Boc-L-phenylalanine xerogel, single crystal and preparation method and application of Boc-L-phenylalanine xerogel

Abstract

The invention discloses Boc-L-phenylalanine xerogel, a single crystal and a preparation method and application of the Boc-L-phenylalanine xerogel and the single crystal, and relates to the technical field of cluster luminescent materials.Structural recombination of Boc-L-phenylalanine from powder to xerogel is achieved through a solvothermal induction method, and the Boc-L-phenylalanine xerogel is obtained; the Boc-L-phenylalanine xerogel is cultured into a Boc-L-phenylalanine single crystal by adopting a crystallization method; moreover, the Boc-L-phenylalanine xerogel and the Boc-L-phenylalanine single crystal prepared by the preparation method disclosed by the invention can be applied as a cluster luminescent material.

Description

Technical Field

[0001] The invention relates to the technical field of cluster luminescent materials, and in particular to a Boc-L-phenylalanine dry gel, a single crystal, and a preparation method and application thereof. Background Art

[0002] Organic light-emitting materials based on valence bond conjugation (TBC) have the characteristics of adjustable emission color, tunable structure and high quantum efficiency. They are widely used in photoelectric sensors, information storage technology, biomedical treatment and other fields. Their luminescence mechanism comes from π-π* transition. However, aromatic compounds often show toxicity and resistance to biodegradation, posing a threat to human health and the ecological environment. In addition, problems such as high cost, complex synthesis routes and quenching effects caused by aggregation also limit their application. Therefore, more and more researchers are turning from traditional organic light-emitting groups to unconventional groups to overcome these challenges and explore safer, more stable and more sustainable light-emitting materials.

[0003] In recent years, a new type of non-conjugated luminescent material has rapidly emerged. This material is different from the traditional TBC theory and its theoretical basis is trans-steric interaction (TSI). Studies have shown that a short channel is formed between the isolated benzene ring and the heteroatom, resulting in orbital splitting and a reduction in the energy gap. Therefore, when aggregation occurs due to TSI, the emission will be red-shifted. These materials can emit visible light even if they have only one benzene ring, lack a large amount of aromatic structure, or do not contain π-conjugated groups. These substances are called non-conjugated cluster luminogens (CLgens) and are usually composed only of electron-rich heteroatoms such as amino and carbonyl groups. Their luminescence originates from n-π* transitions and usually exhibits weak or no luminescence in dilute solutions, but exhibits bright fluorescence in concentrated solutions or aggregated states. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing a Boc-L-phenylalanine xerogel, and to prepare a Boc-L-phenylalanine single crystal using the obtained Boc-L-phenylalanine xerogel; Boc-L-phenylalanine in the form of powder or dilute solution does not emit light, but Boc-L-phenylalanine in the form of a xerogel can emit fluorescence, and Boc-L-phenylalanine in the form of a single crystal can emit brighter fluorescence, so the Boc-L-phenylalanine xerogel and Boc-L-phenylalanine single crystal prepared by the present invention can be used as cluster luminescent materials.

[0005] The technical problem to be solved by the present invention is achieved by adopting the following technical solutions:

[0006] One of the purposes of the present invention is to provide a method for preparing Boc-L-phenylalanine xerogel, and to achieve structural reorganization of Boc-L-phenylalanine from powder to xerogel by solvent thermal induction method.

[0007] The second object of the present invention is to provide a Boc-L-phenylalanine xerogel obtained by the aforementioned method for preparing the Boc-L-phenylalanine xerogel.

[0008] The third object of the present invention is to provide a method for preparing Boc-L-phenylalanine single crystals, wherein the Boc-L-phenylalanine xerogel is cultured into Boc-L-phenylalanine single crystals by a crystallization method.

[0009] A fourth object of the present invention is to provide a Boc-L-phenylalanine single crystal obtained by the aforementioned method for preparing the Boc-L-phenylalanine single crystal.

[0010] The fifth object of the present invention is to provide the application of the Boc-L-phenylalanine xerogel and Boc-L-phenylalanine single crystal as cluster luminescent materials.

[0011] The beneficial effects of the present invention are:

[0012] 1. The preparation method of Boc-L-phenylalanine xerogel and Boc-L-phenylalanine single crystal provided by the present invention is not only environmentally friendly, but also can reduce costs;

[0013] 2. The Boc-L-phenylalanine xerogel and Boc-L-phenylalanine single crystal prepared by the present invention can be used as cluster luminescent materials and have a wide range of application fields, including biology, display, lighting and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the preparation process of Boc-L-phenylalanine xerogel;

[0015] Figure 2 Boc-L-phenylalanine xerogel 1 H NMR spectrum;

[0016] Figure 3 Fluorescence photos of Boc-L-phenylalanine in four forms: powder, large-sized crystals, crystal particles, and single crystals;

[0017] Figure 4 The UV-visible absorption spectra of Boc-L-phenylalanine in three forms: powder, solution and xerogel;

[0018] Figure 5 The fluorescence spectra of Boc-L-phenylalanine xerogel at different wavelengths;

[0019] Figure 6 is the fluorescence lifetime of Boc-L-phenylalanine in the form of powder, solution and xerogel;

[0020] Figure 7 CD spectra of Boc-L-phenylalanine in three forms: powder, diluted solution and xerogel;

[0021] Figure 8 2D NOESY spectrum of Boc-L-phenylalanine xerogel;

[0022] Fig. 9 The XRD patterns of Boc-L-phenylalanine in three forms: powder, xerogel and single crystal;

[0023] Fig.10 FT-IR images of Boc-L-phenylalanine in three forms: powder, xerogel and single crystal;

[0024] Fig.11 The concentrations of Boc-L-phenylalanine solutions are 1 H NMR spectrum. DETAILED DESCRIPTION

[0025] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific embodiments and diagrams.

[0026] like Figure 1 As shown, the present invention provides a method for preparing Boc-L-phenylalanine xerogel, and realizes the structural reorganization of Boc-L-phenylalanine from powder to xerogel by solvent thermal induction method.

[0027] The structural formula of Boc-L-phenylalanine is shown below:

[0028]

[0029] Furthermore, the solvent includes but is not limited to at least one of dichloromethane, chloroform, ethanol, ethyl acetate, and tetrahydrofuran.

[0030] Furthermore, the solvent thermal induction temperature is 50 to 80° C., the pressure is -0.08 to -0.05 MPa, and the time is 2 to 6 hours.

[0031] Furthermore, the solvent thermal induction is carried out in a vacuum drying oven.

[0032] Furthermore, the usage ratio of the solvent to the Boc-L-phenylalanine powder is (1-3) mL: (3-6) g.

[0033] The present invention provides a Boc-L-phenylalanine xerogel obtained by the above-mentioned preparation method of Boc-L-phenylalanine xerogel.

[0034] The present invention also provides a method for preparing a Boc-L-phenylalanine single crystal, which comprises cultivating the Boc-L-phenylalanine xerogel into the Boc-L-phenylalanine single crystal by a crystallization method.

[0035] Furthermore, the crystallization method is a low-temperature crystallization method.

[0036] The present invention provides a Boc-L-phenylalanine single crystal obtained by the above-mentioned method for preparing the Boc-L-phenylalanine single crystal.

[0037] The present invention also provides the application of the Boc-L-phenylalanine xerogel and the Boc-L-phenylalanine single crystal as cluster luminescent materials.

[0038] Example 1

[0039] 6 g of Boc-L-phenylalanine powder was ultrasonically dissolved in 2 mL of dichloromethane to obtain a mixed solution; the mixed solution was then placed in a vacuum drying oven at a temperature of 50°C and a pressure of -0.05 MPa for 4 hours to obtain a colorless and transparent Boc-L-phenylalanine dry gel.

[0040] Example 2

[0041] 3 g of Boc-L-phenylalanine powder was ultrasonically dissolved in 1 mL of chloroform to obtain a mixed solution; the mixed solution was then placed in a vacuum drying oven at a temperature of 60°C and a pressure of -0.08 MPa for 2 h to obtain a colorless and transparent Boc-L-phenylalanine xerogel.

[0042] Example 3

[0043] 5 g of Boc-L-phenylalanine powder was ultrasonically dissolved in 3 mL of ethanol to obtain a mixed solution; the mixed solution was then placed in a vacuum drying oven at a temperature of 80°C and a pressure of -0.06 MPa for 6 hours to obtain a colorless and transparent Boc-L-phenylalanine xerogel.

[0044] Example 4

[0045] The Boc-L-phenylalanine xerogel prepared in Example 1 was rapidly crystallized (placed in a sealed container at room temperature for one week) to obtain large-sized Boc-L-phenylalanine crystals. The large-sized Boc-L-phenylalanine crystals were crushed to obtain Boc-L-phenylalanine crystal particles.

[0046] Example 5

[0047] The Boc-L-phenylalanine xerogel prepared in Example 1 was slowly crystallized (placed in a sealed container at 2-6° C. for two months) to obtain Boc-L-phenylalanine single crystals.

[0048] Structural characterization:

[0049] Figure 2 This is the H NMR spectrum of Boc-L-phenylalanine xerogel ( 1 H NMR spectrum); (a) is Boc-L-phenylalanine xerogel in a deuterated chloroform dilute solution (ρ = 10 mg / mL) 1 H NMR spectrum; (b) Boc-L-phenylalanine xerogel in deuterated chloroform concentrated solution (ρ = 500 mg / mL) 1 H NMR spectrum. Figure 2 It can be seen that the structural reorganization of Boc-L-phenylalanine from powder to dry gel achieved by the solvothermal induction method did not destroy the molecular structure of Boc-L-phenylalanine.

[0050] Performance Testing:

[0051] Figure 3 Fluorescence photos of Boc-L-phenylalanine in four forms: powder, large-size crystal, crushed grains, and single crystal. Figure 3 It can be seen that Boc-L-phenylalanine powder does not emit light; the large-sized crystals obtained by rapid crystallization emit weak blue fluorescence, and the crystal particles obtained by further crushing partially emit blue fluorescence; the single crystals obtained by slow crystallization emit bright blue fluorescence, because through the slow crystallization process, the molecular arrangement is more compact and orderly, and can emit brighter fluorescence.

[0052] Figure 4 The UV-visible absorption spectra of Boc-L-phenylalanine in three forms: powder, solution (Solution) and dry gel (X-Gel). The solution is DCM solution (c = 10 -5 M). Figure 4 It can be seen that the absorption at a wavelength of 250-280 nm comes from a single benzene ring, and the absorption at a wavelength of 300-400 nm is caused by TSI; compared with solutions and powders, the TSI effect of dry gel is stronger.

[0053] Figure 5 The fluorescence spectra of Boc-L-phenylalanine xerogel at different wavelengths. Figure 5 It can be seen that the photoluminescence spectrum of the dry gel can be observed in the excitation wavelength range of 250-390nm, the emission peak corresponding to the benzene ring appears at 302nm, and the emission peak in the range of 320-390nm corresponds to TSI. Obviously, this luminescence shows a significant excitation-dependent effect (EDE), which is a characteristic of cluster luminescence (CL).

[0054] Figure 6 is the fluorescence lifetime (λex = 373 nm) of Boc-L-phenylalanine in the form of powder, solution and xerogel, where the solution is DCM solution (c = 10 -3 M). Figure 6 It can be seen that the fluorescence lifetime of Boc-L-phenylalanine powder is only 2.5×10 -3 ns; the fluorescence lifetime of Boc-L-phenylalanine in DCM solution is 6.81×10 -2 ns; the fluorescence lifetime of Boc-L-phenylalanine xerogel was extended to 2.59 ns, which was significantly longer than that of Boc-L-phenylalanine powder and in solution.

[0055] Figure 7 The circular dichroism (CD) spectra of Boc-L-phenylalanine in three forms: powder, dilute solution, and dry gel. Figure 7 It can be seen that the powder and solution have basically no CD signal, while the dry gel shows an obvious CD signal.

[0056] Figure 8 2D NOESY spectrum of Boc-L-phenylalanine xerogel. Figure 8 It can be seen that the two-dimensional NOESY spectrum of Boc-L-phenylalanine xerogel in CDCl3 solution shows the correlation signal between the protons on the carboxyl group and the protons on the amide group, indicating the existence of CH···π interaction. Theoretical calculation of the single crystal structure of Boc-L-phenylalanine shows that the d(H a -H b ) Shorter distance This indicates that there is a stronger cross-space n-π* interaction in the crystal.

[0057] Fig. 9 The X-ray diffraction patterns (XRD patterns) of Boc-L-phenylalanine in three forms: powder, dry gel and single crystal. Fig. 9 It can be seen that from powder to dry gel, the position of the diffraction peak undergoes an obvious red shift, accompanied by a sharpening of the peak, which is due to the formation of stronger intermolecular interactions in the dry gel; in addition, a further position red shift is observed in the crystal structure, which is because the rigid environment provided by the crystal can effectively maintain the excited state of the molecule, which is conducive to efficient emission.

[0058] Fig.10 The following are Fourier infrared spectra (FT-IR) of Boc-L-phenylalanine in three forms: powder, dry gel and single crystal. Fig.10 It can be seen that the 1712 and 1649 cm-1-1 The bands correspond to the C=O stretching vibrations of the carboxyl group and the amide bond at 3320 cm -1 Compared with the powder, the FT-IR spectrum of the crystal showed an increase of 3 and 5 cm in the C=O stretching vibration peak. -1 The blue shift at 3310cm -1 The NH vibration peak at 10 cm -1 The displacement of the xerogel also changed compared to the powder. Regardless of redshift or blueshift, as long as there is a displacement change, it can explain the influence of the intermolecular interaction force. These results show that more hydrogen bonds are formed in the xerogel and crystal.

[0059] Fig.11 The concentrations of Boc-L-phenylalanine solutions are 1 H NMR spectrum. Fig.11 It can be seen that as the mass concentration increases from 100 mg / mL to 500 mg / mL, the blue line represents the peak corresponding to the carboxyl proton, and the yellow line represents the signal corresponding to the amide proton, which gradually red-shifts. As the concentration increases, the peaks corresponding to the carboxyl and amide bonds gradually red-shift. When the mass concentration is 500 mg / mL, the peak shape becomes sharper, indicating that larger and more compact clusters are formed in the concentrated solution.

[0060] In summary, compared with powder and solution, the cross-space interaction force of dry gel is further enhanced, and the fluorescence shows the characteristics of cluster luminescence.

[0061] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a Boc-L-phenylalanine xerogel, characterized in that: The structural reorganization of Boc-L-phenylalanine from powder to xerogel was achieved by solvothermal induction.

2. The method for preparing the Boc-L-phenylalanine xerogel according to claim 1, characterized in that: The solvent is at least one of dichloromethane, chloroform, ethanol, ethyl acetate and tetrahydrofuran.

3. The method for preparing the Boc-L-phenylalanine xerogel according to claim 1, characterized in that: The solvent thermal induction temperature is 50 to 80° C., the pressure is -0.08 to -0.05 MPa, and the time is 2 to 6 hours.

4. The method for preparing the Boc-L-phenylalanine xerogel according to claim 1, characterized in that: The solvent thermal induction is carried out in a vacuum drying oven.

5. The method for preparing the Boc-L-phenylalanine xerogel according to claim 1, characterized in that: The usage ratio of the solvent to the Boc-L-phenylalanine powder is (1-3) mL: (3-6) g.

6. Boc-L-phenylalanine xerogel obtained by the method for preparing Boc-L-phenylalanine xerogel according to any one of claims 1 to 5.

7. A method for preparing a Boc-L-phenylalanine single crystal, comprising cultivating the Boc-L-phenylalanine xerogel according to claim 6 into a Boc-L-phenylalanine single crystal by a crystallization method.

8. The method for preparing a Boc-L-phenylalanine single crystal according to claim 7, characterized in that: The crystallization method is a low temperature crystallization method.

9. A Boc-L-phenylalanine single crystal obtained by the method for preparing a Boc-L-phenylalanine single crystal according to claim 7 or 8.

10. Use of the Boc-L-phenylalanine xerogel according to claim 9 and the Boc-L-phenylalanine single crystal according to claim 8 as cluster luminescent materials.

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