A solid-state luminescent schiff base two-dimensional covalent organic framework material, a preparation method and application thereof
By preparing highly crystalline Schiff base two-dimensional covalent organic framework materials, the problem of Schiff base COFs being unable to achieve solid-state luminescence has been solved, achieving high-efficiency solid-state luminescence performance and expanding their application range in sensing, imaging and optoelectronic devices.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- INST OF CHEM CHINESE ACAD OF SCI
- Filing Date
- 2024-11-27
- Publication Date
- 2026-05-29
Smart Images
Figure CN122103490A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of materials, specifically to a solid-state luminescent Schiff base two-dimensional covalent organic framework material, its preparation method, and its applications. Background Technology
[0002] Solid-state luminescent COFs hold significant promise for applications in sensing, imaging, and optoelectronic devices. While solid-state luminescence has been achieved in COFs with borate esters, double bonds, and hydrazone linkages, imine-linked COFs remain challenging to achieve due to complex nonradiative transition processes. Recent reports have demonstrated that aliphatic building blocks can disrupt in-plane conjugation and interlayer interactions in Schiff base COFs, thus enabling solid-state luminescence. However, the flexibility of aliphatic building blocks often results in poor crystallinity of the prepared COFs, and the controllability of their photoelectric properties is severely limited, significantly restricting their applications in related fields. Achieving solid-state luminescence of Schiff base COFs prepared from aromatic building blocks remains a considerable challenge.
[0003] Current explanations for the non-luminescence of Schiff base COFs mainly include: aggregation-induced quenching (ACQ) effect, imine bond rotation, and photoinduced electron transfer. The first type of imine COFs that achieve solid-state luminescence primarily achieves this by controlling their stacking pattern, using an AB stacking method to reduce non-radiative transitions caused by the ACQ effect. Another reported example achieves solid-state luminescence by using aliphatic building blocks to break down intraplane conjugation and interlayer interactions. Breaking down intraplane conjugation essentially means the framework restricts molecular vibrations, while increasing interlayer distance effectively reduces the ACQ effect, thereby improving luminescence performance.
[0004] Although there have been some reports on controlling the stacking of COFs, it is difficult to control the stacking mode once the conventional organic light-emitting building blocks are fixed. The disadvantage of aliphatic building blocks is that they result in poor crystallinity of the synthesized COFs, making it difficult to fully utilize their porosity, lacking stability, and thus hindering their application. Summary of the Invention
[0005] The purpose of this invention is to provide a solid-state luminescent Schiff base two-dimensional covalent organic framework material, its preparation method, and its application. The Schiff base two-dimensional covalent organic framework material of this invention has good application prospects in sensing, imaging, optoelectronic devices, and other fields.
[0006] This invention first provides a method for preparing a solid-state luminescent Schiff base two-dimensional covalent organic framework material, comprising the following steps: mixing an amine with C2 symmetry, DAD, a solvent, and an aqueous acetic acid solution, and carrying out a solvothermal reaction to obtain the solid-state luminescent Schiff base two-dimensional covalent organic framework material; The solvent is o-dichlorobenzene and n-butanol.
[0007] The DAD structure is as follows: .
[0008] In the above preparation method, the amine with C2 symmetry is tetra-(4-aminophenyl)pyrene (Py), tetra-(4-aminophenyl)ethylene (PE), or tetra-(4-aminophenyl)benzene (BATA).
[0009] In the above preparation method, the molar ratio of the amine with C2 symmetry to DAD is 1:2-2:1; preferably 1:1.
[0010] In the above preparation method, the volume ratio of o-dichlorobenzene to n-butanol is 1:3-3:1; preferably 1:1. The total molar ratio of the amine with C2 symmetry and DAD to the solvent is 0.068 mmol: 1-3 mL; preferably 0.068 mmol: 2 mL.
[0011] In the above preparation method, the concentration of the acetic acid aqueous solution is 3-9 M, specifically 6 M; The volume of the acetic acid aqueous solution is 0.08-0.12 times the volume of the solvent, specifically 0.1 times.
[0012] In the above preparation method, the solvothermal reaction is carried out in an inert atmosphere; The temperature of the solvothermal reaction is 90-120℃, specifically 120℃; the time is 2-4 days, specifically 3 days.
[0013] In one embodiment of the present invention, the solvothermal reaction is carried out in a polymerization tube; the system is subjected to freeze-drying circulation before the reaction to remove air from the system.
[0014] In the above preparation method, after the solvothermal reaction is completed, there is a step of extracting with tetrahydrofuran until the solution is colorless, and then drying the obtained solid under vacuum; specifically, the drying temperature is 90-120℃, specifically 90℃.
[0015] Furthermore, the present invention provides a solid-state luminescent Schiff base two-dimensional covalent organic framework material prepared by the above preparation method.
[0016] The application of the above-mentioned solid-state luminescent Schiff base two-dimensional covalent organic framework material in bioimaging or in the fabrication of organic optoelectronic devices also falls within the scope of protection of this invention.
[0017] In the bioimaging process, the solid-state luminescent Schiff base two-dimensional covalent organic framework material serves as an imaging agent. In the organic optoelectronic device, the solid-state luminescent Schiff base two-dimensional covalent organic framework material serves as the optoelectronic layer.
[0018] This invention expands the range of solid-state luminescent COFs in the Schiff base field for the first time, providing the possibility for designing and preparing more solid-state luminescent Schiff base COFs.
[0019] The COFs material prepared by this invention has high crystallinity and porosity, and a solid-state absolute luminescence quantum yield of up to 39%. Attached Figure Description
[0020] Figure 1 The preparation process of BATA-DAD COF; Figure 2 Infrared spectrum of BATA-DAD COF; Figure 3 Solid-state NMR for BATA-DAD COF; Figure 4 PXRD and refinement data for BATA-DAD COF; Figure 5 The adsorption-desorption curves of BATA-DAD COF; Figure 6 Absolute luminescent quantum yield data for BATA-DAD COF powder; Figure 7 The preparation process of Py-DAD COF; Figure 8 The infrared spectrum of Py-DAD COF; Figure 9 Solid-state NMR for Py-DAD COF; Figure 10 PXRD and refinement data for Py-DAD COF; Figure 11 The adsorption-desorption curves of Py-DAD COF are shown. Figure 12 Absolute luminescent quantum yield data for Py-DAD COF powder; Figure 13 The preparation process of PE-DAD COF; Figure 14 The infrared spectrum of PE-DAD COF; Figure 15 Solid-state NMR for PE-DAD COF; Figure 16 PXRD and refinement data for PE-DAD COF; Figure 17 The adsorption-desorption curves of PE-DAD COF are shown. Figure 18 The absolute luminescent quantum yield data are for PE-DAD COF powder. Detailed Implementation
[0021] The present invention will be further described in detail below with reference to specific embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.
[0022] Unless otherwise specified, the experimental methods described in the following examples are conventional methods.
[0023] In the quantitative experiments in the following examples, three replicate experiments were set up, and the average value of the results was taken.
[0024] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.
[0025] The absolute luminescent quantum yield in the following examples was detected using a HORIBA fluorescence spectrometer (FluoroMax+).
[0026] Example 1 0.034 mmol of tetra-(4-aminophenyl)benzene (BATA, CAS: 2458125-05-6) and 0.034 mmol of 4,4',4'',4'''-[2,1,3-benzothiadiazole-4,7-diylbis(4,1-phenylenenitrilo)]tetrakis-Benzaldehyde (DAD, CAS: 1446426-30-7) were weighed into a polymerization tube. 1 mL each of o-dichlorobenzene and n-butanol were added, and the mixture was sonicated for 10 min to disperse evenly. Then, 0.2 mL of [the mixture] was added. A 6M aqueous acetic acid solution was sonicated for 5 minutes, followed by three freeze-dry cycles to remove air from the system and seal the tube. After the system cooled to room temperature, it was placed in a 120℃ oven and allowed to react for 3 days. After the reaction was completed, it was removed and allowed to return to room temperature. It was then extracted with THF (tetrahydrofuran) until the solution became colorless. The resulting solid was then dried in a 90℃ vacuum drying oven to obtain BATA-DAD COF.
[0027] Figure 1 The preparation process of BATA-DAD COF is described.
[0028] Figure 2 The infrared spectrum of BATA-DAD COF is shown; the characteristic peaks corresponding to BATA and DAD have significantly disappeared or weakened, combined with the 1623 cm⁻¹ peak. -1 The presence of an imine bond indicates that the reaction proceeded relatively fully and that an imine bond was formed.
[0029] Figure 3Solid-state NMR of BATA-DAD COF; the solid-state NMR assigned its characteristic peaks, with approximately 158 ppm corresponding to imine carbon, confirming the formation of the Schiff base structure.
[0030] Figure 4 The PXRD and refinement data of BATA-DAD COF are shown; the results show that BATA-DAD COF and the refined structure are in good agreement.
[0031] Figure 5 The adsorption-desorption curves of BATA-DAD COF are shown; the results indicate that its specific surface area is as high as 1746 m². 2 / g.
[0032] Figure 6 The data represent the absolute luminescent quantum yield of BATA-DAD COF powder; the maximum emission wavelength is ~600 nm, and the solid-state absolute luminescent quantum yield at room temperature is 39.59%.
[0033] Example 2 Tetra-(4-aminophenyl)pyrene (Py, CAS: 1610471-69-6) (0.034 mmol) and DAD (0.034 mmol) were weighed into a polymerization tube, and 1 mL each of o-dichlorobenzene and n-butanol were added. The mixture was sonicated for 10 min to disperse the components evenly. 0.2 mL of 6M acetic acid aqueous solution was added, and the mixture was sonicated for 5 min. The tube was then subjected to three freeze-drying cycles to remove air from the system and sealed. After the system cooled to room temperature, it was placed in an oven at 120°C and allowed to react for 3 days. After the reaction was completed, the tube was removed and allowed to return to room temperature. THF was used for extraction until the solution became colorless. The solid obtained was then dried in a vacuum drying oven at 90°C to obtain Py-DAD COF.
[0034] Figure 7 The preparation process of Py-DAD COF is described.
[0035] Figure 8 The infrared spectrum of Py-DAD COF is shown; the characteristic peaks corresponding to Py and DAD have significantly disappeared or weakened, combined with the 1623 cm⁻¹ peak. -1 The presence of an imine bond indicates that the reaction proceeded relatively fully and that an imine bond was formed.
[0036] Figure 9 The solid-state NMR of Py-DAD COF was used to assign its characteristic peaks, with the peak around 158 ppm corresponding to imine carbon, confirming the formation of the Schiff base structure.
[0037] Figure 10 The PXRD and refinement data of Py-DAD COF are shown; the results show that Py-DAD COF and the refined structure are in good agreement.
[0038] Figure 11 The adsorption-desorption curves of Py-DAD COF are shown; the results indicate that its specific surface area is as high as 2010 m². 2 / g.
[0039] Figure 12 The data represent the absolute luminescent quantum yield of Py-DAD COF powder; the maximum emitted wavelength is ~600 nm; the solid-state absolute luminescent quantum yield at room temperature is 23.03%.
[0040] Example 3 Tetra-(4-aminophenyl)ethylene (PE, CAS: 1610471-69-6) (0.034 mmol) and DAD (0.034 mmol) were weighed into a polymerization tube. 1 mL each of o-dichlorobenzene and n-butanol were added, and the mixture was sonicated for 10 min to disperse it evenly. 0.2 mL of 6M acetic acid aqueous solution was added, and the mixture was sonicated for 5 min. The tube was then subjected to three freeze-drying cycles to remove air from the system and sealed. After the system cooled to room temperature, it was placed in an oven at 120°C and allowed to react for 3 days. After the reaction was completed, the tube was removed and allowed to return to room temperature. THF was used for extraction until the solution became colorless. The resulting solid was then dried in a vacuum drying oven at 90°C to obtain PE-DAD COF.
[0041] Figure 13 The preparation process of PE-DAD COF; Figure 14 The infrared spectrum of PE-DAD COF is shown; the characteristic peaks corresponding to PE and DAD have significantly disappeared or weakened, combined with the 1623 cm⁻¹ peak. -1 The presence of an imine bond indicates that the reaction proceeded relatively fully and that an imine bond was formed.
[0042] Figure 15 Solid-state NMR of PE-DAD COF; the solid-state NMR assigned its characteristic peaks, with approximately 158 ppm corresponding to imine carbon, confirming the formation of the Schiff base structure. Figure 16 The PXRD and refinement data of PE-DAD COF are shown; the results show that PE-DAD COF and the refined structure are in good agreement.
[0043] Figure 17 The adsorption-desorption curves of PE-DAD COF are shown; the results indicate that its specific surface area is as high as 1685 m². 2 / g.
[0044] Figure 18The data represent the absolute luminescent quantum yield of PE-DAD COF powder; the maximum emitted wavelength is ~600 nm; the solid-state absolute luminescent quantum yield at room temperature is 14.52%.
Claims
1. A method for preparing a solid-state luminescent Schiff base two-dimensional covalent organic framework material, comprising the following steps: mixing an amine with C2 symmetry, DAD, a solvent, and an aqueous acetic acid solution, and carrying out a solvothermal reaction to obtain the solid-state luminescent Schiff base two-dimensional covalent organic framework material; The solvent is o-dichlorobenzene and n-butanol; The DAD structure is as follows: .
2. The preparation method according to claim 1, characterized in that: The amine having C2 symmetry is tetra-(4-aminophenyl)pyrene, tetra-(4-aminophenyl)ethylene, or tetra-(4-aminophenyl)benzene.
3. The preparation method according to claim 1 or 2, characterized in that: The molar ratio of the amine with C2 symmetry to DAD is 1:2-2:1; preferably 1:
1.
4. The preparation method according to any one of claims 1-3, characterized in that: The volume ratio of o-dichlorobenzene to n-butanol is 1:3-3:1; preferably 1:
1. The total molar ratio of the amine with C2 symmetry and DAD to the solvent is 0.068 mmol: 1-3 mL; preferably 0.068 mmol: 2 mL.
5. The preparation method according to any one of claims 1-4, characterized in that: The concentration of the acetic acid aqueous solution is 3-9M; The volume of the acetic acid aqueous solution is 0.08-0.12 times the volume of the solvent.
6. The preparation method according to any one of claims 1-5, characterized in that: The solvothermal reaction is carried out in an inert atmosphere; The solvothermal reaction is carried out at a temperature of 90-120℃ for 2-4 days.
7. The preparation method according to any one of claims 1-6, characterized in that: After the solvothermal reaction is completed, there is a step of extracting with tetrahydrofuran until the solution is colorless, and then drying the resulting solid under vacuum.
8. A solid-state luminescent Schiff base two-dimensional covalent organic framework material prepared by the preparation method according to any one of claims 1-7.
9. The application of the solid-state luminescent Schiff base two-dimensional covalent organic framework material of claim 8 in bioimaging or in the fabrication of organic optoelectronic devices.
10. The application according to claim 9, characterized in that: In the bioimaging process, the solid-state luminescent Schiff base two-dimensional covalent organic framework material serves as an imaging agent. In the organic optoelectronic device, the solid-state luminescent Schiff base two-dimensional covalent organic framework material serves as the optoelectronic layer.