A symmetric tetramethyl hexacyclic cucurbituril-based fluorescent complex, preparation method and application

Abstract

The present invention belongs to the field of chemical synthesis, and particularly relates to a symmetric tetramethyl hexacyclic cucurbituril-based fluorescent complex, a preparation method and an application thereof; the chemical formula of the symmetric tetramethyl hexacyclic cucurbituril-based fluorescent complex is: {[C<subgt;40< / subgt;H<subgt;44< / subgt>N<subgt;24< / subgt>O<subgt;12< / subgt>]<subgt;2< / subgt>•[C<subgt;14< / subgt>H<subgt>10< / subgt>O<subgt>10< / subgt> S<subgt;2< / subgt>]<subgt;1< / subgt>}<subgt; n

Description

Technical Field

[0001] The present invention belongs to the field of chemical synthesis, and particularly relates to a symmetric tetramethyl hexacyclic cucurbituril-based fluorescent complex, a preparation method and applications thereof. Background Art

[0002] Since this century, with the industrial revolution and social progress, more and more chemicals have been produced and used in all aspects of life, ultimately benefiting mankind. Therefore, it is very necessary to develop simple, rapid, highly sensitive and selective analytical methods for detecting these metals.

[0003] Traditional methods for detecting metal ions mainly include atomic absorption spectrometry, inductively coupled plasma method, X-ray fluorescence spectrometry, etc. The detection processes of these methods are usually very cumbersome and the detection costs are expensive, so they cannot be widely applied.

[0004] As is well known, fluorescence sensing, as a method for detecting target pollutants, has attracted a great deal of attention from researchers due to its low cost, easy operation and high sensitivity. The research group of Professor Xiao Xin at Guizhou University successfully synthesized an octacyclic cucurbituril-based supramolecular fluorescent complex with octacyclic cucurbituril as the building block, and applied for and obtained patents for "A Fluorescent Probe for Detecting L-Phenylalanine Based on Octacyclic Cucurbituril and Its Detection Method" and "Octacyclic Cucurbituril-Based Supramolecular Fluorescent Complex and Its Application in Detecting Trinitrophenol". However, there are few reports on detecting heavy metals in water in this type of material.

[0005] Therefore, a symmetric tetramethyl hexacyclic cucurbituril-based fluorescent probe has been invented for the detection of heavy metal ions in water, which is of great significance for environmental protection. Summary of the Invention

[0006] The purpose of the present invention is to provide a preparation of a symmetric tetramethyl hexacyclic cucurbituril-based fluorescent complex and its application in detecting metal ions in water. The present invention shows an obvious fluorescence quenching response to Fe 3+ , Pd 2+ in aqueous solution. Moreover, it has the characteristics of convenient and fast operation method, good selectivity, low detection limit and recyclability. In addition, the cucurbituril-based supramolecular fluorescent complex of the present invention also has the characteristic of simple preparation method.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] A symmetric tetramethyl hexacyclic cucurbituril-based fluorescent complex, the chemical formula of the symmetric tetramethyl hexacyclic cucurbituril-based fluorescent complex is: {[C40H44N24O12]2•[C14H10O10S2]1} n , and the value range of n is an integer greater than or equal to 1.

[0009] Preferably, the molecular weight of the symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex is: 1254.16 n .

[0010] Preferably, the repeating basic unit in the structural formula is: [C40H44N24O12]2•[C14H10O10S2]1.

[0011] Preferably, the preparation method of the symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex is as follows: Weigh 3,3′-disulfonic acid–4,4′-biphenyldicarboxylic acid and symmetric tetramethylhexacyclic cucurbituril, and place the above two organic substances in water and stir vigorously to make them dissolve in water to obtain a mixed solution. Heat the mixed solution under high pressure to cause the 3,3′-disulfonic acid–4,4′-biphenyldicarboxylic acid and symmetric tetramethylhexacyclic cucurbituril in the mixed solution to react to obtain the symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex. Finally, cool, stand, and dry the obtained symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex to obtain the symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex in the form of white powder;

[0012] wherein the molar ratio of 3,3′-disulfonic acid–4,4′-biphenyldicarboxylic acid to symmetric tetramethylhexacyclic cucurbituril is 1:2 - 1:4.

[0013] Preferably, the reaction conditions for heating the mixed solution under high pressure are as follows: First, heat the mixed solution to 100 °C and keep it at a constant temperature for 10 h, then cool it to 30 °C at a rate of 1 °C / 10 min and keep it at a constant temperature for 24 - 36 h.

[0014] Preferably, the symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex can be used to detect heavy metal ions Fe 3+ , Pd 2+ .

[0015] Preferably, the detection method for using the symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex to detect Fe 3+ in water is as follows: Prepare a probe standard solution of the symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex, and record the fluorescence emission spectrum generated by the probe standard solution at an excitation wavelength of 265 nm; Add a single aqueous solution containing Fe 3+ to the probe standard solution, and record the fluorescence spectrum generated by the probe standard solution containing Fe 3+ at an excitation wavelength of 265 nm; According to the change value of the fluorescence intensity at the maximum emission wavelength of 365 nm before and after, the detection of Fe 3+ in water is achieved, and the detection limit reaches 2.66×10 -6 M.

[0016] Preferably, the detection of Pd 2+The detection method is as follows: Prepare a probe standard solution with a symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex, and record the fluorescence emission spectrum generated by the probe standard solution at an excitation wavelength of 265 nm; Add a single aqueous solution containing Pd 2+ to the probe standard solution, and record the fluorescence spectrum generated by the probe standard solution containing Pd 2+ at an excitation wavelength of 265 nm; According to the change value of the fluorescence intensity at the maximum emission wavelength of 365 nm before and after, the detection of Pd 2+ in water is achieved, and the detection limit reaches 1.07×10 -6 M.

[0017] Preferably, the preparation steps of the probe standard solution are as follows: Grind the symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex into a powder, and ultrasonically soak it in deionized water, adjust the pH = 7, and then the probe standard solution can be prepared; The concentration of the prepared probe standard solution is 1 mg / mL.

[0018] Advantages of the present invention:

[0019] 1. The present invention provides a preparation method of a symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex, which has the advantages of simple operation and high yield. By utilizing the characteristics of the 3,3′-disulfonic acid–4,4′-biphenyldicarboxylic acid ligand in "balancing the system charge" and "counter anion", a two-dimensional network supramolecular self-assembly structure is constructed.

[0020] 2. The fluorescent probe in the present invention has the characteristics of convenient and fast operation method, good selectivity, low detection limit, and reusability for detecting Fe 3+ or Pd 2+ in water. Description of the drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0022] Figure 1 is the crystal structure parameter table of the symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex;

[0023] Figure 2 is the crystal structure diagram of the symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex;

[0024] Figure 3 is the structural characterization of the symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex;

[0025] Figure 4Thermogravimetric (TG) characterization of the symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex

[0026] Figure 5 Fluorescence intensity changes before and after adding 1 M standard solutions of different metal ions to the fluorescent probe

[0027] Figure 6 For the fluorescent probe containing Fe 3+ (a) or Pd 2+ (b) Fluorescence titration diagrams of aqueous solutions

[0028] Figure 7 After multiple cycle tests, the detection effects of the fluorescent probe on aqueous solutions containing Fe 3+ (a) or Pd 2+ (b) Specific implementation manners

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0030] The symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex synthesized in the present invention was characterized by means of X-Ray single crystal diffraction, PXRD powder diffraction, DSC-TG, etc. And its performance for detecting Fe 3+ or Pd 2+ in aqueous solutions was studied by fluorescence spectroscopy.

[0031] Crystal preparation

[0032] Example 1: Weigh TMeQ[6] (12.6 mg, 0.012 mmol). Place it in a reagent tube containing 5 mL of distilled water and ultrasonically vibrate for 30 min to evenly disperse the TMeQ[6] particles. Then add 3,3′-disulfonic acid–4,4′-biphenyldicarboxylic acid (1.2 mg, 0.003 mmol) to the above solution and ultrasonically vibrate for 5 min. Place the solution in a high-pressure reaction kettle, program the temperature to rise to 100 °C, keep it at a constant temperature for 10 h, then cool it to 30 °C at a rate of 1 °C / 10 min, keep it at a constant temperature for 36 h, turn off the programmed temperature oven, cool the high-pressure reaction kettle to room temperature, and directly filter after standing for 72 h to obtain colorless block-shaped crystals. The yield is 30 - 40%. The structural characterization is shown in Figure 1 and Figure 2 , and the results show that the obtained sample is a pure phase; the thermogravimetric analysis is shown in Figure 3 .

[0033] Powder preparation

[0034] Example 2: Weigh 3,3′-disulfonic acid–4,4′-biphenyldicarboxylic acid (24 mg, 0.06 mmol) and TMeQ[6] (252 mg, 0.24 mmol) separately. Place them in a round-bottom flask with 35 mL of distilled water, stir vigorously with a strong magnetic stirrer and heat to 80 °C. After 4 h, stop heating and then cool down to 30 °C. Filter the mixture, and dry the filter cake to obtain a white powder with a yield of 50 - 70% (calculated based on TMeQ[6]). The structural characterization is shown in Figure 2 .

[0035] Preparation of a Symmetric Tetramethylhexacyclic Cucurbituril-based Fluorescent Probe

[0036] Example 3: Weigh 50 mg of the sample obtained in Example 1 or 2, grind it thoroughly, add 10 mL of distilled water, ultrasonically vibrate for 30 min, and then transfer it to a 50 mL volumetric flask for volume fixation to obtain a fluorescent probe solution with a concentration of 1 mg / mL.

[0037] A method for determining Fe 3+ or Pd 2+ in water:

[0038] Example 4: A method for determining Fe 3+ in water:

[0039] Take a quartz glassware, add 2 mL of the fluorescent probe solution with a concentration of 1 mg / mL, fix the excitation wavelength at 265 nm, and measure the fluorescence spectrum in the range of 310 - 500 nm. Then, dropwise add a 1 M standard solution containing Fe 3+ , and stir the suspension at a constant rate to ensure uniform mixing. Measure a series of fluorescence curves until the change in the ordinate value of the fluorescence curve is slow, and then stop the titration operation. Using the fluorescence emission intensity of the probe at 365 nm, apply the non-linear Stern-Volmer equation I 0 / I = A e k[Q] + B (where I 0 and I are the fluorescence emission intensities of the suspension before and after adding the MCl x solution respectively, A , B and k are constants, Q is the concentration of the ion) for fitting and calculate the quenching constant according to KSV = A × k and measure the standard deviation σ of 5 blank values. According to the formula, the detection limit (DL) = 3 σ / KSV , calculate the detection limit of the standard solution detected by the fluorescent probe containing Fe 3+ : 2.66×10 -6 M (Fe 3+ ).

[0040] Example 5: A specific operation method for determining Pd 2+ in water:

[0041] Take a quartz glassware, add 2 mL of a fluorescent probe solution with a concentration of 1 mg / mL, fix the excitation wavelength at 265 nm, and measure the fluorescence spectrum in the range of 310 - 500 nm. Then, dropwise add a 1 M standard solution containing Pd 2+ , and stir the suspension at a constant rate to ensure uniform mixing. Measure a series of fluorescence curves until the change in the vertical coordinate value of the fluorescence curve is slow, and then stop the titration operation. Using the fluorescence emission intensity of the probe at 365 nm, apply the non-linear Stern-Volmer equation I 0 / I = A e k[Q] + B (where I 0 and I are the fluorescence emission intensities of the suspension before and after adding the MCl x solution respectively, A , B and k are constants, Q is the concentration of the ion) for fitting and calculate the quenching constant according to KSV = A × k and measure the standard deviation σ of 5 blank values. According to the formula, the detection limit (DL) = 3 σ / KSV , calculate the detection limit of the standard solution detected by the fluorescent probe containing Pd 2+ : 1.07×10 -6 M (Pd 2+ ).

[0042] Another specific operation method for determining Fe 3+ or Pd 2+ in water

[0043] Example 6: Take a 10 cm * 1 cm white paper, immerse it in a 10 mL 1 mg / mL fluorescent probe solution for 1 h, take it out and dry it to make a fluorescent test paper. Drop the target solution onto the test paper, irradiate it with a 365 nm ultraviolet lamp, and observe the fluorescence change of the test paper before and after. If the fluorescence weakens, it proves that the target solution contains Fe 3+ or Pd2+ , otherwise it does not contain.

[0044] The present invention has the characteristics of simple operation and high yield, and is made into a fluorescence probe for determining Fe in water 3+ or Pd 2+ It has the characteristics of convenient and fast operation method, good selectivity, low detection limit and reusability.

[0045] In the description of this specification, the descriptions referring to the terms "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0046] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and the above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A symmetric tetramethyl hexacyclic cucurbituril-based fluorescent complex, characterized in that: The chemical formula of the symmetric tetramethyl hexacyclic cucurbituril-based fluorescent complex is: {[C 40 H 44 N 24 O 12 2·[C 14 H 10 O 10 S2]1} n , where the value range of n is an integer greater than or equal to 1; The preparation method of the symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex is as follows: Weigh 3,3′-disulfonic acid–4,4′-biphenyldicarboxylic acid and symmetric tetramethylhexacyclic cucurbituril, and place the above two organic substances in water and stir vigorously to make them dissolve in water to obtain a mixed solution. Heat the mixed solution under high-pressure conditions to cause the 3,3′-disulfonic acid–4,4′-biphenyldicarboxylic acid and symmetric tetramethylhexacyclic cucurbituril in the mixed solution to react to obtain the symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex. Finally, cool, stand, and dry the obtained symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex to obtain the symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex in the form of a white powder; the molar ratio of 3,3′-disulfonic acid–4,4′-biphenyldicarboxylic acid to symmetric tetramethylhexacyclic cucurbituril is 1:2 - 1:

4.

2. The symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex according to claim 1, wherein: The molecular weight of the symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex is: 1254.16n.

3. A symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex according to claim 1, characterized in that: The repeating basic unit in the said structural formula is: {[C 40 H 44 N 24 O 12 2·[C 14 H 10 O 10 S2]1} n .

4. A symmetric tetramethyl hexacyclic cucurbituril-based fluorescent complex according to claim 1, characterized in that: The reaction conditions for heating the mixed solution under high-pressure conditions are as follows: First, heat the mixed solution to 100 °C and keep it at a constant temperature for 10 h, then cool it to 30 °C at a rate of 1 °C / 10 min and keep it at a constant temperature for 24 - 36 h.

5. Use of a symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex as described in any one of claims 1-4 for detecting heavy metal ions Fe 3+ and Pd 2+ in water.

6. Use of the symmetric tetramethyl hexacyclic cucurbituril-based fluorescent complex according to claim 5, characterized in that: The detection method using a symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex to detect Fe in water 3+ is as follows: Prepare a probe standard solution with the symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex, and record the fluorescence emission spectrum generated by the probe standard solution at an excitation wavelength of 265 nm; Add a single aqueous solution containing Fe 3+ to the probe standard solution, and record the fluorescence spectrum generated by the probe standard solution containing Fe 3+ at an excitation wavelength of 265 nm; According to the change value of the fluorescence intensity at the maximum emission wavelength of 365 nm before and after, the detection of Fe 3+ in water is achieved, and the detection limit reaches 2.66×10 -6 M.

7. Use of the symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex according to claim 5, characterized in that: The detection method using a symmetric tetramethyl hexacyclic cucurbituril-based fluorescent complex to detect Pd in water 2+ is as follows: Prepare a probe standard solution of the symmetric tetramethyl hexacyclic cucurbituril-based fluorescent complex and record the fluorescence emission spectrum generated by the probe standard solution at an excitation wavelength of 265 nm; Add a single aqueous solution containing Pd 2+ to the probe standard solution and record the fluorescence spectrum generated by the probe standard solution containing Pd 2+ at an excitation wavelength of 265 nm; Based on the change value of the fluorescence intensity at the maximum emission wavelength of 365 nm before and after, the detection of Pd 2+ in water is achieved, and the detection limit reaches 1.07×10 -6 M.

8. The application according to any one of claims 6-7, characterized in that: The preparation steps of the probe standard solution are as follows: Grind the symmetric tetramethylhexacyclic cucurbituril-based fluorescent complex into a powder, and ultrasonically soak it in deionized water, and adjust the pH = 7 to prepare the probe standard solution; the concentration of the prepared probe standard solution is 1 mg / mL.

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