.6 is shown in FIG. 3.

EXAMPLE 3

Third-order NLO Performance Test of DMF Solutions of Cluster Compounds [1](ReO.SUB.4.).SUB.4 .and [2](OTf).SUB.6..

[0047] The cluster compounds [1](ReO.sub.4).sub.4 and [2](OTf).sub.6 were formulated into 1.38?10.sup.?4 mol/L solutions in DMF. About 150 ?L of each solution was placed in a 2 mm quartz cuvette, and fixed on a translation platform controlled by a computer. The sample was moved by the translation platform along the z axis, and Z-scan test was performed at room temperature. The light source used in the test was a frequency-doubled mode-locked Q-switched Nd: YAG laser producing 532 nm polarized light, with a pulse width of 4 ns, a repetition frequency of 10 Hz, and a laser energy of 9.6 ?j. The results of Z-scan test are shown in FIG. 4a below. The curves of sample-focus distance Z and normalized transmittance of these cluster compound solutions all show trough-shaped curve characteristics, indicating that they have reversed saturable absorption response, but the response is weak. The minimum normalized transmittance T.sub.min of [1](ReO.sub.4).sub.4 and [2](OTf).sub.6 solutions are 0.99 and 0.98, respectively, and the effective nonlinear absorption coefficient ? are 1.8?10.sup.?11 m/W and 2.4?10.sup.?11 m/W, respectively (FIG. 4b).

EXAMPLE 4

Preparation of [1](ReO.SUB.4.).SUB.4.@PVA and [2](OTf).SUB.6.@PVA Composite Polymer Films

[0048] 0.25 g of polyvinyl alcohol (PVA, having a polymerization degree of about 1700) was placed in a 20 mL glass bottle, 4 mL of deionized water was added, and the PVA solid was heated and stirred in an oil bath at 98? C. to allow it to become a transparent and uniform PVA viscous solution. A DMF solution (2 mL) of [1](ReO.sub.4).sub.4 (0.015 g, 0.003 mmol) is added to the PVA solution dropwise, and stirred until an evenly mixed red-brown viscous solution was obtained. A few drops of the viscous solution was taken by a dropper, dripped and spin coated on a quartz sheet of 1.5 cm?1.5 cm. After the spin coating, the viscous solution was slowly dried in a constant-temperature oven at 60? C., to obtain a [1](ReO.sub.4).sub.4@PVA composite polymer film. By increasing the number of the spin coating process, [1](ReO.sub.4).sub.4@PVA composite polymer films having 2, 4, 6, 8, 10 and 12 layers can be obtained.

[0049] The preparation process of [2](OTf).sub.6@PVA composite polymer films was the same as that for [1](ReO.sub.4).sub.4@PVA composite polymer films. During the preparation process, [1](ReO.sub.4).sub.4 (0.015 g, 0.003 mmol) was replaced by [2](OTf).sub.6 (0.020 g, 0.003 mmol), and other conditions were the same.

[0050] The preparation process is schematically shown in FIG. 5.

EXAMPLE 5

Third-order NLO Performance Test of [1](ReO.SUB.4.).SUB.4.@PVA and [2](OTf).SUB.6.@PVA Composite Polymer Film Prepared by Spin Coating to have 2, 4, 6, 8, 10 and 12 Layers

[0051] The film sample was directly fixed on a translation platform controlled by a computer and subjected to Z-scan test at room temperature. The laser light source and laser energy used in the test were the same as those in the Z-scan test of the above solution samples. As shown in FIG. 6a, the results of Z-scan test show that [1](ReO.sub.4).sub.4@PVA composite polymer films prepared by spin coating to have 2, 4, and 6 layers have no any optical response, and the curves of sample-focus distance Z and normalized transmittance of [1](ReO.sub.4).sub.4@PVA composite polymer films prepared by spin coating to have 8, 10, and 12 layers show trough-shaped curve characteristics, indicating reversed saturable absorption response. Similarly, the Z-scan curves of [2](OTf).sub.6@PVA composite film samples also show similar characteristics. As shown in FIG. 6b, [2](OTf).sub.6@PVA composite films prepared by spin coating to have 2 and 4 layers also have no any NLO response, and [2](OTf).sub.6@PVA composite films prepared by spin coating to have 6 and more layers show reversed saturable absorption response. With increasing layers in the film, the minimum normalized transmittance T.sub.min decreases gradually, and the effective nonlinear absorption coefficient ? increases, indicating that the third-order NLO response increases gradually (FIGS. 6c and 6d). The [1](ReO.sub.4).sub.4@PVA composite film prepared by spin coating to have 12 layers has a ? value of 1.8?10.sup.?7 m/W, which is 10,000 times that of the solution containing the same. The [2](OTf).sub.6@PVA composite film prepared by spin coating to have 12 layers has a ? value of up to 2.6?10.sup.?7 m/W, which is 10833 times that of the solution containing the same.

[0052] Apparently, the [1](ReO.sub.4).sub.4@PVA and [2](OTf).sub.6@PVA composite polymer films mentioned in the present invention are ideal third-order NLO material, which not only improves the machinability of the material, but also lays a good foundation for the development of third-order NLO devices.

[0053] Apparently, 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.