A tetraphenylpyrazine, a tetraphenylpyrazine micro-optical fiber, a preparation method and application thereof, and a waveguide modulator

Abstract

The application provides a tetraphenylpyrazine, a tetraphenylpyrazine micro-optical fiber and a preparation method and application thereof, and a waveguide modulator, and relates to the technical field of luminescent materials.The tetraphenylpyrazine provided by the application has a structure shown in formula I, has an aggregation-induced emission characteristic, can generate extremely strong luminescence in the case of molecular aggregation, exhibits deep blue fluorescent emission under ultraviolet light irradiation, and has good thermal stability and luminescence stability.

Description

Technical Field

[0001] This invention relates to the field of luminescent materials technology, specifically to a tetraphenylpyrazine, a tetraphenylpyrazine microfiber, its preparation method and application, and a waveguide modulator. Background Technology

[0002] Aggregation-induced emission (AIE) materials are a novel type of luminescent material characterized by spatial aggregation before emission to enhance light intensity. These materials are composed of molecules with a special structure called "aggregation-inducing units," whose structure and morphology can be controlled through synthesis to achieve desired optical properties. AIE materials have attracted widespread attention in the field of photonics due to their unique optical properties. Unlike traditional luminescent clusters that rely on electron transitions, AIE materials induce photoluminescence through energy transfer between constituent particles. This energy transfer typically occurs when nanoscale particles come into close contact, leading to the formation of aggregates. The resulting materials exhibit excellent photoluminescence efficiency and stability.

[0003] The unique optical properties, tunability, and versatility of AIE materials make them attractive for a wide range of applications, and continued research in this field is expected to promote further progress in the design, synthesis, and application of these materials. Summary of the Invention

[0004] The purpose of this invention is to provide a tetraphenylpyrazine, a tetraphenylpyrazine microfiber, its preparation method and application, and a waveguide modulator. The tetraphenylpyrazine provided by this invention has aggregation-induced emission properties, can generate extremely strong light emission when molecules are aggregated, exhibits deep blue fluorescence emission under ultraviolet light irradiation, and has good thermal stability and luminescence stability.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a tetraphenylpyrazine having the structural formula shown in Formula I:

[0007]

[0008] This invention provides a method for preparing tetraphenylpyrazine microfibers, comprising the following steps:

[0009] The tetraphenylpyrazine described in the above technical solution is dispersed in a mixed solution of tetrahydrofuran and water to obtain a tetraphenylpyrazine dispersion; the tetrahydrofuran content in the mixed solution of tetrahydrofuran and water is 0.001-0.005 mol / L;

[0010] The tetraphenylpyrazine dispersion was dropped onto the substrate, and the solvent was removed to obtain tetraphenylpyrazine microfibers.

[0011] Preferably, the concentration of tetraphenylpyrazine in the tetraphenylpyrazine dispersion is 0.001 to 0.005 mol / L.

[0012] The present invention provides a tetraphenylpyrazine microfiber prepared by the preparation method described in the above technical solution.

[0013] Preferably, the tetraphenylpyrazine microfiber has a one-dimensional rod-like structure with a length of 400–800 μm and a diameter of 20–30 μm.

[0014] This invention provides the application of the tetraphenylpyrazine microfiber described above as a waveguide material.

[0015] Preferably, one end of the tetraphenylpyrazine microfiber is coated with a fluorescent molecular material with an absorption wavelength of 420–450 nm.

[0016] The present invention provides a waveguide modulator, comprising the tetraphenylpyrazine microfiber described in the above technical solution; one end of the tetraphenylpyrazine microfiber is coated with a mixed fluorescent molecular material containing fluorescent molecular materials with absorption wavelengths in the range of 420 to 450 nm.

[0017] Preferably, white light emission is obtained when one end of the tetraphenylpyrazine microfiber is coated with a mixed fluorescent molecular material of green and red fluorescent molecules.

[0018] Preferably, the green fluorescent molecule is 4,7-bis(4-(1,2,2-triphenylvinyl)phenyl)benzo[c][1,2,5]thiadiazole; and the red fluorescent molecule is 2,3-bis(4-(bis(4-tert-butylphenyl)amino)phenyl)fumaronitrile.

[0019] This invention provides a tetraphenylpyrazine exhibiting aggregation-induced emission (AIE) properties. Generally, luminescent molecules are subject to aggregation-induced quenching, leading to a sharp decrease in luminescence intensity or even quenching. However, the tetraphenylpyrazine (TPP-4OMe) provided by this invention possesses AIE properties, generating extremely strong luminescence even when molecules are aggregated. Furthermore, the luminescence produced by this molecule has been tested and is in the deep blue color gamut, exhibiting highly stable luminescence that can achieve efficient luminescence for up to 4–5 hours. The tetraphenylpyrazine provided by this invention displays deep blue fluorescence emission under ultraviolet light irradiation. Due to the near-horizontal dipole moment (μ) orientation of light propagation along the molecule, the crystal exhibits light propagation and a low optical loss coefficient along the primary growth direction, indicating that this material can serve as a good waveguide.

[0020] This invention also provides a tetraphenylpyrazine microfiber, which possesses excellent optical waveguide properties, a smooth surface, and virtually no optical apertures, making it a highly suitable optical waveguide material. Its waveguide loss is as low as 0.035 dB / μm, which is extremely low compared to some current waveguide materials. Furthermore, this tetraphenylpyrazine microfiber can generate not only active waveguides but also passive waveguides for other visible light, with very low waveguide losses. According to the results of the embodiments, the passive waveguide loss for blue light is 0.166 dB / μm, for green light it is 0.145 dB / μm, and for red light it is 0.176 dB / μm, indicating that this tetraphenylpyrazine microfiber can achieve visible light transmission within its structure. Attached Figure Description

[0021] Figure 1 The structural characterization diagram of the tetraphenylpyrazine crystals prepared in Example 1 is shown.

[0022] Figure 2 The image shows the morphology of the tetraphenylpyrazine microfiber prepared in Example 2.

[0023] Figure 3 The optical properties of the tetraphenylpyrazine microfiber prepared in Example 2 are shown in the figure.

[0024] Figure 4 The endpoint and side PL spectra (a, b) and CIE chromatograms (c, d) of the tetraphenylpyrazine microfiber prepared in Example 2;

[0025] Figure 5 Dark-field microscopy images of tetraphenylpyrazine crystals in solution, aggregate, and solid states (a), fluorescence lifetime spectra of different morphologies (b), and graphs of quantum yield versus fluorescence lifetime data (c).

[0026] Figure 6 Dark-field microscopy image of the tetraphenylpyrazine microfiber prepared in Example 2 over time (a), diameter distribution of the tetraphenylpyrazine microfiber over time (b), time-dependent fluorescence spectrum of the tetraphenylpyrazine microfiber (c), and photostability curves of the tetraphenylpyrazine microfiber and ICG under continuous laser irradiation (d).

[0027] Figure 7 The fluorescence lifetime mapping image of the tetraphenylpyrazine microfiber prepared in Example 2 as a function of power;

[0028] Figure 8 This is a diagram of the experimental setup for testing passive waveguide transmission.

[0029] Figure 9Dark-field microscopy images (a-c) of red, green and blue lasers of different wavelengths transmitted on the tetraphenylpyrazine microfiber prepared in Example 2, and linear fitting of its optical waveguide transmission loss (d-f).

[0030] Figure 10 Dark-field fluorescence microscopy images (a), emission spectra corresponding to the emitting end (b), the relationship between emission intensity at the fixed end and the distance between the excitation point and the emitting end (c), and the relationship between pump power and intensity (d) obtained by exciting the same tetraphenylpyrazine microfiber at different locations;

[0031] Figure 11 XRD diffraction patterns (a) and absorption and emission patterns (b) of TPP-4OMe sample in powder and crystalline form;

[0032] Figure 12 Schematic diagram of BTD and BTF colloidal fluorescence excited by tetraphenylpyrazine microfiber waveguide;

[0033] Figure 13 Dark-field fluorescence microscopy images (a, b) and their corresponding fluorescence spectra (c, d) of tetraphenylpyrazine microfiber waveguide-excited BTD and BTF.

[0034] Figure 14 A schematic diagram (a) of white light emission generated by the recombination of red, green and blue light signals at the end of a tetraphenylpyrazine microfiber; an experimental image of white light emission in a dark field fluorescence microscope (b); a white light emission fluorescence spectrum (c) and a CIE chromaticity diagram (d);

[0035] Figure 15 Comparison of photophysical properties of the tetraphenylpyrazine prepared in this invention with several typical AIE molecules. Detailed Implementation

[0036] This invention provides a tetraphenylpyrazine having the structural formula shown in Formula I:

[0037]

[0038] In this invention, the preferred method for preparing tetraphenylpyrazine includes: mixing anisole, ammonium acetate, acetic anhydride, and acetic acid to obtain a mixed solution; refluxing and stirring the mixed solution, cooling it to room temperature, filtering the precipitate, and washing it with acetic acid to obtain a crude product; recrystallizing the crude product in hot acetic acid to obtain tetraphenylpyrazine. In this invention, the preferred ratio of anisole, ammonium acetate, acetic anhydride, and acetic acid is 73.5 mmol: 220.5 mmol: 110.3 mmol: 100 mL. In this invention, the preferred reflux stirring time is 4 h. This invention uses a one-step reaction method to prepare tetraphenylpyrazine. Compared with existing methods for preparing pyrazine-type AIE molecules, the synthetic steps of this invention are very simple. The TPP and its derivatives obtained by this route can be purified by recrystallization without the need for cumbersome column chromatography, and the yield is very stable.

[0039] In this invention, the tetraphenylpyrazine (TPP-4OMe) is a white needle-like crystal.

[0040] This invention provides a method for preparing tetraphenylpyrazine microfibers, comprising the following steps:

[0041] The tetraphenylpyrazine described in the above technical solution is dispersed in a mixed solution of tetrahydrofuran and water to obtain a tetraphenylpyrazine dispersion; the tetrahydrofuran content in the mixed solution of tetrahydrofuran and water is 0.001-0.005 mol / L;

[0042] The tetraphenylpyrazine dispersion was dropped onto the substrate, and the solvent was removed to obtain tetraphenylpyrazine microfibers.

[0043] This invention disperses the tetraphenylpyrazine in a mixed solution of tetrahydrofuran and water to obtain a tetraphenylpyrazine dispersion. In this invention, the tetrahydrofuran content in the mixed solution of tetrahydrofuran (THF) and water is 0.001–0.005 mol / L, preferably 0.001 mol / L. Using a mixed solution of the above concentration can improve the aggregation-induced emission intensity of tetraphenylpyrazine. In this invention, the dispersion is preferably carried out under ultrasonic conditions, with the ultrasonic power preferably being 500 W and the ultrasonic duration preferably being 5 min.

[0044] In this invention, the concentration of tetraphenylpyrazine in the tetraphenylpyrazine dispersion is preferably 0.001 to 0.005 mol / L, more preferably 0.002 mol / L.

[0045] After obtaining the tetraphenylpyrazine dispersion, the present invention drops the tetraphenylpyrazine dispersion onto a substrate, removes the solvent, and obtains a tetraphenylpyrazine microfiber. In the present invention, the substrate preferably comprises a glass slide or a silicon wafer. In the present invention, the substrate is preferably pretreated before use. In the present invention, the pretreatment preferably includes: immersing the substrate in a piranha solution prepared with concentrated sulfuric acid and hydrogen peroxide solution at a volume ratio of 7:3 for 1 hour, thoroughly cleaning the substrate, washing it once with 1% ammonia water and then twice with deionized water to obtain a clean and hydrophilic substrate. In the present invention, the mass fraction of the concentrated sulfuric acid is preferably ≥98%; the mass concentration of the hydrogen peroxide solution is preferably 30%.

[0046] In this invention, the volume of the tetraphenylpyrazine dispersion added to the substrate is preferably 2 to 10 μL, more preferably 10 μL.

[0047] In this invention, the tetraphenylpyrazine dispersion is preferably added dropwise and then homogenized at a speed of 5000 r / min.

[0048] In this invention, the solvent removal preferably includes: placing the substrate with the added tetraphenylpyrazine dispersion in a constant temperature chamber at 70°C for continuous evaporation for 72 hours, and adjusting the humidity of the constant temperature chamber to 98% using a saturated K2SO4 solution. This invention arranges tetraphenylpyrazine microfibers into an irregular array on a substrate using a solvothermal evaporation method.

[0049] In the process of preparing tetraphenylpyrazine microfibers, the tetraphenylpyrazine crystals aggregate, thereby increasing the luminescence intensity of the tetraphenylpyrazine microfibers.

[0050] This invention provides a tetraphenylpyrazine microfiber prepared by the method described above. In this invention, the tetraphenylpyrazine microfiber preferably exhibits a one-dimensional rod-like structure, with a length preferably of 400–800 μm and a diameter preferably of 20–30 μm. In this invention, the surface of the tetraphenylpyrazine microfiber is relatively smooth, with fewer optical pores, and it possesses excellent optical waveguide performance.

[0051] In this invention, the tetraphenylpyrazine microfiber exhibits deep blue fluorescence emission under ultraviolet light irradiation.

[0052] This invention provides the application of the tetraphenylpyrazine microfiber described above as a waveguide material. In this invention, one end of the tetraphenylpyrazine microfiber is preferably coated with a fluorescent molecular material that absorbs wavelengths in the range of 420–450 nm. In this invention, the other end of the tetraphenylpyrazine microfiber can be irradiated with ultraviolet light to obtain light of the corresponding color.

[0053] This invention provides a waveguide modulator, comprising the tetraphenylpyrazine microfiber described in the above-mentioned technical solution; one end of the tetraphenylpyrazine microfiber is preferably coated with a mixed fluorescent molecular material containing fluorescent molecular materials with absorption wavelengths in the range of 420–450 nm. By coating one end of the tetraphenylpyrazine microfiber with the mixed fluorescent molecular material and irradiating the other end with ultraviolet light, this invention can achieve the purpose of waveguide end emission spectrum modulation by adjusting the composition of the mixed fluorescent molecular material.

[0054] In a specific embodiment of the present invention, white light emission is obtained when one end of the tetraphenylpyrazine microfiber is coated with a mixed fluorescent molecular material of green and red fluorescent molecules. In this invention, the green fluorescent molecule is preferably 4,7-bis(4-(1,2,2-triphenylvinyl)phenyl)benzo[c][1,2,5]thiadiazole (BTD); the red fluorescent molecule is preferably 2,3-bis(4-(bis(4-tert-butylphenyl)amino)phenyl)fumaronitrile (BTF). In this invention, the mass ratio of the green fluorescent molecule to the red fluorescent molecule is preferably 2-3:1-2.

[0055] This invention coats the ends of a tetraphenylpyrazine microfiber with other fluorescent small molecule materials. The tetraphenylpyrazine microfiber is excited by ultraviolet light irradiation, and the fluorescent small molecule materials attached to the ends are excited by the deep blue fluorescence of the microfiber ends. Two fluorescent small molecule materials, red and green, are used. White light emission is achieved by the fluorescence recombination of the three materials at the ends. This method can not only obtain white light emission, but also achieve the purpose of waveguide end emission spectrum modulation through the fluorescence recombination of materials.

[0056] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0057] Example 1

[0058] Add 73.5 mmol of anethole, 220.5 mmol of ammonium acetate, 110.3 mmol of acetic anhydride and 100 mL of acetic acid to a round-bottom flask; reflux the mixture and stir for 4 hours, then cool to room temperature, filter the precipitate and wash with acetic acid; recrystallize the crude product in hot acetic acid to obtain white needle-like crystals, namely tetraphenylpyrazine crystals as shown in Formula I, with a yield of 23.4%.

[0059] The structural characterization diagram of the tetraphenylpyrazine crystal (TPP-4OMe) prepared in this embodiment is shown in the figure below. Figure 1 As shown. Figure 1 a is the TPP-4OMe sample 1 HNMR spectrum, b is 13 C10 NMR spectrum, where c is the calculated relative molecular mass and d is a schematic diagram of molecular orbitals.

[0060] Example 2

[0061] The tetraphenylpyrazine crystals prepared in Example 1 were dispersed in 1 mL of a mixed solution of tetrahydrofuran and water (the concentration of tetrahydrofuran in the mixed solution was 0.001 mol / L) to obtain a tetraphenylpyrazine dispersion; the concentration of tetraphenylpyrazine in the tetraphenylpyrazine dispersion was 0.002 mol / L.

[0062] The size is 1.5×1.5cm 2 After immersing a glass slide in a piranha solution prepared with concentrated sulfuric acid (98% by mass) and hydrogen peroxide solution (30% by mass) in a volume ratio of 7:3 for 1 hour, a 1.5 × 1.5 cm slide was then placed on the slide. 2 The glass slides were thoroughly cleaned by rinsing them once with 1% ammonia solution and then twice with deionized water to obtain clean and hydrophilic glass slides.

[0063] 10 μL of the tetraphenylpyrazine dispersion was dropped onto a clean glass slide and homogenized at a speed of 5000 r / min. The slide was then placed in a constant temperature chamber at 70 °C and allowed to evaporate for 72 hours. The humidity of the chamber was adjusted to 98% using a saturated K2SO4 solution to obtain the tetraphenylpyrazine microfiber.

[0064] Test Example 1

[0065] The morphology of the tetraphenylpyrazine microfiber prepared in Example 2 is as follows: Figure 2 As shown. Figure 2 Image a is a SEM image of a tetraphenylpyrazine microfiber, image b is a magnified image of a selected area in image a, and images c and d are SEM images of the longitudinal section of the tetraphenylpyrazine microfiber.

[0066] Depend on Figure 2 As can be seen from a, the tetraphenylpyrazine microfiber prepared in this invention exhibits a one-dimensional rod-like structure with a length of 600–800 μm and a diameter of 20–30 μm; Figure 2 As can be seen from b, the surface of the tetraphenylpyrazine microfiber is relatively smooth and has few optical pores. Figure 2 Figures c and d show its one-dimensional rod-like shape, and its longitudinal cross-section is relatively smooth, exhibiting a rectangular appearance. Based on the above morphological characteristics, it can be determined that the tetraphenylpyrazine microfiber prepared in this invention possesses relatively excellent optical waveguide performance.

[0067] Test Example 2

[0068] The optical properties of the tetraphenylpyrazine microfiber prepared in Example 2 are as follows: Figure 3 As shown. Figure 3 a) Steady-state absorption spectrum of tetraphenylpyrazine microfiber; b) PL spectrum (10 μM) of TPP in THF-water with different water components (nanoaggregates and solutions); c) DLS distribution of nanoaggregates formed in a THF / water mixture with 90% water content; d) PL spectrum of tetraphenylpyrazine microfiber; e) Dark-field fluorescence microscopy image of tetraphenylpyrazine microfiber; f) CIE color coordinate diagram λ. ex =365nm.

[0069] like Figure 3 As shown in Figure a, the tetraphenylpyrazine microfiber exhibits maximum absorption at 359 nm in a THF / water solution (20 μM). When up to 90% water is added to the THF solution, the emission intensity gradually decreases but then begins to increase rapidly. At 99% water content, the emission intensity is more than 4 times higher than that of the pure THF solution. Figure 3 (b) Since TPP-4OMe is insoluble in water, its molecules must aggregate in aqueous mixtures with high water content. Clearly, TPP-4OMe exhibits AIE properties. The particle size distribution in the solution or suspension is mainly around 229.7 nm. Figure 3 c). Photoexcitation of the solution produces extremely strong deep blue emission at 425 nm. Figure 3 (d) Under 365nm ultraviolet light irradiation, the crystal also emits a deep blue fluorescence (d). Figure 3 (e). According to Figure 3 As can be seen from f, the color gamut of tetraphenylpyrazine crystals is located in the deep blue region.

[0070] Figure 4 The endpoint and side PL spectra (a, b) and CIE chromatograms (c, d) of the tetraphenylpyrazine microfiber prepared in Example 2.

[0071] pass Figure 4As shown in a and b, the luminescence intensity of the tetraphenylpyrazine microfiber differs between its endpoint and side surface, with the endpoint exhibiting a stronger luminescence. This aligns with the propagation characteristics of light, which propagates axially and eventually exits into free space from the endpoint. Due to the unique structure of the tetraphenylpyrazine microfiber, the internal waveguide path allows for the storage and amplification of specific wavelengths of light, resulting in a strong fluorescence signal. At the endpoint, the columnar geometry of the microfiber causes light to propagate along specific paths, creating a waveguide effect that may lead to deep blue fluorescence. Conversely, the special surface geometry of the tetraphenylpyrazine microfiber reflects light back, altering the propagation path and potentially resulting in light blue fluorescence. Figure 4 The CIE color coordinates in c and d can also reflect that the luminescence at the sample endpoint is more dazzling and has a deeper blue light emission.

[0072] Figure 5 Dark-field microscopy images of tetraphenylpyrazine crystals in solution, aggregate, and solid states (a), fluorescence lifetime spectra of different morphologies (b), and graphs of quantum yield versus fluorescence lifetime data (c).

[0073] like Figure 5 As shown in a, when TPP-4OMe is in THF / water solution (f w When fully dispersed in THF / water (10%), TPP-4OMe exhibits only very weak fluorescence emission under UV light irradiation. When the sample is placed in diluted THF / water (f... w In a 90% solution, TPP-4OMe exhibits strong blue light emission due to the addition of water, resulting in an aggregated state. However, when the sample is placed in a test tube in a solid state, TPP-4OMe displays very strong blue light emission due to π-π interactions between molecules. This is highly consistent with the optical properties of AIE compounds. Furthermore, based on the PL decay spectrum, it can be seen that TPP-4OMe achieves its highest fluorescence lifetime and quantum efficiency in the crystalline state. Figure 5 The fluorescence lifetimes (b) are 2.15 ns and 50.9%, respectively. This shows that TPP-4OMe in its crystalline state is very suitable for use as a blue light emitting device. However, in the THF / H2O state with a water content of 90%, the fluorescence lifetime reaches 0.47 ns (b). Figure 5 c) For a single material, the fluorescence lifetime is short and the electron-hole recombination is fast, which does not easily lead to fluorescence quenching, thus ensuring good photostability.

[0074] Test Example 3

[0075] Figure 6Dark-field microscopy image (a) of the tetraphenylpyrazine microfiber prepared in Example 2 over time, diameter distribution of the tetraphenylpyrazine microfiber over time (b), time-dependent fluorescence spectrum of the tetraphenylpyrazine microfiber (c), and photostability curves of the tetraphenylpyrazine microfiber and ICG under continuous laser irradiation (d). Figure 7 The image shows the fluorescence lifetime mapping of the tetraphenylpyrazine microfiber prepared in Example 2 as a function of power.

[0076] First, the photostability of the tetraphenylpyrazine microfiber prepared in this invention under 365nm illumination was studied, such as... Figure 6 As shown in Figure a, the tetraphenylpyrazine microfiber exhibits excellent photostability. Fluorescence microscopy images taken in the dark after 60 minutes of continuous irradiation show almost no change in brightness. Furthermore, the emission intensity in the tetraphenylpyrazine microfiber shows virtually no loss from 0 to 60 minutes. Figure 6 c). Stability in various physiological environments is crucial for biological applications, especially for obtaining stable optical waveguide imaging. Tetraphenylpyrazine microfibers exhibit good colloidal stability because their diameter changes little after two days of storage under environmental conditions. Figure 6 (b) Compared to the more common commercial fluorescent dye indocyanine green (ICG), it can be seen that the emission of tetraphenylpyrazine microfibers remains almost constant over time, while the emission of ICG decreases significantly. Figure 6 These studies demonstrate that tetraphenylpyrazine microfibers exhibit excellent stability under various conditions. Finally, the fluorescence lifetime mapping image ( Figure 7 It was found that the tetraphenylpyrazine microfiber maintained a constant fluorescence lifetime intensity under different powers of 405nm picosecond laser illumination, which also reflects the good stability of the tetraphenylpyrazine microfiber prepared in this invention.

[0077] The test results above show that the tetraphenylpyrazine microfiber prepared by this invention has a smooth surface with almost no optical pores, making it a very suitable optical waveguide material. Furthermore, its luminescence is very stable and can be stored at room temperature for two weeks. Simultaneously, by controlling the groups on the TPP substituents and adding methoxy groups, the multiple C–H…π interactions on the derivatives can help lock molecular motion in the crystal lattice and reduce non-radiative exciton deactivation, enhancing molecular activity and promoting stronger fluorescence emission from TPP-4OMe molecules. The luminescence at the endpoint of the tetraphenylpyrazine microfiber prepared by this invention is more intense than that at the end face; the emission intensity at this endpoint could be considered for activating other small organic molecule materials.

[0078] Test Example 4

[0079] (1) Passive waveguide test of the tetraphenylpyrazine microfiber prepared in Example 2: First, a laser was coupled to the top of the tetraphenylpyrazine microfiber by connecting a single-mode fiber to a laser. The angle between the tapered fiber, after stretching and grinding, and the bundle end face of the laser inlet was 0.2°. The relatively horizontal coupling end face can effectively reduce waveguide distortion and improve the transmission efficiency of the signal laser. The angle between the single-mode fiber used to transmit the laser and the coupling end face of the tetraphenylpyrazine microfiber was 5°. Under the microscope lens, it can be seen that the tapered fiber transmitting the laser has good contact with the coupling surface of the tetraphenylpyrazine microfiber, which is conducive to realizing evanescent wave coupling. Then, another tapered fiber was connected to the other end of the tetraphenylpyrazine microfiber to connect the power meter. Similarly, the end face of the tapered fiber and the sample was kept nearly horizontal by using the microscope lens to ensure the accuracy of the collected power data. The passive waveguide transmission test experimental device is as follows: Figure 8 As shown.

[0080] Figure 9 Dark-field microscopy images (a-c) of red, green and blue lasers of different wavelengths transmitted on the tetraphenylpyrazine microfiber prepared in Example 2, and linear fitting of its optical waveguide transmission loss (d-f).

[0081] The tetraphenylpyrazine microfiber selected on the glass slide was excited using lasers (473 nm, 532 nm, 655 nm) at five different local locations along its length. Figure 9 As can be seen from a to c, besides the excitation site, blue, green, and red emission were also observed at both ends. By extending the distance between the fixed emitting end and the excitation site and observing the light loss during propagation, it can be seen that the closer the excitation end is to the emitting end, the stronger the emission. The square roots (S) of the three propagation distances for different wavelengths of laser light in the experiment were measured. 1 / 2 ) and the logarithm of the laser power at both ends (log 10 [C]) Using equation S 1 / 2 =A*log 10 After performing linear fitting on [C]+B, the following is obtained: Figure 9 The linear relationship diagram from d to f shows a good linear correlation between each propagation distance and laser power, with a correlation coefficient R0. 2 >0.995, which means that TPP-4OMe can be used for low-power passive waveguide transmission, recording the laser power (I) at a fixed transmitter. WG ) and the laser power (I) at the excitation site EX ) and I WG To I EX Based on the passive waveguide transmission loss calculation formula shown in Equation 1, the passive waveguide loss of blue light is 0.166dB / μm, the waveguide loss of green light is 0.145dB / μm, and the waveguide loss of red light is 0.176dB / μm.

[0082]

[0083] (2) Active optical waveguide test of the tetraphenylpyrazine microfiber prepared in Example 2: The optical loss coefficient (α) is an important parameter that determines the performance of waveguide materials. Figure 10 Dark-field fluorescence microscopy images (a), emission spectra corresponding to the emitting end (b), the relationship between emission intensity at the fixed end and the distance between the excitation point and the emitting end (c), and the relationship between pump power and intensity (d) obtained by exciting the same tetraphenylpyrazine microfiber at different locations are shown. To determine the α value, such as... Figure 10 As shown in Figure a, the tetraphenylpyrazine microfiber selected on the coverslip was excited using a uniformly focused laser (365 nm) at six different local locations along its length. Recording at the fixed end (I...) end ) and transmitter (I body The emission intensity (b of 10) was obtained by fitting the data points in the graph and using curve fitting. Figure 10 c), the active waveguide loss of the tetraphenylpyrazine microfiber was calculated according to the waveguide loss coefficient α shown in Equation 2. In Equation 2, X is the distance between the excitation site and the emitting end, and A is the ratio of the light emitted from the excitation site to the light propagating along the rod. Subsequently, the corresponding relationship of light intensity at different powers was also tested. Figure 10 d).

[0084] I end / I body =Aexp -αX Equation 2.

[0085] Based on the above calculations, the α value of the tetraphenylpyrazine microfiber prepared in Example 2 is determined to be 0.035 dB / μm, which is quite low compared with the waveguide loss coefficient of other materials reported so far (as shown in Table 1). The tetraphenylpyrazine microfiber prepared in this invention is a very good waveguide material and is suitable for use as a miniaturized guided wave source. Figure 11 XRD diffraction patterns (a) and absorption and emission spectra (b) of TPP-4OMe samples in powder and crystalline forms. The low optical loss coefficient of TPP-4OMe may be related to its inherent large Stokes shift. Figure 11 (a) This helps reduce self-absorption. Furthermore, as... Figure 11 As shown in b, the X-ray diffraction spectra of the powder and the crystal form match well. The smooth surface and ordered molecular arrangement of the crystalline microfiber may also contribute to this good optical waveguide behavior, which has rarely been reported in TPP derivatives.

[0086] Table 1 Loss coefficients for different types of optical waveguides

[0087]

[0088] The photophysical properties of several typical AIE molecules are shown in Table 2. Figure 15 A comparison of the photophysical properties of the tetraphenylpyrazine prepared in this invention with several typical AIE molecules. (See Table 2 and...) Figure 15 It can be seen that the full width at half maximum (FWHM) of the TPP-4OMe microfiber is determined to be 34 nm, which is much narrower than that of the reported AIE molecules and organic dyes, indicating that it has excellent optical purity.

[0089] Table 2. Photophysical properties of several typical AIE molecules

[0090]

[0091]

[0092]

[0093] Application examples

[0094] Preparation of BTD: 0.005 mmol of Pd(PPh3)4 was added to a well-sealed mixture of toluene (20 mL) / ethanol (4.0 mL) / H2O (4.0 mL) consisting of 0.12 mmol of phenylboronic acid and 0.4 mmol of K2CO3; the resulting mixture was stirred at 80 °C for 24 hours under an argon atmosphere; after cooling, the mixture was evaporated to dryness, and the residue was subjected to column chromatography on silica (eluent: hexane and dichloromethane in a volume ratio of 85:15) to obtain BTD as a yellow-green powder with a yield of 75.0%.

[0095] Preparation of BTF: 0.07 mmol of C8H8NBr was added to 0.15 mmol of sodium methoxide and reacted under an iodine vapor atmosphere at -78 °C. After cooling, the mixture was placed in a drying oven at 90 °C and evaporated to dryness to obtain the residue BBF. The diphenylamine (DPA) derivative was incorporated into the BBF structure and reacted with 0.35 mmol of P(t-Bu)3·HBF4. After sonication, it was added to a well-sealed mixture of toluene (20 mL) / Pd(OAc)2 (0.23 mmol) / H2O (4 mL) consisting of 0.5 mmol CS2O3. The mixture was then dried in a drying oven at 90 °C to obtain BTF as a red powder with a yield of 65.0%.

[0096] Preparation of fluorescent small molecule (BTD) colloid: 5.65 mg of the BTD powder was uniformly dispersed in 7.8 mL of UV gel, and then 1.82 mL of ethanol was added to prepare a colloidal solution with a mass fraction of 2 mg / mL. The solution was stirred for 12 hours, and the resulting product was ultrasonically treated and then allowed to stand for 12 hours to obtain BTD small molecule colloid.

[0097] Preparation of fluorescent small molecule (BTF) colloid: 7.48 mg of the BTF powder was uniformly dispersed in 11.2 mL of UV gel, and then 3.45 mL of ethanol was added to prepare a colloidal solution with a mass fraction of 2 mg / mL. The solution was stirred for 12 hours, and the resulting product was ultrasonically treated and then allowed to stand for 12 hours to obtain BTF small molecule colloid.

[0098] Test Example 5

[0099] The BTD and BTF small molecule colloids prepared above were injected into one end of the tetraphenylpyrazine microfiber prepared in Example 2 using a digital pneumatic microinjection apparatus. The digital pneumatic microinjection apparatus was a DMP-300. The microneedles assembled on the apparatus had a diameter of 10 μm. The amount of BTD small molecule colloid used was 30 nL, and the amount of BTF small molecule colloid used was 20 nL. The injection pressure was 100 kPa, and the time accuracy was 0.1 s. The injection gas was nitrogen, and the power supply was DC. Because the luminescence of the BTD small molecule colloid was relatively dispersed, it was injected 10 times; the luminescence of the BTF small molecule colloid was more obvious, and it was injected 5 times.

[0100] The size is 2×3cm 2 After immersing a glass slide in a piranha solution prepared with concentrated sulfuric acid (98% by mass) and hydrogen peroxide solution (30% by mass) in a volume ratio of 7:3 for 1 hour, a 2×3cm glass slide was placed on the slide. 2 The glass slides were thoroughly cleaned, first with 1% ammonia solution and then twice with deionized water to obtain clean, hydrophilic glass slides. The assembled sample was placed on the cleaned glass slide, which was then placed on the stage. A Zeiss CRAIC 20 / 30PV™ microspectrophotometer was then used to acquire PL spectra and dark-field fluorescence microscopy images. A schematic diagram of tetraphenylpyrazine microfiber waveguide-excited BTD and BTF colloidal fluorescence is shown below. Figure 12 As shown, blue light from a tetraphenylpyrazine microfiber is excited by ultraviolet light, and blue light emitted from the other end of the tetraphenylpyrazine microfiber waveguide is used to excite the fluorescence of these two small molecule materials.

[0101] By adjusting the stage, 365nm incident light is focused onto one end of a tetraphenylpyrazine microfiber. The resulting blue fluorescence propagates along the microfiber, and the blue guided wave signal excites the BTD colloid coated at the other end of the microfiber. Figure 13As shown in Figure a, under blue light transmission in a tetraphenylpyrazine microfiber, the green fluorescence of the BTD colloid at the other end of the microfiber is excited. Because some blue light dissipates during transmission, and the green fluorescence of the BTD colloid exhibits large-scale luminescence with low intensity at single points, the green fluorescence at the other end is somewhat weak. However, through… Figure 13 The emission peak positions of the c-fluorescence spectrum show that green fluorescence was successfully activated, while BTF, due to its high single-point fluorescence intensity, exhibits good red fluorescence emission under blue guided wave signal excitation. Figure 13 (b). A clear red emission peak can also be seen in the fluorescence spectrum. Figure 13 d).

[0102] Using a digital pneumatic microinjection apparatus, the BTD and BTF small molecule colloids prepared above were injected into one end of the tetraphenylpyrazine microfiber prepared in Example 2. The amount of BTD small molecule colloid used was 30 nL, and the amount of BTF small molecule colloid used was 20 nL. After successfully igniting the two fluorescent small molecule materials, BTD and BTF colloids, white light emission was generated through the recombination of red, green, and blue fluorescence. The experimental schematic diagram is shown below. Figure 14 As shown in Figure a, in the specific experimental process, we simultaneously excited the green and red fluorescence of two other small molecule materials using a blue light guided wave signal. The three color light signals recombine at the end of the microscale optical fiber to produce white light. Figure 14 (b) The collected fluorescence spectrum also showed a white light spectrum. Figure 14 c). Color purity and quality have been evaluated using the CIE color space diagram according to the standards established by the International Commission on Illumination (CIE) in 1931, where the color coordinates (0.33, 0.33) are designated as very ideal white light (WL). Our CIE color coordinates for this application are (0.33, 0.35). Figure 14 The coordinates of d) roughly match the specified ideal WL coordinates, which can be used to determine that white light was generated by the fluorescent recombination of the above three materials.

[0103] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a tetraphenylpyrazine microfiber, characterized in that, Includes the following steps: Tetraphenylpyrazine was dispersed in a mixed solution of tetrahydrofuran and water to obtain a tetraphenylpyrazine dispersion; the tetrahydrofuran content in the mixed solution of tetrahydrofuran and water was 0.001~0.005 mol / L. The tetraphenylpyrazine dispersion was dropped onto the substrate, and the solvent was removed to obtain tetraphenylpyrazine microfibers; The concentration of tetraphenylpyrazine in the tetraphenylpyrazine dispersion is 0.001~0.005 mol / L; The tetraphenylpyrazine microfiber exhibits a one-dimensional rod-like structure with a length of 400~800μm and a diameter of 20~30μm; The solvent removal process includes: placing the substrate with the added tetraphenylpyrazine dispersion in a constant temperature chamber at 70°C for continuous evaporation for 72 hours, and adjusting the humidity of the constant temperature chamber to 98% using a saturated K2SO4 solution; The tetraphenylpyrazine has the structural formula shown in Formula I: 。 2. The tetraphenylpyrazine microfiber prepared by the preparation method of claim 1.

3. The application of the tetraphenylpyrazine microfiber of claim 2 as a waveguide material, characterized in that, One end of the tetraphenylpyrazine microfiber is coated with a fluorescent molecular material with an absorption wavelength of 420~450nm.

4. A waveguide modulator, characterized in that, The invention includes the tetraphenylpyrazine microfiber of claim 2; one end of the tetraphenylpyrazine microfiber is coated with a mixed fluorescent molecular material containing fluorescent molecular materials with absorption wavelengths in the range of 420-450 nm.

5. The waveguide modulator according to claim 4, characterized in that, When one end of the tetraphenylpyrazine microfiber is coated with a mixed fluorescent molecular material of green and red fluorescent molecules, white light emission is obtained.

6. The waveguide modulator according to claim 5, characterized in that, The green fluorescent molecule is 4,7-bis(4-(1,2,2-triphenylvinyl)phenyl)benzo[c][1,2,5]thiadiazole; the red fluorescent molecule is 2,3-bis(4-(bis(4-tert-butylphenyl)amino)phenyl)fumaronitrile.

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