Tetraphenyl ethylene salicylaldehyde Schiff base as well as preparation method and application thereof

Abstract

The invention provides a Schiff base compound, the molecular structure of the Schiff base compound is shown in the following formula (I), and the Schiff base compound is high in luminous intensity and high in response sensitivity. # imgabs0 #

Description

Technical Field

[0001] The invention belongs to the technical field of fluorescent material synthesis, and particularly relates to a tetraphenylethylene salicylaldehyde Schiff base and a preparation method and application thereof. Background Art

[0002] Schiff base compounds are obtained by condensation reaction of aldehydes and amines, and salicylaldehyde Schiff bases are prepared by condensation reaction of salicylaldehyde, salicylaldehyde derivatives and different amines. They have the advantages of simple synthesis steps and low cost. Compared with traditional luminescent materials, salicylaldehyde Schiff base fluorescent probes avoid the phenomenon of aggregation fluorescence quenching and are used in ion detection, biosensing, pH, gas sensing, explosive detection, etc. However, the luminescence intensity of salicylaldehyde Schiff base materials is weak, the phenomenon is not obvious, and the detection sensitivity is limited, so it is necessary to improve its fluorescence intensity and response sensitivity by changing the structure of aldehydes and amines.

[0003] Tetraphenylethylene (TPE) is a typical aggregation-induced emission material. The TPE molecule has a propeller-shaped conformation, which is surrounded by an olefin center and four peripheral benzene rings. The TPE molecule hardly emits light in an isolated state, and the dynamic rotational motion of the benzene ring rotor consumes energy in the form of non-fluorescent radiation. When it is in an aggregated state, the intramolecular rotational motion is restricted, and the highly distorted conformation of the molecule hinders the intermolecular π-π stacking effect, and the fluorescence emission of the TPE molecule is turned on. Based on the excellent molecular modification and fluorescence properties of tetraphenylethylene molecules, it is prepared into salicylaldehyde, which is then condensed with amines to form a Schiff base. The aggregation-induced emission effect of the Schiff base fluorescent probe can be enhanced, thereby improving its fluorescence intensity and detection sensitivity. Summary of the invention

[0004] The inventors found that the luminescence intensity of salicylaldehyde Schiff base material is weak, the phenomenon is not obvious, and the detection sensitivity is limited. Therefore, it is necessary to improve its fluorescence intensity and response sensitivity by changing the structure of aldehyde and amine.

[0005] In one aspect of the present invention, the present invention provides a Schiff base compound. According to an embodiment of the present invention, the molecular structure of the Schiff base compound is shown in the following formula (I):

[0006]

[0007] Among them, R 1 OH or NH2;

[0008] R 2 C 1-6 The salicylaldehyde Schiff base material has a strong luminescence intensity, an obvious phenomenon, and a high detection sensitivity.

[0009] According to an embodiment of the present invention, the structure of the compound represented by formula (I) is as follows:

[0010]

[0011] In another aspect of the present invention, the present invention provides a method of the Schiff base compound as described above. According to an embodiment of the present invention, the method comprises:

[0012] 1) subjecting the compound represented by formula (II) to a first heating reaction with urotropine to obtain a compound represented by formula (III);

[0013] 2) Compound represented by formula (III) and R 2 NH2 is subjected to a second heating reaction to obtain a compound represented by formula (I);

[0014]

[0015] Among them, R 1 OH or NH2;

[0016] R 2 C 1-6 alkyl.

[0017] In another aspect of the present invention, the present invention provides a method of the Schiff base compound as described above. According to an embodiment of the present invention, the method comprises:

[0018] 1) reacting phosphorus oxychloride, acetonitrile and N,N-dimethylformamide to obtain a reaction solution;

[0019] 2) dissolving the compound represented by formula (II) in acetonitrile, and then adding it to the reaction solution, and performing a temperature-raising reaction to obtain the compound represented by formula (III);

[0020] 3) Compound represented by formula (III) and R 2 NH2 is subjected to a second heating reaction to obtain a compound represented by formula (I);

[0021]

[0022] Among them, R 1 OH or NH2;

[0023] R 2 C 1-6 alkyl.

[0024] According to an embodiment of the present invention, the above method may further include at least one of the following additional technical features:

[0025] According to an embodiment of the present invention, the structure of the compound represented by formula (I) is as follows:

[0026]

[0027] According to an embodiment of the present invention, the structure of the compound represented by formula (II) is as follows:

[0028]

[0029] According to an embodiment of the present invention, the structure of the compound represented by formula (III) is as follows:

[0030]

[0031] According to an embodiment of the present invention, the R 2 NH2 is tert-butylamine.

[0032] According to an embodiment of the present invention, the first heating reaction is carried out in the following manner:

[0033] The compound represented by formula (II) was dissolved in trifluoroacetic acid, and then urotropine was added, and the mixture was heated to 80° C. and reacted for 16 hours.

[0034] According to an embodiment of the present invention, after the first heating treatment, a first post-treatment is further included, and the first post-treatment is performed by extraction.

[0035] According to an embodiment of the present invention, the second heating reaction is carried out in the following manner:

[0036] R 2 NH2 is dissolved in tetrahydrofuran, the system temperature is raised to 80°C, the compound represented by formula (III) is added, and the reaction is carried out for 5 to 8 hours.

[0037] According to an embodiment of the present invention, after the second heating treatment, a second post-treatment is further included, and the second post-treatment is performed by cooling and filtering.

[0038] According to an embodiment of the present invention, the reaction in step 1) is carried out at -5 to 0° C. under nitrogen.

[0039] According to an embodiment of the present invention, the reaction time in step 1) is 1 hour.

[0040] According to an embodiment of the present invention, the temperature-raising reaction is carried out at a temperature of 50° C. for 1.5 hours.

[0041] According to an embodiment of the present invention, the molar ratio of the compound represented by formula (II) to hexamethylenetetramine is 1:(1-2), for example, 1:1, 1:1.5 or 1:2.

[0042] According to an embodiment of the present invention, the compound represented by formula (III) and R2 The molar ratio of NH2 is 1:(2-6), for example 1:2, 1:3, 1:4, 1:5 or 1:6.

[0043] According to an embodiment of the present invention, the molar ratio of the phosphorus oxychloride, the N,N-dimethylformamide and the compound represented by formula (II) is 1:1:3:.

[0044] In another aspect of the present invention, the present invention proposes the use of the Schiff base compound described above or the Schiff base compound prepared according to the method described above in a fluorescent probe.

[0045] According to the embodiments of the present invention, the present invention has at least one of the following advantages:

[0046] 1) The present invention provides a method for preparing tetraphenylethylene salicylaldehyde Schiff base, which has diversified processes, simple procedures and low costs.

[0047] 2) The present invention utilizes the large rigid conjugated plane of tetraphenylethylene to restrict the intramolecular rotation in the aggregated state, hindering the π-π stacking between molecules, thereby generating the phenomenon of aggregation-induced emission. Tetraphenylethylene is prepared into salicylaldehyde, which reacts with tert-butylamine to synthesize Schiff base, thereby enhancing the fluorescence intensity and sensitivity of Schiff base as a fluorescent probe.

[0048] Terms and Definitions

[0049] Unless otherwise specified, the terms and definitions used in this application, including the specification and claims, are as follows.

[0050] The term "C1-C6 alkyl" is understood to mean a linear or branched saturated monovalent hydrocarbon radical having 1, 2, 3, 4, 5 or 6 carbon atoms. The alkyl radical is, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-methylbutyl, 1-methylbutyl, 1-ethylpropyl, 1,2-dimethylpropyl, neopentyl, 1,1-dimethylpropyl, 4-methylpentyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, 2-ethylbutyl, 1-ethylbutyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1-dimethylbutyl, 2,3-dimethylbutyl, 1,3-dimethylbutyl or 1,2-dimethylbutyl, or the like or isomers thereof. In particular, the radical has 1, 2, 3, 4, 5, 6 carbon atoms ("C1-C6 alkyl"), for example methyl, ethyl, propyl, butyl, isopropyl, isobutyl, sec-butyl, tert-butyl, more particularly, the radical has 1, 2 or 3 carbon atoms ("C1-C3 alkyl"), for example methyl, ethyl, n-propyl or isopropyl. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0052] Figure 1 These are two synthetic routes of tetraphenylethylene salicylaldehyde Schiff base provided by the present invention;

[0053] Figure 2 It is the nuclear magnetic spectrum of tetraphenylethylene salicylaldehyde Schiff base provided by the present invention;

[0054] Figure 3 The present invention provides a tetrahydrofuran solution ultraviolet absorption spectrum of tetraphenylethylene salicylaldehyde Schiff base. DETAILED DESCRIPTION

[0055] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0056] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0057] The present invention is described below with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and do not limit the present invention in any way.

[0058] Embodiment 1

[0059] (1) Synthesis of tetraphenylethylene salicylaldehyde

[0060] First, 4-(1,2,2-triphenylvinyl)phenol (2g, 5.74mmol) was dissolved in trifluoroacetic acid (20mL), and then urotropine (1.61g, 11.48mmol) was added to the reaction solution in batches, heated to 80°C, and reacted for 16h. The system was cooled, deionized water (40mL) was added, extracted with dichloromethane, separated, the organic phase was collected, washed with sodium chloride solution, dried with magnesium sulfate, filtered, dried under reduced pressure, and column chromatography was performed to obtain 1.54g of tetraphenylethylene salicylaldehyde with a yield of 71.2%.

[0061] (2) Synthesis of tetraphenylethylene salicylaldehyde Schiff base

[0062] First, tert-butylamine (0.39 g, 5.32 mmol) was dissolved in tetrahydrofuran, the system temperature was raised to 80°C, tetraphenylethylene salicylaldehyde (1 g, 2.66 mmol) was added, and the reaction was continued for 5 h. The system temperature was lowered, crystals were precipitated, filtered, washed, and dried to obtain 0.83 g of tetraphenylethylene salicylaldehyde Schiff base, with a yield of 72.7%.

[0063] Embodiment 2

[0064] (1) Synthesis of tetraphenylethylene salicylaldehyde

[0065] First, 4-(1,2,2-triphenylvinyl)phenol (5g, 14.35mmol) was dissolved in trifluoroacetic acid (40mL), and then urotropine (3.02g, 21.52mmol) was added to the reaction solution in batches, heated to 85°C, and reacted for 20h. The system was cooled, deionized water (80mL) was added, and extracted with dichloromethane for 3 times, separated, and the organic phase was collected, and then washed with sodium chloride solution, dried with magnesium sulfate, filtered, dried under reduced pressure, and column chromatography was performed to obtain 4.5g of tetraphenylethylene salicylaldehyde with a yield of 83.3%.

[0066] (2) Synthesis of tetraphenylethylene salicylaldehyde Schiff base

[0067] First, tert-butylamine (2.91 g, 31.85 mmol) was dissolved in tetrahydrofuran, the system temperature was raised to 80°C, tetraphenylethylene salicylaldehyde (3 g, 7.97 mmol) was added, and the reaction was continued for 8 hours. The system temperature was lowered, crystals were precipitated, filtered, washed, and dried to obtain 3 g of tetraphenylethylene salicylaldehyde Schiff base, with a yield of 87.2%.

[0068] Embodiment 3

[0069] At -5~0℃, under nitrogen protection, firstly, phosphorus oxychloride (6.6g, 43.05mmol) and acetonitrile (50mL) were mixed, and N,N-dimethylformamide (3.15, 43.05mmol) was added, and the reaction was continued for 1h; then, 4-(1,2,2-triphenylvinyl)phenol (5g, 14.35mmol) was dissolved in acetonitrile and slowly added dropwise to the reaction solution, and after the addition was completed, the temperature was raised to 50℃ and the reaction was continued for 1.5h. After the reaction was completed, ice water and saturated sodium chloride solution were slowly added, the organic phase was separated and collected, and concentrated under reduced pressure, and column chromatography was performed to obtain 3g of tetraphenylethylene salicylaldehyde, with a yield of 55.6%.

[0070] (2) Synthesis of tetraphenylethylene salicylaldehyde Schiff base

[0071] First, tert-butylamine (1.75 g, 23.91 mmol) was dissolved in tetrahydrofuran, the system temperature was raised to 80°C, tetraphenylethylene salicylaldehyde (1.5 g, 3.98 mmol) was added, and the reaction was continued for 5 hours. The system temperature was lowered, crystals were precipitated, filtered, washed, and dried to obtain 1.3 g of tetraphenylethylene salicylaldehyde Schiff base, with a yield of 75.6%.

[0072] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction 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 may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0073] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A Schiff base compound, characterized in that The molecular structure of the Schiff base compound is shown in the following formula (I): Among them, R 1 OH or NH2; R 2 C 1-6 alkyl.

2. The Schiff base compound according to claim 1, characterized in that The structure of the compound represented by formula (I) is shown below:

3. A method for preparing the Schiff base compound according to claim 1 or 2, characterized in that: include: 1) subjecting the compound represented by formula (II) to a first heating reaction with urotropine to obtain a compound represented by formula (III); 2) Compound represented by formula (III) and R 2 NH2 is subjected to a second heating reaction to obtain a compound represented by formula (I); Among them, R 1 OH or NH2; R 2 C 1-6 alkyl.

4. A method for preparing the Schiff base compound according to claim 1 or 2, characterized in that: include: 1) reacting phosphorus oxychloride, acetonitrile and N,N-dimethylformamide to obtain a reaction solution; 2) dissolving the compound represented by formula (II) in acetonitrile, and then adding it to the reaction solution to carry out a temperature-raising reaction to obtain a compound represented by formula (III); 3) Compound represented by formula (III) and R 2 NH2 is subjected to a second heating reaction to obtain a compound represented by formula (I); Among them, R 1 OH or NH2; R 2 C 1-6 alkyl.

5. The method according to claim 3 or 4, characterized in that: The structure of the compound represented by formula (I) is as follows: Optionally, the structure of the compound represented by formula (II) is as follows: Optionally, the structure of the compound represented by formula (III) is as follows: Optionally, the R 2 NH2 is tert-butylamine.

6. The method according to claim 3, characterized in that The first heating reaction is carried out in the following manner: The compound represented by formula (II) was dissolved in trifluoroacetic acid, and then urotropine was added, and the mixture was heated to 80°C and reacted for 16 hours; Optionally, after the first heating treatment, a first post-treatment is further included, and the first post-treatment is performed by extraction.

7. The method according to claim 3 or 4, characterized in that: The second heating reaction is carried out in the following manner: R 2 NH2 is dissolved in tetrahydrofuran, the system temperature is raised to 80°C, the compound represented by formula (III) is added, and the reaction is carried out for 5 to 8 hours; Optionally, after the second heating treatment, a second post-treatment is further included, and the second post-treatment is performed by cooling and filtering.

8. The method according to claim 4, characterized in that The reaction in step 1) is carried out at -5 to 0°C under nitrogen; Optionally, the reaction time in step 1) is 1 hour; Optionally, the temperature-raising reaction is carried out at 50° C. for 1.5 hours.

9. The method according to claim 3 or 4, characterized in that: The molar ratio of the compound represented by formula (II) to hexamethylenetetramine is 1:(1-2); Optionally, the compound represented by formula (III) and R 2 The molar ratio of NH2 is 1:(2-6); Optionally, the molar ratio of the phosphorus oxychloride, the N,N-dimethylformamide and the compound represented by formula (II) is 1:1:3:.

10. Use of the Schiff base compound according to claim 1 or 2 or the Schiff base compound prepared by the method according to any one of claims 3 to 9 in fluorescent probes.

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