Fluorescent covalent organic framework material rich in carboxyl carbazole as well as preparation and multi-mode detection application of fluorescent covalent organic framework material

Abstract

The invention relates to the technical field of fluorescent nano material application, in particular to a fluorescent covalent organic framework material rich in carboxyl carbazole, preparation and multi-mode detection application of the fluorescent covalent organic framework material. By introducing carbazole, COF is endowed with fluorescence through an intramolecular charge transfer (ICT) effect, meanwhile, selective fluorescence quenching is realized, TBBPS can be detected and adsorbed, and meanwhile, Fe < 3 + > and AA are detected in a fluorescence quenching-opening mode. Rich carboxyl has a negative regulation effect on a carbazole ICT mechanism. Adjacent carboxyl complementary D / L-arginine is introduced, and highly selective detection is carried out through fluorescence enhancement.

Description

Technical Field

[0001] This invention relates to the field of fluorescent nanomaterials application technology, and in particular to a fluorescent covalent organic framework material rich in carboxyl carbazole, its preparation and its multi-mode detection application. Background Technology

[0002] Covalent organic frameworks (COFs) are crystalline porous materials constructed from lightweight organic precursors through strong covalent bonds. Their core advantage lies in the diversity of organic precursors, allowing for precise control of specific surface area, pore structure, and surface functional groups, thus demonstrating great potential in adsorption, sensing, catalysis, and drug delivery. Among these, fluorescent COFs, as a special group, achieve highly sensitive and selective fluorescence responses to target analytes by cleverly integrating the inherent optical activity of functional precursors, specific functional groups, and the nano-confinement effect of the framework, making them ideal platform materials for constructing next-generation high-performance fluorescent sensors.

[0003] However, the selectivity of current fluorescent COF sensors is highly limited by the type of interaction forces (hydrogen bonds, π-π stacking, electrostatic interactions, etc.) between the COF and the target analyte, as well as the characteristics of the active site. Most existing COF-based fluorescent sensors can only target a single or specific class of analytes. This inherent single-function nature makes them ineffective in complex environments requiring simultaneous differentiation of multiple analytes. To achieve highly selective detection, precise structural modulation of the fluorescent COF is necessary. Therefore, introducing forces or active sites with higher selectivity is crucial for achieving selectivity and compatibility in dual detection modes.

[0004] The luminescence of fluorescent COFs originates from processes such as intramolecular charge transfer (ICT), excited-state intramolecular proton transfer (ESIPT), and / or photoinduced electron transfer (PET) within their structure. The functional groups (electron-withdrawing or electron-donating) of fluorescent COFs inherently influence ICT, ESIPT, and other related functions. Different analytes can selectively interact with these specific functional groups, perturbing or inducing ICT, ESIPT, PET, and other effects, ultimately achieving bidirectional modulation of fluorescence (i.e., enhancement or quenching, manifested as an "on" or "off" signal). Therefore, by carefully introducing specific electron-withdrawing / donating groups into fluorescent COFs, these groups can directly interact with different analytes, altering the luminescence behavior of the fluorescent COF, thus constructing a multi-analyte sensing platform capable of achieving dual detection modes ("off" and "on").

[0005] As mentioned above, the selectivity of fluorescent COF-based fluorescence sensors mainly depends on the type of interaction force with the target analyte, the number of active sites, and related factors. Compared with traditional forces such as hydrogen bonds and electrostatic interactions, halogen bonds, which possess directional and linear selectivity, can significantly enhance fluorescence recognition selectivity. Furthermore, based on structural features such as rotational flexibility and molecular size, they can more effectively distinguish different halogen-containing compounds, providing a new approach to compatible dual detection modes while improving selectivity. On the other hand, interference from coexisting analytes can be mitigated through chemical masking (e.g., ethylenediamine's effect on Cu). 2+ Alternatively, redox pretreatment can be used to eliminate or attenuate interference. This provides a pathway for selectively detecting originally interfering target analytes using the same fluorescent COF: masking agents block specific interferences; oxidants / reductants modify or transform interfering substances with redox activity. Integrating these strategies allows for the design of multiple fluorescence response modes (e.g., off-on-off) based on a single COF, expanding its multianalyte detection capabilities. Summary of the Invention

[0006] This invention provides a fluorescent covalent organic framework material rich in carboxyl carbazole, the raw materials for which include: an aminocarbazole compound and an aromatic compound rich in carboxyl groups.

[0007] In one embodiment of the present invention, the aminocarbazole compound is 3,6-diamino-carbazole or a derivative thereof.

[0008] In one embodiment of the present invention, the carboxyl-rich aromatic compound is 2,5-bis(4'-formylphenyl)terephthalic acid or a derivative thereof.

[0009] In one embodiment of the present invention, the ratio of the aminocarbazole compound and the carboxyl-rich aromatic compound is (0.05-1) mmol: (0.05-1) mmol.

[0010] As one embodiment of the present invention, the preparation method of a fluorescent covalent organic framework material rich in carboxyl carbazole includes the following steps:

[0011] Step 1: Add the aminocarbazole compound and the carboxyl-rich aromatic compound to the reaction vessel;

[0012] Step 2: Add solvent to the reaction vessel and dissolve by sonication;

[0013] Step 3: After complete dissolution, slowly add glacial acetic acid and continue ultrasonic treatment;

[0014] Step 4: After freezing several times by nitrogen circulation, react at 110-130℃ for 24-72 hours;

[0015] Step 5: After the reaction is complete, wash the product with acetone to remove the solvent;

[0016] Step 6: After washing, place in an oven to dry.

[0017] More specifically, as one embodiment of the present invention, the method for preparing a fluorescent covalent organic framework material rich in carboxyl carbazole includes the following steps:

[0018] The aminocarbazole compound and a carboxyl-rich aromatic compound were mixed in tetrahydrofuran; after sonication, glacial acetic acid was slowly added, and sonication was continued; then the mixture was frozen three times by nitrogen circulation and reacted at 120°C; after the reaction was completed, the reddish-brown precipitate was washed with acetone and the product was collected by centrifugation; finally, the product was dried.

[0019] Another aspect of this invention provides a multi-mode detection application for a fluorescent covalent organic framework material rich in carboxyl carbazole.

[0020] As one embodiment of the present invention, the fluorescent covalent organic framework material rich in carboxyl carbazole is applied to selective fluorescence quenching, detection and adsorption of TBBPS.

[0021] As one embodiment of the present invention, the fluorescent covalent organic framework material rich in carboxyl carbazole is characterized in that it is applied in a fluorescence quenching-on mode to detect Fe. 3+ And AA.

[0022] As one embodiment of the present invention, the fluorescent covalent organic framework material rich in carboxyl carbazole is characterized in that it is used for selective fluorescence enhancement to detect L / D-arginine.

[0023] As one embodiment of the present invention, a multifunctional fluorescent sensor system is constructed based on a fluorescent covalent organic framework material rich in carboxyl carbazole.

[0024] As one embodiment of the present invention, the system integrates detection, identification, adsorption and signal conversion into one unit, and is suitable for the analysis of complex matrices such as water, food and plasma.

[0025] By adopting the above technical solution, the present invention has the following beneficial effects:

[0026] A novel fluorescent covalent organic framework (COF) rich in carboxyl-carbazole, named COF-DABT, has been developed, exhibiting excellent fluorescence performance. This design enables the selective detection of various types of analytes. The introduction of the carbazole group not only endows COF-DABT with fluorescence properties through its inherent ICT effect but also provides halogen bond interaction sites (N), which is beneficial for the selective detection of halogen-containing analytes. Similarly, the incorporation of the carboxyl group (electron-withdrawing group) allows COF-DABT to bind to structurally compatible analytes through multi-site hydrogen bonding and to metal ions (e.g., Fe) through chelation effects. 3+ The interaction between the carboxyl group and the carboxyl group allows for the detection of AA via redox reactions. Furthermore, the interaction alters the effect of the carboxyl group on the electron cloud distribution of COF-DABT, thereby positively or reversibly modulating the carbazole-driven ICT effect and adjusting the fluorescence performance of COF-DABT. To this end, halogenated and halogen-free bisphenol compounds (BPs), amino acids capable of forming hydrogen bonds with the carboxyl group, and metal ions readily chelating with the carboxyl group and interacting with carbazole were selected as analytes to investigate the multianalyte selectivity and mechanism of the synthesized COF-DABT. Through different fluorescence mechanisms—fluorescence quenching, fluorescence quenching-recovery, and fluorescence enhancement—the detection of tetrabromobisphenol S (TBBPS) and Fe... 3+ Selective detection of ascorbic acid (AA) and D / L-arginine (D / L-Arg). Furthermore, in addition to halogen bond coordination and other interactions, COF-DABT can effectively enrich TBBPS, broadening the practical applications of fluorescent COFs. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 Preparation process and application diagram of COF-DABT

[0029] Figure 2 PXRD spectra of COF-MA under different conditions: A. Solvent composition; B. Solvent volume; C. Catalyst dosage; D. Reaction temperature; E. Reaction time

[0030] Figure 3FT-IR spectra of A.BTA, DAC, and COF-DABT; XPS energy spectrum of BE.COF-DABT and its C1s, N1s, and O1s regions; SEM and TEM images of FG.COF-DABT; TGA curve of H.COF-DABT; water contact angle of I.COF-DABT.

[0031] Figure 4 Fluorescence spectra and intensities of AB.COF-DABT at different pH values; fluorescence spectra and intensities of CD.COF-DABT in high-concentration NaCl salt solution; fluorescence spectra and intensities of EF.COF-DABT in high-concentration Na2SO4 salt solution; fluorescence spectra and intensities of GH.COF-DABT after different storage times.

[0032] Figure 5 A. Structural diagrams of TBBPS structural and functional analogs; BC. Selectivity of COF-DABT fluorescence detection.

[0033] Figure 6 Schematic diagrams of AL / D-Arg structural and functional analogs; BC.COF-DABT fluorescence detection selectivity.

[0034] Figure 7 The fluorescence detection selectivity of AB.COF-DABT in solutions of different metal ions.

[0035] Figure 8 A. Fluorescence spectra of COF-DABT at different concentrations of TBBPS; B. Linear relationship between COF-DABT and TBBPS; C. Fluorescence spectra of TBBPS detected by COF-DABT under interference from structural analogs; D. Fluorescence spectra of TBBPS detected by COF-DABT under different concentrations of structural analog interference; E. Static adsorption curve of TBBPS using COF-DABT; F. Dynamic adsorption curve of TBBPS using COF-DABT.

[0036] Figure 9 Fluorescence spectra of AB.COF-DABT at different concentrations of L / D-Arg; linear relationship between CD.COF-DABT and L / D-Arg; fluorescence spectra of EF.COF-DABT for detecting L / D-Arg under structural analog interference. Figure 10 A. COF-DABT at different Fe concentrations 3+ Fluorescence spectra of B.COF-DABT and Fe 3+ Linear relationship between them; detection of Fe under different metal interferences by C.COF-DABT 3+Fluorescence spectra of D.COF-DABT at different concentrations of AA; linear relationship between E.COF-DABT and AA; reusability of F.COF-DABT in the fluorescence detection of TBBPS, Fe3+ and D / L-Arg. Detailed Implementation

[0037] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0038] The reagents used are as follows:

[0039] 3,6-Diamino-carbazole (DAC, purity >98%), 2,5-bis(4'-formylphenyl)terephthalic acid (BTA, purity >95%), tetrahydrofuran, 1,4-dioxane, acetonitrile, glacial acetic acid, acetone.

[0040] Table 1. Specific raw materials used in Examples 1-4

[0041]

[0042] The preparation methods for Examples 1 to 4 are as follows:

[0043] DAC 3,6-diamino-carbazole (9.86 mg, 0.05 mmol) and BTA 2,5-bis(4'-formylphenyl)terephthalic acid (18.72 mg, 0.05 mmol) were added to a 20 mL Piezx tube, along with 6.0 mL of different solvents. After sonication for 10 min, 0.6 mL of HAc (6 M) was slowly added, and sonication was continued for another 5 min. The mixture was frozen three times under nitrogen circulation and reacted at 120 °C for 72 h. Subsequently, the reddish-brown precipitate was washed three times with acetone, and the product was collected by centrifugation (7500 rpm, 5 min). Finally, the product was dried under vacuum at 60 °C for 12 h to obtain reddish-brown powders, namely COF-DABT-1 to COF-DABT-4.

[0044] The COF-DABT-1 to COF-DABT-4 obtained in Examples 1 to 4 were subjected to PXRD spectral analysis. Figure 2 As shown in A, COF-DABT-1 with high crystallinity can be obtained by reacting in tetrahydrofuran.

[0045] Table 2. Specific raw materials used in Examples 5-8

[0046]

[0047] The preparation methods for Examples 5 to 8 are as follows:

[0048] DAC 3,6-diamino-carbazole (9.86 mg, 0.05 mmol) and BTA 2,5-bis(4'-formylphenyl)terephthalic acid (18.72 mg, 0.05 mmol) were added to a 20 mL Piezx tube, along with different volumes of tetrahydrofuran. After sonication for 10 min, 0.6 mL of HAc (6 M) was slowly added, followed by sonication for another 5 min. The mixture was frozen three times under nitrogen circulation and reacted at 120 °C for 72 h. Subsequently, the reddish-brown precipitate was washed three times with acetone, and the product was collected by centrifugation (7500 rpm, 5 min). Finally, the product was dried under vacuum at 60 °C for 12 h to obtain reddish-brown powders, which were then used to obtain COF-DABT-5, COF-DABT-1, COF-DABT-7, and COF-DABT-8, respectively.

[0049] The COF-DABT-5, COF-DABT-1, COF-DABT-7, and COF-DABT-8 obtained in Examples 5-8 were subjected to PXRD spectral analysis. Figure 2 As shown in B, COF-DABT-1 with high crystallinity can be obtained by reacting in 6 mL of tetrahydrofuran solution.

[0050] Table 3. Specific raw materials used in Examples 9-12

[0051]

[0052]

[0053] The preparation methods for Examples 9 to 12 are as follows:

[0054] DAC 3,6-diamino-carbazole (9.86 mg, 0.05 mmol) and BTA 2,5-bis(4'-formylphenyl)terephthalic acid (18.72 mg, 0.05 mmol) were added to a 20 mL Piezx tube, followed by 6 mL of tetrahydrofuran. After sonication for 10 min, different volumes of HAc (6 M) were slowly added, and sonication was continued for another 5 min. The mixture was frozen three times under nitrogen circulation and reacted at 120 °C for 72 h. Subsequently, the reddish-brown precipitate was washed three times with acetone, and the product was collected by centrifugation (7500 rpm, 5 min). Finally, the product was dried under vacuum at 60 °C for 12 h to obtain reddish-brown powders, which were then used to obtain COF-DABT-9, COF-DABT-1, COF-DABT-11, and COF-DABT-12, respectively.

[0055] The COF-DABT-9, COF-DABT-1, COF-DABT-11, and COF-DABT-12 obtained in Examples 9-12 were subjected to PXRD spectral analysis. Figure 2 According to C, COF-DABT-1 with high crystallinity can be obtained under 0.8 mL of HAc catalyst.

[0056] Table 4. Specific raw materials used in Examples 13-16

[0057]

[0058]

[0059] The preparation methods for Examples 13 to 16 are as follows:

[0060] DAC 3,6-diamino-carbazole (9.86 mg, 0.05 mmol) and BTA 2,5-bis(4'-formylphenyl)terephthalic acid (18.72 mg, 0.05 mmol) were added to a 20 mL Piezx tube, followed by 6 mL of tetrahydrofuran. After sonication for 10 min, 0.8 mL of HAc (6 M) was slowly added, and sonication was continued for another 5 min. The mixture was frozen three times under nitrogen circulation and reacted at different temperatures for 72 hours. Subsequently, the reddish-brown precipitate was washed three times with acetone, and the product was collected by centrifugation (7500 rpm, 5 min). Finally, the product was dried under vacuum at 60 °C for 12 h to obtain reddish-brown powders, namely COF-DABT-13, COF-DABT-14, COF-DABT-1, and COF-DABT-15.

[0061] The COF-DABT-13, COF-DABT-14, COF-DABT-1, and COF-DABT-15 obtained in Examples 13-16 were subjected to PXRD spectral analysis. Figure 2 As shown in D, COF-DABT-1 with high crystallinity can be obtained by reacting at 120℃.

[0062] Table 5. Specific raw materials used in Examples 17-19

[0063]

[0064] The preparation methods for Examples 17 to 19 are as follows:

[0065] DAC 3,6-diamino-carbazole (9.86 mg, 0.05 mmol) and BTA 2,5-bis(4'-formylphenyl)terephthalic acid (18.72 mg, 0.05 mmol) were added to a 20 mL Piezerx tube, followed by 6 mL of tetrahydrofuran. After sonication for 10 min, 0.8 mL of HAc (6 M) was slowly added, and sonication was continued for another 5 min. The mixture was frozen three times under nitrogen circulation and reacted at 120 °C for different times. Subsequently, the reddish-brown precipitate was washed three times with acetone, and the product was collected by centrifugation (7500 rpm, 5 min). Finally, the product was dried under vacuum at 60 °C for 12 h to obtain reddish-brown powders, namely COF-DABT-17, COF-DABT-18, and COF-DABT-1.

[0066] The COF-DABT obtained in Examples 17-19 were subjected to PXRD spectroscopy tests. Figure 2 E indicates that COF-DABT-1 with high crystallinity can be obtained after a reaction of 48 hours.

[0067] The synthesis of COFs relies on the reversibility of condensation reactions. This reversibility allows the chemical bonds between monomers to continuously break and reform, enabling the structure to "self-repair" and adjust. This dynamic self-repair process is crucial for the eventual formation of highly ordered crystal structures in COFs. However, since the formation of COFs is inherently thermodynamically controlled, the reaction rate must be precisely controlled. Too fast a reaction hinders ordered arrangement, while too slow a reaction may fail to effectively drive structural optimization; both reduce crystallinity and may even result in a completely amorphous product. Therefore, precisely controlling the reaction conditions to manage the rate is key to obtaining high-quality COF crystals. In this study, based on PXRD characterization results, the synthesis conditions of COF-DABT were systematically optimized. Figure 2 A-2C indicates that a highly crystalline COF-DABT can be obtained by reacting 6 mL of tetrahydrofuran and 0.8 mL of HAc. Furthermore, considering factors such as crystal stability and yield, Figure 2 DE determined 120℃ as the optimal reaction temperature and 48h as the optimal reaction time.

[0068] The fluorescent COF material prepared in Example 18 is characterized below.

[0069] Fourier Transmission Infrared (FT-IR) Analysis

[0070] Infrared spectroscopy display ( Figure 3 A) DAC is between 3396-3197cm -1 The tensile vibration peaks of primary amine NH and carbazole NH appear at the -COOH (3400-2700 cm⁻¹) for BTA. -1The -OH stretching vibration band and -COOH and -CHO (1718cm) -1 The C=O stretching vibration peak of -COOH is very obvious. After the reaction, the stretching vibration bands of -OH and -C=O on -COOH are retained, and the C=N (1664 cm⁻¹) band also appears. -1 The new tensile vibration peaks indicate that a Schiff base reaction occurred between DAC and BTA, generating an imine bond and successfully synthesizing COF-DABT.

[0071] Elemental Analysis (XPS)

[0072] XPS spectra of COF-DABT ( Figure 3 B) shows the presence of elements C (79.32%), N (7.35%), and O (13.33%), consistent with the theoretical structural elemental composition. Among them, the C 1s region ( Figure 3 C) The peaks corresponding to the CC, C=C, C=N, CN, and OC=O bonds appear at 284.4 eV, 284.7 eV, 285.1 eV, 285.8 eV, and 288.7 eV, respectively. In the N1s region ( Figure 3 In D), peaks corresponding to N=C, NC, and NH bonds are observed at 398.6 eV, 399.4 eV, and 400.2 eV. Furthermore, the O 1s region ( Figure 3 E) The peaks corresponding to the OC and O=C bonds appear at 532.9 eV and 531.2 eV, respectively. These results collectively confirm the formation of the imine bond, indicating the successful synthesis of COF-DABT.

[0073] Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis

[0074] like Figure 3 As shown in F-3G, the microstructure and surface morphology of CCOF-DABT were observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The SEM and TEM images reveal that COF-DABT exhibits spherical clusters, layered upon each other, displaying a distinct lattice pattern.

[0075] Thermogravimetric analysis (TGA)

[0076] like Figure 3 As shown in Figure H, the thermal stability of COF-DABT was evaluated using thermogravimetric analysis (TGA). Due to the evaporation of residual solvent and moisture, a weight loss of approximately 7.9% occurred at 300°C. Further weight loss occurred between 300 and 800°C due to the decomposition of the carbon skeleton. The gradual decomposition and collapse of the COF-DABT structure led to a significant increase in weight loss.

[0077] Water contact angle analysis

[0078] The hydrophilicity / hydrophobicity of COF-DABT was studied using an AFES contact angle meter. Figure 3 As shown in Figure I, the measured water contact angle of COF-DABT is 70.97°, demonstrating the hydrophilicity of COF-DABT and its suitability for applications in water systems.

[0079] Application Example 1

[0080] The fluorescence stability of the fluorescent COF material prepared in Example 18 was studied.

[0081] To explore the potential of COF-DABT for multimodal detection in complex samples, the fluorescence stability of COF-DABT was first evaluated. COF-DABT was dispersed in water to obtain 25 μg·mL⁻¹. -1 The COF-DABT aqueous dispersion was prepared. The time stability of COF-DABT was determined by measuring the fluorescence intensity at an excitation wavelength of 315 nm (λex) every hour after the COF-DABT was left to stand for an extended period of time.

[0082] To evaluate the pH stability of COF-DABT, 0.3 mL of solutions with different pH values ​​were added to 2.7 mL of COF-DABT (25 μg / mL). -1 After being thoroughly mixed, the fluorescence intensity was measured at λex = 315 nm.

[0083] To evaluate the anti-ion interference properties of COF-DABT, 0.3 mL of a low-concentration salt solution (0-10 mM) was added to 2.7 mL of COF-DABT, and after thorough mixing, the fluorescence intensity at λex = 315 nm was measured.

[0084] Figure 4 A-4H analysis showed that COF-DABT exhibited fluorescence stability over a wide pH range of 4–9, even at high salt concentrations of 1 mM. Furthermore, the fluorescence of COF-DABT showed only minor fluctuations over 10 h, indicating its robustness and resistance to interference under various environmental conditions.

[0085] Application Example 2

[0086] The fluorescence detection performance of the fluorescent COF material prepared in Example 18 was analyzed.

[0087] To investigate the selectivity and sensitivity of COF-DABT in detecting TBBPS, other bisphenols were used as competing substances. COF-DABT was dispersed in ethanol to obtain 25 μg·mL⁻¹. -1The COF-DABT ethanol dispersion was prepared. 0.3 mL of each analyte (1 mM) was added to 2.7 mL of COF-DABT, and after thorough mixing, the fluorescence intensity was measured at λex = 315 nm to analyze the detection selectivity of COF-DABT.

[0088] Then, 0.3 mL of 0-1 mM TBBPS was added to 2.7 mL of COF-DABT, mixed thoroughly, and the fluorescence intensity was measured at λex = 315 nm to analyze the detection sensitivity of COF-DABT for TBBPS. Subsequently, the fluorescence intensity of COF-DABT detecting TBBPS was measured under different concentrations of structural analogs to explore the anti-interference ability of COF-DABT. A mixture of 0.3 mL of TBBPS and structural analogs (1:1, 1:10, 1:20, or 1:50 equivalents) was added to 2.7 mL of COF-DABT, and the fluorescence intensity at λex = 315 nm was measured.

[0089] To clarify the reusability of COF-DABT in TBBPS detection, a COF-DABT ethanol dispersion (25 μg / mL) was prepared in 2.7 mL of the dispersion. -1 The COF-DABT was added to 0.3 mL of 1 mM TBBPS, and the fluorescence intensity before and after the addition of TBBPS was measured at λex = 315 nm. The remaining COF-DABT was dried, and then ethanol was added back in until the concentration was restored to 25 μg / mL. -1 The fluorescence intensity was measured at λex = 315 nm before and after the addition of TBBPS. This was recorded as one cycle. The cycle was repeated 5 times to demonstrate the reusability of the fluorescence of COF-DABT.

[0090] The selectivity of COF-DABT for the detection of bisphenols was studied. TBBPS was used as the target analyte, and its structural and functional analogues were used as competing analytes. The structures are as follows: Figure 5 As shown in Figure A. Figure 5 B-5C analysis showed that TBBPS significantly quenched the fluorescence of COF-DABT, while the influence of other competing analytes was negligible, highlighting the excellent fluorescence detection selectivity of COF-DABT for TBBPS. Furthermore, Figure 8 A-8B showed that the fluorescence intensity of COF-DABT decreased with increasing TBBPS concentration. A linear relationship was observed for TBBPS concentrations ranging from 0 to 100 μM, R... 2 >0.9947, LODs as low as 167 nM·mL -1These results demonstrate that COF-DABT exhibits excellent sensitivity in detecting TBBPS, enabling precise quantification of low concentrations of TBBPS via fluorescence analysis. Given the structural similarity between TBBPS and its analogues, the fluorescence intensity of COF-DABT was further evaluated to assess its anti-interference capability when structural analogues were mixed with TBBPS in equivalence ratios of 1:1, 1:10, 1:20, or 1:50. Figure 8 C-8D analysis showed that the bisphenol mixture did not alter the overall fluorescence spectral shape of COF-DABT. Even at a 50:1 equivalent ratio, the effect of TCBPA on the fluorescence detection of TBBPS by COF-DABT was negligible. TBBPA, however, showed a slight effect at this ratio, although the effect remained small even at a lower 20:1 equivalent ratio, confirming the excellent selectivity of COF-DABT for TBBPS. Furthermore, fluorescence reusability is an important parameter for evaluating the durability and lifespan of COF-DABT. Figure 10 F shows that after 5 cycles, the fluorescence intensity of COF-DABT fluctuates within an acceptable range, reflecting the stable fluorescence properties and reusability of COF-DABT.

[0091] To investigate the adsorption performance of COF-DABT on TBBPS, static and dynamic adsorption experiments were conducted. In the static experiments, 1.0 mg of COF-DABT was added to ethanol-water solutions (v / v, 1:1, 1.0 mL) containing different concentrations of TBBP. The mixture was shaken at 200 rpm for 3 hours. The supernatant was then obtained by centrifugation at 7000 rpm for 10 minutes and filtered through a 0.22 μm microfiltration membrane. The supernatants were subsequently analyzed by UV-Vis spectroscopy. For the dynamic adsorption experiments, 1.0 mg of COF-DABT was added to a TBBPS solution (150 μg·mL⁻¹, 1.0 mL), and the mixture was shaken for different durations (0–60 min). The supernatant was then obtained by centrifugation at 7000 rpm for 10 minutes and filtered through a 0.22 μm microfiltration membrane. The supernatants were then analyzed by UV-Vis spectroscopy to assess the adsorption performance of COF-DABT on TBBPS.

[0092] The adsorption performance of COF-DABT on TBBPS was studied, and static and dynamic adsorption experiments were conducted. Figure 8 E indicates that the adsorption capacity of COF-DABT for TBBPS gradually increases with increasing concentration, reaching a maximum of 71.2 mg·g⁻¹. -1 To further investigate the dynamic adsorption process of TBBPS by COF-DABT, adsorption experiments were conducted at different time intervals. Figure 8F showed that COF-DABT adsorbed TBBPS at a very rapid rate, reaching 56.3 mg / g within approximately 1 minute. -1 The adsorption capacity was measured, and equilibrium was reached within approximately 5 minutes. The maximum adsorption capacity at equilibrium was determined to be 64.8 mg·g⁻¹. -1 This reflects the effective adsorption of TBBPS by COF-DABT.

[0093] Application Example 3

[0094] The fluorescence detection performance of the fluorescent COF material prepared in Example 18 was analyzed.

[0095] To investigate the selectivity and sensitivity of COF-DABT in detecting L / D-Arg, other amino acids were used as competing substances. COF-DABT was dispersed in water to obtain 25 μg·mL⁻¹. -1 COF-DABT aqueous dispersion. 0.3 mL of each analyte (1 mM) aqueous solution was added to 2.7 mL of COF-DABT. After thorough mixing, the fluorescence intensity was measured at λex = 315 nm to determine the detection selectivity of COF-DABT.

[0096] Then, 0.3 mL of 0-1 mM L / D-Arg was added to 2.7 mL of COF-DABT, mixed thoroughly, and the fluorescence intensity was measured at λex = 315 nm to analyze the detection sensitivity of COF-DABT for L / D-Arg. Subsequently, the fluorescence intensity of COF-DABT detecting L / D-Arg was measured in the presence of the structural analog to investigate the anti-interference ability of COF-DABT. A mixture of 0.3 mL of L / D-Arg and the structural analog (1:1 equivalent) was added to 2.7 mL of COF-DABT, and the fluorescence intensity at λex = 315 nm was measured.

[0097] To clarify the reusability of COF-DABT in L / D-Arg detection, a COF-DABT aqueous dispersion (25 μg / mL) was prepared in 2.7 mL of COF-DABT. -1 The COF-DABT was added to 0.3 mL of L / D-Arg (1 mM), and the fluorescence intensity before and after the addition of L / D-Arg was measured at λex = 315 nm. The remaining COF-DABT was dried, and then water was added back to restore the concentration to 25 μg·mL⁻¹. -1 The fluorescence intensity was measured at λex = 315 nm before and after the addition of L / D-Arg. This was recorded as one cycle. The cycle was repeated 5 times to demonstrate the reusability of the fluorescence of COF-DABT.

[0098] The selectivity of COF-DABT for amino acid detection was studied, using L / D-Arg as the target analyte and its structural analogue as a competing analyte, the structure of which is shown in the figure below. Figure 6 As shown in Figure A. Figure 6 B-6C analysis showed that L / D-Arg significantly enhanced the fluorescence of COF-DABT, while the influence of other competing analytes was almost negligible, highlighting the excellent fluorescence detection selectivity of COF-DABT for L / D-Arg. Furthermore, Figure 9 A-9D analysis showed that the fluorescence intensity of COF-DABT increased with increasing L / D-Arg concentration. A linear relationship was observed for L / D-Arg concentrations ranging from 0 to 60 μM, with R... 2 The fluorescence intensity was >0.9967, and the LODs were as low as 0.33 μM. These results demonstrate that COF-DABT has excellent sensitivity in detecting L / D-Arg, enabling precise quantification of low concentrations of target amino acids via fluorescence analysis. Given the structural similarity between L / D-Arg and its analogues, the fluorescence intensity of COF-DABT was further evaluated by mixing the structural analogue with L / D-Arg in a 1:1 equivalent ratio to assess its anti-interference capability. Figure 9 E-9F analysis showed that the amino acid mixture had little effect on the detection of L / D-Arg by COF-DABT, indicating that COF-DABT exhibits high selectivity for D / L-Arg, making it an effective fluorescence-activated sensor for selective L / D-Arg detection. Furthermore, fluorescence reusability is an important parameter for evaluating the robustness and lifespan of COF-DABT. Figure 10 F shows that after 5 cycles, the fluorescence intensity of COF-DABT fluctuates within an acceptable range, reflecting the stable fluorescence properties and reusability of COF-DABT.

[0099] Application Example 4

[0100] To investigate the detection of Fe by COF-DABT 3+ The selectivity and sensitivity of the material are improved by using other metal ions as competitors, including Pb. 2+ Mg 2+ Fe 3+ Mn 2+ Cu 2+ Na + Mo 2+ Hg 2+ Fe 2+ Ca 2+ and Ba 2+COF-DABT was dispersed in water to obtain a 25 μg·mL⁻¹ COF-DABT aqueous dispersion. 0.3 mL of metal ions (1 mM) was added to 2.7 mL of COF-DABT, and after thorough mixing, the fluorescence intensity was measured at λex = 315 nm to analyze the detection selectivity of COF-DABT.

[0101] Then, 0.3 mL of 0-1 mM Fe was added to 2.7 mL of COF-DABT. 3+ After thorough mixing, the fluorescence intensity was measured at λex = 315 nm to analyze the effect of COF-DABT on Fe. 3+ The detection sensitivity was then assessed. Subsequently, the detection sensitivity of Fe by COF-DABT was measured under different metal ion coexistence conditions. 3+ The fluorescence intensity was measured to investigate the anti-interference ability of COF-DABT. 0.3 mL of Fe... 3+ The mixture with the structural analog (1:1 equivalent) was added to 2.7 mL of COF-DABT, and the fluorescence intensity at λex = 315 nm was measured.

[0102] To clarify the role of COF-DABT in Fe 3+ The reusability in the test was demonstrated in 2.7 mL of COF-DABT aqueous dispersion (25 μg·mL⁻¹). -1 0.3 mL of Fe was added to the solution. 3+ In (1mM), the addition of Fe was measured at λex = 315nm. 3+ Fluorescence intensity before and after. The remaining COF-DABT was dried, and then water was added back until the concentration was restored to 25 μg / mL. -1 And the addition of Fe was measured at λex = 315 nm. 3+ Fluorescence intensity before and after. This was recorded as one cycle. The cycle was repeated 5 times to demonstrate the reusability of COF-DABT fluorescence.

[0103] Finally, due to Fe 3+ A reduction reaction occurred between AA and COF-DABT / Fe 3+ The system can be used for AA detection. COF-DABT was dispersed in water to obtain 25 μg / mL. -1 COF-DABT aqueous dispersion. 0.3 mL of AA at different concentrations and 0.3 mL of Fe3+ (400 μM) were added to 2.4 mL of COF-DABT aqueous solution (25 μg·mL⁻¹). After thorough mixing and incubation for 5 minutes, fluorescence intensity was measured at λex = 315 nm.

[0104] The effect of COF-DABT on Fe was studied. 3+The selectivity is achieved by using other metal ions as competing analytes. Figure 7 A-7B indicates that Fe 3+ The fluorescence of COF-DABT was significantly quenched, while the effects of other competing analytes were almost negligible, highlighting the effectiveness of COF-DABT in inhibiting Fe2+ fluorescence. 3+ It exhibits good fluorescence detection selectivity. Furthermore, Figure 10 A-10B shows that the fluorescence intensity of COF-DABT increases with Fe... 3+ The concentration decreases with increasing concentration. This applies to Fe in the concentration range of 0-100 μM. 3+ The relationship is linear, R 2 >0.9955, LODs as low as 83 nM. These results demonstrate the effectiveness of COF-DABT in detecting Fe. 3+ It exhibits excellent sensitivity and can accurately quantify low concentrations of Fe through fluorescence analysis. 3+ The fluorescence intensity of COF-DABT was further evaluated when other metal ions were mixed in a 1:1 equivalent ratio to examine its anti-interference ability. Figure 10 C shows that the metal ion mixture does not change the overall fluorescence spectral shape of COF-DABT, and even in the presence of competing metal ions, COF-DABT exhibits good fluorescence response to Fe. 3+ It also exhibits significant selectivity, highlighting its strong detection specificity. Furthermore, fluorescence reusability is an important parameter for evaluating the robustness and lifespan of COF-DABT. Figure 10 F shows that after 5 cycles, the fluorescence intensity of COF-DABT fluctuates within an acceptable range, reflecting the stable fluorescence properties and reusability of COF-DABT.

[0105] Finally, considering Fe 3+ Its oxidizing properties allow it to undergo reduction reactions with certain reducing agents. When Fe... 3+ When reacting with a reducing agent, Fe is formed. 2+ This produces a fluorescence shut-off effect, enabling the detection of reducing agents. Due to Fe... 3+ A reduction reaction occurred between AA and COF-DABT / Fe 3+ The system can be used for AA detection. Figure 10 D-10E indicates that in COF-DABT / Fe 3+ In a (40 μM) system, the addition of different concentrations (0-120 μM) of AA resulted in a linear increase in the fluorescence intensity of COF-DABT. This linear relationship was observed for AA concentrations ranging from 0 to 120 μM. 2 >0.9987, LODs as low as 3.33 μM. These results demonstrate that COF-DABT / Fe 3+(40 μM) has excellent sensitivity in detecting AA and can accurately quantify low concentrations of AA through fluorescence analysis.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fluorescent covalent organic framework material rich in carboxyl carbazole, characterized in that, Its raw materials include: aminocarbazole compounds and aromatic compounds rich in carboxyl groups.

2. The fluorescent covalent organic framework material rich in carboxyl carbazole according to claim 1, characterized in that, The aminocarbazole compound is 3,6-diamino-carbazole or a derivative thereof.

3. The fluorescent covalent organic framework material rich in carboxyl carbazole according to claim 1, characterized in that, The carboxyl-rich aromatic compound is 2,5-bis(4'-formylphenyl)terephthalic acid or a derivative thereof.

4. The method for preparing a fluorescent covalent organic framework material rich in carboxyl carbazole according to claim 1, characterized in that, The ratio of the aminocarbazole compound to the carboxyl-rich aromatic compound is (0.05–1) mmol: (0.05–1) mmol.

5. A method for preparing a fluorescent covalent organic framework material rich in carboxyl carbazole according to any one of claims 1 to 4, characterized in that, Includes the following steps: Step 1: Add the aminocarbazole compound and the carboxyl-rich aromatic compound to the reaction vessel; Step 2: Add solvent to the reaction vessel and dissolve by sonication; Step 3: After complete dissolution, slowly add glacial acetic acid and continue ultrasonic treatment; Step 4: After freezing several times by nitrogen circulation, react at 110-130℃ for 24-72 hours; Step 5: After the reaction is complete, wash the product with acetone to remove the solvent; Step 6: After washing, place in an oven to dry.

6. A fluorescent covalent organic framework material rich in carboxyl carbazole according to any one of claims 1 to 4, characterized in that, It is used for selective fluorescence quenching, detection and adsorption of TBBPS.

7. A fluorescent covalent organic framework material rich in carboxyl carbazole according to any one of claims 1 to 4, characterized in that, Applied to fluorescence quench-on mode, for detecting Fe 3+ And AA.

8. A fluorescent covalent organic framework material rich in carboxyl carbazole according to any one of claims 1 to 4, characterized in that, It is used for selective fluorescence enhancement to detect L / D-arginine.

9. A multifunctional fluorescent sensor system based on a fluorescent covalent organic framework material rich in carboxyl carbazole as described in any one of claims 1 to 4.

10. The sensor system as described in claim 9, characterized in that, The system integrates detection, identification, adsorption, and signal conversion, and is suitable for analysis of complex matrices such as water, food, and plasma.

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