Molecular bowl-shaped compound, lanthanide organic polyhedral cage and preparation method and application thereof

Abstract

The invention discloses a molecular bowl-shaped compound, a lanthanide organic polyhedral cage and a preparation method and application thereof, and belongs to the field of functional host molecules. A four-tooth chelating site is combined with a full-rigid'molecular bowl 'structure, and the limitation of a linear or planar ligand for constructing a traditional cypress chart polyhedral structure is broken through. The structure dimension of the rare earth multi-core molecular cage is obviously expanded, and the possibility is provided for realizing more functional applications. In addition, after Eu4 (L1) 4 is prepared into a film, the film shows excellent selectivity and sensitivity to formaldehyde gas, and the detection limit is as low as 19.4 ppb. The application potential of the rare earth nano container in the field of optical sensing is remarkably improved, a brand new direction is opened up for developing a novel rare earth metal-organic supramolecular system with multifunctional characteristics, and important theoretical and practical basis is provided.

Description

Technical Field

[0001] The present application relates to a molecular bowl-shaped compound, a lanthanide organic polyhedral cage, and a preparation method and application thereof, and belongs to the field of functional host molecules. Background Art

[0002] With the rapid development of synthetic chemistry, the precise design and synthesis of new functional host molecules at the molecular and supramolecular levels has become an important frontier field of chemical research. Among them, rare earth metal-organic nanocontainers have shown great potential in the fields of molecular recognition, sensing, imaging and catalysis by virtue of the unique optical, electrical and magnetic properties of rare earth ions, as well as the adjustable functional sites and confined cavities of coordinated nanocontainers. However, compared with the wide variety of transition metal coordinated molecular cages, the structural design of rare earth metal-organic supramolecular cages is still limited to classical Platonic polyhedrons (such as tetrahedrons and cubes) constructed with linear (two-connected) or planar (three-connected, four-connected) organic ligands, and the structural type and functional expansion are greatly restricted. Especially in the exploration of rare earth molecular cages with curved surface properties, the innovative design and synthesis based on bowl-shaped ligands are still blank.

[0003] The introduction of bowl-shaped molecules provides an important opportunity for the design of molecular cages. Their unique structure can significantly expand the three-dimensional cavity, effectively encapsulate large-sized substrates, and promote the construction of non-classical polyhedrons. However, the "molecular bowl" is prone to face-chiral racemization, and the effects of host-guest interactions and mechanical coupling effects in the main skeleton on the stability of face chirality have not been studied in depth. In addition, curved surface molecules with bowl-bowl flipping characteristics as the inner wall of the molecular cage may give the molecular cage dynamic container characteristics, thereby improving its adaptability to diverse substrates. In particular, the rigid face-chiral bowl-shaped molecules, the regulation of their face chirality on the stereoconfiguration (Δ / Λ) of the rare earth metal center, and their application potential in chiral optical activity, cavity chirality recognition and asymmetric catalysis, urgently need to be systematically explored.

[0004] Although the fully rigid "molecular bowl" has attracted much attention in the field of organic functional materials due to its excellent optoelectronic properties, its recognition, transmission and catalytic applications in supramolecular systems are still relatively limited. This is mainly attributed to its large bowl mouth and shallow cavity, which leads to weak host-guest bonding and recognition capabilities. In addition, traditional organic synthesis strategies face significant challenges in deepening the design of bowl cavities. The face chiral racemization problem caused by the rapid bowl-bowl flipping of some chiral bowl-shaped conjugated molecules seriously limits their application in chiral recognition and asymmetric catalysis. Although some studies have attempted to use cup-shaped arenes and CTV-type bowl-shaped supramolecular hosts to enhance the host function through coordination-guided self-assembly strategies, related research on fully rigid "molecular bowls" is still blank. Summary of the invention

[0005] In order to solve the above problems, the present invention designs and synthesizes a series of multidentate ligands based on P / M chiral phosphine bowl-shaped molecules. Crystal structure analysis shows that the ligand L1 molecules form nano-scale porous materials similar to two-dimensional covalent organic frameworks (COFs) through "π-π stacking". 3+ Ions self-assemble to construct a tetrahedral molecular cage Eu4(L1)4 with open coordination sites. Single crystal structure analysis shows that multiple π-π stacking in Eu4(L1)4 and metal coordination of the central phosphorus-oxygen double bond lead to its distorted tetrahedral configuration. After Eu4(L1)4 is prepared into a thin film and exposed to formaldehyde gas, its fluorescence emission is significantly enhanced, showing excellent linear detection performance, with a detection limit as low as 19.4ppb.

[0006] Mechanistic studies have shown that the carbonyl oxygen of formaldehyde and the amide hydrogen of the molecular cage effectively improve the efficiency of the ligand energy level sensitizing europium ions through hydrogen bonding, and inhibit the non-radiative decay caused by energy return, significantly enhancing the luminescence performance of europium ions. The above research provides a new perspective and technical basis for the application of rare earth metal-organic molecular cages in the field of optical sensing.

[0007] The technical problems to be solved by this application are: (1) How to efficiently synthesize chiral bowl-shaped ligand molecules; (2) How to efficiently use chiral "molecular bowl"-based ligands to construct a new type of rare earth metal-organic nanocontainer with a non-traditional polyhedral configuration; (3) How to improve the application of lanthanide molecular cages in optical sensing.

[0008] In order to solve the above technical problems, the technical solutions provided by this application are:

[0009] 1. In the design and synthesis of ligands, we intend to introduce modular design principles: match the phenanthroline tetradentate chelating site with different internal bridging bowl-shaped panels, and synthesize a series of chiral bowl-shaped ligands with different geometric structures, sizes and functions through amide condensation reactions. This design principle can effectively simplify the synthesis steps of the ligand, and replacing different types of intermediate bridging panels can easily obtain bowl-shaped ligands with diverse structures. 2. Use the phenanthroline tetradentate chelating sites contained in the chiral "molecular bowl" based ligand to assemble with rare earth metal ions. Through solution chemistry methods, use nuclear magnetic resonance, high-resolution mass spectrometry, etc. to analyze its structure. 3. Make full use of the empty coordination site characteristics of the metal coordination node, and the substrate to be detected can be coordinated under solution / solid conditions, thereby changing the luminescence intensity of the rare earth complex.

[0010] Furthermore, 1. Through the modular design principle, we can not only obtain a series of bowl-shaped molecules. Moreover, since the bowl-shaped molecules themselves have concave surfaces and π-conjugated electron-rich characteristics, we can further explore their host-guest bonding properties, especially the selective recognition and bonding of electron-deficient substrate molecules such as fullerene derivatives. 2. Compared with molecular bowl ligands, the "bowl-to-cage" strategy achieved by combining coordination-guided self-assembly can significantly increase the internal cavity and molecular bonding ability of the main body, which can be further used in applications such as chiral molecule recognition and encapsulation. 3. This metal organic tetrahedron provides ideas and strategies for the design and synthesis of new tetrahedrons, and demonstrates a possible direction for the preparation of supramolecular cage structures with open coordination sites, which has certain reference significance. When designing ligands, not only the influence of the chelating arm on the coordination environment can be considered, but other parts of the ligand may also participate in the coordination activity and play an unexpected role. Utilizing the open coordination sites, the fluorescent sensing application of the film to formaldehyde was recorded and studied. After binding to the supramolecular cage, the energy level difference between the ligand and europium was changed, the luminescence of europium was enhanced, and highly sensitive and quantitative detection of formaldehyde was achieved.

[0011] According to a first aspect of the present application, a molecular bowl-shaped compound is provided.

[0012] A molecular bowl-shaped compound, wherein the molecular bowl-shaped compound has the structural formula shown in the following formula (I), formula (II), and formula (III):

[0013]

[0014]

[0015] Wherein, when the molecular bowl-shaped compound is a structural formula shown in formula (I), At least one selected from the following structural formulas:

[0016]

[0017] When the molecular bowl-shaped compound is of the structural formula shown in formula (II), Selected from the following structural formula:

[0018]

[0019] When the molecular bowl-shaped compound is of the structural formula shown in formula (III), At least one selected from the following structural formulas:

[0020]

[0021] According to a second aspect of the present application, a method for preparing a molecular bowl-shaped compound is provided.

[0022] A method for preparing a molecular bowl-shaped compound, the preparation method comprising:

[0023] reacting a mixture containing compound A, compound B, HATU, a catalyst, and a solvent to obtain the molecular bowl-shaped compound;

[0024] Wherein, the structural formula of compound B is:

[0025]

[0026] Wherein, when the molecular bowl-shaped compound is a structural formula shown in formula (I), compound A is selected from at least one of the structural formulas shown below:

[0027]

[0028]

[0029] Wherein, when the molecular bowl-shaped compound is a structural formula shown in formula (II), compound A is selected from the structural formula shown below:

[0030]

[0031] Wherein, when the molecular bowl-shaped compound is a structural formula shown in formula (III), compound A is selected from the structural formula shown below:

[0032]

[0033] Optionally, the molar ratio of compound A to compound B is 1:3.0-5.0.

[0034] Optionally, the molar ratio of compound A to HATU is 1:4.0-8.0.

[0035] Optionally, the usage ratio of compound A and catalyst is 1:1.5mL~4.5mL.

[0036] Optionally, the usage ratio of compound A to solvent is 1:180mL to 230mL.

[0037] Optionally, the catalyst is selected from at least one of triethylamine, trimethylamine and tripropylamine.

[0038] Optionally, the solvent is selected from at least one of dimethylformamide, dimethyl sulfoxide, and dimethylacetamide.

[0039] Optionally, the reaction conditions are: reacting in an ice water bath environment for 16 to 36 hours.

[0040] Optionally, after the reaction is completed, the steps of separation, drying and purification are also included.

[0041] According to the third aspect of the present application, a lanthanide organic polyhedral cage is provided. This study innovatively designed and synthesized a chiral "molecular bowl" functional unit, namely a chiral phosphine derivative ligand L1, and constructed a new type of rare earth metal-organic nanocontainer through self-assembly with lanthanide metal ions, whose structure presents an unconventional distorted tetrahedral configuration.

[0042] A lanthanide organic polyhedral cage, wherein the chemical formula of the lanthanide organic polyhedral cage is Ln4(Lig)4(OTf) 12 ;

[0043] Among them, Ln4(Lig)4 has a tetrahedral configuration as shown below:

[0044]

[0045] Among them, Ln represents the lanthanide rare earth element;

[0046] Lig represents a ligand, which is a molecular bowl-shaped compound represented by the above formula (I).

[0047] Optionally, the lanthanide rare earth element is selected from at least one of Eu, La, Tb, Sm, and Nd.

[0048] According to a fourth aspect of the present application, a method for preparing a lanthanide organic polyhedral cage is provided.

[0049] The preparation method of the lanthanide organic polyhedral cage described above comprises:

[0050] reacting a mixture containing ligand Lig, Ln(OTf)3, and a solvent to obtain the lanthanide organic polyhedral cage;

[0051] Wherein, the ligand Lig is a molecular bowl-shaped compound represented by the above formula (I).

[0052] Optionally, the molar ratio of the ligands Lig and Ln(OTf)3 is 1:1.0-1.3.

[0053] Optionally, the usage ratio of ligand Lig and solvent is 1 μmol: 400 μL to 600 μL;

[0054] Optionally, the solvent is a mixed solvent of acetonitrile and methanol.

[0055] Optionally, the reaction conditions are: stirring at 40-60° C. for 1.0-4.0 hours.

[0056] General method for the synthesis of rare earth polyhedral cages: 1 equivalent of organic ligand and 1.1 equivalent of Ln(OTf)3(OTf -:CF3SO3 - ) was dissolved in a mixed solvent of acetonitrile / methanol (v / v=4 / 1) and stirred at 50°C for three hours. The reaction solution gradually changed from the initial suspension to a clear yellow solution. NMR characterization confirmed that there was no residual raw material and a single product was obtained. Mass spectrometry confirmed that the chemical formula of the product was Ln4(L1)4(OTf) 12 The reaction solution was spin dried to obtain a light yellow solid powder.

[0057] According to a fifth aspect of the present application, an application of a lanthanide organic polyhedral cage is provided.

[0058] Application of the above-mentioned lanthanide organic polyhedral cage in the field of optical sensing;

[0059] Optionally, the above-mentioned lanthanide organic polyhedron cage is used in formaldehyde detection.

[0060] The beneficial effects of this application include:

[0061] The molecular bowl-shaped compounds, lanthanide organic polyhedral cages, and their preparation methods and applications provided in this application combine tetradentate chelating sites with fully rigid "molecular bowl" structures for the first time, breaking through the limitations of linear or planar ligands to construct traditional Platonic polyhedral structures. This innovative design significantly expands the structural dimension of rare earth multi-nuclear molecular cages and provides the possibility for more functional applications. In addition, after Eu4(L1)4 is prepared into a thin film, it exhibits excellent selectivity and sensitivity to formaldehyde gas, with a detection limit as low as 19.4ppb. This achievement not only significantly enhances the application potential of rare earth nanocontainers in the field of optical sensing, but also opens up a new direction for the development of new rare earth metal-organic supramolecular systems with multifunctional properties, and provides important theoretical and practical basis. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 A modular synthetic route to chiral "molecular bowl"-based ligands, with bowl-shaped molecular bridging motifs of different symmetries shown in the boxes.

[0063] Figure 2 This is the general formula for the synthesis of rare earth polyhedral cages.

[0064] Figure 3 This is the synthetic route of the bowl-shaped ligand L1.

[0065] Figure 4 This is the UV-visible absorption spectrum of ligand L1 and Eu4(L1)4.

[0066] Figure 5 The excitation and emission spectra of Eu4(L1)4 in acetonitrile solution, concentration 5×10 -6M; where Ex: excitation spectrum; Em: emission spectrum.

[0067] Figure 6 The fluorescence emission spectra of Eu4(L1)4 films after exposure to different concentrations of formaldehyde.

[0068] Figure 7 This is a graph showing the variation of the fluorescence enhancement efficiency of Eu4(L1)4 film with the formaldehyde vapor concentration, where FA is formaldehyde. DETAILED DESCRIPTION

[0069] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0070] Unless otherwise specified, all chemical reagents and solvents in the examples of the present application are from commercial sources and were not further purified before use.

[0071] Unless otherwise specified, conventional methods were used for testing and instrument settings were those recommended by the manufacturer.

[0072] The analysis method in the examples of this application is as follows:

[0073] The NMR data were tested on the German Bruker Biospin AvancceⅢ400MHz and Japanese Electron ECZ600S600MHz NMR analyzers.

[0074] High-resolution mass spectrometry data were tested on the German ImpactⅡUHR-TOF mass spectrometer. The corresponding data analysis was performed on the German Bruker isotope analysis software (version 4.3).

[0075] Excitation and emission spectra were measured on the FS5 spectrometer in Edinburgh, UK.

[0076] The UV-visible absorption spectrum was tested on a Japan Shimadzu UV-2700 UV-VIS SPECTROPHOTOMETER UV-visible spectrometer.

[0077] like Figure 1 Shown is a modular synthetic route for chiral "molecular bowl" based ligands, with bowl-shaped molecular bridging motifs of different symmetries shown in the boxes.

[0078] like Figure 2 Shown is the general formula for the synthesis of rare earth polyhedral cages.

[0079] Taking the bowl-shaped ligand L1 as an example, the synthetic route is as follows Figure 3 The specific steps are shown in Examples 1 to 10.

[0080] Example 1

[0081] Synthesis of intermediate 1: In a 100mL three-necked flask, 4-methylbenzenesulfonic acid pyridine (0.18g, 0.72mmol, 0.01eq.) and 3,4-dihydro-2H-pyran (25g, 300mmol, 4.2eq.) were added, and m-fluorophenol (8.05g, 72mmol, 1.0eq.) was slowly added dropwise in a nitrogen atmosphere, and the reaction mixture was stirred at room temperature for 0.5 hours. After the reaction was completed, the dihydropyran solvent was removed by rotary evaporation, and the residue was dissolved with ethyl acetate. Subsequently, it was washed with 100mL of saturated sodium bicarbonate solution, 100mL of deionized water and 100mL of saturated brine in sequence, and the solvent was removed by rotary evaporation after drying to obtain a crude product. The crude product was purified by silica gel chromatography with pure petroleum ether (boiling range: 60–90°C) to obtain a colorless liquid, which was obtained by low-temperature freezing. Colorless crystals are obtained, which are the target compound 1 (12.37g, yield 88%).

[0082] 1 H NMR (400MHz, CDCl3, 298K) δ = 7.13 (ddd, J = 15.7, 8.3, 0.8Hz), 6.85–6.73 (m), 6.71–6.55 (m), 5.32 (t ,J=3.2Hz),3.91–3.76(m),3.53(dt,J=11.3,4.0Hz),2.08–1.86(m),1.84–1.72(m),1.69–1.40(m). 13 C NMR (101MHz, CDCl3, 298K) δ = 164.85 (s), 162.42 (s), 158.63 (d, J = 10.8Hz), 130.13 (d, J = 10.0Hz), 112.27 (d, J=2.9Hz),108.22(d,J=21.2Hz),104.13(d,J=24.8Hz),96.46(s),61.86(s),30.27(s),25.23(s),18.69(s). 19 FNMR (376MHz, CDCl3, 298K) δ = -111.66 (dd, J = 17.8, 8.2Hz).

[0083] Example 2

[0084] Synthesis of intermediate 2: Compound 1 (11.92 g, 60 mmol, 1.0 eq.) was dissolved in 160 mL of ultra-dry tetrahydrofuran, and the resulting solution was transferred to a 250 mL three-necked flask via a syringe and cooled to -78 ° C under nitrogen protection. Subsequently, n-butyl lithium reagent (25 mL, 2.5 M, 62.5 mmol, 1.03 eq.) was slowly added dropwise. The reaction was maintained at -78 ° C for 1 hour. Subsequently, phosphorus tribromide (5.4 g, 20 mmol, 0.33 eq.) was slowly added dropwise, and the reaction was continued for 2.5 hours after the addition was completed. After the reaction was completed, the system temperature was slowly raised to room temperature, and about 5 mL of methanol was added to quench the reaction. After the solvent was removed by rotary evaporation, 150 mL of saturated brine was added to the residue, and 150 mL of ether was extracted three times. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, and then the organic solvent was removed by rotary evaporation. The obtained crude product was recrystallized with boiling methanol and then washed with cold methanol to obtain white powdery solid Compound 2 (9.13 g, yield 74%).

[0085] 1 H NMR (400MHz, CDCl3, 298K) δ = 7.23–7.11 (m), 7.01–6.85 (m), 6.71–6.48 (m), 5.47–5.33 (m), 3.91–3.62 (m), 3.52 (d, J = 11.0Hz), 1.90–1.18 (m). 13 C NMR (151MHz, CDCl3, 298K) δ = 96.71 (s), 96.01 (d, J = 14.0Hz), 94.85–94.53 (m), 60.63 (s), 59.97 ( d,J=5.4Hz),52.21(s),28.74(s),28.53(s),23.98(s),17.09(s),16.57(s),16.50(d,J=5.6Hz). 31 P(162MHz,)δ=-72.16(s). 19 F NMR (376MHz, CDCl3, 298K) δ = -102.19 (d, J = 19.0Hz).

[0086] Example 3

[0087] Synthesis of intermediate 3: Compound 2 (7.8 g, 12.6 mmol) was added to a 500 mL single-necked flask, 300 mL of methanol was added and stirred evenly. Under stirring, 16 mL of concentrated hydrochloric acid was slowly added dropwise, and the reaction was continued to stir for 2 hours. During the process, the solution gradually changed from turbid to clear. After the reaction was completed, the methanol solvent was removed by rotary evaporation. Under nitrogen protection, 150 mL of chloroform and 150 mL of saturated sodium bicarbonate solution were added and stirred for 2 hours. After completion, the mixture was separated, the organic phase was collected, and the aqueous phase was extracted twice with 100 mL of ether. All organic phases were combined, dried with anhydrous sodium sulfate, filtered and then rotary evaporated to remove chloroform and ether. The crude product was dissolved in boiling toluene, and then n-heptane was slowly added until a precipitate appeared in the solution. The mixture was placed in a -20 ° C refrigerator and allowed to stand overnight. The precipitate was collected by suction filtration, washed with n-hexane, and finally dried to obtain a white powder solid compound 3 (4.49 g, yield 97%).

[0088] 1 H NMR (400MHz, DMSO-d6, 298K) δ = 9.84 (s, 1H), 7.08 (dd, J = 13.5, 8.0Hz, 1H), 6.53 (dd, J = 7.8, 4.3Hz, 1H), 6.41 (t, J = 8.6Hz, 1H). 19 F (376MHz, DMSO-d6, 298K) δ = -102.84 (d, J = 2.5Hz). 31 P NMR (162MHz, DMSO-d6, 298K) δ = -74.30 (s).

[0089] Example 4

[0090] Synthesis of intermediate 4: Compound 3 (6 g, 16.4 mmol) was added to a 250 mL single-necked flask, and 200 mL of chloroform was added and stirred until the substrate was completely dissolved. Subsequently, 20 mL of 30% hydrogen peroxide was added and the reaction was stirred at room temperature for 15 hours. After the reaction was completed, the mixture was allowed to stand for stratification, the organic phase was collected by separation, and dried over anhydrous sodium sulfate. After filtration, the chloroform was removed by rotary evaporation to obtain a white solid compound 4 (5.9 g, yield 94%).

[0091] 1 H NMR (400MHz, DMSO-d6, 298K) δ = 9.84 (s, 1H), 7.08 (dd, J = 13.5, 8.0Hz, 1H), 6.53 (dd, J = 7.8, 4.3Hz, 1H), 6.41 (t, J = 8.6Hz, 1H). 19 F NMR (376MHz, 298K) δ = -102.24 (s). 31P NMR (162MHz, CDCl3, 298K) δ = 39.44 (s).

[0092] Example 5

[0093] Synthesis of intermediate 5: Compound 4 (5 g, 13.1 mmol, 1.0 eq.) was dissolved in 250 mL of dimethylformamide (DMF), and cesium carbonate powder (17 g, 52.4 mmol, 4.0 eq.) and iodomethane (37.8 g, 16.5 mL, 262 mmol, 20.0 eq.) were added. The reaction vessel was wrapped with tin foil to protect from light and stirred vigorously at room temperature for 15 hours. After the reaction was completed, the DMF solvent was removed by rotary evaporation, 150 mL of ultrapure water was added, and chloroform was used for extraction three times, and the organic phase was combined. The organic phase was washed with saturated brine and dried over anhydrous sodium sulfate. After filtration, the solvent was removed by rotary evaporation to obtain white solid compound 5 (4.7 g, yield 85%).

[0094] 1 H NMR (400MHz, CDCl3, 298K) δ = 7.40–7.29 (m, 1H), 6.71–6.53 (m, 2H), 3.62 (s, 3H). 31 P NMR (162MHz, CDCl3, 298K) δ = 4.19 (s).

[0095] Example 6

[0096] Synthesis of intermediate 6: Compound 5 (4 g, 9.5 mmol, 1.0 eq.) was added to a 250 mL single-necked flask, 150 mL of chloroform was added to dissolve it, reduced iron powder (1.6 g, 28.5 mmol, 3.0 eq.) and liquid bromine (15.6 g, 5 mL, 95 mmol, 10.0 eq.) were added, and the solution became dark brown-red, and tin foil was used for light protection, and stirred at room temperature for 22 hours. After the reaction was completed, an excess of saturated sodium sulfite aqueous solution was added, and stirring was continued for 2 hours, and then the organic phase was separated, and the aqueous phase was extracted with chloroform, and the organic phases were combined, and the solvent was spin-dried after drying with anhydrous sodium sulfate to obtain white solid compound 6 (4.1 g, yield 66%).

[0097] 1 H NMR (400MHz, CDCl3, 298K) δ = 7.64–7.56 (m, 1H), 6.61 (dd, J = 8.8, 5.0Hz, 1H), 3.67 (s, 3H). 31 P NMR (162MHz, CDCl3, 298K) δ = 3.79 (s).

[0098] Example 7

[0099] Synthesis of intermediate 7: Compound 6 (3g, 4.6mmol, 1.0eq.) was dissolved in 150mL chloroform, placed in a 250mL single-necked flask, and a boron tribromide solution (2.5M, 37mL, 92mmol, 20.0eq.) was added dropwise while stirring, and the reaction was stirred at room temperature for 15 hours. After the reaction was completed, the reaction solution was slowly poured into ice water, followed by addition of 100mL of 1M dilute hydrochloric acid, and stirred for 30 minutes to ensure complete reaction. The aqueous phase was extracted three times with dichloromethane, and after the organic phase was combined, the organic layer was dried over anhydrous sodium sulfate, filtered and the solvent was removed by rotary evaporation. Compound 7 (1.9g, 68% yield) was finally obtained as a white solid powder.

[0100] 1 H NMR (400MHz, CDCl3, 298K) δ=9.74 (s, 1H), 7.71–7.56 (m, 1H), 6.75 (dd, J=8.9, 5.3Hz, 1H).

[0101] Example 8

[0102] Synthesis of intermediate 8: Compound 7 (1.9 g, 3.1 mmol, 1.0 eq.) and potassium tert-butoxide (1.4 g, 12.4 mmol, 4.0 eq.) were added to a 250 mL single-necked flask, and 150 mL of DMF was added to dissolve it. The reaction system was heated to 140 ° C and stirred at reflux for 23 hours. After the reaction was completed, the DMF solvent was removed by rotary evaporation. An appropriate amount of chloroform was added to the residue and washed with water several times. After separation, the organic phase was collected, dried over anhydrous sodium sulfate, filtered and then rotary evaporated to remove the chloroform solvent. The crude product was purified by silica gel column chromatography, and the eluent was petroleum ether: dichloromethane (v / v=3 / 2). Finally, a white solid powder compound 8 (1.5 g, yield 88%) was obtained.

[0103] 1 H NMR (400MHz, CDCl3, 298K) δ = 7.79–7.70 (m), 7.29–7.19 (m). 13 C NMR (101MHz, CDCl3, 298K) δ = 157.82 (s), 154.81 (s), 136.26 (s), 116.35 (d, J = 5.7Hz), 110.48 (s), 109.42 (s), 107.09 (d, J = 7.0Hz). 31 P NMR (162MHz, CDCl3, 298K) δ = -49.05 (s).

[0104] Example 9

[0105] Synthesis of intermediate 9: Compound 8 (500 mg, 0.9 mmol, 1.0 eq.), 3-aminophenylboronic acid pinacol ester (790 mg, 3.6 mmol, 4.0 eq.) and tetrakis(triphenylphosphine)palladium (210 mg, 0.18 mmol, 0.2 eq.) were added to a 250 mL three-necked flask. Under nitrogen protection, 160 mL of water and tetrahydrofuran (v / v=1 / 2) mixed solvent was added and stirred until all solids dissolved to form a bright yellow solution. The reaction system was heated to 85°C and maintained at this temperature for 72 hours, and the solution gradually turned orange-yellow. After the reaction was completed, the solvent was removed by rotary evaporation, and dichloromethane was added to the residue to dissolve the solid. The crude product was purified by silica gel column chromatography, and the eluent was dichloromethane: methanol (v / v=20 / 1). After spin drying, a light ochre solid powder compound 9 (520 mg, yield 97%) was obtained.

[0106] 1 H NMR (400MHz, DMSO-d6) δ = 7.56 (d, J = 8.6Hz), 7.31 (dd, J = 8.5, 4.7Hz), 7.07 (t, J = 7.8Hz), 6.74 (s), 6.64 (d, J = 7.6Hz), 6.55 (d, J = 8.0Hz), 5.18 (s). 13 C NMR (101MHz, DMSO-d6) δ = 158.18 (s), 155.37 (s), 149.04 (s), 135.30 (d, J = 8.7Hz), 129.69 (d, J = 5. 1Hz),129.35(s),116.84(s),115.93(d,J=4.9Hz),114.64(s),113.89(s),110.85(s),109.79(s). 31 P NMR (243MHz, DMSO-d6) δ = 46.77 (s).

[0107] High-resolution mass spectrometry characterization of compound 9: [C 36 H 24 N3O4P+Na] 1+ The simulated mass-to-charge ratio value is 616.1397, and the measured mass-to-charge ratio value is 616.1396.

[0108] Example 10

[0109] Synthesis of ligand L1: Compound 9 (300 mg, 0.5 mmol, 1.0 eq.) and compound 10 (525 mg, 1.7 mmol, 3.3 eq.) were added to a single-necked flask, and 100 mL of DMF solvent was added to dissolve. The reaction system was placed in an ice-water bath, cooled to 0°C, HATU (1140 mg, 3.0 mmol, 6.0 eq.) was added, and then triethylamine (2 mL) was added dropwise. The reaction was continued in an ice-water bath for 24 hours under continuous stirring. After the reaction was completed, the DMF solvent was removed by rotary evaporation, the product was extracted with dichloromethane and water, the organic phases were combined and dried over anhydrous sodium sulfate. After dichloromethane was dried, a pale yellow crude product was obtained. The crude product was purified by silica gel column chromatography, and the eluent was methanol: dichloromethane (v / v=1 / 20). After purification, a white powder solid ligand L1 (587 mg, yield 80%) was obtained.

[0110] 1 H NMR (400MHz, CDCl3, 298K) δ = 10.80 (s, 1H), 8.71 (d, J = 8.2Hz, 1H), 8.62 (d, J = 8 .2Hz,1H),8.52(d,J=8.3Hz,1H),8.46(d,J=8.2Hz,2H),8.39(s,1H),7.96(s, 2H),7.81(d,J=7.8Hz,1H),7.68(d,J=8.6Hz,1H),7.58(t,J=7.8Hz,1H),7.43 (t, J=8.7Hz, 2H), 4.41 (dd, J=13.8, 6.8Hz, 1H), 1.40 (dd, J=15.4, 6.5Hz, 5H).

[0111] 13 C NMR (101MHz, CDCl3, 298K) δ = 163.30 (s), 162.04 (s), 159.35 (s), 156.07 (s), 150.21 (s),149.42(s),144.01(s),138.23(s),138.10(s),137.86(s),136.64(s),134.82 (s),130.76(s),130.59(s),129.15(s),128.20(s),127.63(s),125.76(s),121.76 (s),121.48(s),120.39(s),119.07(s),115.74(s),41.75(s),23.01(d,J=6.4Hz).

[0112] 31 P NMR (162MHz, CDCl3, 298K) δ = 47.42 (s).

[0113] High-resolution mass spectrometry characterization of ligand L1: [C 87 H 63 N 12 O 10 P+H] 1+ The simulated value of the mass-to-charge ratio is 1467.4600, and the measured value of the mass-to-charge ratio is 1467.4533; [C 87 H 63 N 12 O 10 P+Na] 1+ The simulated value of the mass-to-charge ratio is 1489.4340, and the measured value of the mass-to-charge ratio is 1489.4420.

[0114] Embodiment 11

[0115] Synthesis of tetrahedral cage Eu4(L1)4: Ligand L1 (2.00 mg, 1.36 μmol) was suspended in 600 μL of a mixed solvent of acetonitrile and methanol (v / v = 2 / 1), followed by the addition of Eu(OTf)3 (0.90 mg, 1.50 μmol). The mixture was stirred at 50°C for about 1 hour. During the reaction, the initially turbid suspension gradually turned into a homogeneous yellow solution.

[0116] Phosphorus spectrum analysis showed quantitative formation of a single compound. 31 P NMR (243MHz, CD3CN / CD3OD v / v=2 / 1)δ=-131.68–-153.57(m).

[0117] Characterization of Eu4L4(OTf) by High Resolution Mass Spectrometry 12 :[Eu4L4(OTf)0-4H] 8+ The simulated mass-to-charge ratio is 809.1837, and the measured mass-to-charge ratio is 809.1628; [Eu4L4(OTf)0-5H] 7+ The simulated mass-to-charge ratio is 924.7808, and the measured mass-to-charge ratio is 924.7561; [Eu4L4(OTf)1-4H] 7+ The simulated mass-to-charge ratio is 946.2036, and the measured mass-to-charge ratio is 946.1788; [Eu4L4(OTf)0-6H] 6+ The simulated value of the mass-to-charge ratio is 1078.5758, and the measured value is 1078.5477; [Eu4L4(OTf)1-5H] 6+ The simulated value of the mass-to-charge ratio is 1103.5691, and the measured value is 1103.5402; [Eu4L4(OTf)2-4H] 6+The simulated value of the mass-to-charge ratio is 1128.5623, and the measured value is 1128.5333; [Eu4L4(OTf)3-3H] 6+ The simulated value of the mass-to-charge ratio is 1153.5556, and the measured value is 1153.5262; [Eu4L4(OTf)0-7H] 5+ The simulated mass-to-charge ratio is 1294.2892, and the measured mass-to-charge ratio is 1294.2555; [Eu4L4(OTf)1-6H] 5+ The simulated mass-to-charge ratio is 1324.2827, and the measured mass-to-charge ratio is 1324.2477; [Eu4L4(OTf)2-5H] 5+ The simulated value of mass-to-charge ratio is 1354.2737, and the measured value is 1354.2342; [Eu4L4(OTf)3-4H] 5+ The simulated value of the mass-to-charge ratio is 1354.2651, and the measured value is 1354.2297; [Eu4L4(OTf)4-3H] 5+ The simulated value of the mass-to-charge ratio is 1414.2575, and the measured value is 1414.2208; [Eu4L4(OTf)0-8H] 4+ The simulated value of the mass-to-charge ratio is 1617.3597, and the measured value is 1617.3178; [Eu4L4(OTf)1-7H] 4+ The simulated value of the mass-to-charge ratio is 1654.8500, and the measured value is 1654.8046; [Eu4L4(OTf)2-6H] 4+ The simulated value of mass-to-charge ratio is 1692.3386, and the measured value is 1692.2949; [Eu4L4(OTf)3-5H] 4+ The simulated value of mass-to-charge ratio is 1729.8298, and the measured value is 1729.7842; [Eu4L4(OTf)4-4H] 4+ The simulated value of mass-to-charge ratio is 1767.3197, and the measured value is 1767.2756; [Eu4L4(OTf)5-3H] 4+ The simulated value of the mass-to-charge ratio is 1804.8090, and the measured value of the mass-to-charge ratio is 1804.7627.

[0118] Photophysical properties of Eu4(L1)4

[0119] The UV-visible absorption spectra of ligand L1 and Eu4(L1)4 were tested, such as Figure 4 As shown, the maximum absorption wavelength of ligand L1 is 350nm, and the corresponding molar absorption coefficient is 1.8×104M -1 cm -1In contrast, the maximum absorption wavelength of the assembled Eu4(L1)4 is located at 330nm, showing a 20nm blue shift. Under 330nm light excitation, Eu4(L1)4 exhibits Eu in both solution and solid phase. 3+ The characteristic red fluorescence of the ion corresponds to 5 D0→ 7 F J (J = 0–4) transition (see Figure 5 In addition, the photoluminescence quantum yield of Eu4(L1)4 in acetonitrile solution (φ=1.1%) is significantly lower than that in the solid phase (φ=13.0%), which indicates that the solvent molecules may interact with Eu4(L1)4 in the solution. 3+ The potential coordination of the center causes Eu 3+ Vibrational quenching effect of emission.

[0120] Formaldehyde fluorescence sensor

[0121] Preparation of thin film: First, Eu4(L1)4 solution (CH3NO2 / CH3OH, volume ratio 2:1, concentration 5 mM) was spin-coated at 3000 rpm for 60 seconds using a KW-4A desktop spin coater to prepare a Eu4(L1)4 thin film on a quartz wafer.

[0122] Preparation of the gas to be tested: Organic vapor of a certain concentration can be prepared by diluting saturated vapor with nitrogen. The specific operation is: Place the organic liquid in a Schlenk round-bottom flask at 20°C and evaporate overnight, then dilute with nitrogen through a syringe to obtain organic vapor of different concentrations. Since formaldehyde is gaseous at room temperature, its vapor can be released by the self-decomposition of trioxymethylene solid.

[0123] After exposing the Eu4(L1)4 film to formaldehyde vapor of different concentrations, it was observed that formaldehyde can significantly enhance the fluorescence emission intensity of the film. In order to quantitatively describe the relationship between the fluorescence enhancement effect and the concentration of volatile aldehydes, we measured the emission intensity change at 612nm after the Eu4(L1)4 film was exposed to formaldehyde vapor at 20℃. The results show that with the increase of formaldehyde concentration, the fluorescence emission intensity of the Eu4(L1)4 film shows a trend of gradual enhancement, such as Figure 6 As shown in Figure 2, the film's response to formaldehyde is particularly significant. 3 ppm, its fluorescence emission intensity increased by 1.7 times. In addition, the relationship between the fluorescence enhancement efficiency (I / I0-1) of the film and the formaldehyde concentration is shown in the figure. Based on the detection capability of a well-calibrated photodetector for an intensity change of 0.1%, the standard curve fitting analysis shows that Figure 7As shown in the figure, the formaldehyde detection limit of Eu4(L1)4 film is as low as about 19.4ppb. This detection limit is significantly lower than the concentration limit (80ppb) of formaldehyde that humans can be exposed to sustainably as stipulated by the World Health Organization (WHO).

[0124] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A molecular bowl-shaped compound, characterized in that: The molecular bowl-shaped compound has the structural formula shown in the following formula (I), formula (II), and formula (III): Wherein, when the molecular bowl-shaped compound is a structural formula shown in formula (I), At least one selected from the following structural formulas: When the molecular bowl-shaped compound is of the structural formula shown in formula (II), Selected from the following structural formula: When the molecular bowl-shaped compound is of the structural formula shown in formula (III), At least one selected from the following structural formulas:

2. The method for preparing the molecular bowl-shaped compound according to claim 1, characterized in that: The preparation method comprises: reacting a mixture containing compound A, compound B, HATU, a catalyst, and a solvent to obtain the molecular bowl-shaped compound; Wherein, the structural formula of compound B is: Wherein, when the molecular bowl-shaped compound is a structural formula shown in formula (I), compound A is selected from at least one of the structural formulas shown below: Wherein, when the molecular bowl-shaped compound is a structural formula shown in formula (II), compound A is selected from the structural formula shown below: Wherein, when the molecular bowl-shaped compound is a structural formula shown in formula (III), compound A is selected from the structural formula shown below:

3. The preparation method according to claim 2, characterized in that: The molar ratio of compound A to compound B is 1:3.0-5.0; Preferably, the molar ratio of compound A to HATU is 1:4.0-8.0; Preferably, the usage ratio of compound A and catalyst is 1 mmol: 1.5 mL to 4.5 mL; Preferably, the usage ratio of compound A to solvent is 1 mmol: 180 mL to 230 mL.

4. The preparation method according to claim 2, characterized in that: The catalyst is selected from at least one of triethylamine, trimethylamine and tripropylamine; The solvent is selected from at least one of dimethylformamide, dimethyl sulfoxide and dimethylacetamide.

5. The preparation method according to claim 2, characterized in that: The reaction conditions are: reacting in an ice water bath environment for 16 to 36 hours; Preferably, after the reaction is completed, the steps of separation, drying and purification are also included.

6. A lanthanide organic polyhedral cage, characterized in that: The chemical formula of the lanthanide organic polyhedral cage is Ln4(Lig)4(OTf) 12 ; Among them, Ln4(Lig)4 has a tetrahedral configuration as shown below: Among them, Ln represents the lanthanide rare earth element; Lig represents a ligand, which is a molecular bowl-shaped compound represented by formula (I) in claim 1.

7. The lanthanide organic polyhedral cage according to claim 6, characterized in that: The lanthanide rare earth element is selected from at least one of Eu, La, Tb, Sm and Nd.

8. The method for preparing the lanthanide organic polyhedral cage according to claim 6, characterized in that: The preparation method comprises: reacting a mixture containing ligand Lig, Ln(OTf)3, and a solvent to obtain the lanthanide organic polyhedral cage; Wherein, the ligand Lig is a molecular bowl-shaped compound represented by formula (I) in claim 1.

9. The preparation method according to claim 2, characterized in that: The molar ratio of the ligand Lig and Ln(OTf)3 is 1:1.0-1.3; Preferably, the usage ratio of ligand Lig and solvent is 1 μmol: 400 μL to 600 μL; Preferably, the solvent is a mixed solvent of acetonitrile and methanol; Preferably, the reaction conditions are: stirring at 40-60° C. for 1.0-4.0 hours.

10. Application of the lanthanide organic polyhedral cage according to claim 6 in the field of optical sensing; Preferably, the lanthanide organic polyhedron cage is used in formaldehyde detection.

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