Metal-organic framework material with photo-thermal conversion performance and preparation method and use thereof

Abstract

The application discloses metal organic framework materials with photo-thermal conversion performance, a preparation method and application. 170 H 138 Co4N6O 18.5 , a molecular weight is 990.41, a cell parameter a=14.733(0)Å, b=19.3288(10)Å, c=25.8317(10)Å, alpha=95.6 degrees, beta=94.56 degrees, gamma=102.78 degrees. NBU-X4-2, a cell parameter a=14.7378(12)Å, b=15.4251(12)Å, c=16.6989(13)Å, alpha=110.163(2) degrees, beta=92.657(3) degrees, gamma=103.108(3) degrees.

Description

Technical Field

[0001] This invention belongs to the field of crystal functional materials technology, specifically relating to a class of metal-organic framework materials with excellent near-infrared photothermal conversion performance, their preparation methods, and applications for visual sensing and display based on the differences in photothermal performance of these materials. Background Technology

[0002] In recent years, metal-organic frameworks (MOFs) have attracted much attention due to their structural designability and functional diversity. MOFs exhibit stimulus-responsiveness, undergoing reversible structural transformations in response to external stimuli such as light and temperature, providing a foundation for dynamic functional regulation and promising broad application prospects in sensing, information storage, and other fields. Current research also faces a key challenge: how to combine the dynamic nature of MOF structures with photothermal effects to develop novel sensing applications. Currently, there is no mature solution that can utilize the stable and significant photothermal temperature difference induced by the reversible phase transition of MOFs to achieve visualized, repeatable, and memory-enabled sensing signal output. Therefore, developing a class of MOF materials with structural transformation capabilities and systematically studying their photothermal performance differences and underlying mechanisms is not only of significant fundamental scientific importance but also lays a crucial material foundation and application prototype for the innovative development of next-generation intelligent sensing and display technologies based on dynamic MOF photothermal effects. Summary of the Invention

[0003] This invention addresses the problems existing in the prior art by providing two metal-organic framework materials with photothermal conversion properties, their preparation methods, and applications.

[0004] This invention uses H2L1 as the core ligand, coordinating with L2 and cobalt ions, to successfully synthesize two triple-intercalated MOF materials: NBU-X4-1 and NBU-X4-2. Among them, 3,3'-(9,9-diethyl-9H-fluorene-2,7-diyl)benzoic acid (H2L1), as a typical fluorene ligand, becomes a high-quality building block for constructing metal-organic frameworks (MOFs) due to its rigid conjugated framework and good coordination compatibility. 1,4-bis(4-pyridyl)naphthalene (L2), due to the strong coordination ability of the nitrogen-containing heterocycle and the π-conjugated structure of the naphthalene ring, plays an important role in regulating the crystal stacking and functional properties of MOFs. The relatively flexible configuration of the naphthalene ring provides the potential for dynamic structural adjustment.

[0005] The first technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: A metal-organic framework material with photothermal conversion properties has been named NBU-X4-1. It belongs to the triclinic crystal system and has a space group of [missing information]. The molecular formula is C. 170 H 138Co4N6O 18.5 The molecular weight is 990.41, and the unit cell parameters are a = 14.733(0) Å, b = 19.3288(10) Å, c = 25.8317(10) Å, α = 95.6°, β = 94.56°, and γ = 102.78°. Figure 1 The crystal shows that its asymmetric unit cell comprises four symmetrically independent Co atoms. 2+ Four L1 ligands, two L2 ligands, two DMF molecules, and one H2O guest molecule with a occupancy of 0.5. Four crystallographically distinct Co molecules. 2+ Three types of binuclear "propeller"-shaped Co2 clusters are formed at the center: Co1-Co3, Co2-Co2, and Co4-Co4. The Co1-Co3 cluster has eight oxygen atoms coordinated in its equatorial plane from four different L1 ligands, and two pyridine nitrogen atoms coordinated in its axial direction from L2(I) and L2(II). The Co2-Co2 cluster is connected by eight oxygen donors from two L1(I) and two L1(II) ligands, and two pyridine nitrogen atoms coordinated in its axial direction from two L2(II) ligands. Similarly, the Co4-Co4 cluster has eight oxygen atoms coordinated in its equatorial plane from two L1(III) and two L1(IV) ligands, and two pyridine nitrogen atoms coordinated in its axial direction from two L1 ligands. Using the binuclear Co2 clusters as nodes, a three-dimensional framework is formed through bidirectional bridging of L1 and L2 ligands; this three-dimensional framework further interweaves through inter-framework interactions to form the triple interpenetrating structure of NBU-X4-1. Figure 3 ).

[0006] The second technical solution adopted by this invention to solve the above-mentioned technical problems is as follows: a metal-organic framework material with photothermal conversion properties, named NBU-X4-2, belongs to the triclinic crystal system and has a space group of The molecular formula is C 82 H 62 Co2N2O8, with a molecular weight of 1320, has the following unit cell parameters: a = 14.7378(12) Å, b = 15.4251(12) Å, c = 16.6989(13) Å, α = 110.163(2)°, β = 92.657(3)°, and γ = 103.108(3)°. Figure 2 The results show that the asymmetric unit cell of this crystal comprises two symmetrically independent Co units. 2+Two L1 ligands and one L2 ligand. There are two typical binuclear "propeller" type Co2 clusters. In each cluster, the equatorial plane is coordinated by eight oxygen atoms from two L1(I) and two L1(II) ligands, while the axial plane is coordinated by two pyridine nitrogen atoms from two L2(I) ligands. Using the binuclear Co2 cluster as nodes, a three-dimensional framework topology is ultimately formed through the bidirectional bridging effect of ligands L1 and L2. Figure 4 ).

[0007] The present invention also provides a method for preparing the metal-organic framework material, the method comprising the following steps: Method 1: Weigh ligands H2L1, L2 and Co(NO3)2·6H2O into a reaction flask, and add... NN Dimethylformamide, ethanol, and deionized water were ultrasonically treated for 15 min, heated in a 90℃ oven for 2 days, and then cooled at a rate of 5℃ / h at the end. The product was filtered, washed with ethanol, and dried at room temperature to obtain black-green blocky crystals, which were named NBU-X4-1.

[0008] The volume ratio of DMF, ethanol, and water is 3:2:2; The molar ratio of the ligands H2L1, L2 and Co(II) ions is 2:1:1; Option 2 method: Heat NBU-X4-1 crystals to 120℃, or soak NBU-X4-1 crystals in deionized water for three days, filter the product, and dry at room temperature to obtain black-green blocky crystals NBU-X4-2.

[0009] The ligand 3,3'-(9,9-diethyl-9H-fluorene-2,7-diyl)dibenzoic acid, abbreviated as H2L1, has the following structural formula (Ⅰ):

[0010] Equation (Ⅰ); The ligand 1,4-bis(4-pyridyl)naphthalene, abbreviated as L2, has the following structural formula (II):

[0011] Equation (II); The chemical formula of the cobalt nitrate is Co(NO3)2·6H2O; All substances or solvents participating in the reaction are chemically pure.

[0012] This invention also provides applications for the two crystalline materials, and systematically evaluates the photothermal conversion performance of NBU-X4-1 and NBU-X4-2 on glass (thickness ≈ 1 mm) and alumina (thickness = 0.25 mm) substrates. On glass substrates, NBU-X4-1 exhibits a photothermal conversion performance of 0.1~1.0 W / cm². -2 With a power density of 38.3~191℃ under near-infrared light irradiation at a wavelength of 808 nm, NBU-X4-2 achieves a temperature range of 0.1~1.6 W / cm². -2 Under near-infrared light irradiation at a power density of 808 nm, the temperature ranged from 42.4 to 294 °C, with the photothermal performance ranking as NBU-X4-2 > NBU-X4-1. On alumina substrates, the sample temperature was slightly lower than on glass substrates at the same power, but the photothermal performance ranking remained unchanged. NBU-X4-1 showed better performance in the range of 0.1–1.0 W / cm². -2 The temperature range is 27.5~120℃; NBU-X4-2 is available at 0.1~1.7 W / cm². -2 Temperatures reach 29.5~197℃. For memory-type photothermal sensing applications: utilizing the high thermal conductivity of the alumina substrate and 0.2 W / cm²... -2 A stable 5°C temperature difference between X4-2 and X4-1 under laser illumination (X4-1: 37.1 ± 0.3°C; X4-2: 42.3 ± 0.3°C), combined with thermochromic ink patterns with color-changing temperatures of 35°C (“NOR”) and 40°C (“!UN”), achieves selective color development. X4-1 only activates “NOR”, and the power is increased to 1.0 W cm⁻¹. -2 When X4-1 undergoes a single-crystal to single-crystal structural transformation to X4-2, the “!UNNOR” warning pattern is activated. This signal has memory properties and can retain warning information about abnormal optical power events.

[0013] Compared with the prior art, the present invention is characterized by: The ligand combination has specific conjugated delocalized π units. Under specific conditions, the ligands and metal ions form specific spatial interpenetration structures and conformations, which makes the obtained material have photothermal conversion performance with specific parameters.

[0014] This study reveals how the non-uniform torsion of ligands modulates the structural adaptability and photothermal properties of the dynamic coordination framework.

[0015] NBU-X4 exhibits structural adaptability mediated by ligand non-uniform torsion, enabling reversible single-crystal-to-single-crystal transformations between NBU-X4-1 and NBU-X4-2, thereby modulating its photothermal response properties. On an alumina substrate, NBU-X4-1 and NBU-X4-2 at 0.2 W / cm²... -2At a laser power density, more than 50 stable photothermal cycles can be achieved, and the temperature difference between the two remains consistent during the cycle, which has the potential to realize memory-type photothermal sensing applications.

[0016] The above findings establish the structure-activity relationship between ligand torsional adaptability and photothermal behavior, providing an important theoretical reference for designing stimulus-responsive crystal materials with tunable energy conversion properties. Attached Figure Description

[0017] Figure 1 This is the smallest asymmetric structural unit of the NBU-X4-1-MOF of the present invention; Figure 2 This is the smallest asymmetric structural unit of the NBU-X4-2-MOF of the present invention; Figure 3 This is the triple-intercalation structure of the NBU-X4-1-MOF of the present invention; Figure 4 This is the triple-intercalation structure of the NBU-X4-2-MOF of the present invention; Figure 5 Photothermal conversion curves of NBU-X4-1-MOF and NBU-X4-2-MOF of the present invention under different near-infrared laser intensities (glass substrate). Figure 6 For the present invention, NBU-X4-1 and NBU-X4-2 are used at 0.2 W / cm². -2 Schematic diagram of temperature difference under laser intensity (glass substrate); Figure 7 Photothermal conversion curves of NBU-X4-1-MOF and NBU-X4-2-MOF of the present invention under different near-infrared laser intensities (alumina substrate). Figure 8 The NBU-X4-1-MOF and NBU-X4-2-MOF of this invention are at 0.2 W / cm². -2 Photothermal cycling curves after 50 cycles at laser intensity (alumina substrate); Figure 9 This is an application diagram of the NBU-X4-1-MOF and NBU-X4-2-MOF of the present invention in temperature-changing inks on an alumina substrate; Figure 10 This is a schematic diagram showing the pattern changes of the NBU-X4-1-MOF and NBU-X4-2-MOF of the present invention on temperature-sensitive ink. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to the embodiments.

[0019] NBU-X4-1-MOF Example 1: Weigh out ligand H2L1 (9.65 mg, 0.02 mmol), 1,4-bis(4-pyridyl)naphthalene (2.82 mg, 0.01 mmol), and Co(NO3)2·6H2O (2.91 mg, 0.01 mmol) and place them in a 5 mL reaction flask. Add 1.28 mL of [unspecified ingredient]. NN Dimethylformamide, 0.86 mL ethanol, and 0.86 mL deionized water were ultrasonically treated for 15 min, heated in a 90°C oven for 2 days, and then cooled to room temperature at a rate of 5°C / h. After filtration, the mixture was washed with ethanol and dried to obtain blackish-green blocky crystals. This is the metal-organic framework material NBU-X4-1.

[0020] NBU-X4-2-MOF Example 2: Under normal pressure, NBU-X4-1 can be heated at 120°C for 12 hours, or NBU-X4-1 can be soaked in an aqueous solution for three days to obtain the solvent-free crystalline product NBU-X4-2.

[0021] X-ray diffraction analysis characterized NBU-X4-1 as a triclinic crystal system with space group [missing information]. The molecular formula is C. 170 H 138 Co4N6O 18.5 The molecular weight is 990.41, and the unit cell parameters are a = 14.733 Å, b = 19.3288(1) Å, c = 25.8317(1) Å, α = 95.6°, β = 94.56°, γ = 102.78°. Figure 1 In this crystal, the asymmetric unit cell comprises four symmetrically independent Co² units. + (Co1²) + Co2² + Co3² + and Co4² + The DMF consists of four L1 ligands (L1(I), L1(II), L1(III), and L1(IV)), two L2 ligands (L2(I) and L2(II)), two DMF molecules, and one half-occupied H2O molecule. The pyridines at the two terminal groups of the L2 ligands interact with Co. 2+ Coordination, and simultaneously the O atom on L1 with Co 2+ It is a bidental coordination mode. The coordination structural units are bridged by ligands L1 and L2, forming a three-dimensional network structure with triple interpenetration. Figure 3 ).

[0022] NBU-X4-2 was characterized by X-ray diffraction and was found to belong to the triclinic crystal system with space group [missing information]. The molecular formula is C 82 H 62Co2N2O8 has a molecular weight of 1320 and unit cell parameters a = 14.7378(12) Å, b = 15.4251(12) Å, c = 16.6989(13) Å, α = 110.163(2)°, β = 92.657(3)°, and γ = 103.108(3)°. Figure 2 In this crystal, the asymmetric unit cell comprises two symmetrically independent Co atoms. 2+ (Co1) 2+ and Co2 2+ It contains two L1 ligands (L1(I) and L1(II)) and one L2 ligand (L2(I)). The pyridines on the two terminal groups of the L2 ligand react with Co. 2+ Coordination, and simultaneously the O atom on L1 with Co 2+ It is a bidental coordination mode. The coordination structural units are bridged by ligands L1 and L2, forming a three-dimensional network structure with triple interpenetration. Figure 4 ).

[0023] To better study the photothermal properties of the two metal-organic framework materials, the photothermal conversion performance of NBU-X4-1 and NBU-X4-2 on glass (thickness ≈ 1 mm) and alumina (thickness = 0.25 mm) substrates was evaluated using an infrared thermal imaging camera (FLIR C5) system. Infrared images and real-time temperatures were extracted from the video using FLIR software. Figure 5 The results show that, on a glass substrate, the NBU-X4-1 sample, under 808 nm laser irradiation, exhibits performance at power densities ranging from 0.1 to 1.0 W / cm². -2 Within 10 seconds, the surface temperatures reached 38.3, 58.9, 77.3, 96.9, 114, 129, 145, 164, 175, and 191 °C, respectively. After NBU-X4-1 underwent a single-crystal to single-crystal (SCSC) transformation into NBU-X4-2, under 808 nm laser conditions and power densities of 0.1–1.6 W / cm², the surface temperatures reached [the desired values]. -2 Under these conditions, the surface temperatures reached 42.4, 64.5, 86.1, 106, 123, 142, 157, 173, 186, 200, 216, 229, 244, 260, and 294°C within 10 seconds, respectively. Furthermore, a certain temperature difference exists between NBU-X4-1 and NBU-X4-2 under low power conditions. Figure 6 ), at power densities of 0.1, 0.2, and 0.3 Wcm -2 At that time, the temperature increased by 4.1, 5.6 and 8.8 °C respectively.

[0024] On the alumina substrate, the surface temperature of NBU-X4-1 and NBU-X4-2 samples was consistently lower than that on the glass substrate. Figure 7 The results show that under 808 nm laser irradiation, when the power density is between 0.1 and 1.0 W / cm², -2 During the test, the surface temperature of the NBU-X4-1 sample gradually increased, reaching 27.5, 37.2, 49.8, 60.6, 71.2, 81.4, 92.3, 102, 111, and 120℃ respectively. When the same experiment was conducted with the same series of NBU-X4-2 samples, the power density increased from 0.1 W / cm² within 10 seconds. -2 Increased to 1.7 Wcm -2 During the process, the sample surface temperature further increased, reaching 29.5, 42.7, 54.8, 67.6, 78.1, 89.8, 101, 112, 122, 132, 142, 151, 162, 170, 181, 190, and 197℃ respectively. On the alumina substrate, both samples were at 0.2 W / cm². -2 The photothermal temperature remained stable even after 50 cycles at low power. Figure 8 ).

[0025] NBU-X4, a photothermal metal-organic framework material with single-crystal-to-single-crystal transition properties, has shown potential for practical applications in the field of photothermal sensing. Based on the stable 5°C temperature difference between NBU-X4-1 and NBU-X4-2 at the same power density, such as... Figure 9 As shown, handwritten patterns were created on an alumina substrate using two thermochromic inks with different color-changing temperatures. The substrate was then placed on an NBU-X4 sample surface. The pattern "NOR" changed from light to dark blue at temperatures above 35°C, while the pattern "!UN" changed from light to dark green at temperatures above 40°C. Utilizing the photothermal temperature difference before and after the NBU-X4 crystal transformation, selective color development was achieved: only "NOR" was displayed at temperatures between 35 and 40°C; and "!UNNOR" was displayed at temperatures above 40°C. This was achieved using an 808 nm laser with a power density of 0.2 W / cm². -2 Under these conditions, the surface temperature of the sample with the initial crystal form NBU-X4-1 was 37.1±0.3℃, which falls within the 35~40℃ range, thus selectively activating only the "NOR" pattern. When the laser power density was increased to 1.0 Wcm²... -2 At the above point, NBU-X4 undergoes a single-crystal-to-single-crystal transformation, changing its crystal form to NBU-X4-2, accompanied by the appearance of the "!UNNOR" warning pattern. Figure 10 Even after the laser is turned off and then irradiated again, the warning signal remains because at a power density of 0.2 Wcm², the warning signal persists. -2 Under irradiation with an 808nm laser, the surface temperature of NBU-X4-2 can be stably maintained at 42.3±0.3℃.

[0026] The above results demonstrate that the memory-type photothermal sensing system based on the dynamic metal-organic framework material NBU-X4 can realize the application between ligand torsional adaptation and photothermal behavior, and can retain warning information related to abnormal optical power events.

Claims

1. A metal-organic framework material with photothermal conversion properties, characterized in that, The metal-organic framework material is named NBU-X4-1, belongs to the triclinic crystal system, and has a space group of [missing information]. The molecular formula is C 170 H 138 Co4N6O 18.5 The molecular weight is 990.41, and the unit cell parameters are a = 14.733 Å, b = 19.3288(1) Å, c = 25.8317(1) Å, α = 95.6°, β = 94.56°, γ = 102.78°. The asymmetric unit cell of this metal-organic framework material includes four symmetric independent Co² units. + Four L1 ligands, two L2 ligands, two DMF molecules, and one half-occupied H2O molecule; four crystallographically distinct Co² molecules. + Three types of binuclear "propeller" type Co2 clusters are formed at the center: Co1-Co3 cluster, Co2-Co2 cluster, and Co4-Co4 cluster. Among them, the equatorial plane of the Co1-Co3 cluster is coordinated by eight oxygen atoms from four different L1 ligands, and the axial plane is coordinated by two pyridine nitrogen atoms from L2(I) and L2(II). The Co2-Co2 cluster is connected by eight oxygen donors from two L1(I) and two L1(II) ligands, and the axial plane is coordinated by two pyridine nitrogen atoms from two L2(II) ligands. The equatorial plane of the Co4-Co4 cluster is coordinated by eight oxygen atoms from two L1(III) and two L1(IV) ligands, and the axial plane is coordinated by two pyridine nitrogen atoms from two L2 ligands. With the binuclear Co2 cluster as nodes, a three-dimensional framework is formed through the bidirectional bridging effect of L1 and L2 ligands. This three-dimensional framework is further interwoven through inter-framework interactions to form the triple interpenetrating structure of NBU-X4-1.

2. A metal-organic framework material with photothermal conversion properties, characterized in that, The metal-organic framework material is named NBU-X4-2, belongs to the triclinic crystal system, and has a space group of [missing information]. The molecular formula is C 82 H 62 Co2N2O8, with a molecular weight of 1320, has unit cell parameters a = 14.7378(12) Å, b = 15.4251(12) Å, c = 16.6989(13) Å, α = 110.163(2)°, β = 92.657(3)°, and γ = 103.108(3)°. The asymmetric unit cell of this metal-organic framework material's crystal includes two symmetrically independent Co... 2+ Two L1 ligands and one L2 ligand; there are two typical binuclear "propeller" type Co2 clusters. The equatorial plane of each cluster is coordinated by eight oxygen atoms from two L1(I) and two L1(II) ligands, while the axial plane is coordinated by two pyridine nitrogen atoms from two L2(I) ligands. With the binuclear Co2 cluster as the node, a three-dimensional skeleton topology is finally formed through the bidirectional bridging effect of ligands L1 and L2.

3. The method for preparing a metal-organic framework material with photothermal conversion properties according to claim 1, characterized in that, The preparation method includes the following steps: Weigh 19.65 mg and 0.02 mmol of ligand H2L, 2.82 mg and 0.01 mmol of 1,4-bis(4-pyridyl)naphthalene L2, and 2.91 mg and 0.01 mmol of Co(NO3)2·6H2O into a 5 mL reaction flask, and add 1.28 mL of [the solution / concentrate]. NN Dimethylformamide, 0.86 mL ethanol, and 0.86 mL deionized water were ultrasonically treated for 15 min, heated in a 90°C oven for 2 days, and then cooled to room temperature at a rate of 5°C / h. The mixture was filtered, washed with ethanol, and dried to obtain black-green blocky crystals, which is the metal-organic framework material NBU-X4-1. The molar ratio of the ligands H2L1, L2 and Co(II) ions is 2:1:

1.

4. The method for preparing a metal-organic framework material with photothermal conversion properties according to claim 2, characterized in that, The preparation method includes the following steps: Under normal pressure, NBU-X4-1 can be heated at 120°C for 12 hours, or NBU-X4-1 can be soaked in an aqueous solution for three days to obtain the solvent-free crystalline product NBU-X4-2.

5. The use of the metal-organic framework material according to claim 1 or 2, characterized in that, The NBU-X4-1 or NBU-X4-2 has applications in constructing memory-type photothermal sensing systems.

Images