Near-infrared photothermal semiconductor material and preparation method thereof

Abstract

The invention relates to the technical field of near-infrared photothermal conversion materials, in particular to a near-infrared photothermal semiconductor material and a preparation method thereof. The chemical formula of the near-infrared photothermal semiconductor material is {[BaCd (ONDI) 2 (H2O) 3]. H2O} n, the near-infrared photothermal semiconductor material belongs to a triclinic system, and the space group is P-1. The ligand in the coordination polymer is tightly and bidirectionally arranged, so that the coordination polymer has a wide light absorption range from an ultraviolet region to a near-infrared region and shows an excellent near-infrared photothermal effect under 808 nm laser irradiation, and the efficiency is as high as 45%. The coordination polymer provided by the invention shows semiconductor characteristics, and promotes transmission of charges along two directions, including jump type and strip charge transmission.

Description

Technical Field

[0001] This invention relates to the field of near-infrared photothermal conversion materials technology, and in particular to a near-infrared photothermal semiconductor material and its preparation method. Background Technology

[0002] Near-infrared photothermal semiconductor materials are a class of semiconductor compounds with significant near-infrared photothermal effects. Their core advantage lies in their ability to efficiently capture near-infrared light and convert it into heat energy, while simultaneously possessing the electron transport characteristics of semiconductor materials. They have significant application value in fields such as solar-driven seawater desalination, photothermal catalysis, photoelectron detectors, and biophotothermal therapy. With the rapid development of these fields, increasingly higher demands are being placed on the performance of near-infrared photothermal semiconductor materials. Crystalline compounds that simultaneously possess excellent semiconductor properties and broad-spectrum near-infrared absorption capabilities have become the core research target due to their ability to achieve efficient photothermal conversion and stable performance output. However, the design and synthesis of such compounds still face significant challenges. On the one hand, traditional near-infrared photothermal materials struggle to balance semiconductor properties with broad-spectrum absorption performance: while some inorganic semiconductor materials possess good semiconductor properties, their near-infrared absorption spectrum is narrow, limiting photothermal conversion efficiency; and while some organic photothermal materials can achieve broad-spectrum absorption through molecular design, they generally suffer from weak semiconductor properties and low electron transport efficiency, failing to meet the requirements of applications such as photoelectron detection that demand specific electron transport characteristics. On the other hand, the construction of crystalline structures further exacerbates the design difficulty. Although the ordered structure of crystalline materials is beneficial to improving performance stability, it is often difficult to precisely control the molecular arrangement during crystal growth to simultaneously optimize semiconductor performance and spectral absorption range. This results in existing crystalline near-infrared photothermal materials generally having performance shortcomings that cannot fully meet the needs of practical applications.

[0003] In recent years, coordination polymers based on functional organic ligands have become a promising research direction due to their strong structural tunability and excellent synergistic performance. Coordination polymers form ordered crystalline structures through the coordination of metal ions with organic ligands. By selecting different metal centers and organic ligands, the electronic structure, optical properties, and crystal structure of the materials can be precisely controlled. Naphthalimide derivatives, as a class of electron-deficient organic compounds with large conjugated planes, possess excellent chemical stability, redox activity, and photophysical properties. The anionic radicals generated by their single-electron reduction can significantly redshift the absorption band to the near-infrared region, making them an ideal ligand choice for constructing near-infrared photoresponsive materials.

[0004] Although coordination polymers based on naphthalimide derivatives have shown potential advantages in the near-infrared light response field, there is limited design and optimization for their near-infrared photothermal conversion performance, and it is difficult to simultaneously achieve a synergistic improvement in semiconductor performance and broad-spectrum near-infrared absorption. While some materials possess certain near-infrared absorption capabilities, their semiconductor performance is weak and electron transport efficiency is low due to unreasonable molecular arrangement and poor modulation of ligand-metal center interactions. Furthermore, some materials have narrow near-infrared absorption spectral ranges, failing to fully utilize near-infrared light resources and limiting their photothermal conversion efficiency. Therefore, developing a coordination polymer-based near-infrared photothermal material based on naphthalimide derivatives that possesses both excellent semiconductor performance and broad-spectrum near-infrared absorption capabilities is of great significance for overcoming existing technological bottlenecks and promoting technological progress in related fields. Summary of the Invention

[0005] The purpose of this invention is to provide a near-infrared photothermal semiconductor material and its preparation method to solve the problems existing in the prior art.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: One of the technical solutions of this invention provides a near-infrared photothermal semiconductor material with the chemical formula {[BaCd(ONDI)2(H2O)3]·H2O} n , The near-infrared photothermal semiconductor material belongs to the triclinic crystal system and has a space group of [missing information]. P -1, the unit cell parameters are: a = 7.2041(7) Å, b = 8.8896(8) Å, c = 22.048(2) Å, α = 88.296(3)°, β = 89.149(3)°, γ = 71.730(2)°, V = 1340.2(2) Å 3 .

[0007] The second technical solution of the present invention provides a method for preparing the above-mentioned near-infrared photothermal semiconductor material, comprising the following steps: Barium salt, cadmium salt, water, and 2,7-dihydroxybenzo[ lmn [3,8]phenanthroline-1,3,6,8(2 H 7 H A suspension of α-tetraketones was mixed, and nitric acid solution was added to carry out the reaction, thereby obtaining a near-infrared photothermal semiconductor material.

[0008] In a preferred embodiment of the present invention, a mixture of barium salt and cadmium salt is first dissolved in water, and then 2,7-dihydroxybenzo[] is added. lmn [3,8]phenanthroline-1,3,6,8(2 H 7 H A suspension of α-tetraketones was mixed, and then nitric acid solution was added dropwise to carry out the reaction. After the reaction was completed, the mixture was cooled at a certain cooling rate to precipitate dark brown columnar crystals. After removing impurities, a near-infrared photothermal semiconductor material was obtained.

[0009] In a preferred embodiment of the present invention, the 2,7-dihydroxybenzo[ lmn [3,8]phenanthroline-1,3,6,8(2 H 7 H The CAS number for )-tetraketone (H2ONDI) is 34217-58-8.

[0010] In a preferred embodiment of the present invention, the barium salt includes barium nitrate; the cadmium salt includes cadmium chloride.

[0011] In a preferred embodiment of the present invention, the molar ratio of the barium salt to the cadmium salt is 1:1 to 1.25, for example, it can be 1:1, 1:1.1 or 1:1.25.

[0012] In a preferred embodiment of the present invention, the ratio of barium salt to water is 0.05 mmol : 2~3 mL, for example, 0.05 mmol : 2 mL, 0.05 mmol : 2.75 mL or 0.05 mmol : 3 mL, etc.

[0013] In a preferred embodiment of the present invention, the 2,7-dihydroxybenzo[ lmn [3,8]phenanthroline-1,3,6,8(2 H 7 H )-Tetraketone suspension composed of 2,7-dihydroxybenzo[ lmn [3,8]phenanthroline-1,3,6,8(2 H 7 H The 2,7-dihydroxybenzo[] was prepared by dispersing a tetraketone in N,N-dimethylformamide; lmn [3,8]phenanthroline-1,3,6,8(2 H 7 H The ratio of α-tetraketone to N,N-dimethylformamide is 0.1 mmol : 2~4 mL, for example, 0.1 mmol : 2 mL, 0.1 mmol : 3 mL or 0.1 mmol : 4 mL, etc.

[0014] In a preferred embodiment of the present invention, the molar ratio of the barium salt to 2,7-dihydroxybenzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetraone is 0.5:1 to 1.5, for example, it can be 0.5:1, 0.5:1.2, 0.5:1.4 or 0.5:1.5, etc.

[0015] In a preferred embodiment of the present invention, the concentration of the nitric acid solution is 0.5~2 mol / L, for example, it can be 0.5mol / L, 1mol / L, 1.5mol / L or 2mol / L, etc.; the ratio of the amount of barium salt to nitric acid solution is 0.05 mmol : 0.1~0.3 mL, for example, it can be 0.05 mmol : 0.1 mL, 0.05 mmol : 2 mL, 0.05 mmol : 0.25 mL or 0.05 mmol : 0.3 mL, etc.

[0016] In a preferred embodiment of the present invention, the reaction temperature is 110~130 ℃, for example, 110 ℃, 120 ℃ or 130 ℃, and the time is 48~96 h, for example, 48 h, 72 h or 96 h.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a coordination polymer {[BaCd(ONDI)2(H2O)3]H2O} based on a naphthalimide derivative. n The tight bidirectional arrangement of ligands in this coordination polymer gives it a wide light absorption range from the ultraviolet to the near-infrared region. Under irradiation with an 808 nm laser, it exhibits excellent near-infrared photothermal effect with an efficiency of up to 45%.

[0018] The coordination polymer provided by this invention exhibits semiconductor properties, which facilitates charge transport in two directions, including hopping and band charge transport.

[0019] The coordination polymer provided by this invention has important application value in fields such as solar-driven seawater desalination, photothermal catalysis, photoelectronic detectors, and biophotothermal therapy. Attached Figure Description

[0020] Figure 1 The single-crystal X-ray diffraction pattern of compound 1 is shown below. a A three-dimensional dense network of compound 1 observed from the axial perspective; Figure 2 The image shows the single-crystal X-ray diffraction pattern of compound 1, where (a) is the X-ray diffraction pattern of compound 1 along the... a The stacking structure and intermolecular interaction distance of the axial ligands, (b) is the distance along the axial ligands in compound 1. bThe packing structure of axial ligands and the intermolecular interaction distances; Figure 3 The solid-state UV-Vis-NIR absorption spectrum of compound 1; Figure 4 The figures show the test results of the near-infrared photothermal conversion performance of compound 1. (a) shows the surface temperature change curves of compound 1 under 808 nm laser irradiation at different power densities; (b) shows the surface temperature change curves of compound 1 at a fixed power density of 1.25 W / cm². 2 (c) is the photothermal cycling performance of compound 1 under continuous 808 nm laser irradiation; (d) is the surface temperature decay curve of compound 1 after the 808 nm laser source is removed; (e) is the t-lnθ data and fitting curve of compound 1. Figure 5 Figure 1 shows the semiconductor performance test results of compound 1, where (a) is the IV curve of compound 1 at different temperatures; and (b) is the temperature-dependent conductivity curve. Detailed Implementation

[0021] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0022] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0023] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0024] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0025] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0026] The room temperature described in this invention is 25±2℃.

[0027] All raw materials used in this invention can be obtained commercially or prepared using existing technologies.

[0028] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0029] Example 1 A mixture of Ba(NO3)2 (0.05 mmol) and CdCl2·2.5H2O (0.05 mmol) was dissolved in 2.75 mL of water and mixed with a suspension of H2ONDI (0.1 mmol) in 3 mL of DMF. The mixture was sealed in a polytetrafluoroethylene-lined reactor, and 0.25 mL of 1 mol / L nitric acid solution was added dropwise. The mixture was maintained at 110 °C for 72 hours, and then cooled to 30 °C at a rate of 10 K / h. Dark brown columnar crystals precipitated from the product. After removing impurities, approximately 42 mg of the product was finally obtained, with a yield of approximately 80%, and the product was designated as compound 1.

[0030] Comparative Example 1 The only difference from Example 1 is that no nitric acid solution is added.

[0031] Result: Compared with [Ba(ONDI)(H2O)2] n It forms with other impurities, but no compound 1 is formed.

[0032] Comparative Example 2 The only difference from Example 1 is that the nitric acid solution is replaced with a hydrochloric acid solution.

[0033] Results: The majority of the product was [Cd₂Cl₂(ONDI)] n Compound 1 contains almost no other impurities.

[0034] The reaction results of Example 1 and Comparative Examples 1-2 show that the addition of dilute nitric acid may inhibit Ba... 2+ with cd 2+ It reacts alone with an organic ligand, allowing both metal ions to react simultaneously with the organic ligand, thereby generating a bimetallic ion coordination polymer.

[0035] Crystal structure of test example 1: Single-crystal X-ray diffraction (SC-XRD) results showed that compound 1 belongs to...P The space group is -1, and each unit cell contains two molecular formula units. Each Ba 2+ The ions are in a decacoordinate environment, formed by four ONDIs. 2- The seven oxygen atoms of the ligand are coordinated with the three oxygen atoms from the coordinated water molecule. Each Cd 2+ Ions from four ONDI 2- The six oxygen atoms of the ligand are in six-coordinate configurations, exhibiting a rare octahedral coordination structure. Figure 1 It is worth noting that the ligand ONDI in compound 1 2- ligands and Ba 2+ and Cd 2+ It exhibits a variety of different coordination modes, thereby forming a three-dimensional dense network. Figure 2 Among them, organic ligands are along... a shaft and b It exhibits a continuous stacked structure along the axial direction.

[0036] Test Example 2: Optical Absorption Performance Under indoor lighting conditions, compound 1 appears dark brown. Figure 3 Solid-state UV-Vis-NIR absorption spectroscopy revealed that compound 1 exhibited two distinct absorption bands, covering almost the entire visible spectrum and extending into the infrared region. The absorption peak at 346 nm can be attributed to the π-π* transition of the organic ligand, while the broad absorption band at 578 nm can be attributed to NO. - Intramolecular charge transfer from functional groups to the NDI core. This is similar to previously reported ONDI. 2- Compared to the derived coordination polymer, compound 1 exhibits a redshift in its optical absorption spectrum, with its absorption edge terminating at 950 nm. Previous studies have shown that intermolecular π-π interactions in materials lead to a redshift and broadening of the optical absorption band. In this invention, compound 1 along... a shaft and b Both axial directions exhibit bidirectional π-π ligand stacking pillars, thus possessing effective intermolecular π-π interactions. Therefore, the light absorption broadening of compound 1 at 600 nm can be attributed to bidirectional continuous intermolecular π-π interactions. The absorption in the near-infrared region of compound 1 can be attributed to the formation of stack-assisted intermolecular charge-transfer states. The absorption peak of compound 1 in the visible light region shows a significant redshift, located at 578 nm, which may be due to Cd... 2+ The introduction of this increases the interaction distance between organic ligands, alters the excited-state electronic coupling between molecules, and thus causes a redshift in the absorption spectrum.

[0037] Test Example 3: Near-infrared photothermal conversion performance: Since the spectral changes of compound 1 caused by light exposure are very significant, its near-infrared (NIR) photothermal behavior after xenon lamp irradiation was investigated.

[0038] Compound 1, with a mass of 13.2 mg, was compressed using a tablet press at a pressure of 1800 Pa for 5 min. After compression, a disc with a diameter of 5 mm was obtained for subsequent testing.

[0039] After saturation irradiation with a xenon lamp, compound 1 exhibited significant near-infrared photothermal properties under 808 nm laser irradiation. When using a power density of 1.25 W / cm²... 2 When irradiated with an 808 nm laser, the surface temperature of compound 1 rapidly increased from room temperature (23 °C) to 72 °C. Figure 4 (a) As the power density increases from 0.125 W / cm² 2 Increased to 1.25 W / cm 2 Its stable surface temperature increased from 28 °C to 72 °C. Figure 4 (a) indicates that it has effective thermal control capabilities. Furthermore, the near-infrared photothermal effect of compound 1 remains stable over at least six irradiation cycles ( Figure 4 (b) indicates that it has excellent durability. Based on the temperature decay curve of the compound ( Figure 4 c) and t-lnθ curve ( Figure 4 (d), which is at 1.25 W / cm 2 The photothermal efficiency under 808 nm laser irradiation is 45%. Previous studies have shown that the presence of charge transfer processes promotes nonradiative transitions of molecular excited states. Therefore, the possible photothermal process of compound 1 can be described as follows: First, compound 1 absorbs incident light at a wavelength of 808 nm (1.53 eV), generating high-energy excited states. Subsequently, these excited states are converted into low-energy intramolecular and intermolecular charge transfer states (1.47 eV and 1.29 eV, respectively) through internal conversion or vibrational relaxation. Finally, these charge transfer states return to the ground state through nonradiative decay of vibrational relaxation, accompanied by heat release. Furthermore, for compound 1, the presence of abundant intermolecular π-π interactions due to the bidirectional π-π stacking pillars of the ligands facilitates photothermal conversion under 808 nm laser irradiation. Therefore, the near-infrared photothermal conversion of compound 1 can be attributed to the formation of ligand charge transfer states and the bidirectional π-π stacking structure.

[0040] Test Example 4 Semiconductor Performance Due to the rare bidirectional π-π packing structure in compound 1, a two-contact method was used to measure its conductivity under DC conditions using pressed crystalline powder samples (square pellets with a thickness of 0.38 mm and a side length of 5 mm). The conductivity was determined based on the IV curve (…). Figure 5 (a) The conductivity of compound 1 at room temperature (20 °C) in a nitrogen atmosphere was calculated to be 2.2 × 10⁻⁶.-9 S / cm. Furthermore, the conductivity of compound 1 gradually increased with increasing test temperature, reaching 1.1 × 10⁻⁶ at 70 °C. -8 The conductivity (S / cm) exhibits typical semiconductor characteristics. This was determined through temperature-dependent conductivity measurements. Figure 5 (b) Estimate the activation energy ( E a The conductivity is 0.26 eV. Since the contributions of grain boundary resistance and sample anisotropy are difficult to determine, the conductivity estimated from pressed crystalline samples is typically two orders of magnitude smaller than the intrinsic value of the material. The relatively low conductivity of compound 1 compared to previously reported naphthalimide-derived coordination polymers is likely due to its lower carrier concentration. Since intermolecular interactions favor electron delocalization and transport, and compound 1 exhibits continuous π-π interactions along two crystal axes, the semiconductor properties of the compound can be attributed to charge transport facilitated by the bidirectional stacking structure.

[0041] 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 near-infrared photothermal semiconductor material, characterized in that, The chemical formula is {[BaCd(ONDI)2(H2O)3]·H2O} n , The near-infrared photothermal semiconductor material belongs to the triclinic crystal system and has a space group of [missing information]. P -1, the unit cell parameters are: a = 7.2041(7)Å, b = 8.8896(8) Å, c = 22.048(2) Å, α = 88.296(3)°, β = 89.149(3)°, γ = 71.730(2)°, V = 1340.2(2) Å 3 .

2. A method for preparing the near-infrared photothermal semiconductor material according to claim 1, characterized in that, Includes the following steps: Barium salt, cadmium salt, water, and 2,7-dihydroxybenzo[ lmn [3,8]phenanthroline-1,3,6,8(2) H 7 H A suspension of α-tetraketones was mixed, and nitric acid solution was added to carry out the reaction, thereby obtaining a near-infrared photothermal semiconductor material.

3. The preparation method according to claim 2, characterized in that, The barium salt includes barium nitrate; the cadmium salt includes cadmium chloride.

4. The preparation method according to claim 2, characterized in that, The molar ratio of the barium salt to the cadmium salt is 1:1 to 1.

25.

5. The preparation method according to claim 2, characterized in that, The ratio of barium salt to water is 0.05 mmol: 2~3 mL.

6. The preparation method according to claim 2, characterized in that, The 2,7-dihydroxybenzo[ lmn [3,8]phenanthroline-1,3,6,8(2) H 7 H )-Tetraketone suspension composed of 2,7-dihydroxybenzo[ lmn [3,8]phenanthroline-1,3,6,8(2) H 7 H The 2,7-dihydroxybenzo[] was prepared by dispersing a tetraketone in N,N-dimethylformamide; lmn [3,8]phenanthroline-1,3,6,8(2) H 7 H The ratio of α-tetraketone to N,N-dimethylformamide is 0.1 mmol : 2~4 mL.

7. The preparation method according to claim 6, characterized in that, The barium salt and 2,7-dihydroxybenzo[ lmn [3,8]phenanthroline-1,3,6,8(2) H 7 H The molar ratio of )-tetraketone is 0.5 : 1~1.

5.

8. The preparation method according to claim 2, characterized in that, The concentration of the nitric acid solution is 0.5~2 mol / L; the ratio of the amount of barium salt to the amount of nitric acid solution is 0.05 mmol : 0.1~0.3 mL.

9. The preparation method according to claim 2, characterized in that, The reaction was carried out at a temperature of 110-130 °C for 48-96 h.

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