Circularly polarized luminescent material based on ag6 cluster pair enantioselective light harvesting system and preparation method and application thereof

Abstract

The application belongs to the cross field of supramolecular chemistry and inorganic nanomaterials, discloses a circularly polarized luminescent material based on Ag6 cluster pair enantioselective light trapping system and a preparation method and application thereof. The application firstly self-assembles chiral binaphthyl derivatives into helical nanofibers as chiral / energy donors. Chiral Ag6 clusters are used as chiral / energy acceptors. By introducing chiral Ag6 clusters into the hatching stock solution of the nanofiber of the donor, after co-assembly, a chiral light trapping system based on Ag6 clusters is constructed. Through strong intermolecular interaction and chiral matching between the donor and the acceptor, obvious chiral / energy transfer occurs between the donor and the acceptor, which significantly improves the circularly polarized luminescence value of the cluster g lum The application can realize the construction of a high g lum value hybrid circularly polarized luminescent material based on the cluster through enantioselective co-assembly of the donor and the acceptor, and obtain a high g lum value white light circularly polarized luminescent material. By regulating the fluorescence and circularly polarized luminescence of the homochiral light trapping system, the application can be used for advanced three-dimensional information encryption.

Description

TECHNICAL FIELD

[0001] The present application belongs to the cross field of supramolecular chemistry and inorganic nanomaterials, and mainly relates to a circularly polarized luminescent material based on an Ag6 cluster enantioselective light harvesting system and a preparation method and application thereof. BACKGROUND

[0002] In nature, proteins and enzymes distinguish themselves from their mirror images through enantioselective recognition. This is crucial for a comprehensive understanding of the origin of biological homochirality. Inspired by biomolecules in nature, people explore two key biological processes in artificial supramolecular assembly systems, namely enantioselective recognition and energy transfer. Exploration of these artificial systems helps better understand the hierarchical evolution of chirality. Circularly polarized luminescence (CPL) is an indicator of chiral optical information in the excited state of matter. CPL materials have great potential in practical applications, including three-dimensional display, information encryption, and circularly polarized organic light-emitting diodes, etc. In addition, it also provides a method for monitoring the transfer of excited state chirality and energy transfer. Ligand-protected atomically precise chiral metal clusters can explore the relationship between structure and chiral optical properties at the atomic level and reveal the origin of nanoscale chirality. Although a considerable number of cluster materials with CPL activity have been obtained, these ultra-small chiral metal clusters still face the challenges of low asymmetric factor (g lum ) values and difficulty in achieving enantioselectivity. Chiral light harvesting with resonance energy transfer (FRET) involves the remote migration of excitation energy. Recently, a chiral light harvesting system based on nanofibers has been shown to have the effect of enantioselectively sensitizing CPL performance, which largely depends on the chiral compatibility between the chiral donor and acceptor. Complex helical superstructures can enhance each other's chiral signals and promote efficient energy transfer between the donor and the acceptor. Therefore, realizing a cluster-based chiral light harvesting system that enantioselectively promotes chiral / energy transfer and improves g lum and quantum yield (QY) can solve the challenges of enantioselectivity and low g lum of cluster assemblies. SUMMARY

[0003] To improve the circularly polarized luminescence performance of chiral metal cluster assemblies, the present application aims to provide a circularly polarized luminescent material based on an Ag6 cluster enantioselective light harvesting system, and to provide a method for constructing an enantioselective light harvesting system for clusters.

[0004] To achieve the purpose of the present application, the present application enhances the CPL signal of metal clusters based on the principles of energy transfer between clusters-supramolecules and chiral matching. The specific technical solutions are as follows:

[0005] Firstly, the application synthesizes a pair of chiral binaphthyl donors (abbreviated as: R / S-BPOA) emitting blue light based on a cluster-based enantioselective light trapping system, which is obtained by nucleophilic substitution reaction of the compound shown in formula I with binaphthol.

[0006] It has a molecular formula shown in formula II, and its solution state has almost no CPL signal, however, by self-assembly, it emits strong supramolecular helix CPL signal, g lum The value is 0.0037.

[0007]

[0008] R is C 2-20 alkyl.

[0009] Then, a chiral, energy acceptor Ag6 cluster emitting yellow light is synthesized, and the synthesis method is as follows:

[0010] The organic ligand in formula III and AgNO3 are dissolved in a mixed solution of N,N-dimethylacetamide and acetonitrile, and a yellow clear solution is obtained by stirring, and yellow block crystals of chiral nanosilver clusters are obtained by slow evaporation at room temperature, which is the structure in formula IV (for specific properties and synthesis method, see patent CN 110330513 B). The chemical formula of the chiral nanosilver cluster is: C 54 H 48 Ag6N6S 12 (abbreviated as: Ag6PL6 / PD6), which belongs to a monoclinic system, and the space group is a chiral space group P213,

[0011] Wherein, PL / PD is (S / R)-4-phenylthiazolidine-2-thione, and the structural formula is as follows:

[0012]

[0013] Finally, the application uses R / S-BPOA emitting blue light as a chiral, energy donor, and Ag6 cluster emitting yellow light as a chiral, energy acceptor, and performs self-assembly to obtain a circularly polarized luminescent material.

[0014] The assembly method of the circularly polarized luminescent material is as follows:

[0015] (1) Dissolve the chiral binaphthyl R / S-BPOA emitting blue light shown in formula II in an organic system, incubate at room temperature, and obtain the nanofiber material of the chiral, energy donor by interfacial self-assembly; the organic system is a system formed by mixing dichloroethane and methylcyclohexane, and the volume ratio of the methylcyclohexane is 40-60%, preferably 50%. The molar concentration of the chiral binaphthyl long chain R / S-BPOA is 0.05-0.3 mM, preferably 0.1 mM.

[0016] (2) The above solution is added with a solution of a good solvent of a Ag6 cluster shown in formula IV which is homochiral or heterochiral with the donor, and is again co-incubated to prepare a supramolecular co-assembly by interfacial assembly. The good solvent is dichloromethane, trichloromethane or dichloroethane, and dichloroethane with a higher boiling point is preferred. The molar concentration of the Ag6 cluster is 1-30 μM, and 10 μM is preferred. The incubation time can be from 4 to 96 hours, and 24 hours is preferred.

[0017] The present application uses a large spectral overlap between the donor and the acceptor and excellent chiral matching to construct an artificial light harvesting system. The system has enantioselectivity, wherein the energy transfer efficiency of the homochiral light harvesting system is greater than that of the heterochiral one; more importantly, the homochiral light harvesting system has excellent circularly polarized energy transfer behavior, greatly amplifying the circularly polarized luminescence g lum value of the cluster.

[0018] Figure 8 As shown in the figure, due to the chiral, large spectral overlap area between the energy donor and the acceptor, there is obvious energy transfer between the homochiral donor and the acceptor. After interfacial assembly and annealing of the co-assembly stock solution, the circularly polarized luminescence performance of the cluster is enhanced, and the g lum value of the cluster reaches 0.015;

[0019] Innovations and advantages of the present application: 1. The absorption spectrum of the Ag6 cluster has a large overlap area with the emission spectrum of the R / S-BPOA donor. Circularly polarized luminescence is first realized from nothing to something through self-assembly of the chiral binaphthyl long chain. Second, the chiral Ag6 cluster is introduced, and the enantioselective co-assembly method realizes the construction of the circularly polarized composite luminescent material with improved g lum value of the cluster, as shown in the figure. Figure 9

[0020] 2. Through strong intermolecular interaction between the donor and the acceptor and chiral matching, there is obvious chiral / energy transfer between the donor and the acceptor, which significantly improves the circularly polarized luminescence g lum value of the cluster. By adjusting the proportion of the donor and the acceptor in the homochiral light harvesting system, a white light harvesting system with a high g lum value is successfully constructed.

[0021] 3. Based on the adjustable fluorescence and circularly polarized luminescence properties of the light harvesting system, it can be used for advanced three-dimensional anti-counterfeiting and information encryption. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Atomic force microscope image of self-assembly of S-BPOA in dichloroethane and methylcyclohexane mixed solvents to form nanofibers. ​

[0023] Figure 2 CPL spectrum of R / S-BPOA self-assembly of the present application.

[0024] Figure 3 Absorption spectrum of silver cluster of the present application and emission spectrum of chiral binaphthyl compound.

[0025] Figure 4 Fluorescence spectrum comparison chart of homochiral S-BPOA / S-Ag6 and heterochiral S-BPOA / R-Ag6 under the same conditions.

[0026] Figure 5 Comparison chart of the ratio of the emission intensity of acceptor at 572 nm to the emission intensity of donor at 454 nm of homochiral S-BPOA / S-Ag6 and heterochiral S-BPOA / R-Ag6 under the same conditions.

[0027] Figure 6 Atomic force microscope chart of R-Ag6 cluster of the present application self-assembled to form nanofiber in dichloroethane and methylcyclohexane mixed solvent. The g lum value is 0.0024.

[0028] Figure 7 Atomic force microscope chart of homochiral S-BPOA / S-Ag6 co-assembly of the present application forming composite helical nanofiber.

[0029] Figure 8 CPL spectrum chart of homochiral R-BPOA / R-Ag6 and S-BPOA / S-Ag6 co-assembly of the present application under excitation at 310 nm and 370 nm.

[0030] Figure 9 Comparison chart of g values of chiral BPOA, chiral Ag6, homochiral and heterochiral BPOA / Ag6 cluster of the present application under excitation at 310 nm and 370 nm. lum DETAILED DESCRIPTION

[0031] The present application is further illustrated by examples as follows:

[0032] Example 1: Synthesis of R / S-BPOA chiral binaphthyl supramolecular material (Formula II) of the present application, taking R as an example with 18 carbon chains:

[0033]

[0034] ​1) Boc protected beta-alanine (5 g, 26.42 mmol) was dissolved in 200 mL of dichloromethane with stirring until completely dissolved, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC.HCl, 5.06 g, 26.42 mmol) and 1-hydroxybenzotriazole (HOBT, 3.57 g, 26.42 mmol) were added to the above solution system, the mixed solution was stirred at room temperature for 24 hours, the crude product was filtered and washed with dichloromethane, the filter cake was dissolved in tetrahydrofuran, a large amount of water was added, and the precipitated solid was the desired product. The crude product was washed with methanol and dried to obtain a white solid, which was the relatively pure intermediate product A (9.58 g, 82.3%).

[0035] Structural characterization data are as follows:

[0036] 1 H NMR (600 MHz, CDC13) δ 3.42 (t, J = 5.9 Hz, 2H), 3.25 (dd, J = 13.1, 7.0 Hz, 2H), 2.41 (t, J = 5.8 Hz, 2H), 1.50 (dd, J = 14.1, 7.1 Hz, 2H), 1.45 (s, 9H), 1.35-1.25 (m, 30H), 0.90 (t, J = 7.0 Hz, 3H).

[0037] 2) Intermediate product A (8 g, 18.16 mmol) was dissolved in 80 mL of dichloromethane with stirring until completely dissolved, trifluoroacetic acid (TFA, 12 mL) was added, and stirring was continued at room temperature for 5 hours. The mixture was rotary evaporated, 10 mL of tetrahydrofuran was added, saturated sodium bicarbonate solution was added, filtered, and the filter cake was washed with water and methanol to obtain a white solid product (6.02 g, 97.4%) represented by formula B.

[0038] Structural characterization data are as follows:

[0039] 1 H NMR (600 MHz, CDC13) δ 3.42 (t, J = 5.9 Hz, 2H), 3.25 (dd, J = 13.1, 7.0 Hz, 2H), 2.41 (t, J = 5.8 Hz, 2H), 1.50 (dd, J = 14.1, 7.1 Hz, 2H), 1.45 (s, 9H), 1.35-1.25 (m, 30H), 0.90 (t, J = 7.0 Hz, 3H).

[0040] 3) The product of formula B (6 g, 17.63 mmol) was dissolved in 40 mL of glacial acetic acid with 4,5-difluorophthalic anhydride (2.7 g, 14.69 mmol) and the reaction was carried out at 110 °C for about 4 hours. The reaction solution was cooled to room temperature. Filtration, methanol washing and drying gave the intermediate product I (4.56 g, 61.3%) as a white powder.

[0041] Structural characterization data are as follows:

[0042] 1 H NMR (600 MHz, CDC13) δ 7.66 (t, J = 7.2 Hz, 1H), 4.00 (t, J = 7.2 Hz, 2H), 3.21 (dd, J = 13.2, 6.9 Hz, 2H), 2.60 (t, J = 7.2 Hz, 2H), 1.48 - 1.40 (m, 2H), 1.34 - 1.18 (m, 30H), 0.88 (t, J = 7.0 Hz, 3H).

[0043] 4) The product of formula I (1.6 g, 3.17 mmol), R- or S-dinaphthylmethane (1 g, 3.49 mmol), potassium carbonate (K2C03, 2.19 g, 15.87 mmol) and potassium iodide (KI, 2.63 g, 15.87 mmol) were added to a 100 mL three-necked flask, which was vacuumed and filled with nitrogen three times, and then 30 mL of degassed N,N-dimethylformamide was added. The reaction was carried out at 65 °C for 10 hours. After the reaction was completed, the reaction mixture was cooled to room temperature, a large amount of cold water was added, and a large amount of white solid precipitated. The solid product was separated by centrifugation, washed with methanol, dried, and purified with ethyl acetate and petroleum ether (volume ratio 1:2) as eluent to obtain pure light yellow solid R or S-BPOA (961 mg, 40.3%).

[0044] Structural characterization data are as follows:

[0045] R-BPOA: 1 H NMR (600 MHz, CDC13) δ 7.96 (dd, J = 25.6, 8.5 Hz, 4H), 7.73 (s, 2H), 7.51 (dd, J = 17.6, 8.1 Hz, 4H), 7.39 (t, J = 7.8 Hz, 4H), 4.03 - 3.92 (m, 2H), 3.21 (dd, J = 13.3, 6.8 Hz, 2H), 2.59 (t, J = 7.2 Hz, 2H), 1.44 (dd, J = 14.2, 6.9 Hz, 2H), 1.32 - 1.18 (m, 30H), 0.87 (t, J = 7.0 Hz, 3H).

[0046] R-BPOA: 13C NMR (151 MHz, CDC13) δ 169.42, 167.13, 153.58, 150.07, 132.06, 131.97, 131.03, 128.66, 128.46, 127.14, 126.63, 125.94, 125.41, 120.61, 118.32, 39.67, 34.89, 34.69, 31.93, 29.71, 29.67, 29.65, 29.59, 29.55, 29.53, 29.37, 29.30, 26.9, 22.7, 14.12.

[0047] R-BPOA: ESI + HRMS m / z calcd for C 49 H 56 N2O5 753.4267[M+H] + ,775.4087[M+Na] + ,found 753.4833[M+H] + ,775.4683[M+Na] + .Elemental analysis for C 49 H 56 N2O5: calcd C 78.16, H 7.50, N 3.72; found C 77.30, H 7.67, N 3.42.

[0048] S-BPOA: 1 H NMR (600 MHz, CDC13) δ 7.97 (dd, J = 27.4, 8.5 Hz, 4H), 7.74 (s, 2H), 7.52 (dd, J = 18.3, 8.1 Hz, 4H), 7.43 - 7.38 (m, 4H), 3.98 (tq, J = 14.1, 7.2 Hz, 2H), 3.21 (dd, J = 13.3, 6.7 Hz, 2H), 2.59 (t, J = 7.2 Hz, 2H), 1.45 (dd, J = 15.6, 8.9 Hz, 1H), 1.27 (dd, J = 45.2, 23.6 Hz, 30H), 0.88 (t, J = 6.9 Hz, 3H).

[0049] S-BPOA: 13C NMR (151 MHz, CDC13) δ 169.39, 167.15, 153.59, 150.07, 132.05, 131.98, 131.05, 128.66, 128.47, 127.15, 126.63, 125.95, 125.41, 120.62, 118.34, 39.67, 34.90, 34.68, 31.94, 29.71, 29.68, 29.65, 29.59, 29.55, 29.53, 29.38, 29.30, 26.92, 22.71, 14.14.

[0050] S-BPOA: ESI + HRMS m / z calcd for C 49 H 56 N2O5 753.4267[M+H] + ,775.4087[M+Na] + ,found 753.4826[M+H] + ,775.4647[M+Na] + .Elemental analysis for C 49 H 56 N2O5: calcd C 78.16, H 7.50, N 3.72; found C 77.49, H 7.72, N 3.30.

[0051] Example 2: Chiral binaphthyl supramolecular material R / S-BPOA (Formula II) assembled into supramolecular nanohelix fibers:

[0052] 1) R-BPOA or S-BPOA 1.81 mg was weighed into a 2 mL sample tube, 1 mL of dichloroethane was added, and after being dissolved completely, a 2 mM solution was prepared. 0.2 mL of the solution was taken into a 5 mL sample tube, and 1.8 mL of dichloroethane and 2 mL of methylcyclohexane were sequentially added to prepare a 0.1 mM R-BPOA or S-BPOA solution.

[0053] 2) After the above R-BPOA or S-BPOA solution was incubated for 24 or 48 hours, the helical nanofiber structure was formed by interfacial assembly, as shown in Figure 1 .

[0054] Example 3: Chiral Ag6 cluster self-assembled into supramolecular helical nanofiber:

[0055] 1) Take 1.47 mg of R-Ag6 or S-Ag6 in a 2 mL sample tube, add 1 mL of dichloroethane, dissolve thoroughly, and then prepare a 1 mM solution. Take 40 μL of the solution in a 5 mL sample tube, and then add 1.96 mL of dichloroethane and 2 mL of methylcyclohexane in sequence, to prepare a 0.01 mM solution of R-Ag6 or S-Ag6.

[0056] 2) Incubate the above R-Ag6 or S-Ag6 solution for 4-48 hours, and then form a helical nanofiber structure by interfacial assembly, as shown in Figure 6

[0057] Example 4: Co-assembly of the supramolecular nanofiber structure of chiral binaphthyl supramolecular material R / S-BPOA and chiral Ag6 clusters:

[0058] 1) Add 2%, 5%, 10%, and 15% of the enantiomeric or heterochiral Ag6 clusters formed in Example 3 to the R-BPOA or S-BPOA incubation solution formed in Example 2, respectively;

[0059] The above R-BPOA and R-Ag6, and S-BPOA and S-Ag6 are enantiomeric, and the above R-BPOA and S-Ag6, and S-BPOA and R-Ag6 are heterochiral.

[0060] 2) Incubate the co-assembly solution in step 1) again for about 8 hours, and then obtain a co-assembly body by interfacial assembly; the morphology of the enantiomeric complex helical nanofiber is as shown in Figure 7

[0061] 3) Perform fluorescence spectrum testing and circularly polarized luminescence spectrum testing on the enantiomeric and heterochiral co-assembly bodies prepared above;

[0062] As shown in Figure 4 and Figure 5 , the test results show that the enantiomeric BPOA and Ag6 have a large energy transfer efficiency due to the strong intermolecular interaction and chiral matching between the donor and the acceptor;

[0063] As shown in Figure 8 and Figure 9 , the test results show that the enantiomeric BPOA and Ag6 have a clear chiral energy transfer behavior; when the co-assembly body is added with 10% of the enantiomeric Ag6 clusters in terms of molar equivalent, the g lum value of the circularly polarized light reaches 0.0154, which is 6.4 times that of the cluster self-assembly body (0.0024), significantly improving the g lum value of the cluster.

[0064] ​​The experimental results show that the method of enantioselective co-assembly of the light harvesting system based on Ag6 clusters can significantly improve the circularly polarized luminescence performance of the clusters.

[0065] By regulating the ratio of the donor-acceptor components, the application constructs a white light harvesting system with high g lum value, and the g lum value reaches 0.0087.

[0066] Based on the adjustable fluorescence and circularly polarized luminescence properties of the light harvesting system, the light harvesting system constructed by the application can be used for advanced three-dimensional anti-counterfeiting and information encryption applications.

[0067] The R / S-BPOA supramolecular material and the R / S-Ag6 cluster material of the application are easily soluble in most organic solvents, including dichloromethane, chloroform, tetrahydrofuran, N,N-dimethylformamide, N,N-diethylformamide, dimethyl sulfoxide, acetone, etc., and have good application prospects.

[0068] The above examples are only used to illustrate the content of the application, and the application has other implementation manners in addition thereto. However, all technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope of the application.

Claims

1. A chiral binaphthyl compound, characterized in that: Its abbreviation is: R / S-BPOA, and its molecular structure is shown below. It belongs to a pair of enantiomers. R is C 2-20 of alkyl.

2. A method for synthesizing the chiral binaphthyl compound according to claim 1, characterized in that: This is achieved through the following steps; R is C 2-20 Alkyl; The compound of formula I, R -Binaphthol or S -Binaphthol, potassium carbonate, and potassium iodide were added to a flask, vacuumed and filled with nitrogen, and heated to react. After the reaction was completed, the reaction mixture was cooled to room temperature, centrifuged, and the solid product was separated; after washing, drying, and purification, the target compound was obtained.

3. A circularly polarized luminescent material, characterized in that: The chiral binaphthyl compound of claim 1 is self-assembled in a mixed organic solvent to form nanofibers as chiral and energy donors; R / S -Ag6 cluster compounds self-assemble in mixed organic solvents to form nanofibers, which act as chiral and energy acceptors; The circularly polarized luminescent material is obtained by self-assembling the two; The chemical formula of the chiral R / S-Ag6 cluster compound is: 54 H 48 Ag6N6S 12 , abbreviated as: Ag6PL6 / PD6, belongs to the monoclinic system, the space group is chiral space group P213, a = 14.08920(10) Å, b = 15.76800(10) Å, c =15.0407(2) Å, V = 3138.91(5) Å 3 ; Among them, PL / PD is (S / R)-4-phenylthiazolidine-2-thione, and the structural formula is as follows: ， The donor compound and the acceptor compound are homochiral.

4. The method for assembling the circularly polarized luminescent material according to claim 3, characterized in that: This is achieved through the following steps; (1) Chiral binaphthyl R / S -BPOA is dissolved in an organic system, incubated at room temperature, and a chiral, energy-donating nanofiber material is obtained through interfacial self-assembly; the organic system is a system formed by a mixture of dichloroethane and methylcyclohexane; (2) Adding chiral silver clusters with the same chirality as the donor to the solution in step (1) R / S -Ag6 good solvent solution, co-incubated again, and prepared into an assembly through interfacial assembly; The good solvent is dichloromethane, chloroform or dichloroethane.

5. The method for assembling a circularly polarized luminescent material according to claim 4, wherein: The volume ratio of the methylcyclohexane in the organic system is 40 to 60%; the chiral binaphthyl compound R / S -BPOA molar concentration is 0.05 ~ 0.3 mM; the chiral silver clusters R / S -The molar concentration of Ag6 is 1 ~ 30 μM.

6. The use of the circularly polarized luminescent material according to claim 3, wherein: It is used for three-dimensional anti-counterfeiting or information encryption materials.

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