Abstract
The present invention relates to the technical field of polymer spectral probes, and particularly to a perchloroethylene derivative and use thereof. The perchloroethylene derivative is prepared by reacting a compound A and a perchloroethylene resin. According to the present invention, the fluorescent polymer can be used as a high-selectivity and high-sensitivity enhanced colorimetric and fluorescent polymer probe for Fe.sup.3+ and Cr.sup.3+ As compared with the organic small molecule spectral probe, the polymer spectral probe has improved mechanical property, film forming property and excellent recyclability, and thus has a strong practicability.
Claims
1. A perchloroethylene monomer having a chemical formula of: ##STR00003##
2. A method for preparing a perchloroethylene polymer having a chemical formula comprising reacting a compound A ##STR00004## with a perchloroethylene resin to obtain the perchloroethylene derivative.
3. The method according to claim 2, wherein a mass ratio of the perchloroethylene resin to the compound A is 1:1:87-3.75 a reaction temperature is 60-80° C., and a reaction time is 15-24 h.
4. The method according to claim 2, wherein the reaction is carried out in 1,2-dichloroethane, dichloromethane or tetrahydrofuran.
5. The method according to claim 2, further comprising reacting rhodamine B with aminoethyl sulfide in dichloromethane to prepare the compound A.
6. The method according to claim 5, wherein a molar ratio of the rhodamine B to aminoethyl sulfide is 1:5, a reaction temperature is a reflux temperature (about 40° C.) of solvent dichloromethane, and a reaction time is 24 hours.
7. A Cr.sup.3+ and/or Fe.sup.3+ colorimetric and fluorescent probe comprising the perchloroethylene derivative of claim 1.
8. The Cr.sup.3+ and/or Fe.sup.3+ colorimetric and fluorescent probe according to claim 7, wherein the Cr.sup.3+ and/or Fe.sup.3+ colorimetric and fluorescent probe is used with DMF and H.sub.2O.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIG. 1 is a synthetic route of the present invention;
(2) FIG. 2 is a nuclear magnetic resonance hydrogen spectrogram of the compound A (CDCl.sub.3, 400 MHz);
(3) FIG. 3 is an infrared spectrogram of the RCPVC;
(4) FIG. 4 is a nuclear magnetic resonance hydrogen spectrogram of the RCPVC (CDCl.sub.3, 400 MHz);
(5) FIG. 5 is a graph showing the response of the ultraviolet-visible absorption spectrum of the RCPVC to Fe.sup.3+ and Cr.sup.3+;
(6) FIG. 6 is a graph showing the response of the fluorescence spectrum of the RCPVC to Fe.sup.3+ and Cr.sup.3+;
(7) FIG. 7 is a graph showing the response of the ultraviolet-visible absorption spectrum of the RCPVC to different metal ions;
(8) FIG. 8 is a graph showing the response of the fluorescence spectrum of the RCPVC to different metal ions;
(9) FIG. 9 is a graph showing the relationship between the ultraviolet-visible absorption spectrum of the RCPVC and the concentration of Fe.sup.3+;
(10) FIG. 10 is a graph showing the relationship between the ultraviolet-visible absorption spectrum of the RCPVC and the concentration of Cr.sup.3+;
(11) FIG. 11 is a graph showing the relationship between the fluorescence spectrum of the RCPVC and the concentration of Fe.sup.3+;
(12) FIG. 12 is a graph showing the relationship between the fluorescence spectrum of the RCPVC and the concentration of Cr.sup.3+;
(13) FIG. 13 is a graph showing the influence of co-existing ions on the RCPVC colorimetric detection of Fe.sup.3+;
(14) FIG. 14 is a graph showing the influence of co-existing ions on the RCPVC colorimetric detection of Cr.sup.3+;
(15) FIG. 15 is a graph showing the influence of co-existing ions on the RCPVC fluorescence detection of Fe.sup.3+;
(16) FIG. 16 is a graph showing the influence of co-existing ions on the RCPVC fluorescence detection of Cr.sup.3+;
(17) FIG. 17 shows an RCPVC film; and
(18) FIG. 18 shows the color of the RCPVC film.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
(19) The perchloroethylene resin of the examples of the present invention has a chlorine content of 61 wt %-68 wt % and a viscosity of 14-28 seconds, and is tested by employing a TU-4 cup (a 20% xylene solution, 25° C.).
Example 1: Synthesis of Compound A
(20) Rhodamine B and aminoethyl sulfide were added into dichloromethane in a molar ratio of 1:5 under nitrogen protection, added with triethylamine, and then refluxed, stirred and reacted for 24 h under nitrogen protection. The reaction was ended, and the resulting product was washed with water for 3 times. The organic layer was collected, subjected to rotary evaporation to remove dichloromethane, separated by column chromatography with the eluting agent of methanol/chloroform/petroleum ether (1/10/2, v/v/v), and dried under vacuum to obtain a compound A as yellow solid powder, with the yield of 44.5%.
(21) FIG. 2 is a nuclear magnetic resonance hydrogen spectrogram of the compound A (CDC.sub.3, 400 MHz): .sup.1H NMR (400 MHz, CDCl.sub.3, δ/ppm): 7.89 (s, 1H, PhH), 7.49 (m, 2H, PhH), 7.05 (d, J=8.4 Hz, 1H, PhH), 6.43 (d, J=8.7 Hz, 2H, PhH), 6.37 (s, 2H, PhH), 6.27 (d, J=8.3 Hz, 2H, PhH), 3.42-3.21 (m, 10H, CH.sub.3CH.sub.2N and SCH.sub.2CH.sub.2N), 2.99-2.76 (m, 2H, SCH.sub.2CH.sub.2NH.sub.2), 2.64-2.58 (t, J=6.4 Hz, 2H, SCH.sub.2CH.sub.2N), 2.26-2.15 (t, J=8.0 Hz, 2H, SCH.sub.2CH.sub.2NH.sub.2), 1.21-1.10 (t, J=6.7 Hz, 12H, CH.sub.3CH.sub.2N).
Example 2: Preparation of Perchloroethylene Derivative (RCPVC)
(22) Using 1,2-dichloroethane as the solvent, the perchloroethylene and the compound A in a mass ratio of 1:2.52, as raw materials, were reacted with stirring under the protection of N.sub.2 at the temperature of 70° C. for 18 h; and then the reaction was ended, the solvent was removed, and the product was washed with ethanol for 3 times, and dried in a vacuum drying oven to obtain the RCPVC as a pale yellow solid with the conversion rate of 58.1%, which was used for the following tests.
(23) FIG. 3 is an infrared spectrogram of the RCPVC:IR (KBr) cm.sup.−1:3600 (—N—H), 2964 (Ar—H), 2916, 2848 (—CH.sub.3, —CH.sub.2), 1616 (C=O), 1542, 1508, 1458 (Ar—H), 1261 (C—N), 1091, 1020 (—C—S—C—), 796 (C—Cl).
(24) FIG. 4 is a nuclear magnetic resonance hydrogen spectrogram of the RCPVC (CDC.sub.3, 400 MHz): .sup.1H NMR (CDCl.sub.3, 400 MHz): δ ppm 7.96-6.96 (m, Ar—H in the compound A), 6.55-6.05 (m, Ar—H in the compound A), 3.72 (m, CH.sub.3CH.sub.2NCH.sub.2CH.sub.3 in the compound A), 3.32 (m, SCH.sub.2CH.sub.2N in the compound A), 2.63-1.47 (m, CH, CH.sub.2 and CH.sub.3 other than those listed separately), 1.47-0.47 (t, J=6.8, CH.sub.3CH.sub.2NCH.sub.2CH.sub.3 in the compound A).
(25) Using 1,2-dichloroethane as the solvent, the perchloroethylene and the compound A in a mass ratio of 1:1.87, were reacted with stirring under the protection of N.sub.2 at the temperature of 70° C. for 18 h. The reaction was ended, the solvent was removed, and the product was washed with ethanol for 3 times, and dried in a vacuum drying oven to obtain the RCPVC as a pale yellow solid with the conversion rate of 49.6%.
(26) Using 1,2-dichloroethane as the solvent, the perchloroethylene and the compound A in a mass ratio of 1:3.75, were reacted with stirring under the protection of N.sub.2 at the temperature of 70° C. for 18 h. The reaction was ended, the solvent was removed, and the product was washed with ethanol for 3 times, and dried in a vacuum drying oven to obtain the RCPVC as a pale yellow solid with the conversion rate of 46.1%.
Example 3: Response of Ultraviolet-Visible Absorption Spectrum of RCPVC to Fe.SUP.3+ and Cr.SUP.3+ in Different Solvents
(27) In solvent systems of DMF and H.sub.2O at different proportions, the same concentration of Fe.sup.3+ or Cr.sup.3+ were added into the RCPVC solution, and then the ultraviolet-visible absorption spectra of the RCPVC solution before and after the addition of the ions were tested. The results are shown in FIG. 5. The solvents: DMF and H.sub.2O at the proportions of 1/99, 2/8, 8/2, 99/1 respectively; concentrations: 50 μg/mL (RCPVC), and 50 μM (Fe.sup.3+ or Cr.sup.3+); and solvents: a: DMF/H.sub.2O (1/99, v/v); b: DMF/H.sub.2O (2/8, v/v); c: DMF/H.sub.2O (8/2, v/v); d: DMF/H.sub.2O (99/1, v/v). The addition of Fe.sup.3+ enables obvious changes of the ultraviolet-visible absorption spectrum of the RCPVC, such that the absorbances at 562 nm are increased by 2.63 times, 1.94 times, 1.80 times and 1.31 times respectively. The addition of Cr.sup.3+ enables that the absorbances of the RCPVC at 562 nm are increased by 1.62 times, 1.40 times, 1.23 times and 1.14 times respectively.
Example 4: Response of Fluorescence Spectrum of RCPVC to Fe.SUP.3+ and Cr.SUP.3+ in Different Solvents
(28) In solvent systems of DMF and H.sub.2O at different proportions, the same concentration of Fe.sup.3+ or Cr.sup.3+ were added into the RCPVC solution, and then the fluorescence spectra of the RCPVC solution before and after the addition of the ions were tested. The results are shown in FIG. 6. The solvents: DMF and H.sub.2O at the proportions of 1/99, 2/8, 8/2, 99/1, respectively; concentrations: 50 μg/mL (RCPVC), 50 μM (Fe.sup.3+ or Cr.sup.3+); excitation wavelength: 467 nm, slit width: 5 nm; and solvents: a: DMF/H.sub.2O (1/99, v/v); b: DMF/H.sub.2O (2/8, v/v); c: DMF/H.sub.2O (8/2, v/v); d: DMF/H.sub.2O (99/1, v/v). The addition of Fe.sup.3+ enables that the fluorescence intensities at 578 nm are increased by 11.58 times, 8.42 times, 7.26 times and 6.62 times respectively; and the addition of Cr.sup.3+ enables that the corresponding fluorescence intensities of the RCPVC are increased by 8.75 times, 6.76 times, 5.61 times and 4.92 times respectively.
Example 5: Selectivity and Sensitivity of Ultraviolet-Visible Absorption Spectrum of RCPVC to Fe.SUP.3+ and Cr.SUP.3+
(29) Since both the spectral changes of the RCPVC caused by Fe.sup.3+ and Cr.sup.3+ were the largest in the DMF/H.sub.2O (1/99, v/v) system, subsequent researches were carried out in this system. In the DMF/H.sub.2O (1/99, v/v) system, K.sup.+, Na.sup.+, Mg.sup.2+, Cu.sup.2+, Zn.sup.2+, Cr.sup.3+, Fe.sup.2+, Ca.sup.2+, Pb.sup.2+, Hg.sup.2+, Ni.sup.2+, Mn.sup.2+, Co.sup.2+, Cd.sup.2+, Ag.sup.+ and Fe.sup.3+ were respectively added into the RCPVC solution, and then the ultraviolet-visible absorption spectra of the RCPVC solutions before and after the addition of the ions were determined. The results are shown in FIG. 7. The solvents: DMF/H.sub.2O (1/99, v/v), and concentrations: 50 μg/mL (RCPVC), 50 μM (metal ions). From the following figure, it could be observed that a new obvious absorption peak occurs at 562 nm in the ultraviolet-visible absorption spectrum of the RCPVC solution added with Fe.sup.3+, and the absorbance is increased by 2.63 times, and the color of the solution changes from yellow to pink. The addition of Cr.sup.3+ also causes that a weak absorption peak occurs at 562 nm in the ultraviolet-visible absorption spectrum of the RCPVC solution, and the absorbance at 562 nm is increased by 1.62 times, while the addition of other ions has little effect on the ultraviolet-visible absorption spectrum of the RCPVC solution. This indicates that the RCPVC could be used for colorimetric detection of Fe.sup.3+ and Cr.sup.3+ in the DMF/H.sub.2O (1/99, v/v) system.
Example 6: Selectivity and Sensitivity of Fluorescence Spectrum of RCPVC to Fe.SUP.3+ and Cr.SUP.3+
(30) In the DMF/H.sub.2O (1/99, v/v) system, K.sup.+, Na.sup.+, Mg.sup.2+, Cu.sup.2+, Zn.sup.2+, Cr.sup.3+, Fe.sup.2+, Ca.sup.2+, Pb.sup.2+, Hg.sup.2+, Ni.sup.2+, Mn.sup.2+, Co.sup.2+, Cd.sup.2+, Ag.sup.+ and Fe.sup.3+ were respectively added into the RCPVC solutions, and then the fluorescence spectra of the RCPVC solutions before and after the addition of the ions were determined. The results are shown in FIG. 8. The solvents: DMF/H.sub.2O (1/99, v/v), concentrations: 50 μg/mL (RCPVC), 50 μM (metal ions); excitation wavelength: 467 nm, and slit width: 5 nm. From FIG. 8 it could be observed that, the addition of Fe.sup.3+ enables that the fluorescence intensity at 578 nm in the fluorescence spectrum of the RCPVC is increased by 11.58 times; and the addition of Cr.sup.3+ enables that the fluorescence intensity at 578 nm is increased by 8.75 times, while other ions had little effect on the fluorescence spectrum of the RCPVC. This indicates that the RCPVC could be used as a fluorescent probe for Fe.sup.3+ and Cr.sup.3+ in the DMF/H.sub.2O (1/99, v/v) system.
Example 7: Relationship Between Ultraviolet-Visible Absorption Spectrum of RCPVC and Concentration of Fe.SUP.3+
(31) In the DMF/H.sub.2O (1/99, v/v) system, different concentrations of Fe.sup.3+ were respectively added into the RCPVC solutions, and the ultraviolet-visible absorption spectra of the RCPVC solutions were determined. The results are shown in FIG. 9. The solvents: DMF/H.sub.2O (1/99, v/v); concentrations: 50 μg/mL (CPVCR), and the concentrations of Fe.sup.3+ from top to bottom were sequentially 0, 10, 20, 30, 40, 50, 60, 80, 100, 120, 140, and 160 μM. The inset shows the relationship between the absorbance at 562 nm and the concentration of Fe.sup.3+. It could be observed from the figure that, with the increase of the concentration of Fe.sup.3+, the absorbance at 562 nm is also increased accordingly, and the absorbance of the RCPVC would not increase any more when the concentration of Fe.sup.3+ reaches 80 μM. When the concentration of Fe.sup.3+ is between 0-60 μM, the absorbance at 562 nm shows a good linear relationship with the concentration of Fe.sup.3+, and its linear equation is A=0.0005933×[Fe.sup.3+]+0.06282, and the correlation coefficient R=0.929. At this time the detection limit for Fe.sup.3+ is 1.58×10.sup.−6 M, indicating that the RCPVC could quantitatively detect Fe.sup.3+ through a colorimetric method.
Example 8: Relationship Between Ultraviolet-Visible Absorption Spectrum of RCPVC and Concentration of Cr.SUP.3+
(32) In the DMF/H.sub.2O (1/99, v/v) system, different concentrations of Cr.sup.3+ were respectively added into the RCPVC solutions, and the ultraviolet-visible absorption spectra of the RCPVC solutions were determined. The results are shown in FIG. 10. The solvents: DMF/H.sub.2O (1/99, v/v); concentrations: 50 μg/mL (CPVCR), and the concentrations of Cr.sup.3+ from top to bottom were sequentially 0, 10, 20, 30, 40, 50, 60, 80, 100, 120, 140, and 160 μM. The inset shows the relationship between the absorbance at 562 nm and the concentration of Cr.sup.3. It could be observed from FIG. 10 that, with the increase of the concentration of Cr.sup.3+, the absorbance at 562 nm is also increased accordingly, and the absorbance of the RCPVC would not increase any more when the concentration of Cr.sup.3+ reaches 80 μM. When the concentration of Cr.sup.3+ is between 0-80 μM, the absorbance at 562 nm shows a good linear relationship with the concentration of Cr.sup.3+, and its linear equation is A=0.0007478×[Cr.sup.3+]+0.02462, and the correlation coefficient R=0.974. At this time the detection limit for Cr.sup.3+ is 2.47×10.sup.−6 M, indicating that the RCPVC could quantitatively detect Cr.sup.3+ through a colorimetric method.
Example 9: Relationship Between Fluorescence Spectrum of RCPVC and Concentration of Fe.SUP.3+
(33) In the DMF/H.sub.2O (1/99, v/v) system, different concentrations of Fe.sup.3+ were respectively added into the RCPVC solutions, and the fluorescence spectra of the RCPVC solutions were determined. The results are shown in FIG. 11. The solvents: DMF/H.sub.2O (1/99, v/v); concentrations: 50 μg/mL (CPVCR), and the concentrations of Fe.sup.3+ from top to bottom were sequentially 0, 10, 20, 30, 40, 50, 60, 80, 100, 120, 140, 160 μM; excitation wavelength: 467 nm, and slit width: 5 nm. The inset shows the relationship between fluorescence intensity at 578 nm and the concentration of Fe.sup.3+. It could be observed from FIG. 11 that, with the increase of the concentration of Fe.sup.3+, the fluorescence intensity at 578 nm is also increased accordingly, and the fluorescence intensity of the RCPVC would not increase any more when the concentration of Fe.sup.3+ reaches 100 μM. When the concentration of Fe.sup.3+ is between 0-100 μM, the fluorescence intensity at 578 nm shows a good linear relationship with the concentration of Fe.sup.3+, and its linear equation is F=2111.924×[Fe.sup.3+]+38492.531, and the correlation coefficient R=0.991. At this time the detection limit for Fe.sup.3+ is 7.22×10.sup.−6 M, indicating that the RCPVC could quantitatively detect Fe.sup.3+ through a fluorescence method.
Example 10: Relationship Between Fluorescence Spectrum of RCPVC and Concentration of Cr.SUP.3+
(34) In the DMF/H.sub.2O (1/99, v/v) system, different concentrations of Cr.sup.3+ were respectively added into the RCPVC solutions, and the fluorescence spectra of the RCPVC solution were determined. The results are shown in FIG. 12. The solvents: DMF/H.sub.2O (1/99, v/v); concentrations: 50 μg/mL (CPVCR), and the concentrations of Cr.sup.3+ from top to bottom were sequentially 0, 10, 20, 30, 40, 50, 60, 80, 100, 120, 140, 160 μM; excitation wavelength: 467 nm, and slit width: 5 nm. The inset shows the relationship between fluorescence intensity at 578 nm and the concentration of Cr.sup.3+. It could be observed from FIG. 11 that, with the increase of the concentration of Cr.sup.3+, the fluorescence intensity at 578 nm is also increased accordingly, and the fluorescence intensity of the RCPVC would not increase any more when the concentration of Cr.sup.3+ reaches 100 μM. When the concentration of Cr.sup.3+ is between 0-100 μM, the fluorescence intensity at 578 nm shows a good linear relationship with the concentration of Cr.sup.3+, and its linear equation is F=1274.051×[Cr.sup.3+]+9873.322, and the correlation coefficient R=0.986. At this time the detection limit for Cr.sup.3+ is 1.20×10.sup.−6 M, indicating that the RCPVC could quantitatively detect Cr.sup.3+ through a fluorescence method.
Example 11: Effect of Co-Existing Ions on RCPVC Colorimetric Detection of Fe.SUP.3+
(35) In the DMF/H.sub.2O (1/99, v/v) system, other common metal ions were added into the RCPVC-Fe.sup.3+ solutions, and then the ultraviolet-visible absorption spectra were determined, so as to investigate the anti-interference condition when the RCPVC was used for detecting Fe.sup.3+ by the absorbance at 562 nm. The results are shown in FIG. 13. The solvents: DMF/H.sub.2O (1/99, v/v), and concentration: 50 μg/mL (RCPVC). The addition of 20 μM of Hg.sup.2+, Mg.sup.2+, Pb.sup.2+, Ni.sup.2+, Cd.sup.2+, Fe.sup.2+ and 50 μM of K.sup.+, Na.sup.+, Ca.sup.2+, Cu.sup.2+, Zn.sup.2+, Mn.sup.2+, Co.sup.2+ and Ag.sup.+ has little effect on the ultraviolet-visible absorption spectrum of the RCPVC-Fe.sup.3+ solution. The aforementioned results show that the RCPVC has a strong anti-interference capability when used for detecting Fe.sup.3+ by a colorimetric method.
Example 12: Effect of Co-Existing Ions on RCPVC Colorimetric Detection of Cr.SUP.3+
(36) In the DMF/H.sub.2O (1/99, v/v) system, other common metal ions were added into the RCPVC-Cr.sup.3+ solutions, and then the ultraviolet-visible absorption spectra were determined, so as to observe the anti-interference condition when the RCPVC was used for detecting Cr.sup.3+ by the absorbance at 562 nm. The results are shown in FIG. 14. The solvents: DMF/H.sub.2O (1/99, v/v), and the concentration: 50 μg/mL (RCPVC). The addition of 20 μM of Pb.sup.2+, Ni.sup.2+, Cu.sup.2+, Fe.sup.2+, and 50 μM of K.sup.+, Na.sup.+, Mg.sup.2+, Ca.sup.2+, Zn.sup.2+, Hg.sup.2+, Mn.sup.2+, Co.sup.2+, Cd.sup.2+ and Ag.sup.+ has little effect on the ultraviolet-visible absorption spectrum of the RCPVC-Cr.sup.3+ solution. The aforementioned results show that the RCPVC has a strong anti-interference capability when used for detecting Cr.sup.3+ by a colorimetric method.
Example 13: Influence of Co-Existing Ions on RCPVC Fluorescence Detection of Fe.SUP.3+
(37) In the DMF/H.sub.2O (1/99, v/v) system, other common metal ions were added into the RCPVC-Fe.sup.3+ solutions, and then the fluorescence spectra were determined, so as to investigate the anti-interference condition when the RCPVC was used for detecting Fe.sup.3+ by observing the fluorescence intensity at 578 nm. The results are shown in FIG. 15. The solvents: DMF/H.sub.2O (1/99, v/v), and concentration: 50 μg/mL (RCPVC). The addition of 20 μM of Hg.sup.2+, Mg.sup.2+, Pb.sup.2+, Ni.sup.2+, Cd.sup.2+, Fe.sup.2+ and 50 μM of K.sup.+, Na.sup.+, Ca.sup.2+, Cu.sup.2+, Zn.sup.2+, Mn.sup.2+, Co.sup.2+ and Ag.sup.+ has little effect on the fluorescence spectrum of the RCPVC-Fe.sup.3+ solution. The aforementioned results show that the RCPVC has a strong anti-interference capability when used for detecting Fe.sup.3+ by a fluorescence method.
Example 14: Influence of Co-Existing Ions on RCPVC Fluorescence Detection of Cr.SUP.3+
(38) In the DMF/H.sub.2O (1/99, v/v) system, other common metal ions were added into the RCPVC-Cr.sup.3+ solutions, and then the fluorescence spectra were determined, so as to observe the anti-interference condition when the RCPVC was used for detecting Cr.sup.3+ by the fluorescence intensity at 578 nm. The results are shown in FIG. 16. The solvents: DMF/H.sub.2O (1/99, v/v), and the concentration: 50 μg/mL (RCPVC). The addition of 20 μM of Pb.sup.2+, Ni.sup.2+, Cu.sup.2+, Fe.sup.2+, and 50 μM of K.sup.+, Na.sup.+, Mg.sup.2+, Ca.sup.2+, Zn.sup.2+, Hg.sup.2+, Mn.sup.2+, Co.sup.2+, Cd.sup.2+ and Ag.sup.+ has little effect on the fluorescence spectrum of the RCPVC-Cr.sup.3+ solution. The aforementioned results show that the RCPVC has a strong anti-interference capability when used for detecting Cr.sup.3+ by a fluorescence method.
Example 15: Film-Forming Property and Mechanical Strength of RCPVC
(39) A RCPVC solution with a concentration of 250 μg/mL was formulated with dichloromethane, and evenly coated on a glass slide with a size of 1.5 cm×2.5 cm. After the solvent volatilized completely, a plastic thin film with excellent mechanical strength was formed, as shown in FIG. 17. Moreover, the solution of the small-molecule compound A in dichloromethane (1×10.sup.−3 mol/L) was coated on a glass slide of the same size, and the film could not be obtained after the solvent volatilized completely. It could be seen that the film-forming property and mechanical strength of the RCPVC are obviously better than those of the small-molecule compound A.
Example 16: Reusability of RCPVC
(40) The RCPVC-coated film prepared in Example 15 was soaked in 6 mL of a colorless and transparent hydrochloric acid aqueous solution with a concentration of 0.1 mol/L, and the color of the film became pink after 12 h, as shown in FIG. 18a, which was due to the ring opening of the rhodamine unit in the RCPVC as caused by hydrogen ions in the hydrochloric acid aqueous solution. Then the pink film was soaked in 6 mL of a colorless and transparent NaOH aqueous solution with a concentration of 0.1 mol/L, and the pink color of the film was faded (FIG. 18b), which was due to recovering of a closed ring of the rhodamine unit as caused by hydroxide ions in the NaOH aqueous solution. Therefore, it could be seen that the RCPVC could be reused.
(41) In the present invention, a novel perchloroethylene derivative (RCPVC) is prepared, which can be used as the enhanced Fe.sup.3+ and Cr.sup.3+ spectral probe, and opens up a new application field of the perchloroethylene resin.
