A host-guest interaction-mediated dual-state luminescent material and preparation method thereof

Abstract

The present invention discloses a dual-state luminescent material mediated by host-guest interaction and a preparation method thereof. Dual-state luminescence refers to the material being able to photoluminesce in both solution and solid states. The present invention designs and synthesizes a tetraphenylethylene-bridged biphenylpyridinium salt guest G. Due to its structural rigidity, it can combine with CB[8] in a "dual host, dual guest" mode. This combination gives the host-guest complex a special luminescence mechanism, which enables it to have strong fluorescence in both solution and solid states. The supramolecular dual-state luminescent material provided by the present invention has the following advantages: simple preparation and modular synthesis; the luminophore is a host-guest complex that can be dynamically controlled; the material has a wide range of luminescent states and can emit light in aggregated states such as dilute solution, concentrated solution, solid state and crystalline state, and is green and environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of organic photoluminescent materials, and in particular to a dual-state luminescent material mediated by host-guest interaction and a preparation method thereof. Background Art

[0002] In 2021, Braulio Rodríguez-Molina et al. published a perspective article in Matter magazine titled "One molecule to light it all: The era of dual-state emission" (Matter 2021, 4, 2622-2624.), arguing that the "era of dual-state emission" has arrived. People call such molecules that can emit light both in dilute solution and in the aggregated state dual-state emission (DSE) molecules. Traditional organic fluorescent molecules are either aggregation-caused quenching (ACQ) type, such as fluorescein, pyrene, naphthalene / perylene imide derivatives, etc., or aggregation-induced emission (AIE) type, such as hexaphenylthiophene, tetraphenylethylene, cyanostyrene derivatives, etc. These two types of fluorophores have their own advantages and disadvantages. ACQ-type molecules emit efficiently only in dilute solutions; once aggregated, their fluorescence is quenched by π-π stacking. AIE-type molecules emit only in aggregated states and lack fluorescence in dilute solutions. Therefore, the question arises of whether it is possible to create organic compounds that can emit light both in dilute solutions and in aggregated states. Over the past decade, scientists have developed a series of DSE molecules through meticulous design.

[0003] However, to balance the conjugation effect, rigidity, push-pull electron effects, and distorted conformations of organic molecules to promote dual-state luminescence, previously designed DSE molecules are often complex and difficult to synthesize. Furthermore, their preparation methods are not universal and cannot be generalized. Furthermore, these molecules often lack responsive groups and cannot respond to environmental stimuli. Furthermore, these organic molecules are often poorly soluble in water, making them inaccessible for biological applications. These shortcomings significantly limit the application of current DSE materials. Therefore, designing dynamic DSE materials with simple structures, modular customizable synthesis, and universal construction methods is a key scientific issue that urgently needs to be addressed. Summary of the Invention

[0004] In response to the above technical problems, the present invention provides a CB[8]-mediated dual-state luminescent material and a preparation method thereof.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A dual-state luminescent material mediated by host-guest interaction, wherein the dual-state luminescent material uses CB[8] as the host and a tetraphenylethylene derivative G as the guest, and self-assembles in aqueous solution to form a complex G-CB[8] with dual-state luminescent properties.

[0007] Preferably, the chemical structure of the tetraphenylethylene derivative G is as shown in Formula I:

[0008]

[0009] The structure of CB[8] is shown in Formula II:

[0010]

[0011] Preferably, the tetraphenylethylene derivative G is a trans isomer.

[0012] Preferably, the complexation ratio of CB[8] and the tetraphenylethylene derivative G is 1:1.

[0013] Preferably, the host-guest binding mode of the complex G-CB[8] is a double-host-double-guest type, and the complex G-CB[8] contains two molecules of tetraphenylethylene derivative G and two molecules of CB[8].

[0014] Preferably, in the aqueous solution, the concentrations of the tetraphenylethylene derivative G and CB[8] are both 0-1 mM.

[0015] Preferably, the luminescence of the complex G-CB[8] originates at the molecular level, resulting in the complex G-CB[8] being able to emit light both in solution and in the solid state.

[0016] Preferably, the dual-state luminescent material has a competitive guest stimulus response: when a competitive guest is added to the complex G-CB[8], the fluorescence of the dual-state luminescent material is quenched, and the competitive guest includes dimethyladamantaneamine.

[0017] Preferably, the dual-state luminescent material has a light stimulus response: when the complex G-CB[8] is irradiated with light, the tetraphenylethylene derivative G is converted into a cis isomer, and the fluorescence of the dual-state luminescent material is weakened.

[0018] The present invention also provides a method for preparing a dual-state luminescent material mediated by host-guest interaction, comprising the following steps:

[0019] (1) Synthesis of tetraphenylethylene derivative G:

[0020]

[0021] As shown in Formula III, compound 1a and 2,4-dinitrochlorobenzene are heated under reflux at 80-90°C in anhydrous acetonitrile at a molar ratio of 1:(2-4) for 72 hours. After the reaction is completed, the mixture is filtered, and the residue is washed with dichloromethane and dried to obtain compound 1b.

[0022] Under nitrogen atmosphere, compound 1b and p-methylaniline were mixed in an 80% EtOH solution at a molar ratio of 1:(2-4), heated to 80-90°C and refluxed, stirred for 72 h. After the reaction was complete, the solvent was removed by rotary evaporation to obtain a crude solid product, which was washed with acetone and ether and dried to obtain tetraphenylethylene derivative G.

[0023] (2) Synthesis of complex G-CB[8]:

[0024] Tetraphenylethylene derivative G and CB[8] were dissolved in water at a molar ratio of 1:1, and liquid complex G-CB[8] was obtained by ultrasonication. Solid complex G-CB[8] was obtained by evaporating the water.

[0025] Compared with the prior art, the dual-state luminescent material provided by the present invention has the following advantages:

[0026] (1) In the past, in order to achieve dual-state luminescence of organic molecules, it was necessary to reconcile multiple factors such as the conjugation effect, rigidity, push-pull electron effect, and twisted conformation of the organic molecule structure to promote its dual-state luminescence. The designed molecules are often complex in structure and difficult to synthesize. The present invention simplifies the complexities and does not need to consider the above complex factors. It only needs to synthesize a simple guest molecule G and use the supramolecular host to regulate self-assembly to form a "double host and double guest" complex G-CB[8] to achieve dual-state luminescence (strong fluorescence luminescence in aggregated states such as dilute solution, concentrated solution, solid state and crystalline state).

[0027] (2) The host-guest dual-state luminescent material of the present invention has stable properties and can still maintain an efficient luminescent state after being placed for one year.

[0028] (3) The driving force of the host-guest dual-state luminescent material of the present invention is a reversible supramolecular force, so the luminescence characteristics have dynamically adjustable behaviors, such as competitive guest response and light response.

[0029] (4) Most of the dual-state luminescent molecules reported in the past are organic molecules that are difficult to dissolve in water. The dual-state luminescent material of the present invention is soluble in water and has strong luminescence in aqueous solution, and has great potential in biological applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present invention and, together with the description, serve to explain the principles of the invention, in which:

[0031] Figure 1Schematic diagram of the supramolecular self-assembly of guest G with CB[7] and CB[8] respectively.

[0032] Figure 2 This is the NMR titration diagram of guest G and CB[8].

[0033] Figure 3 Isothermal calorimetric titration diagram of guest G and CB[8].

[0034] Figure 4 This is the high-resolution mass spectrum of the complex formed by guest G and CB[8].

[0035] Figure 5 Fluorescence spectra of aqueous solutions of guests G, G-CB[7] and G-CB[8].

[0036] Figure 6 (a) is the solid (needle-shaped crystal) fluorescence spectrum of G-CB[8], and (b) is the solid fluorescence photograph of G-CB[8].

[0037] Figure 7 (a) shows the fluorescence spectrum change of G-CB[8] before and after adding dimethyladamantane, and (b) shows the fluorescence spectrum change of G-CB[8] over time under 420 nm wavelength light. DETAILED DESCRIPTION

[0038] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and configurations of specific examples are described below. Of course, these are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or configurations discussed.

[0039] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are all conventional methods in the art.

[0040] Compound 1a was prepared according to the literature “Zhao, SS; Wang, L.; Liu, Y.; Chen, L.; Xie, Z., Stereochemically Dependent Synthesis of Two Cu(I) Cluster-Based Coordination Polymers with Thermochromic Luminescence. Inorg. Chem. 2017, 56, 13975-13981.” Cucurbituril CB[8] was prepared according to the literature “Bardelang, D.; Udachin, KA; Leek, DM; Margeson, JC; Chan, G.; Ratcliffe, CI; Ripmeester, JA, Cucurbit[n]urils (n=5–8): A Comprehensive Solid State Study. Cryst. Growth Des. 2011, 11, 5598-5614.”

[0041] A large tetraphenylethylene group (TPE, a typical AIE group) is embedded in the middle of a biphenylpyridinium salt to prepare a guest molecule G. Then, a host-guest complex is formed by a "double host, double guest" complex with a CB[8] host. The two CB[8] macrocycles act like coils to firmly "bind" the two guest molecules G, causing the two TPE groups in the two guest molecules G to be very tightly squeezed together. This greatly restricts the intramolecular motion of the two TPE groups, and the excitation energy cannot relax through non-radiation, thereby exhibiting strong fluorescence. This fluorescence mechanism originates at the molecular level. Although the guest molecule G itself is almost non-luminescent, it can produce a special "double host, double guest" complex by utilizing the CB[8] host, thereby emitting strong light. The luminescence is based on the interaction between these four microscopic molecules and originates from the interaction of several molecules. This interaction is based on the level of several molecular levels. Therefore, the host-guest complex has strong luminescence characteristics regardless of whether it is in a dilute state (solution) or an aggregated state (solid state), making it an excellent dual-state luminescent material. In contrast, the "double host, single guest" type complex formed by the guest molecule G itself or the guest molecule G and CB[7] shows very weak fluorescence in solution due to the lack of this intramolecular motion restriction mechanism. The schematic diagram of the "double host, double guest" type supramolecular complex formed by the guest molecule G and CB[8] is shown in the attached figure. Figure 1 As shown, the structural formula of the complex G-CB[8] is shown in Formula V and Formula VI:

[0042]

[0043] Wherein, the chemical structure of the guest molecule G is shown in Formula I:

[0044]

[0045] The chemical structure of compound CB[8] is shown in Formula II:

[0046]

[0047] In the technical solution of the present invention, in the dual-state luminescent system, the guest molecule G and the compound CB[8] form a 1:1 complexed "double host double guest" type complex through host-guest interaction.

[0048] The guest molecule G has cis-trans isomers. The guest molecule G provided by the present invention is the trans isomer. After the cis isomer and CB[8] undergo a 1:1 complexation, the fluorescence intensity is poor due to the steric effect. The structures of the cis-trans isomers are as follows:

[0049]

[0050] The synthesis of guest molecule G is as follows:

[0051]

[0052] Compound 1a was synthesized according to the reference (Inorganic Chemistry 2017, 56, 13975-13981). Compound 1a and 2,4-dinitrochlorobenzene were heated to reflux in anhydrous acetonitrile at a molar ratio of 1:3.5. After the reaction, the mixture was filtered, the residue washed with dichloromethane, and dried to obtain compound 1b. Under a nitrogen atmosphere, compound 1b, p-methylaniline, and 80% EtOH solution were added to a reaction vessel. The temperature was raised to reflux and stirred for 72 hours. Upon completion of the reaction, stirring was stopped and the solvent was removed by rotary evaporation to obtain a crude solid product. The solid was then washed with acetone and diethyl ether and dried to obtain guest molecule G.

[0053] The guest molecule G and CB[8] can be complexed in a "double host and double guest" mode in aqueous solution. The NMR titration experiment shows that the NMR spectrum of the guest molecule G with 0.5 equivalent CB[8] is relatively "chaotic", while it can form a set of regular peaks with 1 equivalent CB[8], and the aryl pyridinium salt part shifts to the high field due to the host-guest interaction, as shown in the attached Figure 2 As shown in the figure, it shows that the optimal complexation ratio of guest molecule G and CB[8] is 1:1. Isothermal titration calorimetry experiments further determined that the binding ratio is 1:1, as shown in the attached figure. Figure 3 High-resolution mass spectrometry experiments show that the host-guest complex provided by the present invention carries four positive charges, and the mass-to-charge ratio is consistent with the calculated value, as shown in the attached Figure 4 The above laboratory confirmed the “double host double guest” binding mode between the guest molecule G and CB[8].

[0054] Example

[0055] ① Preparation of compound 1b:

[0056] Under nitrogen protection, compound 1a (200 mg, 0.41 mmol, 1.0 eq), 2,4-dinitrochlorobenzene (291 mg, 1.43 mmol, 3.5 eq), and anhydrous acetonitrile (25 mL) were added to a 100 mL three-necked flask and heated to reflux for 72 h. After completion of the reaction, the solvent was removed by swirl to obtain a crude orange-red solid. DCM (40 mL) was added to the crude product, ultrasonically washed for 2 h, and filtered to obtain compound 1b (230 mg, 0.28 mmol) in a 68% yield. 1 H NMR (300MHz, DMSO-d6): δ (ppm) = 9.35 (d, J = 6.9Hz, 4H, PyH), 9.14 (d, J = 2.7Hz, 2H, PhH), 8.98 (dd, J = 8.7Hz, J = 2.4Hz, 2H, PyH), 8. 76(d,J=7.5Hz,4H,PyH),8.41(d,J=8.7Hz,2H,PhH),8.12(d,J=8.7Hz,4H,PhH),7.34-7.25(m,10H,PhH),7.16-7.14(m,4H,PhH), 13 C NMR (75MHz, DMSO-d6): δ (ppm) = 156.7, 149.5, 148.4, 146.2, 143.7, 142.5, 141.7, 139.0, 132.7, 131.5, 130.7, 128.8, 128.0, 124.1, 121.9.

[0057] ② Preparation of compound G:

[0058] Compound 1b (100 mg, 0.12 mmol, 1.0 eq) and p-methylaniline (32 mg, 0.3 mmol, 2.5 eq) were added to a 50 mL three-necked flask. Anhydrous ethanol (12 mL) and distilled water (3 mL) were added and refluxed for 72 h. After completion of the reaction, the mixture was filtered, the filtrate collected, and the solvent was removed in vacuo to obtain a crude solid product. 100 mL of acetone was added to the crude product residue, ultrasonically washed for 2 h, and filtered to obtain Compound G (50 mg, 0.07 mmol) as a yellow solid in a 58% yield. 1H NMR (400MHz, D2O, 298.15K): δ (ppm) = 8.91 (d, J = 5.8Hz, 4H), 8.29 (d, J = 7.6Hz, 4H), 7.76 (d, J = 8.1Hz, 4H ),7.54(d,J=8.2Hz,4H),7.47(d,J=6.3Hz,4H),7.35(d,J=9.0Hz,4H),7.23-7.13(m,10H),2.4(s,6H). 13 C NMR (100MHz, D2O, 298.15K): δ (ppm) = 147.76, 143.71, 142.65, 142.31, 141.54, 139.89, 13 2.47,132.36,131.80,131.27,130.83,128.21,127.61,127.36,124.40,123.50,20.24.HR ESI-MS for[TPEV-2Cl] 2+ :calc.m / z=334.1590, found m / z=334.1585.

[0059] ③ Preparation of dual-state luminescent host-guest complex G-CB[8]:

[0060] The guest molecules G and CB[7] were dissolved in water at a molar ratio of 1:2, i.e., CB[7] = 4 × 10 -5 mol / L, G=2×10 -5 mol / L, ultrasonically for 30 minutes, to prepare a G-CB[7] aqueous solution. Figure 5 It can be seen that the aqueous solution of guest molecule G has almost no fluorescence emission under ultraviolet light (excitation wavelength = 365nm), and the fluorescence intensity of the aqueous solution of G-CB[7] is also very low.

[0061] The guest molecules G and CB[8] were dissolved in water at a molar ratio of 1:1, and the concentration was controlled not to exceed 1 mM (the concentration was 2×10 -5 mol / L) and ultrasonically treated for 30 minutes to prepare a dual-state luminescent aqueous solution of G-CB[8]. The solid powder of G-CB[8] was obtained by evaporating the water. The solution-state luminescent spectrum of G-CB[8] is shown in the attached figure. Figure 5 As shown, G-CB[8] in aqueous solution exhibits strong fluorescence emission compared to the guest molecule G or G-CB[7]. Compared to the guest molecule G itself, the fluorescence intensity of G-CB[8] increases 30 times.

[0062] The complex G-CB[8] formed by the guest molecule G and CB[8] in aqueous solution also has strong luminescence after the water evaporates and the solid powder is dried. Figure 6b; the needle-shaped crystals formed by the guest molecule G and CB[8] also have strong fluorescence, as shown in the attached Figure 6 In summary, the G-CB[8] developed in the present invention has excellent dual-state luminescence properties and can be applied in the fields of chemical sensing, organic light-emitting diodes, etc.

[0063] Furthermore, the G-CB[8] prepared by the present invention also has dual stimulus responsiveness. One is that when a competitive guest such as 3,5-dimethyladamantaneamine (DMADA) is added, since DMADA has a higher complexation constant with CB[8] and its competitive ability is stronger than that of the guest molecule G, the guest molecule G can be dissociated from G-CB[8], thereby destroying the dual host and dual guest binding mode, resulting in fluorescence quenching, and realizing the competitive guest stimulus response of G-CB[8]. For example, Figure 7 As shown in a, G-CB[8](2×10 -5 When 1.1 equivalents of DMADA were added to a solution of 1.5 mol / L, the fluorescence intensity decreased by about 20 times.

[0064] Another method is to irradiate G-CB[8] with ultraviolet light, so that the guest molecule G is transformed into a cis isomer. Although a double host and double guest complex is still formed, the fluorescence intensity of the complex formed by the cis isomer of the guest molecule G and CB[8] is poor due to the steric effect, thus achieving the ultraviolet light stimulation response of G-CB[8]. Figure 7 As shown in b, the G-CB[8] (2×10 -5 mol / L) solution, under 420nm wavelength light, the fluorescence intensity gradually decreased and approached equilibrium after 120 minutes.

[0065] Other embodiments of the present invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the invention and include common knowledge or customary techniques in the art. The description and examples are to be considered as exemplary only, with the true scope and spirit of the invention being indicated by the claims.

[0066] It should be understood that the present invention is not limited to the exact construction described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A dual-state luminescent material mediated by host-guest interaction, characterized in that: The dual-state luminescent material uses CB[8] as a host and a tetraphenylethylene derivative G as a guest, and self-assembles in an aqueous solution to form a complex G-CB[8] having dual-state luminescent properties; The tetraphenylethylene derivative G is a trans isomer, and the chemical structure of the tetraphenylethylene derivative G is as shown in Formula I: The structure of CB[8] is as shown in Formula II: The host-guest binding mode of the complex G-CB[8] is a dual-host-dual-guest type, and the complex G-CB[8] contains two molecules of the tetraphenylethylene derivative G and two molecules of the CB[8]. The structural formula of the complex G-CB[8] is as shown in Formula V and Formula VI:

2. The host-guest interaction-mediated dual-state luminescent material according to claim 1, characterized in that: The complexation ratio of the CB[8] and the tetraphenylethylene derivative G is 1:

1.

3. The host-guest interaction-mediated dual-state luminescent material according to claim 1, characterized in that: In the aqueous solution, the concentrations of the tetraphenylethylene derivative G and the CB[8] are both 0 to 1 mM.

4. The host-guest interaction-mediated dual-state luminescent material according to claim 1, characterized in that: The luminescence of the complex G-CB[8] originates at the molecular level, resulting in the complex G-CB[8] being able to emit light both in solution and in the solid state.

5. The host-guest interaction-mediated dual-state luminescent material according to claim 1, characterized in that: The dual-state luminescent material has a competitive guest stimulus response: when a competitive guest is added to the complex G-CB[8], the fluorescence of the dual-state luminescent material is quenched, and the competitive guest includes dimethyladamantaneamine.

6. The host-guest interaction-mediated dual-state luminescent material according to claim 1, characterized in that: The dual-state luminescent material has a light stimulation response: when the complex G-CB[8] is irradiated with light, the tetraphenylethylene derivative G is converted into a cis isomer, and the fluorescence of the dual-state luminescent material is weakened.

7. The method for preparing a host-guest interaction-mediated dual-state luminescent material according to any one of claims 1 to 6, characterized in that: The steps include: (1) Synthesis of tetraphenylethylene derivative G: As shown in Formula III, compound 1a and 2,4-dinitrochlorobenzene are heated under reflux at 80-90°C in anhydrous acetonitrile at a molar ratio of 1:(2-4) for 72 hours. After the reaction is completed, the mixture is filtered, and the residue is washed with dichloromethane and dried to obtain compound 1b. Under nitrogen atmosphere, the compound 1b and p-methylaniline were mixed in an 80% EtOH solution at a molar ratio of 1:(2-4), heated to 80-90°C and refluxed, and stirred for 72 hours. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a crude solid product, which was washed with acetone and ether and dried to obtain the tetraphenylethylene derivative G. (2) Synthesis of complex G-CB[8]: The tetraphenylethylene derivative G and the CB[8] are dissolved in water in a molar ratio of 1:1, and the liquid complex G-CB[8] is obtained by ultrasonication. The solid complex G-CB[8] is obtained by evaporating the water.

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