阅读说明：本技术 硫脲类希夫碱及其制备方法和作为Zn2+、Al3+荧光探针的应用 (Thiourea Schiff base, preparation method thereof and Zn serving as same2+、Al3+Application of fluorescent probe ) 是由 程景惠 曾露露 关会娟 于 2021-07-06 设计创作，主要内容包括：本发明公开了一种硫脲类希夫碱及其制备方法和作为Zn～(2+)、Al～(3+)荧光探针的应用,硫脲类希夫碱包括硫脲类希夫碱L4(硫代氨基脲,4-(二乙基氨基)水杨醛)、L5(硫代氨基脲、2-羟基-4-甲氧基苯甲醛合成的希夫碱)、L11(硫代卡巴肼和2-羟基-4-甲氧基苯甲醛),L4、L5和L11在加入Zn～(2+)后出现荧光增强,希夫碱配体对Zn～(2+)具有很好的选择性,其他金属离子对Zn～(2+)不存在干扰；此外L11配体在加入Al～(3+)后也出现荧光增强,L11实现了对Zn～(2+)和Al～(3+)的双检测。硫脲类希夫碱作为Zn～(2+)、Al～(3+)荧光探针在环境监测和生物检测等领域具有重要的实际应用。(The invention discloses thiourea Schiff base, a preparation method thereof and Zn serving as the Schiff base 2+ 、Al 3+ The fluorescent probe is applied, and the thiourea Schiff bases comprise thiourea Schiff bases L4 (thiosemicarbazide, 4- (diethylamino) salicylaldehyde), L5 (Schiff bases synthesized by thiosemicarbazide and 2-hydroxy-4-methoxybenzaldehyde), L11 (thiocarbazide and 2-hydroxy-4-methoxybenzaldehyde), and L4, L5 and L11 are added with Zn 2+ Then the fluorescence is enhanced, and the Schiff base ligand pair Zn appears 2+ Has good selectivity, and other metal ions are in Zn 2+ No interference exists; in addition, the L11 ligand is added with Al 3+ Then, fluorescence enhancement also appears, and L11 realizes Zn 2+ And Al 3+ Double detection of (2). Thiourea Schiff base as Zn 2+ 、Al 3+ The fluorescent probe has important practical application in the fields of environmental monitoring, biological detection and the like.)

1. A thiourea schiff base L4 (thiosemicarbazide, 4- (diethylamino) salicylaldehyde), L4 has the structural formula:

2. a thiourea Schiff base L5 (Schiff base synthesized by thiosemicarbazide and 2-hydroxy-4-methoxybenzaldehyde) has a structural formula of L5:

3. a thiourea schiff base L11 (thiocarbazoic hydrazine and 2-hydroxy-4-methoxybenzaldehyde), L11 has the structural formula:

4. the thiourea-based Schiff base ligand L4 of claim 1 in Zn²⁺Application in probe, L4 can realize Zn²⁺Specific selective recognition of.

5. The thiourea-based Schiff base ligand L5 of claim 2 in Zn²⁺Application in probe, L5 can realize Zn²⁺Specific selective recognition of.

6. A thiourea-based schiff base ligand (L11) as claimed in claim 3 in Zn²⁺And Al³⁺Application in probe, L11 can identify Zn with high selectivity²⁺And Al³⁺。

7. The thiourea-based Schiff base ligand L11 of claim 3, for Al under aggregation-induced fluorescence conditions³⁺The ratio type detection application of (1) is that the L11 ligand realizes the detection of metal ions by a ratio type probe under the condition of aggregation induced fluorescence, and realizes the recognition of the metal ions with high selectivity and high sensitivity.

8. The preparation method of the thiourea schiff base ligand L4 as claimed in claim 1, which is characterized by comprising the following steps:

adding 4mmol of 4- (diethylamino) salicylaldehyde into a 100mL three-neck flask, then adding 10-20mL of absolute ethanol, heating the mixture in an oil bath kettle at 80 ℃ until the mixture is completely dissolved, putting 2mmol of thiosemicarbazide into a small beaker, adding 50mL of ethanol into the small beaker, completely dissolving the thiosemicarbazide, dropwise adding the mixture into the reaction mixed solution in the three-neck flask, finally dropwise adding 0.5mL of triethylamine serving as a catalyst, condensing and refluxing the mixture for 5 hours at 80 ℃ in the oil bath kettle, and filtering to obtain a brown yellow solid.

9. The preparation method of the thiourea schiff base ligand L5 as claimed in claim 2, which is characterized by comprising the following steps:

adding 4mmol of 2-hydroxy-4-methoxybenzaldehyde into a 100mL three-neck flask, then adding 10-20mL of absolute ethanol, heating the mixture in an oil bath kettle at 80 ℃ until the mixture is completely dissolved, putting 2mmol of thiosemicarbazide into a small beaker, adding 50mL of ethanol into the small beaker, completely dissolving the mixture, dropwise adding the mixture into the reaction mixed solution in the three-neck flask, finally dropwise adding 0.5mL of triethylamine serving as a catalyst, carrying out condensation reflux for 5 hours at 80 ℃ in the oil bath kettle, and filtering to obtain yellow crystals.

10. The preparation method of the thiourea Schiff base ligand L11, according to claim 3, is characterized by comprising the following steps:

adding 4mmol of 2-hydroxy-4-methoxybenzaldehyde into a 100mL three-neck flask, then adding 10-20mL of absolute ethyl alcohol, heating the mixture in an oil bath kettle at 80 ℃ until the mixture is completely dissolved, putting 2mmol of thiocarbohydrazide into a small beaker, adding 50mL of ethyl alcohol into the small beaker, completely dissolving the mixture, dropwise adding the mixture into the reaction mixed solution in the three-neck flask, finally dropwise adding 1mL of triethylamine serving as a catalyst, carrying out condensation reflux for 5 hours at 80 ℃ in the oil bath kettle, and filtering to obtain a light green solid.

Technical Field

The invention relates to thiourea Schiff base, a preparation method thereof and Zn serving as Zn²⁺、Al³⁺Application of fluorescent probe.

Background

The structural characteristics of thiourea Schiff base ligands determine that the thiourea Schiff base ligands have good optical properties, the thiourea Schiff base ligands can be chelated and coordinated with various metal ions under certain conditions, the ligands and the complexes have important functions in the fields of stereochemistry, structure, stereoisomerism, magnetism, spectroscopy, coordination chemistry, catalysis, analytical chemistry, photography, electro-optic display, agriculture, photochromism and the like, and some thiourea Schiff base ligands are successfully applied to the field of fluorescence detection of metal ions. The use of fluorescent probes in the biological field has attracted considerable interest.

Most of traditional organic luminescent materials show a self-polymerization fluorescence quenching phenomenon, however, in practical production and application, the organic luminescent materials are often required to have excellent luminescent performance in an aggregation state, which seriously restricts the development and application prospect of the field. Until 2001, the Tang-Ben-loyd college and universities team discovered for the first time a phenomenon that the fluorescence of the organic luminescent material is very weak or even no in the dilute solution state, but the fluorescence is rather greatly enhanced in the aggregation state, which is called "auto-polymerization induced fluorescence".

Disclosure of Invention

The invention aims to solve the technical problem of providing thiourea Schiff base, a preparation method thereof and Zn serving as Zn aiming at the defects of the prior art²⁺、Al³⁺Application of fluorescent probe. A series of thiourea Schiff bases with high sensitivity and high selectivity are synthesized by introducing salicylaldehyde derivatives containing different substituents and thiourea compounds through addition condensation reaction, and the thiourea Schiff bases are used as Zn^{2 +}、Al³⁺The fluorescent probe has important practical application in the fields of environmental monitoring, biological detection and the like and can be used for Al under the condition of aggregation-induced fluorescence³⁺The ratio formula (2).

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a thiourea schiff base L4 (thiosemicarbazide, 4- (diethylamino) salicylaldehyde);

the structural formula of L4 is:

a thiourea Schiff base L5 (Schiff base synthesized by thiosemicarbazide and 2-hydroxy-4-methoxybenzaldehyde);

the structural formula of L5 is:

a thiourea Schiff base L11 (thiocarbazone and 2-hydroxy-4-methoxybenzaldehyde);

the structural formula of L11 is:

the preparation method of the L4 comprises the following steps:

adding 4mmol of 4- (diethylamino) salicylaldehyde into a 100mL three-neck flask, then adding 10-20mL of absolute ethanol, heating the mixture in an oil bath kettle at 80 ℃ until the mixture is completely dissolved, putting 2mmol of thiosemicarbazide into a small beaker, adding 50mL of ethanol into the small beaker, completely dissolving the thiosemicarbazide, dropwise adding the mixture into the reaction mixed solution in the three-neck flask, finally dropwise adding 0.5mL of triethylamine serving as a catalyst, condensing and refluxing the mixture for 5 hours at 80 ℃ in the oil bath kettle, and filtering to obtain a brown yellow solid.

The preparation method of the L5 comprises the following steps:

adding 4mmol of 2-hydroxy-4-methoxybenzaldehyde into a 100mL three-neck flask, then adding 10-20mL of absolute ethanol, heating the mixture in an oil bath kettle at 80 ℃ until the mixture is completely dissolved, putting 2mmol of thiosemicarbazide into a small beaker, adding 50mL of ethanol into the small beaker, completely dissolving the mixture, dropwise adding the mixture into the reaction mixed solution in the three-neck flask, finally dropwise adding 0.5mL of triethylamine serving as a catalyst, carrying out condensation reflux for 5 hours at 80 ℃ in the oil bath kettle, and filtering to obtain yellow crystals.

The preparation method of the L11 comprises the following steps:

adding 4mmol of 2-hydroxy-4-methoxybenzaldehyde into a 100mL three-neck flask, then adding 10-20mL of absolute ethyl alcohol, heating the mixture in an oil bath kettle at 80 ℃ until the mixture is completely dissolved, putting 2mmol of thiocarbohydrazide into a small beaker, adding 50mL of ethyl alcohol into the small beaker, completely dissolving the mixture, dropwise adding the mixture into the reaction mixed solution in the three-neck flask, finally dropwise adding 1mL of triethylamine serving as a catalyst, carrying out condensation reflux for 5 hours at 80 ℃ in the oil bath kettle, and filtering to obtain a light green solid.

The thiourea Schiff base ligand L4 is Zn²⁺Application in probe, L4 can realize Zn²⁺Specific selective recognition of.

The thiourea Schiff base ligand L5 is Zn²⁺Application in probe, L5 can realize Zn²⁺Specific selective recognition of.

A thiourea-based schiff base ligand (L11) as claimed in claim 3 in Zn²⁺And Al³⁺Application in probe, L11 can identify Zn with high selectivity²⁺And Al³⁺。

The thiourea Schiff base ligand L11 is used for reacting Al under the condition of aggregation-induced fluorescence³⁺The ratio type detection application of (1) is that the L11 ligand realizes the detection of metal ions by a ratio type probe under the condition of aggregation induced fluorescence, and realizes the recognition of the metal ions with high selectivity and high sensitivity.

Wherein L4, L5 and L11 are added with Zn²⁺Then the fluorescence is enhanced, and the Schiff base ligand pair Zn appears²⁺Has good selectivity, and other metal ions are in Zn²⁺No interference exists; in addition, the L11 ligand is added with Al³⁺Then, fluorescence enhancement also appears, and L11 realizes Zn²⁺And Al³⁺Double detection of (2). Thiourea Schiff base as Zn²⁺、Al³⁺The fluorescent probe has important practical application in the fields of environmental monitoring, biological detection and the like.

The invention also realizes the ratio type detection of metal ions under the condition of aggregation-induced fluorescence, is a ratio type probe with double signal units, and has high selectivity and high sensitivity.

Drawings

FIG. 1 is the structural formula of L4;

FIG. 2 is a structural formula of L5;

FIG. 3 is a structural formula of L11;

FIG. 4 shows ligand L4 in acetonitrile (1.0X 10)^-4mol·dm^-3) In the system, fluorescence emission spectra (excitation wavelength 380nm) when different metal ions are added;

FIG. 5 shows ligand L5 in acetonitrile (1.0X 10)^-4mol·dm^-3) In the system, fluorescence emission spectra (excitation wavelength 380nm) when different metal ions are added;

FIG. 6 shows ligand L11 in acetonitrile (1.0X 10)^-4mol·dm^-3) In the system, fluorescence emission spectra (excitation wavelength 350nm) when different metal ions are added;

FIG. 7 shows MeCN-H at different values of f (volume fraction of water) for L11₂Fluorescence emission spectrum in O mixed solvent (excitation wavelength: 400 nm);

FIG. 8 shows ligand L11 in MeCN-H₂Fluorescence emission spectra (excitation wavelength 390nm) in O mixed solvent when different metal ions are added;

Detailed Description

The present invention will be described in detail with reference to specific examples.

Example 1: preparation method of thiourea Schiff base ligand

The preparation method of L4 is as follows:

adding 4mmol of 4- (diethylamino) salicylaldehyde into a 100mL three-neck flask, then adding 10-20mL of absolute ethanol, heating the mixture in an oil bath kettle at 80 ℃ until the mixture is completely dissolved, putting 2mmol of thiosemicarbazide into a small beaker, adding 50mL of ethanol into the small beaker, completely dissolving the thiosemicarbazide, dropwise adding the mixture into the reaction mixed solution in the three-neck flask, finally dropwise adding 0.5mL of triethylamine serving as a catalyst, condensing and refluxing the mixture for 5 hours at 80 ℃ in the oil bath kettle, and performing suction filtration to obtain a brown-yellow solid.

All the above operations were carried out in a dark environment, with a yield of 76%.¹H NMR(400MHz,DMSO-d₆)δppm 1.12-1.16(12H,m),3.45-3.50(8H,m),6.56-6.59(2H,dd,J＝2Hz,6.4Hz),6.77-6.79(2H,d,J＝8.4Hz),7.57-7.59(2H,d,J＝6.4Hz),8.18(1H,br),11.67(1H,br),11.94(1H,br)

The preparation method of L5 is as follows:

in a 100mL three-necked flask, 4mmol of 2-hydroxy-4-methoxy group was addedBenzaldehyde, then 10-20mL of absolute ethyl alcohol is added, heating is carried out in an oil bath kettle at 80 ℃ until complete dissolution, 2mmol of thiosemicarbazide is put into a small beaker, 50mL of ethyl alcohol is added and completely dissolved, then dropwise addition is carried out on the mixture into a reaction mixed solution in a three-neck flask, finally 0.5mL of triethylamine is dropwise added as a catalyst, condensation reflux is carried out in the oil bath kettle at 80 ℃ for 5h, and a yellow crystal is obtained through suction filtration. The yield was 78%.¹H NMR(400MHz,DMSO-d₆)δppm 3.75(6H,m),6.55-6.58(2H,dd,J＝2Hz,6.3Hz),6.76-6.78(2H,d,J＝8.3Hz),7.56-7.58(2H,d,J＝6.3Hz),8.13(1H,br),11.64(1H,br),11.91(1H,br)

The preparation method of L11 is as follows:

adding 4mmol of 2-hydroxy-4-methoxybenzaldehyde into a 100mL three-neck flask, then adding 10-20mL of absolute ethyl alcohol, heating the mixture in an oil bath kettle at 80 ℃ until the mixture is completely dissolved, putting 2mmol of thiocarbohydrazide into a small beaker, adding 50mL of ethyl alcohol into the small beaker, completely dissolving the mixture, dropwise adding the mixture into the reaction mixed solution in the three-neck flask, finally dropwise adding 1mL of triethylamine serving as a catalyst, carrying out condensation reflux for 5 hours at 80 ℃ in the oil bath kettle, and carrying out suction filtration to obtain a light green solid.

The yield is 89%¹HNMR(400MHz,[D₆]DMSO):δ＝7.23–7.25(d,2H),7.39–7.43(m,2H),7.59–7.63(m,2H),7.88–7.95(m,4H),8.24–8.52(br,2H),9.16–9.64(br,2H),10.61(br,1H),12.07(s,2H),12.88(br,1H)ppm.¹³C NMR(400MHz,[D₆]DMSO):δ＝109.3,118.7,121.0,123.5,127.8,127.9,128.7,131.7,132.6,145.8,157.1,174.0ppm.MS(EI):414.48.C₂₃H₁₈N₄O₂S(414.48):calcd.C 66.65,H 4.38,N13.52,S 7.74；found C 66.7,H 4.39,N 13.51,S 7.72.

Example 2: thiourea Schiff base ligands (L4, L5) in Zn²⁺Application in probes

The fluorescence emission spectra of the 14 metal ions were obtained by identifying the 14 metal ions with L4 and L5 and measuring the fluorescence emission intensity of each addition of different metal ions, and Zn was observed from the fluorescence emission spectra as shown in FIGS. 4 and 5²⁺The addition of (2) makes the fluorescence emission intensity of L4 and L5 ligands obviously enhanced, while the addition of Ag⁺,Al³⁺,Ce³⁺,Co²⁺,Cr²⁺,Cu²⁺,Mg²⁺,Mn²⁺,Na⁺,Ni²⁺,Cd²⁺,Pb²⁺And Sr²⁺The fluorescence intensity of the Schiff base ligand is almost the same as that of the Schiff base ligand, and the fluorescence emission intensity is increased with the addition of Zn²⁺The ion ratio is negligible, which shows that L4 and L5 realize Zn²⁺Specific selective recognition of.

Example 3: thiourea Schiff base ligand (L11) in Zn²⁺And Al³⁺Application in probes

The fluorescence emission spectra of 14 metal ions were identified by L11, and the fluorescence emission spectra of Zn was obtained by measuring the fluorescence emission intensity of each metal ion addition, as shown in FIG. 6²⁺And Al³⁺The addition of (2) significantly enhanced the fluorescence intensity of the L11 ligand, compared to L4 and L5, the L11 ligand can recognize Zn²⁺In addition, Al can be identified³⁺And Al³⁺Fluorescence emission intensity ratio Zn of L11 after addition²⁺The added fluorescence intensity is high; and Na⁺,Ag⁺,Cd²⁺,Ce³⁺,Co²⁺,Cr²⁺,Cu²⁺,Mg²⁺,Mn²⁺,Ni²⁺,Pb²⁺And Sr²⁺The fluorescence intensity of the Schiff base ligand is almost the same as that of the Schiff base ligand, and the fluorescence emission intensity is increased with the addition of Zn²⁺And Al³⁺The comparison is negligible. This indicates that L11 can highly selectively recognize Zn²⁺And Al³⁺。

Example 4: thiourea Schiff base ligand (L11) on Al under aggregation-induced fluorescence condition³⁺By ratiometric detection of

The L11 ligand shows a very obvious AIE effect, namely, strong fluorescence in a solid state or an aqueous solution, and very weak fluorescence in a pure organic solvent acetonitrile dilute solution. As shown in FIG. 7, according to the fluorescence emission spectrum, Schiff base emits very weak light in acetonitrile (water content is 0%) which is an organic solvent, and has large Stokes shift, which is probably due to free rotation of N-N single bond and fast proton in moleculeCaused by the process of the transfer. However, when water is added, molecules are subjected to self-polymerization to form a nano particle suspension, and simultaneously, the fluorescence enhancement phenomenon is accompanied, when the volume fraction of the water reaches 98%, the fluorescence intensity reaches the maximum value, and then the MeCN-H of L11 can be obtained₂The optimal water content of the O mixed solvent is 98%, so that the subsequent detection of the metal ions by the ratio probe under the aggregation-induced fluorescence condition by the L11 ligand based on the condition can realize the high-selectivity and high-sensitivity identification of the metal ions.

MeCN-H of L11 obtained from FIG. 7₂The optimal water content of the O mixed solvent is 98%, under the condition, 14 metal ions are identified through L11, the fluorescence intensity corresponding to each addition of different metal ions is recorded, and the fluorescence emission spectrum of the O mixed solvent can be obtained, as shown in fig. 8, according to the fluorescence emission spectrum, when the emission wavelength is about 430nm, Al is observed³⁺The addition of (2) significantly enhances the fluorescence emission intensity of the L11 ligand, which appears as blue light; adding Cr²⁺,Zn²⁺,Al³⁺,Ag⁺,Cd²⁺,Ce³⁺,Mg²⁺,Co²⁺,Cu²⁺,Sr²⁺,Na⁺,Ni²⁺And Pb²⁺The fluorescence of the L11 ligand at the emission wavelength of around 500nm is significantly quenched. It can be shown that L11 can be used as a ratio type fluorescent probe to detect metal ions under the condition of aggregation-induced fluorescence, and can identify Al with high selectivity and high sensitivity³⁺。

It will be understood that modifications and variations can be made by persons skilled in the art in light of the above teachings and all such modifications and variations are intended to be included within the scope of the invention as defined in the appended claims.